Alloaesthesia.

Alloaesthesia is a condition in which a sensory stimulus given on one side of the body is perceived at the corresponding area on the other side. We observed this in 20 out of 123 patients with hypertensive cerebral haemorrhage in the acute stage (within twenty days), all except 1 in the right hemisphere. This phenomenon was observed in 17 out of 35 patients with right putaminal haemorrhage and only 1 out of 30 patients with right thalamic haemorrhage, suggesting it may be useful in differentiating putaminal from thalamic haemorrhage in the right hemisphere. Three patients, with cervical tumour, cervical disc herniation and multiple sclerosis also showed alloaethesia. They had anterolateral lesions of the spinal cord. The cerebral and spinal cord lesions presented similar symptomatic characteristics of alloaesthesia. It is suggested that as alloaesthesia is produced by noxious stimuli not only in spinal cord but also in cerebral lesions it may represent an elementary sensory disturbance of sensory pathways, and not a higher cortical dysfunction.