ENG in 16-year-old with a history of dizziness since early childhood.

A 16-year-old girl came to the office complaining of dizzy spells. Her spells occurred approximately every 4 weeks and lasted about 3 to 5 hours; they always occurred some time after 1 p.m. Her episodes were characterized by a lack of balance while standing and walking and a rotary feeling while lying down and getting up. These spells were occasionally accompanied by nausea and vomiting. She would sometimes experience dizziness while running, but not while swimming. She also reported problems in school with comprehension and reading, but not with tracking words visually.

She reported that she had been experiencing dizziness since early childhood. Her records showed that she had been born with hyaline membrane disease. During her early infancy, she had experienced periodic vomiting, after which she would fall asleep. She first began to experience dizzy spells later on in childhood; they were accompanied by nausea and vomiting.

Subjective dizziness could not be induced during testing, and the results of positional testing were quite abnormal. Electronystagmography (ENG) in the 0[degrees] supine position produced an oblique right-down-beating nystagmus in both the horizontal and vertical channels. Some rotary component might have also been present. Turning the neck to the right induced a 32[degrees]/sec left-beating nystagmus. The baseline shifted, as revealed by the cut-off of the nystagmus. The velocity of the nystagmus was greatly reduced by straightening the neck with a 6[degrees]/sec induced left-beating nystagmus as her body was turned on her right side. Turning the neck to the left or lying on the left side produced a similar right-beating nystagmus, with a shift of the baseline to the right. There was no nystagmus in the 30[degrees] supine position.

The alternate binaural bithermal test produced hyperactive responses ([greater than]25[degrees]/sec), suggesting a possible lack of central suppression. Use of Jongkee's formula did not reveal any significant reduced vestibular response or directional preponderance; both calculated at 2%. The simultaneous binaural bithermal test (not shown) revealed nystagmus only with the cool stimulus of 5[degrees]/sec left-beating nystagmus.