1305 - Touching a Nerve: Refractory Cancer Pain from Obturator Nerve Compression

Case Diagnosis: Obturator nerve compression secondary to metastatic prostatic rhabdomyosarcoma

Case Description: A 27-year-old male with a history of metastatic prostatic rhabdomyosarcoma presented with worsening left lower limb and pelvic pain refractory to his home palliative pain regimen. His physical exam was notable for left limb paresthesia with severe pain in all ROM, and mild hip adductor weakness. Due to intractable pain despite increasing opioid doses, MRI was obtained and revealed tumor expansion with severe compression of the obturator nerve and new osseous metastases in the thoracolumbar spine and femur. Through a multispecialty approach including PM&R, the patient’s pain was managed with multimodal pharmacologic interventions and initiation of inpatient chemotherapy. The patient was weaned from intravenous opioids, had significant functional improvement with therapies, and discharged home to continue chemotherapy in outpatient setting.

Discussions: Nearly 20% of patients with advanced cancer experience cancer-related pain resistant to standard analgesic measures. In this case, repeat imaging of the patient was essential to identifying compression of the obturator nerve, a rare cause of cancer-related pain. Additionally, a multispecialty approach was paramount to evaluating the differential sources of pain. Physiatry’s involvement led to a discussion of potential additional interventions for the patient’s neuropathic pain, including obturator nerve block, TENS therapy, and rehabilitation during chemotherapy. Given the patient’s significant response to intravenous dexamethasone
and concurrent initiation of chemotherapy, additional intervention was deferred.

Conclusions: Physiatrists should consider obturator neuropathy in patients with cancer who present with severe lower extremity numbness, weakness, or pain refractory to standard analgesics. Early imaging and multispecialty involvement can identify potential tumor burden and atypical pain sources such as nerve compression to allow for targeted therapies to improve pain control and guide cancer therapy. Effective pain control is crucial to rehabilitation as it is directly associated with improved functional status and therapy tolerance.