Contributed by 1John P. Rossiter MB, BCh, PhD, 2Donald G. Brunet MD
Queen's University and Kingston General Hospital, Kingston, Ontario K7L 3N6, Canada
A woman in her late 60's presented in the 1980's with a 6 month history of lower limb numbness and difficulty going downstairs. In the lower limbs there was 4/5 weakness from the hips distally, absent deep tendon reflexes, diminished sensation distally to light touch and pinprick, the neurological examination otherwise being unremarkable. Multiple investigations, including myelography, were within normal limits. By 9 months post-onset she had stocking distribution burning dysesthesias, diminished vibration sensation throughout her lower limbs, wide-based gait and electrophysiological evidence of axonal neuropathy in the right leg. By 14 months she was wheelchair dependent, with perineal numbness, urinary incontinence and repetitive flexor withdrawal movements of her lower limbs. A cauda equina / lower cord lesion was suspected, but CT myelography was unremarkable. Over several days there was further deterioration, with power 0-1/5 distally to 2-3/5 proximally, absent position and vibration sensation and reduced pinprick to mid lumbar level. By 20 months there was extensive denervation electrophysiologically in L5-S2 nerve root distributions. Several years later the patient died of pneumonia and a consented autopsy was performed.
On the dorsal surface of the lumbosacral and lower thoracic spinal cord there was a tortuous blood vessel (arrowed in Figures 1 and 2). Microscopy of the lower two-thirds of the lumbar (Figure 2, 3; solochrome cyanine R stain) and upper-sacral cord, showed atrophy and gliosis of the posterior half and to a lesser extent of the ventral horns. There was partial cavitation of the posterior cord, where there was a network of hyalinized microvessels (examples arrowed in Figure 3). Destruction of the posterior columns at these caudal levels was reflected by atrophy of the gracile fasciculi rostrally (Figures 4 and 5, upper thoracic cord, g = gracile, c = cuneate fasciculi). What is your diagnosis?