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We were interested to read the paper by Burtonet al reporting the association between giant cell arteritis and cervical radiculopathy. The evidence for giant cell arteritis seems incontrovertible, but the possibility remains that this patient might have had motor neuron disease coexisting with giant cell arteritis. Details of the clinical examination, investigations, and pathology point to this possibility. Furthermore, the neuropathological report does not include immunocytochemical studies that would be necessary to exclude the diagnosis of motor neuron disease.
The clinical picture is one of a lower motor neuron syndrome affecting all four limbs without objective sensory involvement. Denervation was confirmed in all four limbs, whereas the vascular inflammatory changes concentrated around the radicular arteries in the lower cervical roots. Pathological examination of the spinal cord demonstrated “diffuse pallor of myelin” with minor loss of anterior horn cells “and chromatolysis”. In the differentiation of the syndrome from motor neuron disease, it must be confirmed that the classic pathological features are absent. In addition to myelin pallor in the corticospinal tracts, staining for the microglial marker CD68 and astrocyte marker GFAP should be performed. Furthermore, staining of the motor cortex, brain stem, and spinal cord sections for ubiquitin and neurofilament should be performed to exclude a primary motor neuron degeneration.
Lymphocyte cuffing and microglial infiltration are common in motor neuron disease, even in those cases attributable to mutant SOD1.1 Ubiquitin staining is a very sensitive and specific marker for motor neuron disease, and should be searched for extensively before the diagnosis can be excluded with confidence.2 It is well known that motor neuron disease may present with symptoms due to respiratory muscle weakness,3 and otherwise the clinical phenotype in this case is very suggestive of the flail arm variant of the disease,4 and we would hope that a comprehensive neuropathological search for this diagnosis was performed in a case such as this before it was ascribed to a vasculitis and recorded as such in the literature.
Winer et al reply:
We are pleased that Leigh and Shaw found our report of interest and that the evidence that the patient had from giant cell arteritis is incontrovertible.
We also agree that the clinical features were very suggestive of motor neuron disease, which was in fact the antemortem clinical diagnosis. The only disagreement is whether the patient had two diseases or just giant cell arteritis.
Histological studies of the postmortem material, however, showed evidence of arteritis in the exact distribution of the clinical deficit—that is, the cervical roots associated with diaphragmatic function which we found convincing as the sole explanation for the clinical picture.
We agree that it is not possible to exclude the rare possiblity of both motor neuron disease and arteritis and will undertake the suggested staining of sections of the brain stem, spinal cord and motor cortex with ubiquitin.
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