Bortezomib-induced motor neuropathy: A case report.

INTRODUCTION: Bortezomib is a proteasome inhibitor used in the treatment of multiple myeloma, Waldenström's macroglobulinemia, mantle cell lymphoma. The most reported adverse effects include fatigue, thrombocytopenia, gastrointestinal symptoms, and peripheral neuropathy, which mostly manifests as sensory neuropathic symptoms. We present a case of a patient who experienced motor neuropathy after initiating treatment with bortezomib. CASE REPORT: An 87-year-old male was diagnosed with multiple myeloma and started on treatment with bortezomib, dexamethasone, and lenalidomide (VRd). After five cycles of therapy, he developed lower extremity weakness, which was severely debilitating, affecting his ability to walk, and this prompted his visit to the emergency department. MANAGEMENT AND OUTCOME: The patient was admitted for further workup and underwent electromyography, which was consistent with demyelinating polyneuropathy with active denervation. His symptoms were attributed to bortezomib, and his VRd regimen was held. His symptoms failed to improve despite discontinuation of bortezomib. He then received steroids and intravenous immunoglobulin (IViG) with a gradual resolution of his symptoms. He was thereafter restarted on only lenalidomide and dexamethasone with no recurrence of his neuropathy. DISCUSSION: Clinicians need to be aware of the likely risk for motor neuropathy associated with bortezomib. Risk factors like older age and pre-existing neuropathy can predispose patients to this adverse effect, and clinicians should monitor for this toxicity and facilitate dose reduction or discontinuation of therapy if warranted. Sometimes, patients may also need further treatment with steroids or IVIG.