Subacute combined degeneration of the spinal cord (SCD) is the most frequent neurological manifestation of vitamin B₁₂ deficiency. It is now seen much less often than in former years as the diagnosis is made earlier in most patients on haematological grounds. Nevertheless, patients in whom the initial manifestations are neurological still occur and it is a tragedy if early diagnosis is not made in this treatable condition. Presentation is either with a distally predominant sensory neuropathy, accompanied or preceded by myelopathy, and sometimes by optic atrophy or cognitive change. Suspicions that a sensory neuropathy may be related to vitamin B₁₂ deficiency can be raised by an upper limb onset and the occurrence of Lhermitte's symptom.

Hemmer et al in this issue (pp 822-827) document retrospectively the clinical, electrophysiological, and MRI findings in nine patients with SCD. In four the disorder was related to pernicious anaemia, in four others to gastrointestinal . . . [Full text of this article]