Electronystagmography in a patient labeled 'learning-disabled'.

A 29-year-old man came to the office with a history of difficulty reading since childhood. When he was in elementary school, he was told that he was learning-disabled. His essay-writing skills were good. His problem was that he had difficulty comprehending what he read. His reading speed had not increased over time. Otherwise, the patient said that his left side felt weak; when he walked, he looked uncoordinated. He had no significant hearing loss and no tinnitus or aural fullness, although there was a family history of hearing loss. He had ulcerative colitis and was taking a corticosteroid.

Clinical examination revealed that the patient had difficulty performing the sharpened tandem Romberg's test. He also had bilateral nuchal tenderness.

Electronystagmography revealed minimal positional nystagmus. His alternate binaural bithermal caloric response was normal with a 7% reduced vestibular response (RVR) and a 16% directional preponderance. The simultaneous binaural bithermal caloric test elicited a type 2 response with an RVR left. The results of audiometry, including acoustic immittance testing, were normal. The patient's history was common for a child who is labeled as learning-disabled or dyslexic. More often than not, such children have a vestibular system abnormality--usually a peripheral vestibular disorder. A vestibular disorder has a tonic effect on the extraocular muscles through the medial longitudinal fasciculus, which makes it difficult or impossible to track words across a printed page. Medications directed at vestibular suppression for dizziness have been effective. The author's preference is to seek an etiology for the vestibular abnormality and then to treat the cause, which should ultimately alleviate the patient's symptoms.

The nuchal tenderness is sign of an overactive vestibulospinal or vestibulocollic reflex emanating from the inner ear. Spasms in the neck muscles can affect head position and impair reading.