Disclosures: Francis Lee, DO: No financial relationships or conflicts of interest

Case Description: 83 year old female initially presenting with chief complaint of lower back pain with radiating pain and weakness in bilateral lower extremities. Physical exam was pertinent for diminished sensation in both lower extremities. Muscle strength testing revealed bilateral weakness in plantarflexors and dorsiflexors. Heel and toe walking were impaired. Nerve conduction studies combined with needle electromyography testing revealed abnormal compound muscle action potentials, sensory nerve action potentials, and F wave latencies in multiple tested nerve segments. These electrophysiologic findings were consistent with a peripheral sensorimotor neuropathy with axonal and demyelinating features. MAG-3 IgM antibody levels were checked, which revealed a titer >70,000. Patient was referred for further hematologic workup, and the diagnosis of Myelin-Associated Glycoprotein Gammopathy was made.

Setting: Outpatient Neurophysiology Clinic

Patient: 83 year old female with progressively worsening lower back pain with bilateral radiating lower extremity pain, sensory deficits and weakness.

Assessment/Results: Patient was referred to hematology & oncology for further diagnostic investigation. Bone marrow biopsy revealed small lymphoplasmacytic cells testing positive for MYD88 confirming the diagnosis of Waldenstrom’s Macroglobulinemia. Further workup is being performed for other potential malignancies. Patient is currently undergoing consideration for immunotherapy treatment with Rituximab or Ibrutinib.

Discussion: Indolent monoclonal gammopathies are a very uncommon phenomenon that may present with common clinical symptoms such a lower back pain with radicular symptoms. This is a case in which electrodiagnostic studies proved to be a vital initial component in diagnosing what is otherwise a rare clinical entity.

Conclusion: Electrophysiologic evidence of demyelinating polyneuropathy can help steer in making the diagnosis of indolent monoclonal gammopathies which likely would have been difficult to diagnose otherwise. The available treatments generally provide good improvement in symptoms and a favorable long term prognosis. However, they require practitioners to make the proper diagnosis. This case strongly supports the role and vast potential utility of electrodiagnostic medicine.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/electrophysiologic-guidance-in-diagnosing-myelin-associated-glycoprotein-gammopathy-a-case-report/