Pathologic Causes of Vertigo

The eighth cranial nerve is vulnerable to fractures involving the petrous part of the temporal bone and by tumors affecting the brainstem or cerebellum. Vertigo may be caused by central or peripheral pathology, but the distinction is not always readily clear, and thus, diagnostic circumspection is often warranted because posterior circulation strokes may manifest with the complaint of vertigo. Brainstem involvement from stroke or, at times, multiple sclerosis, may often be distinguished from a peripheral etiology by symptoms or signs indicating damage to other brainstem structures, such as dysmetria, diplopia, dysphagia, dysarthria, sensory loss, or weakness.

Cochlear

Conductive hearing loss refers to disrupted sound wave transmission to the cochlea from external ear canal, tympanic membrane, or ossicular dysfunction. Sensorineural hearing loss relates to impairment of the cochlea (sensory), cochlear nerve, or nuclei (neural), or any part of the brain auditory pathway (central).

Auditory nerve dysfunction usually results in subjective tinnitus in addition to sensorineural hearing loss. Tinnitus, the sensation of ringing in the ears without significant stimulus, is more frequently noted with peripheral than central lesions. Pulsatile tinnitus is often associated with vascular abnormalities such as arteriovenous malformations, glomus tumors, hemangiomas, meningiomas, vascular loops, high-grade carotid stenosis, intracranial aneurysm, and dural arteriovenous fistulae. Pulsatile tinnitus is also a feature of idiopathic intracranial hypertension. Although bilateral deficits reflect general processes such as ototoxicity (aminoglycosides, salicylates, or loop diuretics), noise exposure, and age-related hearing loss (presbycusis), unilateral hearing loss should raise concern of neoplastic, vascular, neurologic, or inflammatory etiologies. Fluctuating symptoms are seen in Ménière disease, while progressive loss may indicate tumor (e.g., vestibular schwannoma). Ménière disease typically results in low roaring tinnitus, while high-pitched tinnitus may suggest tumor or presbycusis. Sudden hearing loss occurs with viral neuritis or vascular processes that occlude the cochlear blood supply from the internal auditory artery, a terminal branch of the anterior inferior cerebellar artery or the basilar artery. This can also occur from compression by a tumor in the internal auditory canal. A stroke from occlusion of the anterior inferior cerebellar artery itself may cause infarction of the pons, with ipsilateral hearing loss, vestibular symptoms, gait ataxia, conjugate gaze palsy, ipsilateral facial paralysis, and sensory loss, as well as contralateral body loss of pain and temperature sensation. Combined symptoms of tinnitus and vertigo are inner ear symptoms and indicate involvement of the cochlea, vestibular labyrinth, auditory nerve, or a combination of structures.

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