How to manage foot drop in a patient with multiple myeloma?

Management of Foot Drop in Multiple Myeloma Patients

For patients with multiple myeloma who develop foot drop, a comprehensive approach including treatment of the underlying cause, physical therapy, and orthotic devices is required to improve mobility and quality of life.

Causes of Foot Drop in Multiple Myeloma

• Foot drop in multiple myeloma patients can result from peripheral neuropathy caused by the disease itself (present in up to 20% of patients at diagnosis) or as a side effect of treatments such as thalidomide and bortezomib 1
• Multiple myeloma-associated peripheral neuropathy is primarily sensory or sensorimotor, with symptoms including paresthesia, numbness, burning sensation, and weakness 1
• Treatment-induced peripheral neuropathy has specific characteristics:
  • Thalidomide-induced neuropathy is cumulative, dose-dependent, and often permanent 1
  • Bortezomib-induced neuropathy is related to dose, schedule, and mode of administration, and is mostly reversible 1

Assessment of Peripheral Neuropathy

• All multiple myeloma patients receiving potentially neurotoxic drugs should be routinely assessed for signs of peripheral neuropathy before and during treatment 1
• The Total Neuropathy Score is recommended for grading peripheral neuropathy severity 1:
  • Score 0: No peripheral neuropathy
  • Score 1-9: Mild peripheral neuropathy
  • Score 10-19: Moderate peripheral neuropathy
  • Score ≥20: Severe peripheral neuropathy
• Motor symptoms assessment ranges from:
  • Score 0: None
  • Score 1: Slight difficulty
  • Score 2: Moderate difficulty
  • Score 3: Requires help or assistance
  • Score 4: Paralysis 1

Management Strategies

Medication Adjustments

• Dose modifications remain the gold standard for managing bortezomib or thalidomide-induced peripheral neuropathy 1
• For bortezomib-induced neuropathy, reduction of peripheral neuropathy can be achieved by:
  • Prompt dose modification (1.3→1.0→0.7 mg/m²)
  • Once weekly instead of twice weekly administration
  • Subcutaneous rather than intravenous administration 1
• Consider switching to carfilzomib, which has shown encouraging results in patients with renal dysfunction and potentially less neurotoxicity 1

Physical Support and Rehabilitation

• For patients with severe foot drop of any cause, an ankle foot orthosis is recommended to enable better and safer walking 2
• Physical activity designed to improve mobility should be encouraged as tolerated to maintain function 3
• Regular mobility assessments should be performed to monitor progression or improvement 4

Treatment of Underlying Disease

• Bortezomib-based regimens plus high-dose dexamethasone (either alone or with addition of a third agent such as thalidomide, doxorubicin, or cyclophosphamide) should be used as first-choice therapy for multiple myeloma patients with complications 1
• For elderly or comorbid patients, the combination of bortezomib with melphalan and prednisone (VMP) may be preferred 1
• In cases of severe peripheral neuropathy, consider regimens with lower neurotoxicity profiles 1

Prevention Strategies

• Prevention is a key strategy for maintaining patients' quality of life and ongoing treatment options 1
• Early detection of peripheral neuropathy and use of dose adjustment algorithms should help reduce side effects while maintaining anti-tumor efficacy 1
• Regular neurological evaluations are essential to detect early signs of peripheral neuropathy 1

Special Considerations

• Foot drop may also be related to other causes such as spinal cord compression, which requires immediate evaluation and intervention 2
• In rare cases, foot drop might be associated with type I cryoglobulinemia in multiple myeloma patients, requiring immediate composite therapeutic approach 5
• Multiple myeloma can also cause pathologic fractures in the foot that may contribute to mobility issues 6

Monitoring and Follow-up

• Regular assessment of mobility and safety is essential for multiple myeloma survivors 4
• Fall risk assessment should be incorporated into routine follow-up care 4
• Continued monitoring of disease status and treatment response is necessary to adjust management strategies accordingly 7