Transient bilateral vestibular dysfunction caused by intoxication with low doses of styrene

Abstract

Bilateral vestibulopathy is a frequent cause of postural imbalance and gait disorder, particularly in elderly subjects [1]. In three out of four cases the etiology remains unclear, as was shown in a study on 255 patients [2]. The three most frequent known causes are the use of ototoxic antibiotics, bilateral Meniere’s disease and meningitis. In most cases, there is a permanent persisting deficit without recovery of vestibular function [3]. A 76-year-old man was admitted to our dizziness unit. Seven months prior to that, symptoms had started with a progressive spasmodic sensation in the forehead and writer’s cramp. The first neurological examination at that time revealed a slight pallhypesthesia of the distal extremities, which has not been noted since that time, and a slight unsteadiness. Laboratory examinations showed only an elevated level of creatine kinase, which had been present for many years and was of unknown origin. MRI of the brain, duplex sonography and EEG were normal. There was no history of brain infection, ototoxic medication, noise exposure, or nicotine or excessive alcohol abuse. He did not report any distinct new hearing problems. No oscillopsia-like symptoms and no deterioration in darkness were reported. In the following months the symptoms worsened. The patient reported additional dizziness (postural vertigo), postural imbalance (especially with eyes closed), weakness and headache. In addition, concentration problems appeared. 3 months after the first symptoms had started the patient organized an environmental engineering analysis of his apartment as he had noticed a pungent odor since the renovation of the floor pavement and parquet floor in his bedroom after water damage (caused by a burst pipe). This event correlated with the first symptoms. For moistureprotective reasons the floor was covered with a sheet of epoxide. The laboratory report showed a fourfold higher concentration of styrene (1,350 lg/m) in the air of the bedroom than is permitted in Germany (RW II 300 lg/m). From that time the patient avoided the contaminated room. The patient came to our dizziness unit 7 months after the first symptoms had begun. Our first examination showed a normal head-impulse test (HIT) [4]. There was reduced vibration perception at the distal lower extremities on both sides (3/8). Testing of the vestibulospinal reflexes (Romberg’s sign) showed increased sway with closed eyes. To examine the function of the peripheral vestibular organ separately, we used the commercially available EyeSeeCam VOG (www.eyeseecam.com). Video-oculography (VOG) measures eye movements directly using infrared cameras. The camera is attached to goggles with semitransparent glasses that prevent fixation of the surroundings. We applied a standard protocol for caloric irrigation (cold and warm water on both sides) and revealed a significant bilateral hyporesponsiveness of the horizontal canals (peak slow-phase velocity of the caloric nystagmus C. S. Fischer (&) O. Bayer M. Strupp German Center for Vertigo and Balance Disorders, University Hospital Munich, Campus Grosshadern, Marchioninistrasse 15, 81377 Munich, Germany e-mail: carolin_simone.fischer@med.uni-muenchen.de