Intractable pruritus in neuromyelitis optica

Abstract

Neuromyelitis optica (NMO) is an immune-mediated disease of the central nervous system. Pruritus in patients with NMO has rarely been reported. We aimed to explore the characteristics and underlying mechanisms of pruritus in NMO patients. We reviewed the case records of 64 NMO patients who visited the Department of Neurology at the Third Hospital of Sun Yat-sen University between 2009 and 2015. Of the 64 aquaporin-4 antibody-positive NMO patients, 18 had pruritus. Spinal magnetic resonance imaging (MRI) showed lesions in all of these patients. A total of 13 patients presented with brain lesions, and four had lesions in the periaqueductal gray matter on cerebral MRI. However, the anatomical distribution of pruritus did not always correspond to the dermatomal distributions of the involved spinal cord segments. Pruritus was completely or partially relieved after treatment. Pruritus is not a rare occurrence and may be a characteristic feature of NMO.

Complexity and wide range of neuromyelitis optica spectrum disorders: more than typical manifestations

“… 75 In this regard, Xiao et al retrospectively analyzed 64 Chinese NMOSD patients who were AQP4-IgG positive, and found that 28% (18/64) of these patients had the symptom of pruritus. 76 Furthermore, recent studies have reported identical findings and further revealed that pruritus can be detected as an initial symptom before the attack. Hence, this may indicate a new episode of myelitis in patients with NMOSD.…”

“…This reflects the typical centralized location of lesions in the spinal cord that affects dorsal horn neurons and gray matter in patients with NMOSD. 76 A third possible mechanism may be that neurons involved in the regulation of neuropathic pruritus may highly express AQP4, and thereby be preferentially involved in NMOSD. 75 …”

Letter re “Is pruritus an indicator of aquaporin-positive neuromyelitis optica?”

“…Recently, pruritus has been reported as a common symptom in neuromyelitis optica (NMO)/NMOSD patients, particularly in relapses of longitudinally extensive transverse myelitis (LETM). 1–4…”

“…In addition, pruritus may be observed as a first symptom in NMOSD patients, even before other neurological disorders. 1–4…”

“…Therefore, pruritus can be due to ephaptic activation (axonal irritation) within a partially demyelinated lesion in fiber tracts as also seen in paroxysmal tonic spasm (PTS). 1–5 Proteinase-activated receptor 2 or 4 in spinothalamic tract has been reported as activated by pruritus trigger. In addition, brainstem descending modulatory pathways and astrocyte damage (due to AQP4-ab against astrocyte foot) are well-known factors that contribute to pruritus and PTS.…”