Somatosensory functions are subdivided into 2 large groups: the elementary somatosensory functions, which consist of light
touch, pain, thermal sensation, joint position sense, and vibration sense, and the intermediate somatosensory functions, which
include 2-point discrimination, tactile localization, weight, texture, and shape perception. In this report, we describe a
patient with somatosensory dysfunction after infarction of the postcentral gyrus. On physical examination a month after the
onset of the infarction, voluntary movements were skilful, and both the elementary and intermediate somatosensory functions
were disturbed in the right hand. The patient also displayed a decrease in the skin temperature of the right hand. The sensory-evoked
potential in response to electrical stimulation of the right median nerve was normal, and brain MRI showed that the infarction
was located in the posterior half of the left postcentral gyrus. These findings suggested that the lesion was situated at
areas 1 and 2, and that area 3b was preserved. Thermography revealed that the skin temperature of the right hand was decreased
predominantly on the ulnar side, and that recovery from cooling with ice water was delayed. By comparing the results of our
patient with a case report that showed no disturbance of the elementary somatosensory functions with a localized lesion in
the postcentral gyrus, we suggest that area 1 participates in the elementary somatosensory functions and that skin temperature
may be controlled somatotopically in the somatosensory cortex.
Key words postcentral gyrus - elementary somatosensory functions - intermediate somatosensory functions - thermography - cerebral infarction
Received: 19 February 2002, Received in revised form: 16 April 2002, Accepted: 18 April 2002
Correspondence to M. Satoh