A Woman with Leg Numbness and Weakness

Clinical History

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.

Pathology

On the dorsal surface of the lumbosacral and lower thoracic spinal cord there was a tortuous blood vessel (arrowed in Figure 1a and 1b). Microscopy of the lower two‐thirds of the lumbar (Figure 1b, 1c; 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 1c). Destruction of the posterior columns at these caudal levels was reflected by atrophy of the gracile fasciculi rostrally (Figure 1d and 1e, upper thoracic cord, g = gracile, c = cuneate fasciculi). What is your diagnosis?

Figure 1.

 

Diagnosis

Foix‐Alajouanine syndrome (Spinal dural arteriovenous fistula and related changes in spinal cord).

Discussion

The present case shows very characteristic features of ‘spinal dural arteriovenous fistula’ (Spetzler 4 classification: arteriovenous fistula, intradural, dorsal type A [single arterial feeder]) and related changes in the spinal cord, historically classified as Foix‐Alajouanine syndrome 1.

At the dura the arteriovenous shunt (Figure 1a, yellow arrow) between a radiculomeningeal artery and radicular vein is partially obscured by a nerve root. The arterialized vein courses rostrally before turning (Figure 1a, red arrow) caudally along the posterior surface of the spinal cord and shows evidence of remote thrombosis (Figure 1b, inset).

Spinal dural arteriovenous fistula is a rare acquired condition, typically affecting middle‐aged men (M:F ∼ 5:1). The arteriovenous shunt causes chronic venous congestion and hypertension (reflected in the abnormal network of microvessels) and resulting progressive ischemic myelopathy. The initial symptoms are often non‐specific and the clinical evolution variable 2. In the pre‐MRI era (present case), the diagnosis was often delayed or missed. MR‐imaging typically shows longitudinal T2‐signal abnormality in the central cord and perimedullary flow voids. Catheter angiography identifies the exact level of the fistula and influences selection of its therapeutic neurosurgical disconnection or endovascular occlusion 3. In the present case, remote Wallerian degeneration of the gracile fasciculi (Figure 1d and 1e) correlated with the clinical finding of complete loss of position and vibration sensation below a mid lumbar level.