Possible clinical overlap between postencephalitic parkinsonism and progressive supranuclear palsy.

Two somatosensory projection areas, S I and S II, have been shown to exist in the brains of mammals of various species.3 S I, located in the postcentral gyrus, is especially concerned with the integration of sensory experience and with the discriminative qualities of sensation. S II has been mapped to the parietal operculum in many animal species,3 including humans.4 According to recent studies with monkeys, the cortical area defined as S II lies limited to the inner bank of the parietal operculum, which is smaller in size than previously considered.5 The organisation of S II in humans remains unclear, although it has been considered as a cortical locus for pain perception.3 Penfield and Jasper4 initially identified an S II in humans in the precentral and postcentral cortex-using reports of sensations after electrical stimulation near the sylvian fissure. They proposed that S II was located in the superior bank of the sylvian fissure and contributed to somatic sensation. They also reported that no sensory disturbances occurred in patients after ablating S II. Conversely, the parietal operculum and insula have been described as producing various sensory disturbances such as impairment of all sensory modalities, impaired cortical sensation, or decreased pain and temperature sensation.6 To the best of our knowledge, there are no prior studies describing cortical infarction of a limited area in the inner bank of the parietal operculum. There have been reports of pure sensory stroke due to lesion along the common human sensory pathway including parietal cortical infarctions of S I.2 This patient showed restricted sensory impairment in light touch, pain, and temperature senses of the entire right side and fulfilled the criteria of pure sensory stroke. This sensory dysfunction seems to have resulted from a circumscribed cortical infarction on the inner bank of the contralateral parietal operculum, presumably S II. TETSUYOSHI HORIUCHI TAKASHI UNOKI AKIRA YOKOH Department ofNeurosurgery, Suwa Red Cross Hospital, Suwa, Japan SHIGEAKI KOBAYASHI KAZUHIRO HONGO Department ofNeurosurgery, Shinshu University School ofMedicine, Matsumoto, Japan