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Question

Difficulty: MediumEnd-of-Life and Palliative Care

A 72-year-old man is evaluated in the palliative care clinic for new-onset pain. He has a history of metastatic prostate cancer with diffuse osteoblastic bone metastases and symptomatic benign prostatic hyperplasia. He is currently maintained on an extended-release morphine regimen that adequately controls his baseline dull, aching bone pain. Over the past two weeks, he has developed severe, "shooting and burning" pain radiating down his right posterior thigh and calf. He rates this new pain as an 8 on a 10-point scale. Neurologic examination reveals decreased pinprick sensation over the lateral aspect of the right lower leg. His motor strength is 5/5 in all extremities. He has normal anal sphincter tone and reports no issues with bowel function or new urinary symptoms. He is alert, oriented, and demonstrates a clear understanding of his prognosis and treatment options.

Which of the following is the most appropriate next step in the management of this patient?

  1. Initiate therapy with oral gabapentinAnswer
  2. B
    Initiate therapy with oral amitriptyline
  3. C
    Order an emergent magnetic resonance imaging scan of the spine
  4. D
    Arrange immediate hospital admission for a continuous intravenous ketamine infusion
  5. E
    Request a psychiatric consultation to determine the patient's legal competence

Answer

The most appropriate next step is to initiate therapy with oral gabapentin to treat the patient's neuropathic pain.
This patient is experiencing neuropathic pain, characterized by his description of "shooting and burning" pain radiating down his leg in a radicular distribution. In the setting of palliative care, neuropathic pain often responds poorly to opioid dose escalation alone and requires the addition of an adjuvant medication. Gabapentin, an anticonvulsant that binds to voltage-gated calcium channels, is a first-line agent for neuropathic pain and is safe to use in this patient.

Step-by-Step Solution

1
Identify the type of pain based on the clinical description.
The pain is described as "shooting and burning" in a radicular distribution, which is highly characteristic of neuropathic pain rather than nociceptive bone pain.
Differentiating nociceptive from neuropathic pain is crucial because neuropathic pain typically responds poorly to opioid dose escalation alone and requires targeted adjuvant therapy.
2
Assess for oncologic emergencies that would alter the immediate management plan.
The neurologic examination shows normal motor strength and normal bowel/bladder function, ruling out malignant spinal cord compression.
The absence of "red flag" symptoms means the patient does not require an emergent MRI or neurosurgical intervention, allowing for focus on outpatient symptom management.
3
Select the optimal pharmacologic agent while accounting for the patient's comorbidities.
Gabapentin is selected. Amitriptyline is avoided due to the patient's symptomatic benign prostatic hyperplasia.
Tricyclic antidepressants like amitriptyline possess significant anticholinergic properties that can precipitate acute urinary retention in patients with an enlarged prostate.

Key Concept

Management of neuropathic pain in palliative care requires the use of adjuvant medications (e.g., gabapentinoids), with careful selection to avoid adverse effects related to the patient's underlying comorbidities.
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Topics

End-of-Life and Palliative Care

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