Cerebral microangiopathy (CM) is a general term for small ischemic changes related to small blood vessels in the brain. Immune thrombocytopenia (ITP) is a rare acquired autoimmune disease that is characterized by low platelet count and increased risk of hemorrhage. We describe vestibular testing completed on a 64-year-old patient with CM and ITP presenting with complaints of general instability and listing while walking, decreased stability in dark environments, and blurred vision with head movement. Results indicated a severe loss of horizontal semicircular canal function bilaterally with a somatosensory-dependent pattern of postural instability.
 This case emphasizes the importance of vestibular testing to determine the level of involvement of the vestibular system in the patient’s symptomatology with known CM. Due to the increased risk of severe injury in those with ITP and the unknown effects this may have on the vestibular and balance systems, what is known about the pathophysiology of ITP and possible implications are reviewed.
 Case report.
 Previous audiological and medical records were obtained. Vestibular testing included videonystagmography; video head impulse test (vHIT); rotational chair including sinusoidal harmonic acceleration (SHA), step velocity, SHA with fixation, and visual vestibular SHA; computerized dynamic posturography battery including sensory organization test (SOT), motor control test, and adaptation test.
 Audiological evaluation indicated a mild to moderately severe sensorineural hearing loss bilaterally. Ocular motor evaluation results indicated abnormal “cog-wheel” like tracings in smooth pursuit, hypometric saccades with abnormally increased latencies and reduced optokinetic gain. The patient also demonstrated apogeotropic nystagmus during head/body right and head/body left positions when fixation was denied. Bilateral bithermal calorics indicated a bilateral hypofunction. Horizontal vHIT results indicated reduced gain bilaterally. SHA results confirmed significant gain reductions at all frequencies tested and step velocity results indicated reduced gain and reduced time constants during all prerotary and postrotary measures. SOT results indicated a somatosensory-dependent pattern (i.e., reduced equilibrium index scores and falls in conditions 4, 5, and 6).
 These findings emphasize the importance of comprehensive vestibular evaluations of patients with CM, ITP, and complaints of instability. Identification and quantification of residual peripheral vestibular function as well as central system involvement can provide significant information pertinent to falls risk reduction and vestibular rehabilitation strategies, outcomes, and goals.

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