A case of segmental myoclonus in amputation stump: evidence for spinal generator and physiopathogenetic hypothesis

Abstract

We describe a 68-year-old woman who experienced pain and phantom limb sensation following an above-the-knee amputation of the right leg. A month later, the patient had myoclonic jerks of the stump. Polymyo-graphic recordings showed synchronous jerks in the vastus medialis and adductors of the thigh on the right side. The patient responded to clonazepam. We conclude that the myoclonic jerks were of spinal cord origin.

Jumping stump phenomenon: a case report

“…2,3,[5][6][7][8][9][10] Intriguingly, symptoms can persist during sleep (as in our case) or, by contrast, disappear. 1,3,8,11,12 On clinical examination, muscle contractions decreased when performing active movements, which was also noted in other studies. 3,7,9,12 Nevertheless, forced immobilization is also seen to reduce symptoms, and active movement could aggravate symptoms.…”

“…9,11 A neuroma can be an ectopic trigger zone, with increasing rate of contractions when local stimulation is applied. 1,9,10,12 However, in our case and in the case presented in the study conducted by Briand et al, 13 the neuroma showed no triggerable electric point, so local treatment was not indicated. Technical upper motor neuron workup in other cases, including brain and spine imaging, sensoryevoked potential, and electroencephalogram, were normal, except for one case with a lacunar infarct in the left anterolateral thalamus, known to be associated with dystonia and tremor.…”

“…14 Electromyography showed (a) rhythmic spontaneous short bursts of several motor unit potentials, myokymic discharges, or was normal. 1,5,7,9,11,13 One case showed a circadian rhythm (symptoms being worse at night) with a highly elevated index for periodic limb movements with reduced sleep efficiency on polysomnography, which is why pramipexole was suggested. 8 Drug treatment seems generally ineffective, as shown in our case.…”

“…8 Drug treatment seems generally ineffective, as shown in our case. 1,3,5,7,8,[10][11][12][13][14] Botulinum toxin treatment seems to have promising results, however, only temporarily. 1,6,7,9,13,14 Except for the, presumably psychiatric, case in 1852 described by Hancock, we found no other cases with a need for an amputation at a higher level.…”

“…The jumping stump phenomenon is a rare peripherally induced movement disorder that is due to peripheral nerve damage leading to involuntary, rhythmic or arhythmic, quick muscle jerks at the remaining residual limb. 1 Hancock described the first case in 1852. He suggested that a neuroma could trigger an ectopic excitation, when a myoclonus trigger zone is present.…”