A 23-year-old man comes to the office for evaluation of right leg pain. The patient underwent a below-knee amputation 4 months ago following a motorcycle collision in which he sustained nonsalvageable devascularization of the right foot. The patient reports having severe postoperative pain and expresses frustration that it hasn't gone away. The pain is shooting in quality and located in the absent portion of the extremity. It is often worse on urination or defecation. Vitals signs are normal. Examination of the right lower extremity shows a well-healed surgical scar and adequate soft tissue padding over the distal bone. The distal stump is nontender to palpation and percussion. Range of motion at the spine, hip, and right knee are full and nonpainful. Which of the following is the best next step in management of this patient?

Question

A 23-year-old man comes to the office for evaluation of right leg pain.  The patient underwent a below-knee amputation 4 months ago following a motorcycle collision in which he sustained nonsalvageable devascularization of the right foot.  The patient reports having severe postoperative pain and expresses frustration that it hasn't gone away.  The pain is shooting in quality and located in the absent portion of the extremity.  It is often worse on urination or defecation.  Vitals signs are normal.  Examination of the right lower extremity shows a well-healed surgical scar and adequate soft tissue padding over the distal bone.  The distal stump is nontender to palpation and percussion.  Range of motion at the spine, hip, and right knee are full and nonpainful.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

Explanation: This patient who required below-knee amputation following trauma now has persistent pain in the absent portion of the limb. This presentation is most consistent with phantom limb pain (PLP) and should prompt initiation of a multimodal pain regimen that includes both pharmacotherapy and adjuvant therapies. PLP is a complex and incompletely understood pain syndrome that is extremely common (~50%-85%) among amputees. The pain, which is perceived in the absent portion of the limb, is usually neuropathic (eg, shooting, burning) and may have seemingly unrelated, innocuous triggers (eg, urination, defecation). Severe preoperative pain (eg, due to devascularizing trauma) and/or postoperative pain likely increase the risk of developing PLP. Treatment of PLP is typically multimodal and may include: pharmacotherapy: antidepressants (eg, tricyclics), antiepileptics (eg, gabapentin), N-methyl-d-aspartate (NMDA) receptor antagonists (eg, ketamine), and analgesics (eg, acetaminophen, opioids). adjuvant therapies: biofeedback, cognitive behavioral therapy, and mirror therapy (ie, using a mirror to watch the reflection of the residual limb moving at the location of the absent limb). (Choice A) Duplex ultrasonography of the lower extremities can evaluate for deep venous thrombosis (DVT). Although pain can be the presenting symptom of DVT, it would be located in the residual portion (vs absent portion) of the limb. In addition, leg swelling would likely be present. (Choice B) Regrowth of transected nerve fibers into a tangled mass of unmyelinated nerve endings can cause posttraumatic neuroma with neuropathic pain. Neuroma pain would be temporarily relieved (and, therefore, diagnosed) by local anesthetic injection; however, in contrast to this patient's pain, it would be located in the distal amputation stump and exacerbated by palpation or percussion. (Choice C) MRI can help diagnose lumbosacral radiculopathy (eg, L5, S1), which may cause shooting pain that radiates into the foot. However, radiculopathy typically has associated back pain, and range of motion testing at the hip (ie, similar to the straight leg raise test) often exacerbates symptoms. (Choice E) Surgical stump revision may be necessary for a patient whose stump fails to heal postoperatively or cannot tolerate a prosthesis (eg, due to awkward stump shape or inadequate soft tissue padding). In contrast, this patient has a well-healed surgical scar and adequate soft tissue padding. Educational objective: Phantom limb pain is common following extremity amputation. The neuropathic pain, which is perceived in the absent portion of the limb, is best managed with a multimodal pain regimen consisting of pharmacotherapy and adjuvant therapies. References: Postamputation pain: epidemiology, mechanisms, and treatment. (http://www.ncbi.nlm.nih.gov/pubmed/23426608) Recent advances in understanding and managing phantom limb pain. (http://www.ncbi.nlm.nih.gov/pubmed/31354940)

A 23-Year-Old Man Comes to the Office for Evaluation of Right