Dr Kelkar rightly points out the difficulties one might have in making the correct diagnosis in patients with multifocal sensory and motor neuropathy of otherwise unknown cause. It may not always be possible to know for sure whether the neuropathy is demyelinating or axonal or whether vasculitis is present.
The correct diagnosis can be made with certainty if there is clear evidence of primary demyelination on results of electrodiagnostic or pathologic studies or if there is evidence of vasculitis in nerve biopsy specimens. In many cases, however, the diagnosis is not so clear-cut. Various electrodiagnostic criteria for demyelination have been proposed that differ in their sensitivity or specificity.1 In addition, obtaining a nerve biopsy specimen may not be possible, or certain pathologic features may be missed if an uninvolved nerve segment is examined.
Alaedini A, Sander HW, Latov N. Forme Fruste Manifestations of Chronic Inflammatory Demyelinating Polyradiculoneuropathy—Reply. Arch Neurol. 2004;61(6):984. doi:10.1001/archneur.61.6.984-b