Vestibular Function Impairment in Alzheimer's Disease.

Background: Falls and fractures due to impaired balance in patients with Alzheimer's disease (AD) have an adverse effect on the clinical course of the disease.

Objective: To evaluate balance impairment in AD from the viewpoint of vestibular functional impairment.

Methods: The subjects were 12 patients with AD, 12 dementia-free elderly adults, and 12 younger adults.

Residual central nervous system damage due to organoarsenic poisoning.

Background: Drinking well water contaminated with the organoarsenic compound diphenylarsinic acid (DPAA) causes central nervous system (CNS) disorders that improve within several years after last drinking such water. Subjective symptoms such as lightheadedness and dizziness appear to persist, however, suggesting CNS damage. We evaluated CNS damage due to DPAA by detecting abnormal eye movements.

Downbeat nystagmus due to a paramedian medullary lesion.

Cell groups of the paramedian tract, which are located in the paramedian region of the lower brainstem, are eye-movement-related neurons that project to the cerebellar flocculus. Their inactivation produces downbeat nystagmus, which resembles eye movement disorders resulting from lesions of the cerebellar flocculus in animal experiments. Therefore, paramedian tract cells are assumed to fulfill an important function in ocular movement control, such as gaze-holding and maintaining vestibular balance.

Recurrent isolated abducens nerve paresis associated with persistent trigeminal artery variant.

We report a 74-year-old woman who presented with recurrent isolated abducens nerve paresis. Cranial magnetic resonance imaging revealed that the right abducens nerve was sandwiched between the right internal carotid artery and a persistent trigeminal artery (PTA) variant, which might have led to neurovascular compression of the abducens nerve, resulting in abducens nerve damage. Normal variants of PTA, which are cerebellar arteries originating from a precavernous portion of the internal carotid artery, must be carefully observed as such variants can potentially cause a neurovascular compression of the abducens nerve.