Rosen Notes – Chapter 103 – Brain And Cranial Nerve Disorders

Front 1

Trigeminal Neuralgia:
-S/S

-Dx

-Tx

Back 1

s/s – lancinating paroxysms of pain in lips/teeth/gums/chin; associated with physical triggers (brushing teeth, shaving); clustered, usually spontaneous remission

- CT/MRI should be done to r/o posterior fossa tumor
- tx
o Tegretol: 100 mg po bid and titrate up to 100 mg po tid
o Can be increased by 100 mg per dose up to a max of 400 tid (1200/day)
o Alternative: dilantin, valproate, gabapentin
o Failure of medical Rx: injections, peripheral neurectomy, radiation, or surgical decompression

Front 2

Facial Nerve Paralysis:

motor, sensory fnc

main causes

Back 2

Motor: facial muscles; sensory: anterior 2/3 of tongue, auditory canal, soft palate, pharynx
- 3 main categories – infectious, traumatic, neoplastic

Front 3

bells palsy

Back 3

iral etiology (HSV 1 has been demonstrated in nerves); lower motor neuron paresis progressing to paralysis over 1 week; may have prodromal illness
§ s/s – ear pain, ¯tearing and dry eye, tear overflow on face, abN acute hearing (hyperacusis), impaired taste
§ Treatment
· Eye drops, eye patching at night
· steroids x 7 days, (acyclovir x10days tx controversial)
· treat within 7 days of symptom onset
§ Meta-analysis: steroids +/- antiviral
· JAMA 2009. 302(9) p985
· 18 RCT blinded and unblinded involving 2786 patients
· Steroids are beneficial
· Antivirals appear to have no effect – may work synergistically with steroids
§ Prognosis: 60-80% recover within few months

Front 4

infectious cause facial palsy

Back 4

Ramsay Hunt syndrome – unilateral facial paralysis, herpes zoster rash and vestibulocochlear dysfunction; pain worse than Bell’s palsy
§ tx – steroids + antivirals; prognosis worse
o Lyme disease – can occur during any phase of infection; bilateral facial paralysis is Lyme disease until proven otherwise
o Bacterial – infection of middle ear, mastoid, external auditory canal; 0.2% of AOM with abx tx

Front 5

trauma,neoplasis facial palsy

Back 5

Dysbarism – middle ear squeeze can cause this
- trauma – results from temporal bone #; sx repair indicated if definitive transection
- neoplasm – usual onset over 3 weeks, recurrent ipsilateral facial paralysis, pain, cerebellopontine angle
- ix – if upper motor neuron lesion (spares forehead), needs CT for brain evaluation
- f/u – may consider eye patching with ophtho f/u as high risk of corneal abrasion

Front 6

Vestibular Schwannoma / Acoustic Neuroma:

Back 6

- rare cause of sensorineural hearing loss, may occur with unilateral tinnitus
- comnplain of unsteadiness, early there is peripheral vertigo, late is central vertigo, can’t distinguish similar sounds early (cart, smart, dart…)
- compresses acoustic branch of CN8 (cochlear), very slow growing
- ix – audiogram, MRI
- ddx – Ménières’s (tinnitus usually intermittent), meningioma
- tx – sx/rads; ENT/neurosx referral

Front 7

Diabetic Cranial Mononeuropathy:

Back 7

- usually affect EOM, caused by ischemia of CN3; parasympathetic fibres usually spared which spares pupillary response
- s/s – acute onset unilateral retroocular/supraorbital pain, diplopia, ptosis
- tx – usually dx of exclusion; analgesia, patching, antiplatelet tx; prognosis good

Front 8

causes 3rd nerve palsy

Back 8

Third Nerve Palsy
- Brain Stem (Edinger Westphal nucleus)
o Tumor, Bleed, Infarct, Herniation
- Cranial Nerve
o Diabetic related inffarct
o Compression by uncal herniation
o Posterior cerebral ANEURYSM (also superior cerebellar artery aneurysm)
o Tumor of IIIrd nerve
o Millar Fischer variant of GBS
- Ciliar Ganglion
o Viral infection
- Neuromuscular Junction
o Myasenia gravis

Front 9

Cerebral Venous Thrombosis:

Back 9

- cerebral blood drained into dural sinuses; underlying causes – infectious (sinusitis, OM, cellulitis) and non-infectious (direct injury to dural sinuses by trauma/sx/tumor/dehydration/any predisposition to hypercoagulable state)
- s/s – variable (depends on clot location) – headache, papilledema, seizures; extent depends on amount of collateral blood drainage
o CN palsies: II, IV, V, VI
- dx – angiography (gold std); MRI/MR venography; CT not sensitive enough; LP shows opening pressure
- tx – heparin, IVR for local thrombolytics

Front 10

Multiple Sclerosis:

cause+ symptoms

Back 10

- demyelination of discrete areas leading to episodes of neurol dysfunction that evolve over days/resolve over weeks
- genetic and environ factors; organ-specific autoimmune disease with T cells made in response to infection/environmental trigger reactivates years later
- s/s – may involve cognitive impairment, CN dysfunction (optic neuritis), motor/sensory (exaggerated DTR), cerebellar, bowel/bladder/sexual dysfunction

- Diagnosis
o Uhthoff’s phenomenon - body temp temporarily worsen current/pre-existing s/s
o Lhermitte’s sign: electirc shock sensation when the neck is flexed due to demyelination of the posteroir columns of the cervical cord
o Dx criteria – Clinical diagnostic criteria = Two episodes at different times + two separate lesions
o LP - IgG band on electropheresis
o MRI (multiple white matter lesions, marker of disease severity)
-

Front 11

Multiple Sclerosis:

presenting complaint

Back 11

- Presenting complaint
o Weakness 40%
o Optic neuritis 20%
o Paresthesisia 20%
o Diplopia 10%
§ Intranuclear ophthalmoplegia
o Vertigo 5%
o B/B 5%

Front 12

Multiple Sclerosis:

treatment

Back 12

tx – 3 goals –
o halting progression – interferon-β, mimic of myelin polymer (glatiramer)
o acute exacerbations – methylprednisolone 500mg q12h
o modify complications –

baclofen (spasticity),

propranolol/benzos (tremor, ataxia),

carbamazepine (facial pain),

amantadine (fatigue)

Front 13

Cranial Nerve 1

1. Clinical Function Relevant to Emergency Medicine

2. Pathologic Features

3. Possible Causes

Back 13

Cranial nerve I: olfactory nerve

Sense of smell

Unilateral anosmia

Trauma: Skull fracture or shear injury interrupting olfactory fibers traversing the cribriform plate

Tumor: Frontal lobe masses compressing the nerve

Front 14

Cranial Nerve II

1. Clinical Function Relevant to Emergency Medicine

2. Pathologic Features

3. Possible Causes

Back 14

Vision

Unilateral vision loss

Trauma: Traumatic optic neuropathy

Tumor: Orbital compressive lesion

Inflammatory: Optic neuritis (MS)

Ischemic: Ischemic optic neuropathy

Front 15

Cranial Nerve III

1. Clinical Function Relevant to Emergency Medicine

2. Pathologic Features

3. Possible Causes

Back 15

Cranial nerve III: oculomotor nerve

1.Extraoculomotor function via motor fibers to -levator palpbrae,

-superior rectus,

-medial rectus,

-inferior rectus,

-inferior oblique muscles

2.Pupillary constriction via parasympathetic fibers to constrictor pupillae and ciliary muscles

3.Ptosis caused by loss of levator palpebrae function

Eye deviated laterally and down

Diplopia

Dilated, nonreactive pupil

Loss of accommodation

Trauma: Herniation of the temporal lobe through the tentorial opening causing compression and stretch injury to the nerve

Ischemic: Especially in diabetes. microvascular ischemic injury to nerve causes extraocular muscle paralysis, but usually is papillary sparing (often painful)

Vascular: Intracranial aneurysms may press on the nerve leading to dysfunction

Myasthenia gravis can lead to atraumatic ocular muscle palsy

Front 16

Cranial Nerve IV

1. Clinical Function Relevant to Emergency Medicine

2. Pathologic Features

3. Possible Causes

Back 16

Cranial nerve IV: trochlear nerve

Motor supply to the superior oblique muscle

Inability to move eye downward, and laterally

Diplopia

Patients tilt head toward unaffected eye to overcome inward rotation of affected eye

Trauma is the most common cause of nerve dysfunction

Front 17

Cranial Nerve V

1. Clinical Function Relevant to Emergency Medicine

2. Pathologic Features

3. Possible Causes

Back 17

Motor supply to muscles of mastication and to tensor tympani

Sensory to face, scalp, oral cavity (including tongue and teeth)

Partial facial anesthesia

Episodic, lancinating facial pain associated with benign triggers such as chewing, brushing teeth, light touch

Trauma: Facial bone fracture may injure one section leading to area of facial anesthesia

Tic douloureux

Front 18

Cranial Nerve VI

1. Clinical Function Relevant to Emergency Medicine

2. Pathologic Features

3. Possible Causes

Back 18

Motor supply to the lateral rectus muscle

Inability to move affected eye laterally

Diplopia upon attempting lateral gaze

1.Tumor: Lesions in the cerebellopontine angle

2.Any lesion, vascular or otherwise, in the cavernous sinus may compress nerve

3.Elevated intracranial pressure (ICP): Because of its position and long intracranial length, increased ICP from any cause may lead to injury and dysfunction of the nerve

Front 19

Cranial Nerve VII

1. Clinical Function Relevant to Emergency Medicine

2. Pathologic Features

3. Possible Causes

Back 19

1.Motor supply to muscles of facial expression

2.Parasympathetic stimulation of the lacrimal, submandibular, and sublingual glands

3.Sensation to the ear canal and tympanic membrane

Hemifacial paresis: Lower motor neuron lesion with entire side of face paralyzed

-Upper motor neuron lesion leaves forehead musculature functioning

-Abnormal taste

-Sensory deficit around ear

-Intolerance to sudden loud noises

Lower motor neuron

-Infection (viral): The likely cause of Bell's palsy

-Lyme disease: The most common cause of bilateral cranial nerve VII palsy in areas where Lyme disease is endemic

-Bacterial infection extending from otitis media

Upper motor neuron

Stroke, tumor

Front 20

Cranial Nerve VIII

1. Clinical Function Relevant to Emergency Medicine

2. Pathologic Features

3. Possible Causes

Back 20

Cranial nerve VIII: vestibulocochlear nerve

Hearing and balance

Unilateral hearing loss

Tinnitus

Vertigo, unsteadiness

Tumors: Acoustic neuroma

Mimics Ménières's disease, perilymphatic fistula

Front 21

Cranial Nerve IX

1. Clinical Function Relevant to Emergency Medicine

2. Pathologic Features

3. Possible Causes

Back 21

Cranial nerve IX: glossopharyngeal nerve

1.General sensation to posterior third of tongue

2.Taste for posterior third of tongue

3.Motor supply to the stylopharyngeus

Clinical pathology referable to the nerve in isolation is very rare

Occasionally painful paroxysms beginning in the throat and radiating down the side of the neck in front of the ear but behind the mandible

Brainstem lesions

Glossopharyngeal neuralgia

Front 22

Cranial Nerve X

1. Clinical Function Relevant to Emergency Medicine

2. Pathologic Features

3. Possible Causes

Back 22

Cranial nerve X: vagus nerve

1.Motor to striated and muscles of the pharynx, larynx, and tensor (veli) palatini

2.Motor to smooth muscles and glands of the pharynx, larynx, thoracic and abdominal viscera

3.Sensory from larynx, trachea, esophagus, thoracic and abdominal viscera

Unilateral loss of palatal elevation: Patients complain that on drinking liquids the fluid refluxes through the nose

Unilateral vocal cord paralysis: Hoarse voice

Brainstem lesion

Injury to the recurrent laryngeal nerve during surgery

Front 23

Cranial Nerve XI

1. Clinical Function Relevant to Emergency Medicine

2. Pathologic Features

3. Possible Causes

Back 23

Cranial nerve XI: spinal accessory nerve

Motor supply to the sternocleidomastoid and trapezius muscles

Downward and lateral rotation of the scapula and shoulder drop

Trauma to the nerve

Front 24

Cranial Nerve XII

1. Clinical Function Relevant to Emergency Medicine

2. Pathologic Features

3. Possible Causes

Back 24

Cranial nerve XII: hypoglossal nerve

Motor supply to the intrinsic and extrinsic muscles of the tongue

Tongue deviations:

-Upper motor neuron lesion causes the tongue to deviate toward the opposite site

-Lower motor neuron lesion causes the tongue to deviate toward the side of the lesion, and the affected side atrophies over time