How A Below-Knee Amputee’s ‘Jumping Stump’ Syndrome Improved

Amputations, although life-altering, have become increasingly manageable with advancements in prosthetic technology. However, a mysterious and little-known complication known as 'Jumping Stump' syndrome continues to bewilder patients and healthcare providers.

What is 'Jumping Stump' syndrome?  

'Jumping Stump' syndrome manifests as a collection of movement disorders, including dystonia (involuntary muscle contractions that cause slow, repetitive movements), myoclonus (sudden, brief involuntary twitching or jerking of a muscle or group of muscles), tremors, and choreiform movements (jerking or writhing movements). This condition specifically affects amputated residual limbs, thus the term "jumping stump."

Research suggests that postoperative nerve damage can disrupt the crucial connection between the sensory and motor pathways within the central nervous system. This disruption creates an abnormal motor response within the residual limb, leading to the collection of symptoms experienced by those afflicted with 'jumping stump' syndrome. 

The onset of 'jumping stump' syndrome varies among patients, ranging from a few weeks to up to three years post-amputation. 

Complications  

Among the numerous complications associated with 'jumping stump' syndrome, the most debilitating is the significant discomfort users experience while wearing a prosthetic limb. The abnormal movements—dystonia, tremors, and myoclonus—require frequent adjustments of the prosthetic limb and hinder walking. This distressing scenario not only impacts an individual's physical capabilities but also inflicts considerable psychological distress, often leading to repeated visits to physicians' offices.

Because of the significant discomfort, most prosthetic users tend to abandon their prosthetic limbs. This severely limits their mobility and the ability to perform simple day-to-day activities, further compromising an individual's quality of life.

If you or someone you know has 'jumping stump' syndrome, know it's not entirely hopeless. A few isolated reports show temporary relief of symptoms with botulinum neurotoxin type A injections and partial improvement with pramipexole.

Below, we examine how physiatrists improved a patient's 'jumping stump' syndrome. This patient's case was published in Cureus on July 2023 by David Weinberg, MD, and Bradley Tucker, both from the Physical Medicine and Rehabilitation department at the Hospital of the University of Pennsylvania.

The patient  

Researchers encountered the case of a 27-year-old female patient with a midfoot dislocation on the right foot complicated by compartment syndrome (a phenomenon that occurs when pressure rises in and around muscles). This condition required multiple fasciotomies.

Although the patient underwent a below-knee amputation to alleviate the constant pain and limited mobility, she experienced persistent discomfort, decreased ankle mobility, and the development of contractures. In hopes of finding relief, she underwent another surgical intervention, including a neuroma resection, which only offered mild relief.

While dealing with the persistent moderate pain in her residual limb, the patient noticed the involuntary movements of her right residual limb. The myoclonus pain was triggered during knee extension, severely restricting her range of motion.

The patient consulted with a physiatrist, and the examination revealed myoclonus in her hamstrings and a related myoclonus in the quadriceps. However, traditional treatment methods, including various prosthetic limb adjustments and medication trials, proved futile against the pain.

The treatments  

Two months after the onset of symptoms, the physiatrist recommended a daily knee stretching program to improve the patient's range of motion. She was already taking gabapentin and tizanidine at this time. Her stretching regimen included knee extension exercises that could be performed three or more times daily based on her tolerance. After a few weeks, the patient reported a slight reduction in myoclonus severity. The patient continued the home program for at least four months.

Four months after the onset of symptoms, the patient underwent a surface and needle electromyography (EMG). The EMG found nothing remarkable about the electrical activity recorded in various muscle groups during rest periods. But when the patient actively extended and passively bent her knees, the EMG showed that both the posterior and anterior thigh muscles were activated. 

Upon seeing the promising EMG results, the medical team decided to mix science with intuition. They employed an innovative approach by injecting lidocaine (5ml, 1%) into strategic locations. The injections showed favorable results. The team found that the onset of myoclonus was effectively delayed, only manifesting when the knee reached an extended position of about 20 degrees of flexion. What's more, the range of motion of knee extension increased significantly, reaching up to 5 degrees of flexion. 

After the injections proved successful, the medical team performed a diagnostic right sciatic nerve block, administering a mixture of 4ml (2%) lidocaine and 5ml bupivacaine injections. After seeing promising results, the team proceeded to perform a biceps femoris motor point block.

After the motor point block, active knee extensions of up to 10 degrees of flexion no longer trigger spasms or myoclonus. However, full extension caused co-contractions between the knee flexors and extensors, although the intensity of limb movement and electrical signals significantly decreased. 

Approximately two months after the nerve block, the patient's myoclonus symptoms significantly decreased in frequency, with a marked improvement in knee extension range of motion. She continued with her daily home knee stretching program and was eventually refitted with a new prosthetic limb, allowing her to walk with a nearly symmetrical gait for the first time since the onset of symptoms. 

The patient was referred for chemodenervation using botulinum toxin A for long-term relief but could not obtain insurance authorization.

The bottom line  

After amputation surgery, some patients may experience a rare condition called 'Jumping Stump' syndrome. This can cause emotional distress and difficulty with daily activities. One individual tried taking medication, but it did not work. However, a nerve and motor block test provided temporary relief.