Parapharyngeal & Carotid Spaces Presentation Goals • Review anatomy & terminology • Recognize masses by space • Present space-specific DDx H. Christian Davidson, M.D. Suprahyoid Neck Spaces Deep Cervical Fascia Principal Spaces Three Layers • Parapharyngeal ! Superficial layer • Carotid ! Middle layer • Parotid ! Deep layer • Masticator • Pharyngeal Fascial Boundaries “Parapharyngeal” Space(s) Alternative Description • “Prestyloid” space " parapharyngeal • “Poststyloid” space " carotid Ji Hoon Shin, et. al. AJR, 2001, Parapharyngeal Space Parapharyngeal Space (proper) Contents • Fat . a.k.a. Importance • Easily identified Prestyloid Parapharyngeal • Infection conduit • Displacement by Space pathology other spaces * Parapharyngeal Space Extent • Skull base to hyoid bone • Limited to SHN • Contiguous with submandibular space Parapharyngeal Space Skull Base • Bland interaction with skull base • No arteries, veins or cranial nerves • Infection or tumor affects PPS secondarily Parapharyngeal Space 1° Lesions • Lipoma • Lymphatic malformation • Minor salivary rest tumor Parapharyngeal Space Parapharyngeal Space Infection (2°) Neoplasm (2°) • Pharyngeal abscess (peritonsillar) • Pharyngeal mucosa " NPC • Mandibular odontogenic " tonsillar SCCa • Parotiditis • Masticator space (obstructive) " sarcoma, lymphoma • Suppurative • Parotid space adenopathy " deep lobe Parapharyngeal Space Importance • Displacement defines lesion space of origin Carotid Space a.k.a. Poststyloid Parapharyngeal Space Carotid Space Fascia • All 3 layers, DCF • Tensor-styloid fascia Contents • ICA, IJV, upper CN • Internal jugular nodes Carotid Space Carotid Space Extent Skull base • Skull base to arch • Abuts T/O bones • SHN & IHN " Carotid canal Importance " Jugular foramen " Hypoglossal canal • Neurovascular • Critical contents structures " ICA, IJV • Adjacent nodes " CN 9-12 Carotid Space Pathology Carotid Space Mass Effect Upper • PPS anteriorly • Styloid process anterolaterally Lower • Post. belly digastric anterolaterally • May splay ECA-ICA bifurcation Carotid Space Mass Effect Carotid Space Mass Effect Upper • PPS anteriorly General Clue • Styloid process • Long lesions anterolaterally • Identify upper & lower Lower margins within CS • Post. belly digastric anterolaterally • May displace or splay carotid bifurcation Carotid Space Carotid Space Vascular Lesions Carotid Artery • ICA Lesions Pseudoaneurysm " Atherosclerosis • Post-traumatic, " Dissection post-dissection " Pseudoaneurysm • Carotidynia • Vagal neuropathy • IJV Lesions • Complex ovoid " Thrombophlebitis enhancing mass " Thrombosis Carotid Space Carotidynia • Pain & tenderness over cervical carotid artery • Thickened, enhancing CA wall, w/o luminal abnormality • Responds to steroids or NSAIDs Carotid Space Jugular Vein • Thrombosis " tumor mimic " nonenhancing clot on CT/MR • Thrombophlebitis " infection mimic " clot plus cellulitis Carotid Space Carotid Space Benign Neoplasms Paraganglioma • Benign tumor of glomus • Paraganglioma body; location defines " carotid body tumor terminology " glomus vagale • Carotid bifurcation • Nerve sheath tumor " carotid body tumor " vagal schwannoma " glomus caroticum " vagal neurofibroma • Nodose ganglion of CN X " glomus vagale Carotid Body Tumor Imaging • CT: enhancing mass " splays ICA-ECA • MR: flow voids " “pepper”; “salt” rare • Angio: AV shunting " intense tumor blush Glomus Vagale Paraganglioma Imaging • Similar to CBT • Except ~2 cm below SB • May abut SB but does not enter JF • Pushes into PPS from P # A Vagal Schwannoma Vagal Neurofibroma Etiology & Imaging Etiology & Imaging • Arises from Schwann • Arises from Schwann cells of CN X in CS cells; isolated > NF1 • Fusiform mass; • Fusiform CS mass intramural cysts • CECT: Lower density, • CECT: Mixed poor enhancement enhancement • MR: No flow voids • MR: No flow voids Summary Parapharyngeal Space Carotid Space • “Prestyloid PPS” • “Poststyloid PPS” • Few primary lesions • Vascular lesions • Regional spread of intrinsic ICA / JV infection & tumor from • Neoplasms adjacent spaces paragangliomas • Displacement gives (CBT, GV) clue to space of origin nerve sheath tumors (schwannoma, NF) .