Cognitive Dysfunctions in Patients With Severe Obstructive Sleep Apnea Syndrome: Neuropsychological Test and Event-Related Potential Study

BACKGROUND: Patients with obstructive sleep apnea syndrome (OSAS) show variety of dysfunctions in cognitions including general cognitive function, attention, and frontal lobe and executive function. However, there is no consensus on the main features of the cognitive dysfunction in OSAS patients. So we performed neuropsychological tests and event-related potential (ERP) studies in patients with severe OSAS to evaluate the cognitive dysfunctions and changes of auditory and visual P300. METHODS: Twenty-eight men with severe OSAS (apnea hypopnea index (AHI)=63.1+/-17.8/hr) and 16 age, sex, education- matched normal controls (AHI=2.9+/-1.8/hr) underwent neuropsychological tests and ERP studies. RESULTS: Patients with severe OSAS showed deficits in corsi block forward and backward test during neuropsychological evaluation, and delayed latency and decreased amplitude of auditory P300. There were significant correlations between auditory P300 amplitudes and digit span forward or corsi block forward test scores, and between visual P300 amplitudes and digit symbol test scores. CONCLUSIONS: These findings suggest that severe OSAS patients may have deficits in attention and short-term memory, and abnormal auditory P300.

Compressive Tibial Neuropathy Induced by Myxoid Liposarcoma in the Popliteal Fossa

Tibial nerve compression occurs most often at the ankle. A proximal tibial nerve entrapment at the popliteal fossais rare because of the deep location of the nerve. We report a case of tibial neuropathy caused by a myxoid liposarcoma at the popliteal fossa, which was diagnosed by electrophysiologic studies, magnetic resonance imaging and an open excisional biopsy. This case illustrates that tumors should be considered when patients present with an entrapment neuropathy of the proximal tibial nerve.