Bilateral Parsonage-Turner Syndrome in a Young Adult Man Due to Parvovirus B19 Infection

Parsonage-Turner syndrome (PTS) is a rare neuromuscular disorder. Parvovirus B19 infection commonly causes a childhood exanthematous illness. Most previous case reports have documented unilateral parvovirus B19-associated PTS along with the systemic manifestations of parvovirus infection. This report highlights parvovirus B19-associated bilateral PTS without systemic manifestations. A 20-year-old gentleman was asymptomatic one and a half months ago when he developed an acute onset of excruciating right shoulder pain. After 7-10 days, he developed weakness and wasting in the right shoulder girdle. One month into the illness, he developed similar complaints in the left shoulder. At presentation, there was marked wasting of the bilateral deltoids, biceps, triceps, and the periscapular muscles. The motor power was Medical Research Council (MRC) grade 0/5 at the right shoulder, elbow, and wrist joints and grades 1/5 and 4/5 at the left shoulder and elbow joints, respectively. Bilateral hand grip was weak. The deep tendon reflexes were absent in both upper limbs. Touch, pain, and temperature sensation were lost by 50-60% over the right upper limb and by 30-40% over the left upper limb. Nerve conduction studies and electromyography (NCS-EMG) were suggestive of a bilateral pan-brachial plexopathy. The brachial plexus MRI showed short-tau inversion recovery (STIR) hyperintensity involving all the roots, divisions, and cords of the bilateral brachial plexus. Cerebrospinal fluid (CSF) revealed five cells and mildly elevated protein levels. Parvovirus B19 DNA was detected in both the CSF and serum. Serum parvovirus B19 IgG antibodies were positive, while IgM antibodies were negative. Thus, a diagnosis of parvovirus B19-associated bilateral PTS was made. He was given analgesics, gabapentin, nortriptyline, and duloxetine for pain. He received intravenous methylprednisolone (1000 mg) followed by oral steroids (1 mg/kg) along with intravenous immunoglobulin (IVIG) and physiotherapy. Clinicians must consider parvovirus B19-associated PTS as a possibility, especially when evaluating rapidly progressive bilateral brachial plexitis, even in the absence of typical viral prodromal symptoms such as fever, rash, and arthralgia.