Objective:

The aim of this study is to better understand the clinical characteristics of polyneuropathy in patients with anti-Plexin D1 antibodies.

Background:

A novel autoantibody against Plexin D1 was recently discovered in some patients with neuropathic pain. A case series study found that immunosuppressants ameliorate neuropathic pain in patients with anti-Plexin D1 antibodies. However, the symptoms, disease course, and optimal treatment in patients with this antibody are still unclear. 

Design/Methods:

A retrospective study included 43 patients with polyneuropathy or neuropathic pain who were referred to a neuromuscular subspecialty clinic between March 2021 and January 2022. All patients were tested for serum anti-Plexin D1 antibodies by the Western blot test. Clinical data and test results were then collected. 

Results:

7 patients (16%) out of 43 had anti-Plexin D1 antibodies. Four were males, and three were females. Common symptoms included pain (n=6 [85%]), numbness (n=5 [71%]), and paresthesia (n=5 [57%]). Four patients (67%) had other autoimmune antibodies. In terms of final diagnosis, four patients had length-dependent polyneuropathy (one had superimposed lateral femoral cutaneous neuropathy), two had small fiber neuropathy, and one had peripheral nerve hyperexcitability disorder. Symptoms were mostly tolerated with gabapentinoids. Only one patient received immunotherapy and had no response. There was no significant difference in age, gender, presenting symptoms, type of neuropathy, and neuropathic pain control between patients with anti-Plexin D1 antibodies and patients without anti-Plexin D1 antibodies. 

Conclusions:

Anti-Plexin D1 antibody is sometimes detected in polyneuropathy patients with predominant sensory symptoms. These patients usually respond to gabapentinoids. However, the presence of this antibody is not associated with a specific clinical phenotype. Further investigations are needed to determine the role of anti-Plexin D1 antibody in clinical practice.