Cerebellopontine angle syndrome
What are the clinical features of the cerebellopontine angle syndrome?
Lesions at the space between the cerebellum and the pons often compress and interfere with the functions of the nearby cranial nerves V, VII, and VIII.
Symptoms may include depression or absence of the ipsilateral corneal reflex, facial numbness, and weakness of the mastication muscles (cranial nerve V); facial myokymia or ipsilateral lower motor neuron paralysis (cranial nerve VII); and hearing loss, tinnitus, and vertigo (cranial nerve VIII).
Enlarging lesions may distort the brain stem, producing long-tract signs or obstruction of the aqueduct to cause hydrocephalus and increased intracranial pressure.
Compression of the cerebellar hemisphere adjacent to the cerebellopontine angle presents with ipsilateral limb ataxia and intention tremor or nystagmus.
What are the causes of the cerebellopontine angle syndrome?
Vestibular schwannoma (also called acoustic neuroma ) is the most common extra-axial cause.
It originates from Schwann cells in the sheath of cranial nerve VIII, close to its attachment to the brain stem.
Early cranial nerve VIII involvement is characteristic, while cranial nerve VII is spared until much later.
Early cranial nerve VII involvement should suggest other lesions, such as meningioma, epidermoidoma, craniopharyngioma, glomus jugulare tumor, and aneurysm of the basilar artery. Intra-axial masses of the brain stem and cerebellum also may cause the syndrome if they are sufficiently large and extend into the cerebellopontine space