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40 Cards in this Set

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Head and Neck Part II

Masticator Space

Masticator Space Lesions DDx - Most common
1. Odontogenic abcess 2. Sarcoma 3. NHL 4. SCC from oropharynx (retromolar trigone) 5. Rhadomyosarcoma in pediatric population 6. Accessory parotid gland 7. Benign Masseteric Hypertrophy
Masticator Space Lesions DDX - by category
1. Pseudotomor a. Accessory parotid gland b. Benign Masseteric hypertrophy c. V3 denervation atrophy 2. Congenital d. Hemangioma e. Lymphangioma 3. Inflammatory f. Odontogenic abscess g. Mandibular osteomyelitis 4. Benign tumor h. Osteoblastoma i. Leiomyoma j. Neural sheath tumor 5. Malignant Tumor k. Sarcoma i. soft tissue ii. chondrosarcoma iii. osteosarcoma l. Malignant schwannoma m. NHL n. SCC from retromolar trigone of oropharynx o. Mandibular mets p. Rhabdomyosarcoma in peds
What is a complication of MS infection? In which direction does infection spread?
1. Skull base osteomyelitis (destruction of pterygoid wing) 2. Upward via least resistance
What makes malignant tumor from MS unresectable?
1. Invasion of skull base 2. Check for suprazygomatic MS spread to adjust radiation ports!!
Which way is the PPF (prestyloid paraphyngeal fat) displaced in Masticator space lesions?
1. Posteriomedially
If tumor in MS, what cranial nerve should be inspected for perineural spread? What is the route?
1. V3 2. 2. via foramen ovale (medial pterygoid fascia inserts medial to FO)
Which motor nerve supplies muscles of mastication?
1. Masticator nerve (motor branch) of V3
What are the masticator muscles?
1. Masseter 2. Medial pterygoid 3. Lateral pterygoid 4. Temporalis
What are the two nerves that enter the masticator space?
1. Masticator nerve (to all masticator muscles) 2. Inferior alveolar nerve
What are the routes of infection/malignancy into the skull base?
1. Muscle attachments to skull base (infection goes up b/c firm attachment of periosteum to inferior mandible 2. V3 through foramen ovale à Meckel’s cave à root entry zone in lateral pons
What 3 clinical features suggest involvement of V3 by tumor?
1. Atrophy of masseter 2. Mandibular pain 3. Serous otitis media (due to tensor palatini dysfunction due to V3 branch involvement causig Eustachian tube malfunction)
What is the temporal fossa?
1. The suprazygomatic MS
What is the infratemporal fossa? Aka?
1. Between PPF and zygomatic arch at level of nasopharynx 2. Nasopharyngeal MS
What borders the MS?
1. Posteromedially = masticator space 2. Anteriorly - buccal space 3. Posteriorly - parotid space 4. What is in the buccal space? 5. Buccinator muscle 6. Parotid duct 7. Facial artery and vein 8. Buccal fat pad
What is a pitfall in perineural spread imaging for V3?
1. Not imaging along its entire course i.e. 2. Inferior alveolar nerve and masticator nerve 3. Mandibular foramen 4. Foramen ovale 5. Meckel’s cave 6. root entry zone along lateral pons
What is the significance of MS infection involving mandible (osteomyelitis)? Tumor?
1. Longer antibiotics 2. More likely perineural spread along IAN or V3 main trunk
Why is CT the initial study of choice in evaluating patients with suspected infection of MS?
1. Identify duct stone 2. R/o mandibular osteomyelitis
Name 3 pseudomasses of MS?
1. Accessory parotid gland 2. Benign masseteric hypertrophy 3. Cranial nerve V3 motor atrophy
Benign Masseteric hypertrophy - most common cause, pitfall, most characteristic appearance? Imaging recc if not pathognomonic?
1. Bruxism (molar grinding) 2. Unilateral mass with infiltrating margins - tumor/infection! 3. Well defined bilateral hypertrophy or if accompanied by pterygoid/temporalis hypertrophy and atrophy with hx of bruxism 4. Close radiologic f/u to r/o tumor
What muscles does the motor root of V3 innervate?
1. Masticator muscles 2. Anterior belly of digastric 3. Mylohyoid muscle 4. Tensor veli palatini, tensor tympani
What are imaging signs of V3 denervation atrophy? How long after injury?
1. Fatty infiltration 2. Volume reduction 3. 6 weeks
What is initial symptom in odontogenic Abscess?
1. Trismus
Odontogenic abscess with “lumpy jaw” - what should you think?
1. Actinomycosis
Check list for imaging of inflammatory disease of masticator space?
1. Parotid duct calculus present? - make sure CT performed 2. Osteomyelitis present - mandible OR skull base - longer abx 3. Any other spaces involved - need separate drain 4. Is suprazygomatic space involved?
Sarcoma - where does chondrosarcoma arise from? Osteosarcoma?
1. Chondrosarcoma - from TMJ 2. Any along mandible
Tubular Mass?
1. Malignant schwannoma along IAN, V3 2. Perineural spread
W hat key features suggests malignancy?
1. Infiltrating border
What secondary feature of MS mass suggests NHL?
1. Other cervical nodes, extranodal lymphatic disease (i.e. waldeyer’s ring)
What is most typical for SCC of MS?
1. Prior hx of treatment of oral cavity or oropharyngeal SCC 2. Look for perineural spread by IAN
ORBIT

RETRO-OCULAR MASS (Intraconal)
1. Hemangioma - - enhance - phleboliths seen in 10% 2. Optic nerve glioma 3. Optic nerve meningioma 4. Angioma 5. Lymphangioma 6. AVM
Extraconal-intraorbital Lesion - DDx
1. Benign Tumor a. 1. Dermoid Cyst b. Teratoma c. Capillary Hemangioma d. Lymphangioma e. Plexiform neurofibroma f. Inflammatory orbital pseuydotumor g. Histiocytosis X (usually arises from bone) 2. Malignant Tumor a. Lymphoma/Leukemia b. Metastasis c. Rhabdomyosarcoma
Masticator Space Lesions DDx – Most common
1.
Masticator Space Lesions DDX – by category
1.
What is a complication of MS infection? In which direction does infection spread?
1.
What makes malignant tumor from MS unresectable?
1.
Which way is the PPF (prestyloid paraphyngeal fat) displaced in Masticator space lesions?
1.
If tumor in MS, what cranial nerve should be inspected for perineural spread? What is the route?
1.