Position sense in the lateral funiculus?
In recent years the traditional pathway for position sense in the lower extremities has been challenged and it has been proposed that in the upper spinal cord the relevant fibres ascend not in fasciculus gracilis but in the dorsolateral part of the lateral funiculus with the dorsal spinocerebellar tract. To determine whether this premise is correct we have re-examined the clinical findings of five patients with spinal cord lesions and 62 patients who had undergone medullary tractotomy at a level where the dorsal spinocerebellar tract overlies the spinal tract of V. Of the five patients with spinal cord lesions, four had interrupted dorsal columns but intact dorsal spinocerebellar tracts. They had a loss of position sense, vibratory sense and tactile discrimination. Another patient with a severed dorsal spinocerebellar tract and an incomplete lesion of the dorsal columns had no loss of position or vibratory sense but possibly some tactile impairment. None of the 62 medullary tractotomy patients had any loss of position, vibratory or tactile sensibility. These observations do not support the premise that position sense from the lower extremities is carried by fibres of the dorsal spinocerebellar tract at any level but do support the traditionally accepted pathway for position sense. Other papers that address this and related problems in humans are also reviewed.