The comments made by Ferroli et al regarding our report on linear pontine trigeminal root lesions in MS1 are important, and we would like to respond to them.
We are very much pleased to know that Ferroli et al reported that 12 out of 15 patients with MS and trigeminal neuralgia showed T2 hyperintensity along pontine trigeminal pathways on MRI.2 Although they did not show the precise MRI appearance in their report, Ferroli et al confirmed that trigeminal neuralgia was frequently associated with linear pontine trigeminal root lesions in MS. Among our subjects, however, MS patients with linear pontine trigeminal root lesions had various facial sensory impairments, and not all patients with trigeminal symptoms had linear pontine trigeminal root lesions. We think these peculiar MRI lesions are common in MS patients with trigeminal symptoms,1,3 but they may be not specific to MS patients with trigeminal neuralgia. Ferroli et al also stated that linear pontine trigeminal root lesions were "at times" found in patients with trigeminal neuralgia in whom MS had been excluded. But this was not confirmed in an MRI study of 600 cases of trigeminal neuralgia (mostly non-MS) by a Japanese neurosurgeon (A. Kondo, MD; oral communication; March 13, 2001). We would be very interested to know the frequency of linear pontine trigeminal root lesions on MRI among the patients of Ferroli et al who had trigeminal neuralgia.
Nakashima I, Fujihara K, Itoyama Y. In reply. Arch Neurol. 2001;58(8):1311-1312. doi: