Methylenetetrahydrofolate reductase deficiency revealed by a neuropathy in a psychotic adult.

there was wasting and weakness of deltoid, biceps, and brachioradialis bilaterally; biceps and supinator reflexes were absent bilaterally but the triceps reflexes were present and there were no sensory symptoms or signs. Tone, power, and reflexes in the lower limbs were normal and both plantars were flexor. Abdominal wall movements with respiration were paradoxical and vital capacity fell from 3-2 litres sitting to 19 litres lying. The ESR was now 90 mm/hour. Electrical studies showed normal nerve conduction with evidence of acute C5 and C6 denervation bilaterally. An MRI scan of the cervical region and cerebrospinal fluid examination were normal. A gradual improvement in the patient's condition occurred but the ESR remained high and he continued to complain of occasional headaches. Eleven weeks after presentation a temporal artery biopsy was performed. Microscopy showed features typical of temporal arteritis with numerous giant cells within the wall of the artery, intimal fibrosis, and fragmentation of the internal elastic lamina. Steroid treatment was started immediately with prompt relief of the remaining headache and malaise; the strength in both arms and the exertional dyspnoea continued to improve. Observation over the next 12 months failed to find any other cause for his symptoms and signs. MRI (including MR angiography) of the brain showed that the pituitary tumour and the aneurysm of the ophthalmic artery had not increased in size; both are being managed conservatively. He remains well on a gradually reducing course of steroids and clinical examination of the eyes and upper limbs is now normal. In this case temporal arteritis was associated with a third nerve palsy, a bilateral classical intemuclear ophthalmoplegia, and a radiculopathy affecting the fifth and sixth anterior cervical roots bilaterally. On clinical grounds it seemed that the patient had associated impairment of diaphragm function but this was not assessed formally by transdiaphragmatic pressure measurements. Although other vascular risk factors were present, and a pituitary tumour, these could not be implicated in the pathogenesis of all the neurological deficits seen. The third nerve palsy was probably due to involvement of branches of the intraorbital ophthalmic artery as there were no features to suggest a nuclear or a fascicular third nerve palsy. A bilateral classical internuclear ophthalmoplegia is a rarely reported complication of temporal arteritis'2 and is probably due to emboli from the vertebral artery occluding perforating branches of the basilar artery. Both the vertebral and ophthalmic arteries are recognised as being frequently and severely affected in temporal arteritis.3 A cervical radiculopathy is an unusual feature of temporal arteritis and the aetiology is less clear. Five cases have been reported47 and in all cases the fifth anterior cervical root has been involved, unilaterally or bilaterally, and in only one case were there sensory signs; in one case there was also evidence of unilateral involvement of the sixth and seventh anterior cervical roots. Constitutional symptoms but no other neurological signs were present in the four cases for which details are available and in all of these patients considerable improvement occurred with prednisolone treatment. Two other cases of upper limb paresis occuring in patients with temporal arteritis have been reported but the aetiology of the weakness was not established.8 A review of the blood supply of the cervical spinal cord and roots provides a possible explanation for the pattem of root involvement seen. The main supply comes from the anterior and posterior spinal arteries, branches of the vertebral arteries. These vessels anastomose with anterior and posterior radicular arteries that enter the spinal canal alongside their corresponding roots. There is great variation in the number, size, and location of the radicular arteries,9 but if present those to the upper six cervical roots also originate from the vertebral arteries whereas those for C7, C8, and Ti originate from other vessels in the vicinity including the thyrocervical trunk and the costocervical trunk. Therefore the first six cervical segments and roots are dependent solely on a blood supply originating from the vertebral arteries. We think that the most likely explanation for the radiculopathy is arteritic or embolic occlusion of the relevant radicular artery due to involvement of the parent vertebral artery. A myelopathy has not been seen in association with the radiculopathies suggesting that essential downwards flow in the spinal arteries is maintained. This downwards flow may be able to compensate via anastomotic channels for involvement of radicular arteries to the upper cervical roots but not to the lowest "vertebral artery dependent" roots, C5 and C6; this may explain why these roots are so commonly affected. It has been suggested that the impairments seen are due to damage to the cords of the brachial plexus caused by a vasculitis in the neighbouring subclavian and axillary arteries7 but this seems unlikely as sensory involvement has been a feature in only one case and was restricted to a single dermatome. This case serves as a reminder of the many neurological signs that may occur in temporal arteritis and of their natural history. The diagnosis of temporal arteritis should always be considered in patients with multiple or fluctuating neurological signs involving the vertebrobasilar circulation, even if the ESR is not grossly raised at presentation.