Tired legs—a gut diagnosis

Abstract

In March, 2009, a 66-year-old man presented to us with a 1-year history of recurrent right leg fatiguability and painful cramps in the leg on waking. 10 years earlier he had had a transient ischaemic attack (TIA) causing right hemiparesis. On neurological examination, he had no signs in the right leg, but had slight weakness of the left extensor hallucis brevis, left extensor digitorum brevis, left tibial anterior, and left peroneal muscles. He had decreased pinprick sensation over the dorsum of his left foot. The symptoms of fatiguability and cramps did not fi t with a diagnosis of recurrent TIA. Restless leg syndrome, characterised by leg discomfort at rest with urge to move the legs, was also considered unlikely because his symptoms were not relieved by movement, and walking caused fatigue. We considered a diagnosis of lumbar canal stenosis, which can present with neurogenic claudication and radiating leg pain on walking. Electro myography was normal, making this diagnosis unlikely. We investigated somato sensory pathways in the legs by recording somatosensory evoked potentials (SEPs), after tibial nerve stimulation. Our patient had normal cauda equina and lumbar enlargement responses, but cortical responses were absent bilaterally (fi gure). These results suggested dysfunction of somatosensory conduc tion along the spinal dorsal columns. A spinal cord vascular malformation can cause intermittent gait and sensory disturbance with back or root pain, and could explain the SEP abnormality. However, spinal cord MRI showed only intervertebral disc protrusions at C6–C7 and L4–L5 with no spinal cord or nerve root compression; these minor abnormal ities could not explain his symptoms and signs. We then considered metabolic and nutritional, viral, toxic, autoimmune, and paraneoplastic myelopathies as possible diagnoses. Blood tests showed raised IgM antibody to cardiolipin 185 U/mL (normal range <10) and IgM antibody to β2 glycoprotein-I 71 U/mL (<25); low serum folate concentration 5·2 nmol/mL (6·8–40), and serum B12 140·2 pmol/L (118–443). Anti phospholipid antibodies can cause myelopathy by vascular and immune mechanisms. However, the characteristic myelopathy is a transverse myelitis with acute paraparesis and a positive MRI. Vitamin B12, and folate defi ciencies are characterised by SEP abnormalities. Although our patient had no gastrointestinal symptoms, we investigated whether he had asymptomatic malabsorp tion; the concentration of antibodies to trans glutaminase 228 U/mL (normal range <25) was very high and antiendomysial antibodies were detected. Duodenal hist ology was diagnostic of coeliac disease. A gluten-free diet was introduced with folic acid, oral vita min E, and parenteral vitamin B supplementation. In January, 2010, our patient was in complete remission and his SEP abnormalities had improved (fi gure). Although neurological symptoms occur in patients with coeliac disease, myelopathy has rarely been described. Our patient’s SEP abnormalities suggested a dorsal column involvement that might have been related to vitamin defi ciencies secondary to malabsorption. Dorsal column demyelination is common in vitamin B12 defi ciency; however, at autopsy both demyelination and infl ammatory cell infi ltration of dorsal columns have been reported in patients with ataxia and gluten sensitivity, suggesting that immune mechanisms might also cause spinal cord damage. Physicians should consider coeliac disease as a cause of unexplained neurological abnormalities, even in older patients.