Cerebellopontine angle syndrome

David Goldemund M.D.
Updated on 11/06/2024, published on 22/01/2024
  • the cerebellopontine angle (CPA) is the space between the cerebellum and the pons, filled with cerebrospinal fluid (CSF)
  • the main structures located in the CPA are:
    • vestibulocochlear nerve (CN VIII)
    • facial nerve (CN VII)
  • pathological processes in this area (most commonly vestibular schwannoma), therefore, lead to damage to these nerves
  • the initial clinical manifestations depend on the nature and location of the pathological process


  • most commonly schwannoma (neuroma) ~ 80-90% of cases
  • meningioma (often involving the apex → Gradenigo syndrome)
    • more homogeneous, though cysts can also be present
    • attached to the dura
    • no internal acoustic meatus enlargement
    • calcifications are more commonly present
  • arachnoiditis (e.g., from otogenic infection)
  • ependymoma
    • younger patients
    • absence of internal acoustic meatus enlargement
  • epidermoid
    • no contrast enhancement
    • high signal on DWI
    • absence of internal acoustic meatus enlargement
  • metastasis
    • relatively rare
  • cholesteatoma
  • glomus jugulare

Vestibullar schwannoma

  • vestibular schwannoma (also called acoustic neuroma) accounts for ~ 7.5% of all intracranial tumors and about 80-90% of all CPA tumors
  • benign encapsulated tumor of Schwann cells (WHO grade 1); schwannoma is composed of spindle cells and arises eccentrically from the parent nerve, with the nerve fibers splayed along their surface
  • most lesions are sporadic and unilateral (90%)
  • bilateral schwannomas are found in:
    • neurofibromatosis type 2 (NF2)
    • familial forms without other manifestations of NF2
  • schwannomatosis presents with multiple schwannomas without the concomitant involvement of CN VIII
  • peak presentation between the 4th and 6th decades; earlier manifestation is typical for NF2 (~ by the 3rd decade)

Clinical presentation

  • presentation depends on the location of the tumor, and symptoms are due to local mass effect or dysfunction of the nerve they arise from
  • the first symptoms usually arise from the cochlear branch lesion:
    • irritation of the nerve causes tinnitus
    • later, a loss of hearing on the affected side develops
  • vestibular disturbances (in the form of peripheral vestibular syndrome) are usually more troublesome:
    • initially, the lesion may cause tonic deviations towards the healthy side and nystagmus towards the affected side (potentially leading to misidentification of the side of the vestibular disorder)
    • soon, tonic deviation towards the side of the disorder and nystagmus beating in the opposite direction occur
  • less commonly, the CPA syndrome begins with paresis of the facial nerve
    • paresis may sometimes be preceded by irritation of the nerve, causing intermittent hemispasm
  • CPA tumors cause additional symptoms due to their growth and compression of nearby structures
  • upward and medial propagation compresses the cerebellum, particularly the cerebellar hemisphere, leading to ipsilateral neocerebellar symptoms
  • medial or downward propagation leads to compression of the brainstem:
    • contralateral pyramidal symptoms + ipsilateral lesion of CN VI and further progression may affect CN IX, X, and even CN XI

Diagnostic evaluation

Computed tomography (CT)

  • enlargement of the internal acoustic meatus (schwannoma)
  • signs of adjacent bone remodeling
  • variable density on non-contrast scans with possible cystic component
  • contrast enhancement (homogenous in small tumors, heterogeneous in the larger ones) – schwannoma, meningioma, metastasis

Magnetic resonance imaging (MRI)

  • method of choice – optimally visualized on post-contrast T1-weighted images (T1C+)
  • the most common schwannoma has a typical radiological appearance
enhancing mass T1 hyperintense mass CSF density
  • vestibular schwannoma: most common by far (~80%)
  • meningioma: second most common (~10%)
  • trigeminal schwannoma
  • facial nerve schwannoma
  • ependymoma
  • metastasis (e.g., breast, lung, melanoma)
  • hemorrhagic vestibular schwannoma
  • neurenteric cyst
  • thrombosed berry aneurysm
  • cerebellopontine angle lipoma
  • ruptured intracranial dermoid cyst
  • epidermoid cyst: third most common (~5%)
  • arachnoid cyst
Schwannoma on CT
Schwannoma in the cerebellopontine angle on MRI
Acoustic neuroma on T1C+


  • neurosurgical procedure is the treatment of choice (various surgical approaches are used)
    • schwannomas do not infiltrate the nerve and thus can usually be separated from it
  • stereotactic radiosurgery
    • extensive tumor, high-risk patient
  • conservative approach – observation of benign lesions, such as schwannoma or meningioma
    • in older patients and smaller tumors where slow growth can be expected

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Cerebellopontine angle syndrome