[Hyperalgesia with loss of temperature sensation in one side of the body due to pinpoint infarction of contralateral spinothalamic tract].

We report a 67-year-old man who presented sudden loss of temperature sensation associated with hyperalgesia in the left trunk and extremities. No abnormal lesions were found on routine magnetic resonance image (MRI) in the brain and spinal cord. He did not show common manifestations of the lateral medullary syndrome including vertigo, nystagmus, ataxia, Horner's syndrome and ipsilateral facial sensory loss. We however suspected this syndrome, because he complained of characteristic, severe pain and electrical sensations in one side of his body. Reexamined, thinly sliced T2-weighted MRI showed a very small high intensity spot in the right medulla, corresponding to the location of lateral spinothalamic tract. Oral carbamazepine was partially effective to ameliorate the intractable central poststroke pain.