[Neuro-otological Studies of Patients Suffering from Dizziness with Cerebrospinal Fluid Hypovolemia after Traffic Accident-associated Whiplash Injuries].

Vertigo and dizziness are common clinical manifestations after traffic accident-associated whiplash injury. Recently, Shinonaga et al. (2001) suggested that more than 80% of patients with whiplash injury complaining of these symptoms showed cerebrospinal (CSF) hypovolemia on radioisotope (RI) cisternography (111In-DTPA). However, neuro-otological studies to investigate the pathophysiological mechanisms underlying these symptoms have been insufficient. In the present study, patients complaining of these symptoms with CSF hypovolemia after traffic accidents were investigated with posturography and electronystagmography (ENG). Fourteen patients (4 men, 10 women; 24-52 yr) were examined with posturography and showed parameters (tracking distance & area) significantly (p<0.01) larger than those of healthy subjects. Among them, five cases (1 man, 4 women; 31-52 yr) were further investigated with ENG. The slow phase peak velocities of optokinetic nystagmus (OKN) and optokinetic-after nystagmus (OKAN) were significantly (p<0.01) reduced (62.64±6.9 SD deg/sec, 60.76±10.74 SD deg/sec, respectively) and frequencies of OKN were reduced (139.7±10.75 SD), while the ocular smooth pursuit was relatively preserved. Magnetic resonance images (sagittal view) of these five patients demonstrated the downward displacement of the cerebellar tonsils and flattening of the pons, which are characteristic features of CSF hypovolemia, called "brain sagging." Our results suggest that brain sagging due to CSF hypovolemia impairs vestibular and vestibulocerebellar functions, which may cause dizziness and vertigo.