Primary Sjögren’s syndrome is an autoimmune disorder that primarily affects exocrine glands, presenting with xerostomia and keratoconjunctivitis sicca. However, atypical manifestations such as dysautonomia may also occur, these include postural orthostatic tachycardia syndrome (POTS), gastrointestinal dysmotility, tachycardia, heat intolerance, in severe cases, autonomic neuropathy with numbness and pain in the extremities. These symptoms likely result from autoimmune-mediated injury to the autonomic nervous system. Further, the coexistence of antiphospholipid and thyroid autoantibodies may indicate an underlying polyautoimmune state called overlap syndrome, delaying the diagnosis and management. 

A 32-year-old man with 4 year history of lightheadedness, fatigue, excessive sweating, bowel & bladder incontinence, and palpitations on exertion or standing. Initial vital signs showed a pulse of 90/min supine and 130/min standing, blood pressure of 110/70 mmHg supine and 90/60 mmHg standing, and a respiratory rate of 14/min. Physical examination revealed reduced sensation in both lower extremities. The tilt-table test and Valsalva maneuver were abnormal.

Workup:
Serum studies showed positive lupus anticoagulant and anticardiolipin IgM antibodies, along with elevated anti-thyroid peroxidase antibody. Histopathological examination of lip biopsy revealed periacinar, perivascular, and periductal lymphocytic infiltrates. Absent lower limb sympathetic skin response suggested small fiber involvement. Nerve conduction studies showed reduced sural nerve amplitudes bilaterally.

Course:
The patient was initially treated with intravenous immunoglobulin (IVIG), resulting in modest clinical improvement. He was subsequently started on gabapentin 100 mg once daily for neuropathy and metoprolol 25 mg twice daily for tachycardia. Supportive treatment was provided for his autonomic symptoms, and the patient remains clinically stable on follow up.

This case highlights autoimmune dysautonomia and neuropathy as neurological manifestation of Primary Sjögren’s syndrome with possible polyautoimmunity, which may delay diagnosis. Management is mostly supportive and involves immunosuppressive therapy. Early recognition of symptoms is essential as; timely immunotherapy may improve clinical outcomes and prevent disease progression.