A Case in Which Acute Spasmodic Pain in the Left Lower Extremity Was Completely Relieved by Sub-Dural Division of the Posterior Roots of Certain Spinal Nerves, All other Treatment Having Proved Useless. Death from Sudden Collapse and Cerebral Hæmorrhage on the Twelfth Dat after the Operation, at the Commencement of Apparent Convalescence