Lecom - Neuroanatomy 05: Brain And Environs: Cranium, Ventricles, And Meninges

Front 1

SCALP

Back 1

Skin - Connective Tissue - Aponeurotica - Loose Areolar CT - Pericranium (periosteum)

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Anterior Fossa

Back 2

Contains Frontal Lobe, divided from the middle fossa by the lesser wing of sphenoid bone

Front 3

Middle Fossa

Back 3

Contains Temporal lobe, divided from the posterior fossa by the petrous ridge of the temporal bone as well as by a sheet of meninges - Tentorium Cerebelli

Front 4

Posterior Fossa

Back 4

Contains the cerebellum and brainstem

Front 5

Falx Cerebri

Back 5

Flat sheet of Dura that is suspended from the roof of the cranium and separates the right and left cerebral hemispheres, running in the interhemispheric fissure

Front 6

Tentorium Cerebelli

Back 6

Tent like sheet of Dura that covers the upper surface of the cerebellum

Front 7

Supratentorial

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Above the Tentorium Cerebelli

Front 8

Infratentorial

Back 8

Below the Tentorium Cerebelli

Front 9

Tentorial Notch

Back 9

Also known as Tentorial Incisure, narrow opening in the tentorium cerebelli which the midbrain passes through. At the level of CNIII and the Interpeduncular fossa.

Front 10

Virchow-Robin Space

Back 10

where pia surrounds initial portion of each blood vessel as it penetrates the brain surface forming a perivascular space and then fuses with the blood vessel wall

Front 11

Epidural Space

Back 11

between dura and skull; contains the middle meningeal artery

Front 12

Middle Meningeal Artery

Back 12

Enters skull through the foramen spinosum and runs in the epidural space between the Dura and the skull

Front 13

Subdural Space

Back 13

Potential space between the inner layer of Dura and the loosely adherent arachnoid

Front 14

Bridging Veins

Back 14

Traverse the subdural space and drain the cerebral hemispheres and pass through the subdural space en route to several large Dural venous sinuses

Front 15

Dural Sinuses

Back 15

Large venous channels that lie enclosed within the two layers of Dura, Dural sinuses drain blood mainly via the sigmoid sinuses to reach the internal jugular vein.

Front 16

Subarachnoid Space

Back 16

CSF filled space between arachnoid and pia, also major arteries of the brain travel within the subarachnoid space and then send smaller penetrating branches inward through the pia

Front 17

Epidural Fat

Back 17

In spinal canal only layer between the Dura and the periosteum

Front 18

Ependymal cells

Back 18

line the ventricles

Front 19

Choroid Epithelial Cells

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Blood vessels of the choroid plexus are lined with ependymal like cuboidal cells called Choroid Epithelial Cells

Front 20

Lateral ventricles

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one in each cerebral hemisphere
Anterior (frontal) horn: anterior to foramen of Monro and extends to frontal hemisphere
Body: Posterior to foramen of Monro; within frontal and parietal lobe
Atrium (trigone): area of convergence of the occipital horn, and the body of the lateral ventricle
Occipital (posterior) horn: Extends from the atrium posteriorly into the occipital lobe
Temporal (inferior) horn: Extends from the atrium inferiorly into the temportal lboe

Front 21

Third ventricle

Back 21

within the thalamus and hypothalamus

Front 22

Fourth ventricle

Back 22

within the pons, medulla, and cerebellum

Front 23

General Flow of CSF

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Lateral Ventricles ---(foramen of monro)--> Third Ventricle ---(cerebral aqueduct/aqueduct of Sylvius)---> fourth ventricle ----(foramina of Lushka and foramen of Magendie) --> outsideeee world

Front 24

Normal total CSF volume adults

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150cc

Front 25

Rate of CSF production

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20cc/hour (500cc/day)

Front 26

Cisterns

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Areas where subarachnoid space widens in a few areas to form larger CSF collections called Cisterns

Front 27

Ambient Cistern

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located lateral to the midbrain

Front 28

Quadrigeminal Cistern

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posterior to the midbrain, beneath the posterior portion of the corpus callosum (quad bc four bumps of superior and inferior colliculi)

Front 29

Interpenduncular Cistern (Interpeducular fossa)

Back 29

located on the ventral surface of the midbrain between the cerebral peduncles

Front 30

Prepontine Cistern

Back 30

located just ventral to the pons, contains the basilar artery and the 6th nerves as they ascend from the pontomedullary junction along the cilvus

Front 31

Cisterna Magna (cerebellomedullary cistern)

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largest cistern; located beneath the cerebellum near the foramen magnum

Front 32

Lumbar Cistern

Back 32

located in the lumbar portions of the spinal column, contains the cauda equina and is the region from which CSF is obtained during a lumbar puncture or spinal tap

Front 33

What substances permeate readily across the cell-membrane of the blood-brain and blood-CSF barriers

Back 33

O2 and CO2

Front 34

Arachnoid Villus Cells

Back 34

Carries out one-way bulk flow of CSF from subarachnoid space to venous sinuses via giant vacuoles

Front 35

Circumventricular Organs

Back 35

Blood-brain barrier is interrupted allowing the brain to respond to changes in the chemical milieu of the remainder of the body 1. Organum Vasculosum 2. Median Eminence 3. Neurohypophysis 4. Area Postrema - also known as the chemotactic trigger zone, involved in detecting circulating toxins that cause vomiting 5. Subcommissural Organ 6. Pineal 7.Subfornical Organ

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Area postrema

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the only paired circumventricular organ; located on the caudal wall of 4th ventricle in the medulla
Also known as chemotactic trigger zone --> detects circulating toxins that cause vomiting

Front 37

Cytotoxic Edema

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Cellular damage that can cause excessive intracellular fluid accumulation within the brain cells

Front 38

Vasogenic Edema

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Disruption of the blood-brain barrier resulting in the extravasation of fluids into the interstitial space

Front 39

Headache mechanism

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Caused by mechanical traction, inflammation, or irritation of the structures in the head that are innervted (blood vessels, meninges, scalp, skull)

Front 40

Innervation supratentorial dura

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Trigeminal (CN V)

Front 41

Innervation dura of posterior fossa

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CN X (to a lesser extent CN IX and first 3 cervical nerves)

Front 42

Vascular Headache

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not fully understood, but thought to involve inflammatory, autonomic, serotonergic, neuroendocrine and other associated symptoms (migraine or cluster headache)

Front 43

Migraine

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75% of patients have a positive family history, suggesting a genetic basis, symptoms may be provoked by certain foods, stress, eye strain, menstrual cycle, changes in sleep pattern. Usually unilateral; presence of aura

Front 44

Symptoms of Migraine

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Often preceded by an aura or warning symptoms, classically involving visual blurring, shimmering, scintillating distortions or fortification scotoma, pain is often throbbing and may be exacerbated by light (photophobia) sound (phonophobia) or sudden head movement. Nausea and vomiting may occur. 30 minutes - 24 hours

Front 45

Fortification Scotoma

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Characteristic region of visual loss bordered by zigzagging lines resembling the walls of a fort

Front 46

Complicated Migraine

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May be accompanied by a variety of transient focal neurologic deficits including sensory phenomena motor deficits visual loss brainstem findings in basilar migraine and impaired eye movements in ophthalmoplegic migraine

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Treatment of Migraines

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Acute attacks usually respond well to nonsteroidal anti-inflammatory drugs, anti-emetics, triptans (seretonin agonists, or resting in a quiet dark room)

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Migraine Prevention

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prophylaxis with beta-blockers, topriamate, valproate, calcium channel blockers, tricyclic antidepressants, NSAIDS

Front 49

Cluster Headache

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Less than 1/10th as common as migraine. 5x more common in males than in females. Lasts 30-90 minutes usually felt behind eyes. Usually accompanied by unilateral autonomic symptoms

Front 50

Tension Headache

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(aka tension-type headache) steady dull ache sometimes described as a bandlike sensation

Front 51

Tx Tension Headache

Back 51

muscle relaxation techniques, NSAIDS, other analgesics, tricyclic antidepressants

Front 52

Sudden "explosive" onset of severe headache differential dx

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subarachnoid hemorrhage

Front 53

Headache accompanied by fever, stiff neck, sensitivity to light

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possible infectous meningitis

Front 54

Idiopathic Intracranial Hypertension

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(aka Pseudotumor cerebri) condition of unknown cause characterized by headache and elevated intracranial pressure with no mass lesion. More common in adolescent females, treated with ACETAZOLAMIDE (or with shunting procedures)

Front 55

Temporal Arteritis (Giant Cell Arteritis)

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Important treatable cause of headaches, this disorder seen most commonly in elderly individuals, vasculitis affects the temporal arteries and other vessels, including those supplying the eye. Temporal artery is characteristically enlarged and firm.

Front 56

Diagnosis of Temporal Arteritis

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Diagnosis by erythrocyte sedimentation rate (ESR) and temporal artery biopsy

Front 57

Effects of Intracranial Mass Lesion

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1. Compression and destruction of adjacent regions of the brain causing neurological abnormalities
2. Mass located within cranial vault can raise the intracranial pressure causing certain characteristic symptoms and signs
3. Mass lesions can displace nervous system structures so severely that they are shifted from one compartment into another situation called herniation

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Mass Effect

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Distortion of normal brain geometry due to a mass lesion - can be as subtle as a mild flattening or effacement of sulci next to a lesion.

Front 59

Midline Shift

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results from mass effect caused by large masses which dramatically shift brain structures away from the side of the lesion, can compression ventricular system and obstruct CSF flow producing hydrocephalus.

Front 60

Landmark the measures midline shift

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pineal calcification

Front 61

Elevated Intracranial Pressure

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Severely elevated intracranial pressure can cause decreased cerebral blood flow and brain ischemia, cerebral blood flow depends on cerebral perfusion pressure.

Front 62

Cerebral Perfusion Pressure

Back 62

Mean arterial pressure minus the infusion pressure (CPP = MAP - ICP)
As intracranial pressure increases, cerebral perfusion pressure decreases. Autoregulation of cerebral vessel caliber can compensate for modest reductions in cerebral perfusion pressure leading to relatively stable cerebral blood flow however large increases in intracranial pressure can exceed the capacity of autoregulation leading to reduced cerebral blood flow and brain ischemia

Front 63

Symptoms of Elevated Intracranial Pressure

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-Headache (often worse in morning due to brain edema increasing overnight from effects of gravity)
-Altered mental status (especially irritability and depressed level of alertness and attention)
-Nausea and vomiting (typically suddenly and without much nausea known as projectile vomiting)
-Papilledema (elevation of optic disc)
-Visual Loss
-Diplopia
-Cushing's Triad (Hypertension, Bradycardia, Irregular respirations)

Front 64

Cushing's Triad

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Hypertension, Bradycardia, and irregular respirations

Front 65

Normal Intracranial Pressure

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In adults is less than 20 cm H2O or less than 15 mm Hg (torr)

Front 66

Contraindication of Lumbar Puncture

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Severely increased intracranial pressure (can precipitate herniation)

Front 67

Tx Intracranial Pressure: Elevation of head of bed to 30 degrees,maintaining head straight

Back 67

Immediate effect; promotes venous drainage

Front 68

Tx Intracranial Pressure: Hemicraniectomy

Back 68

Immediate effect; decompresses intracranial cavity (experimental)

Front 69

Tx Intracranial Pressure: intubation and hyperventilation to PCO2 of 25-30mmHg

Back 69

Onset = 30 seconds; causes cerebral vasoconstriction

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Tx Intracranial Pressure: IV mannitol and furosemide

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Onset = 5 minutes; promotes removal edema and other fluids from CNS while maintaining cerebral perfusion

Front 71

Tx Intracranial Pressure: Ventricular drainage

Back 71

Onset = minutes; removal of CSF decreases intracranial pressure

Front 72

Tx Intracranial Pressure: barbiturate-induced coma

Back 72

Only if all other measures fail; onset = 1 hour; causes cerebral vasoconstriction and reduced metabolic demands

Front 73

Tx: Intracranial Pressure: Steroids

Back 73

Onset = hours; reduces cerebral edema, possibly by strengthening blood-brain barrier; may also work by other mechanisms

Front 74

Herniation

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Occurs when mass effect is severe enough to push intracranial structures from one compartment into another.

Front 75

3 Most Clinically important Herniation Syndromes?

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1. Herniation through tentorial notch (transtentorial herniation)
2. Herniation centrally and downward (central herniation)
3. Herniation under the falx cerebri (Subfalcine herniation)

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Transtentorial Herniation

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Herniation of medial temporal lobe, especially the uncus (uncal herniation) inferiorly through the tentorial notch.

Front 77

Clinical Triad Uncal Herniation

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Heralded by clinical triad of "blown" pupil, hemiplegia, and coma.
Compression of Oculomotor (CN III) ipsilateral (85% of time) to the lesion produces first a dilated unresponsive pupil (blown pupil)

Front 78

Compression of the cerebral peduncles can cause

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hemiplagia (often contralateral to lesion)

Front 79

Kernohan's Phenomenon

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Sometimes in uncal herniation the midbrain is pushed all the way over until it is compressed by the opposite side of the tentorial notch, in these cases the contralateral corticospinal tract is compressed producing hemiplegia that is ipsilateral to the lesion.

Front 80

Distortion of the midbrain reticular formation leads to...

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decreased level of consciousness and ultimately, coma

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Central herniation

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central downard displacement of the brainstem

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Causes central herniation

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any lesion associated with elevated intracranial pressure

Front 83

Mild central herniation

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Traction of the abducens nerve --> lateral rectus palsy

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Tonsillar herniation

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herniation of the cerebellar tonsils downward through the foramen magnum --> associated with compression of the medulla and usually leads to respiratory arrest, blood pressure instability, and death

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Subfalcine herniation

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Herniation under the falx cerebri from one side of the cranium to another; can lead to infarcts of the anterior cerebral artery

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Concussion

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reversible impairment of neurologic function for a period of minutes to hours following a head injury; mechanism unknown

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Clinical features concussion

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loss of consciousness, headache, dizziness, nausea, vomiting; anterograde or retrograde amnesia

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postconcussive syndrome

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headaches, lethary, mental dullness lasting severeal months after accident

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Diffuse axonal shear injury

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causes widespread or patchy damage to the white matter and cranial nerves

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Petechial hemorrhages

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small spots of blood in the white matter

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Types of intracranial hemorage

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1. Epidural Hematoma (EDH)
2. Subdural Hematoma (SDH)
3. Subarachnoid hemorrhage (SAH)
4. Intracerebral or intraparenchymal hemorrage (ICH)

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Location EDH

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in the tight potential space between the dura and the skill

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Causes EDH

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Rupture of the middle meningeal artery due to fracture of the temporal bone by head trauma

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Clinical features and radiological appearance EDH

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Rapidly expanding hemorrhage under arterial pressure peels dura away from the inner surface of the skull; LENS shaped
Sx: initially, none; elevated intracranial pressure and ultimately, herniation

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Location SDH

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In the potential space between the dura and arachnoid

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Usual causes of SDH

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Rupture of the bridging veins

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Radiological appearance SDH

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crescent-shaped hematoma

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Chronic SDH

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often seen in elderly patients; blood collects over long period of time; headache, cognitive impairment, unsteady gait, focal seizures

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Acute SDH

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high impact velocity; areas in imaging are hyperdense and bright (acute blood) --> clot in 1-2 weeks (isodense); 3-4 weeks (hypodense)
continuous bleeding = mixed density

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hematocrit effect

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With mixed-density hematomas, the denser acute blood settles to the bottom

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Location SAH

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In the CSF-filled space between the arachnoid and the pia, which contains the major blood vessels of the brain

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Radiological appearance SAH

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Blood can be seen on CT to track down into the sulci following the contours of the pia (blood EVERYWHERE)

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Nontraumatic (Spontaneous) SAH

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presents as "the worst headache of my life"
causes: arterial aneurysm (or less commonly an AV malformation)

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Risk factors intracranial aneurysm

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atherosclerotic disease, congenital anomalies in cerebral blood vessels, polycystic kidney disease, connective tissue disorders (Marfan's)

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Berry aneurysms

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usually arise from Circle of Willis; typically have a neck and dome that can rupture
over 85% occur in the anterior circulation (carotid artery and its branches)

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Most common locations: Berry aneurysms

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AComm (30%), PComm (25%), MCA (20%), vertebrobasilar system (15%)

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Are fusiform or saccular aneurysms less prone to rupture?

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fusiform

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Consequences of PComm aneurysm

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Third nerve palsy

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Risk factors aneurysm rupture

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hypertension, smoking, alcohol, situations with elevation of BP

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Type of scan to run for suspected hemorrhaging

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CT scan WITHOUT contrast; both subarachnoid blood and contrast material appear white on the scan

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Triple H Therapy

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treatment of vasospasm following hemorrhage--> Induced Hypertension, hypervolemia, and hemodilution

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Traumatic Subarachnoid Hemorrhage

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caused by bleeding into the CSF from damaged blood vessels associated with cerebral contusions and other traumatic injuries; more common than spontaneous; severe headache

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Location ICH

Back 113

Within the brain parenchyma in the cerebral hemisphere, brainstem, cerebellum or spinal cord

Front 114

Traumatic ICH

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Contusions which are common at the temportal and frontal poles
Contusions occur on the side of the impact (coup injury) as well as on the side opposite the impact (contrecoup injury) because of rebound of the brain against the skull

Front 115

Nontraumatic ICH Causes

Back 115

hypertension, brain tumors, secondary hemorrhage after ischemic infarction, vascular malformations, blood coag abnormalities, infections, vessel fragility caused by deposition of amyloid protein in the blood vessel wall (amyloid angiopathy), vasculitis, mycotic (infectious) aneurysms in the setting of endocarditis

Front 116

Hypertensive hemorrhage

Back 116

most common cause of nontraumatic ICH
often involves small, penetrating blood vessels
uncertain pathogenesis, but may be related to chronic pathologic effects of hypertension on the small vessels (lenticulostriate arteries, including lipohyalinosis and microaneurysms of Charcot-Bouchard)

Front 117

Most common locations of hypertensive hemorrage

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Basal ganglia (usually the putamen)
thalamus
cerebellum
pons

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Intraventricular extension

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aka intraventricular hemorrhage; hemorrhages that involve the ventricles

Front 119

Lobar hemorrhage

Back 119

bleeding involves the occipital, parietal, temporal, or frontal lobe

Front 120

Common cause of lobar hemorrhage

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amyloid (congopilic) angiopathy

Front 121

Vascular Malformations

Back 121

1. AV malformations
2. Cavernomas
3. Capillary telangiectasias (capillary angiomas)
4. Developmental venous anomalies (venous angiomas, venous malformations)

Front 122

Ateriovenous malformations (AVMs)

Back 122

congential abnormalities in which there are abnormal direct connections between arteries and veins, often forming a tangle of abnormal blood vessels visible as flow voids on MRI scan, but best seen on conventional angiography

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Tx AVM

Back 123

neurosurgical removal, intravascular embolization, sterotactic radiosurgery

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Cavernomas

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abnormally dilated vascular cavities lines by only one layer of vascular endothelium
not visible on conventional angiography
Have a characteristic MRI appearance (central 1-2cm core of increased signal on T1 or T2, surrounded by a dark rim on T2-weighted sequences because of hemosiderin)

Front 125

Capillary telangiectasia

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small regions of abnormally dilated capillaries; rarely give rise to intracranial hemorrhage

Front 126

Developmental venous anomalies

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dilated veins usually visible on MRI scans as a single flow void extending to the brain surface

Front 127

Hemotympanum

Back 127

hemorrage in the inner ear

Front 128

Hemorrage in subcutaneous tissue

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results in Battle's sign or "racoon eyes"

Front 129

Subgaleal hemorrhage

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hemorrage in the loose space between the external periosteum and galea aponeurotica; can produce a "goose egg"

Front 130

cephalohematoma

Back 130

bleeding during delvery of newborns that occurs between the skull and external periosteum (pericranium)

Front 131

Causes of hydrocephalus(3)

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1) excess CSF production 2) Obstriction in ventricles or subarachnoid space 3) decrease in reabsorption via arachnoid granulations

Front 132

Excess CSF Production

Back 132

rare, seen in choroid plexus papilloma

Front 133

Obstruction of CSF flow

Back 133

common cause, especially at narrow points-foramen of monro, cerebral aqueduct, 4th ventricle

Front 134

Decreased CSF Resorption

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difficult to distinguish from obstruction and often has similar causes.

Front 135

Communication Hydrocephalus

Back 135

impaired CSF resorption in arachnoid agranulation, obstricution of flow in the subarachnoid space, or (rarely) by excess CSF production

Front 136

Noncommunication hydrocephalus

Back 136

obstruction fo flow w/in the ventricular system

Front 137

Symptoms of hydrocephalus

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Headache, nausea, vomiting, coagnitive impairment, decreased level of consciousness, papilledema, decreased vision, 6th N palsies(incomplete or slow abduction of eye), magnetic gait[feet barely leave the floor](assc with frontal lobe) and incontinence

Front 138

Parinaud's Syndrome

Back 138

dilation of the suprapineal recess of the posterior 3rd ventricle pushing downward onto the collicular plate. Causes limited upward gaze.

Front 139

"setting sun" sign

Back 139

bilatreal deviaton of the eyes downward and inward. Most often in children with acute hydrocephalus

Front 140

Ventriculoperitoneal shunt

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shunt tubing from lateral ventricle tunneled under the skin into the peritoneal cavity of the abdomen. Valve prevents reverse fluid direction.

Front 141

Endoscopic Neurosurgery

Back 141

cannula introduced into the cranium through small incision and passing instruments through it

Front 142

Normal Pressure Hydrocephalus

Back 142

condidtion usually in elderly, chronically dilated ventricles. Present with clinical triad of gait difficulties, urinary incontinence, and mental decline. Thought to be form of communicating hydrocephalus with impaired CSF resorption at the arachnoid villi.

Front 143

Hydrocephalus Ex Vacuo

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Refers to excess CSF in a regionwhere brain tissue was lost as a result of stroke, surgery, atrophy, trauma or other insult.

Front 144

2 broad categories of brain tumors

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Primary CNS tumors and Metastatic Tumors

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Primary CNS tumors

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arose from abnormal proliferation of cells originating in the nervous system

Front 146

Metastatic tumors

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arise from neoplasms originating elsewhere in the body that spread to the brain

Front 147

Most common brain tumors

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gliomas and meningiomas

Front 148

Supratentorial tumors are more common in

Back 148

adults

Front 149

Infratentorial tumors are more common in

Back 149

children

Front 150

Most common brain tumors in children

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astrocytoma and medulloblastoma, followed by ependymoma

Front 151

Various symptoms of brain tumors

Back 151

headache and other signs of increased intracranial pressure, seizure and focal symptoms

Front 152

Tumors that are more commonly associated with seizures

Back 152

low-grade gliomas and meningiomas

Front 153

Types of gliomas

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Glioblastoma multiforme
Astrocytoma Grades I and II
Asytrocytoma Grade III
Oligodendriglioma
Ependymoma
Other

Front 154

Meningiomas

Back 154

arise from the arachnoid villus cells and occur, in order of decreasing frequency, over the lateral convexities, in the falx, and along the basal regions of the cranium
In female pts, there may be an association between meningiomas and breast cancer

Front 155

Pituitary adenomas

Back 155

Can cause endocrine disturbances or compress the optic chiasm

Front 156

Tx pituitary adenoma

Back 156

dopaminergic agonists or transsphenoidal resection

Front 157

Prolactinomas

Back 157

most common type of pituitary adenoma

Front 158

Most common schwannoma location

Back 158

CN VIII

Front 159

Lymphoma

Back 159

increased incidence attributable to increase in HIV
Arises from B cells
controlled by chemotherapy and radiation therapy

Front 160

Pineal region tumor

Back 160

Relatively uncommon
Includes pinealomas, germinomas, and rarely, teratomas or gliomas
Tumors in this region can obstruct cerebral aqueduct or compress the dorsal midbrain, causing Parinaud's syndrome

Front 161

Most common cancers that spread to brain

Back 161

lung, breast, melanoma

Front 162

Cerebellar astrocytoma

Back 162

Grade I astrocytoma; often cured by surgical ressection

Front 163

Common age range medulloblastoma

Back 163

before age 10

Front 164

Common age range cerebellar astrocytoma

Back 164

between 2 and 20

Front 165

Paraneoplastic syndrome

Back 165

Relatively rare neurologic disorder caused by remote effects of cancer in the body, leading to an abnormal autoimmune response
Examples: limbic or brainstem encephalitis, cerebellar Purkinje cell loss, spinal cord anterior horn cell loss, neuropathy, impaired neuromuscular junction (Lambert-Eaton syndrome), and opsoclonus myoclonus (characterized by irregular jerking movements of the eyes and limbs)

Front 166

Infectious Meningitis

Back 166

infection of the CSF in the subarachnoid space

Front 167

Causes infectious meningitis

Back 167

bacteria, viruses, fungi, or parasites

Front 168

Sx infectious meningitis

Back 168

Headache, lethargy, photophobia, phonophobia

Front 169

Dx of meningitis

Back 169

CT followed by lumbar puncture

Front 170

CSF characteristics of Bacterial meningitis

Back 170

CSF = high white blood cell count with polymorphonuclear predominance
High protein
Low glucose

Front 171

Most common pathogens in bacterial meningitis

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depends on age

Front 172

Most common tx bacterial meningitis

Back 172

depends on age

Front 173

Most common pathogen bacterial meningitis for children <3 months

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E Coli, Group B, D Streptococcus, Listeria

Front 174

Most common pathogen bacterial meningitis 1 month-7 years

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Haemophilus influenzae, Neisseria meningitidis, streptococcus pneumoniae

Front 175

Most common pathogen bacterial meningitis ages 7 years-adult

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Listeria, Neisseria meningitidis, Streptococcus pneumoniae

Front 176

Most common tx bacterial meningitis ages 0-3 months

Back 176

Ampicillin + ceftriaxone

Front 177

Most common tx bacterial meningitis ages 3 months - 7 years

Back 177

Ceftriaxone

Front 178

Most common tx bacterial meningitis ages 7 years - adult

Back 178

Ampicillin + ceftriaxone

Front 179

Complications of bacterial meningitis

Back 179

seizures, cranial neuropathies, cerebral edema, hydrocephalus, herniation, cerebral infarcts, and death

Front 180

What do you do with children following recovery of bacterial meningitis?

Back 180

screen for hearing loss

Front 181

Brain abcess

Back 181

bacterial infection of the nervous system; presents as an expanding intracranial mass, much like a brain tumor, but with a much more rapid course

Front 182

presentation brain abcess

Back 182

headache, lethargy, fever (60% of cases), nuchal rigidity, nausea, vomiting, seizures, focial signs

Front 183

Common infecting organisms: brain abscess

Back 183

streptococci, Bacteriodes, enterobacteriaeae, Staphylococcus aureus, toxoplasma gondii, Nocardia

Front 184

Tx patients small brain abscess (<2.5 cm)

Back 184

antibiotics and observation

Front 185

Tx pts with large brain abscess (>2.5cm)

Back 185

stereotactic needle aspiration or surgical removal + antibiotics

Front 186

CSF of Viral Meningitis

Back 186

increased WBC (10-300); increased protein (50-100); normal glucose (exception = herpes, mumps, lymphocytic choriomeningitis virus)

Front 187

CSF of Herpes meningoencephalitis

Back 187

0-500 lymphocytes (normal = <5-10); increased protein (5-100); Normal or reduced glucose; RBCs or xanthochromia may be present

Front 188

CSF of tuberculous menigitis or cryptococal meningitis

Back 188

increased lymphocytes (10-200); increased protein (100-200); reduced glucose (<50)

Front 189

Most common location epidural abscess

Back 189

spinal canal

Front 190

Common presentation epidural abscess

Back 190

back pain, fever, elevated peripheral white blood cell count, headache, signs of nerve root or spinal cord compression

Front 191

Ex epidural abscess

Back 191

surgical drainage and antibiotics (nafcillin and ceftriaxone)

Front 192

Pathogen epidural abscess

Back 192

Staphylococcus aureus, streptococci, Gram-negative bacilli, and aneorobes

Front 193

Sudbdural empyema

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collection of pus in the subdural space, usually resulting from direct extension from an infection of the nasal sinuses or inner ear

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Tx subdural empeyma

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ceftriaxone + metronidazole

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Pott's disease

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tuberculous involvement of the epidural space

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Tx tuberculous meningitis

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combination of isonizid, rifampicin, ethambutol, and pyrazinamide

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Lymphocyte-Predominant Meningitis

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"Aseptic meningitis"
most commonly viral in origin

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2 most important spirochetal infections of the nervous system

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neurosyphilis and Lyme disease

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Syphilis pathogen

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Treponema pallidum

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Primary syphillis

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painless skin lesions called chancres appear at the site of infection about 1 month after exposure

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Secondary syphilis

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more diffuse skin lesions appear ~ 6 months (palms and soles)

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Tertiary syphilis

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neurologic manifestations

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meningovascular syphilis

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chronic meningeal involvement causes arteritis, typically involving medium sized vessels, that results in diffuse white matter infarcts

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What occurs if meningovascular syphilis goes untreated?

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general paresis-- accumulation of lesions causes dementia, behavioral changes, delusions of grandeur, psychosis, and diffuse UMN-type weakness

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Tabes dorsalis

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syphilitic myelopathy with degeneration of spinal cord dorsal roots; sensory loss and high stepping gait pattern and incontinence; Argyll Robertson pupils and optic atrophy

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Dx neurosyphilis

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blood tests for treponems (FTA-ABS or MHA-TP) + CSF w/ lymphocyte-predominant meningitis

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Tx neurosyphilis

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IV penicillin G

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Lyme disease pathogen

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Borrelia burgdorferi carried by Ixodes species of deer tick

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Sx Lyme Disease

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erythema chronicum migrans (rash); some cases show neurologic manifestations (lymphocyte-predominant meningitis, mild meningoencephalitis, emotional changes, crainial neuropathies (most commonly CN VIII)); arthritis and cardiac conduction abnormalities

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Tx Lyme Disease

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IV ceftriaxone

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Causes viral meningitis

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enterocviruses such as echovirus, coxsackievirus, mumps virus

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Viral encephalitis

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viral infections that involve the brain parenchyma

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Most common cause viral encephalitis

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herpes simplex Type I

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Herpes Simplex encephalitis

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causes necrosis of unilateral or b/l temporal and frontal sutures; progresses within days to coma and death

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Tx Herpes Simplex encephalitis

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Acyclovir

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Subacute sclerosing panencephalitis

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A delayed, slowly progressive fatal encephalitis often associated with measles

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Herpes Zoster

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shingles; infection caused by the same virus as chickenpox
primary sx = painful rash conforming to nerve root distributions

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HTVL-1 virus

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causes chronic type of spinal cord disease called HTVL-1 associated myelopathy, or tropical spastic paraparesis

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Causes of transverse myelitis

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enteroviruses (coxsakie and poliomyelitis), varicella-zoster virus, HIV
less commonly, Epstein-Barr virus, cytomegalovirus, herpes simplex, rabies, Japanese B virus

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HIV-associated neurocognitive disorder (HAND)

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common neurologic manifstation of HIV, with increasd frequency late in the course of the illness; Tx with antiviral agents (highly active antiretrovial therapy, or HAART) can cause improvement in AIDS related dementia

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Common viral infections in pts with HIV

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encephalitis, herpes simplex virus, varicella-zoster virus, or cytomegalovirus

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Progressive multifocal leukoencephalopathy (PML)

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Disorder that can occur in patients w/ AIDS or immunodeficiency status; caused by papvavirus called the JC virus and results in gradual demyelination of the brain (death within 3-6 months)

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Important bacterial infections in pts with AIDS

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tuberculous meningitis and neurosyphilis

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Cryptococcal meningitis

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common fungal infection in AIDS pts; should be suspected in all HIV-positive pts with chronic headache; organism can be identified by India ink stain

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Tx cyrptococal meningitis

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IV amphotercin B followed by oral fluxonazole

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Exposure to toxoplasma

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undercooked meat or cysts in cat feces; initial exposure is usually asymptomatic

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Toxoplasma and AIDS pts

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infection becomes reactivated and spreads to the CNS, forming brain abscesses visible on MRI scans as ring-enhancing lesions

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Most common cause of intracranial mass lesions in pts with HIV

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toxoplasmosis (second = primary nervous system lymphoma)

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Tx toxoplasmosis

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pyrimethamine and sulfadiazine

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Primary nervous system lymphoma

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B cell lymphoma that can appear radiologically similar to toxoplasmosis

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Tx primary nervous system lymphoma

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steroids and radiation therapy

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Pathogen African sleeping sickness

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Trypanosoma brucei

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Cysticerosis

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caused by ingestion of the eggs of the pork tapework Taenua solium; organism migrates through the bloodstream to the whole body forming multiple cysts in the muscles, eyes, and CNS

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Sx Cysticerosis

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Seizures, headache, nausea, vomiting, lymphocytic meningitis, focal deficits, hydrocephalus

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Tx Cysticerosis

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albendazole

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Mucormycosis

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Potentially fatal fungal infection that occurs mainly in diabetics in the rhinocerebral form and involves the orbital apex

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Rhinocerebral mucormycosis

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causes opthalmoplegia, facial numbness, visual loss, facial weakness; typical violet coloration of the tips of the eyelids

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Tx mucormycosis

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Amphotercin C; steroids should be avoided

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Prion related illnesses

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infectious agents that are protein-based contains no DNA or RNA
Pathologically diffuse degeneration of the brain and spinal cord occurs, with multiple vaculoes results in a spongiform appearance

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Examples prion related illness

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Creutzfeldt-Jakob disease, Gerstmann-Strauessler-Scheinker disease, kuru, and fatal familial insomnia

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Creutzfeldt-Jakob Disease

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presents with rapidly progressive dementia, an exaggerated startle response, myoclonus, visual distortions or hallucinations, and ataxia; MRI shows periodic sharp wave complexes and CSF shows increased 14-3-3 protein; no treatment available; may have been caused by ingestion of cattle infected with bovine spongiform encephalopathy

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What should you do before performing a lumbar puncture?

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Perform head CT to avoid risk of herniation

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Normal CSF pressure in adults

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less than 20 cm H2O

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Ending spinal cord in adults

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L1/L2

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Loation of Lumbar puncture

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between L4/L5; posterior iliac crest = landmark

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Indication of RBCs are present in CSF

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hemorrhagic encephalitis

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Traumatic tap

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damage to blood vessels caused by spinal needle at the time of the lumbar puncture

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Presence of xanthochromic supernatant in CSF

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indication that the hemorrhage is older

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Pterion

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region over the temporal where the frontal, parietal, temporal and sphenoid bones meet

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Pterional craniotomy

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provides access to the inferiortemporal lobes; used for surgey on anterior circulation and basilar tip aneurysms, the cavernous sinus, and suprasellar tumors

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Temporal craniotomy

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a more lateral approach; used for operating on the temporal lobe to resect seizure foci and for decompression of most intracranial hematomas

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Frontal craniotomy

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used for frontal lobe lesions such as tumors

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Suboccipital craniotomy

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access to posterior fossa stuctures such as cerebellopontine angle, vertebral artery, brainstem, and lower cranial nerves

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transspenoidal approach

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pituitary region reached through nasal passages

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sterotactic procedures

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an instrument is introduced through a small burr hole and directed to a specific target within the deep brain

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Sx: Lt hemiparesis and Lt Babinski sign, Visual and tactile extinction(form of hemineglect) on the Lt, Rt sided headaches, Generalized fatigue All gradually worsening following a car crash 3 mos ago

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Right hemisphere cortical and or subcortical lesion affecting corticospinal and attentional pathways. Gradual worsening suggests chronic subdural hematoma(crescent shape on MRI) (2-3 weeks for hematoma to become hyp0dense, acute=hyperdense) midline shift seen with mild subfalcine herniation. Treated by surgical evacuation.

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Sx: Unresponsiveness except to painful stimuli, Abscent Rt corneal reflex, and no Rt arm or leg movement in response to pain, with plantar response absent on the Rt and upgoing on the Lt. Drunk at the bottom of stairs

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Alcohol can skew neuro exams but it should get better with time, if not imaging done immediately. Most likely epidural hematoma, acute subdural hematoma, cerebral contusion or cerebral edema. Coup Contrecoup-blow to one side of the head is accompanied by decelration ninjury on the opposite side of the brain as it bangs against the inner surface of the skull; frontal and temporal poles especially susceptible to contusion. Midline shift seen at the level of the pineal calcification(>10mm shift is usually assc with profound coma.) Also had early Lt uncal transtentorial herniation. basal cisterns at near complete effacement. Lt lat ventricle and culci completely obliterated. Lt hemispheres swollen and somewhat hypodense, consistent with diffuse cerebral edema.