Phantom limb pain among veterans

Many veterans return from combat having sustained wounds that make it necessary for their limbs to be amputated. Though the surgery removes the immediate health risks associated with a severely wounded limb, it can also bring about an extremely painful experience called phantom limb pain. The origins of phantom limb pain are not well understood. Some theories propose that nerves are left behind at the amputation site, and that the brain misrepresents the information to include the entire leg. Another theory proposes that a reorganization of the somatosensory cortex causes the brain to produce sensations in the amputated limbs, though amputations that occur in younger individuals usually lack phantom limb pain.

Phantom limb pain can cause severe discomfort for the patient - some individuals experience intense episodes of momentary debilitating pain, while others experience continuous pain. Because pain-relieving medications and physical therapy do not always improve symptoms, patients are forced to over-medicate or seek alternative therapies. In military populations there has been increased interest in complementary and alternative medicine, especially auricular acupuncture for pain management.

Amelie is a $24$‍ year old female military amputee who experiences chronic phantom limb pain. She typically rates her pain intensity as $5$‍/$10$‍ during the day and $8$‍/$10$‍ in the evening. In an attempt to manage her pain she takes morphine and oxycodone as needed and attends regular physical therapy sessions. However, her symptoms have not improved during the last six months she has been in treatment. Her doctor suggests auricular acupuncture as a potential treatment plan. The following excerpt is from Amelie’s patient notes:

“Initial assessment resulted in an overall pain rating of $6$‍/$10$‍. Auricular acupuncture was performed on the left ear with an ear needle, inserted onto the cingulate gyrus point (one of the standard points for military acupuncture). After $60$‍ seconds the patient rated the pain as a $2$‍/$10$‍. She returned the next day for a follow-up session, this time reporting an overall pain rating of $4$‍/$10$‍. After $90$‍ seconds the patient rated the pain as a $0$‍/$10$‍.”

Which of the following is least likely to be associated with Amelie's phantom limb pain?