The value of transcranial cerebral sonography in diagnosing neurootological disorders.

Transcranial cerebral sonography (TCCS) is a noninvasive technique that allows the clinician to detect abnormal intracranial-inner-ear fluid interactions in terms of nanoliter tympanic membrane displacements. The displacements recorded in TCCS are evoked either by the acoustic stapedius reflex or spontaneous movements generated by intracranial cardiovascular or by respiratory pressure waves transmitted through the inner ear to the stapes and thence to the tympanic membrane. Analysis of the amplitude and direction of these displacements has enabled neurosurgeons and neurologists to estimate cerebrospinal fluid pressures in patients evaluated by TCCS. This procedure allows for applications in neurootology, particularly in those patients who present with symptoms of pulsating tinnitus, dizziness and imbalance, or hearing loss. This study describes the application of TCCS tests in a series of patients whose diagnoses included perilymphatic fistula and a variety of neurological conditions such as idiopathic intracranial hypertension, type I Arnold-Chiari malformation, sigmoid sinus thrombosis, hydrocephalus, and cerebrovascular malformations. We conclude that both raised intracranial pressure and abnormal intracranial pressure waves are associated with common neurootological symptoms, including tinnitus, dizziness, and hearing dysfunction. Furthermore, TCCS is a valuable addition to neurootologists' test batteries.