New Paresthesias in a Patient on Hydroxychloroquine
A 58-year-old woman with SLE and Sjögren syndrome has been on hydroxychloroquine 400 mg daily (5.9 mg/kg actual body weight) for 9 years, with cumulative exposure estimated above 1,500 g. She presents with 4 months of progressive numbness and burning in both feet ascending to the mid-shin, new bilateral hand clumsiness, and unsteadiness in the dark. Examination shows reduced vibration and pinprick sensation to the mid-shin bilaterally, absent ankle reflexes, mild intrinsic hand weakness, and a positive Romberg. She has no diabetes, no alcohol use, normal B12 and TSH, and no monoclonal protein. Fundoscopy and cardiac evaluation are unremarkable. SLE is otherwise quiescent on low-dose prednisone and mycophenolate.
1. What is the most likely cause of her neuropathy, and what is the immediate management?
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The pattern is a symmetric, length-dependent, sensory-predominant, progressive large- and small-fiber polyneuropathy with onset after ~9 years and a cumulative HCQ dose well above the ~1,000 g threshold, in a patient without competing causes. Hydroxychloroquine-induced (and structurally related chloroquine-induced) neuromyopathy is the leading diagnosis, and it can include myopathy contributing to hand weakness and proximal findings. Key management: stop hydroxychloroquine now - it is the only intervention that halts progression; recovery is often incomplete and slow. Do not simply reduce the dose. Confirm with nerve conduction studies/EMG (axonal sensorimotor neuropathy ± myopathic units) and consider nerve/skin biopsy if diagnosis is uncertain, but do not delay discontinuation for testing. Address SLE/Sjögren control with the remaining regimen, and arrange PT/gait safety and fall precautions. Counsel that residual deficits are common, so early recognition matters.
2. The patient asks whether she can restart hydroxychloroquine at a lower dose once symptoms improve. How do you answer, and how would you have monitored her differently?
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Rechallenge is not advised: recurrence and progression are described, and there is no established safe re-exposure protocol after clinically significant HCQ neuromyopathy. She should remain off the drug; alternatives for SLE/Sjögren (e.g., optimizing mycophenolate, considering belimumab or other steroid-sparing agents depending on organ involvement) should be chosen with rheumatology input. Monitoring lessons: dose by actual body weight (≤5 mg/kg/day) rather than fixed 400 mg, since she was above the recommended threshold; annual screening for neuropathy symptoms, annual dilated eye exam after 5 years (or sooner with risk factors), and periodic weight/renal review. Document cumulative dose and reassess whether HCQ remains indicated at each visit.