Resolution of Lhermitte’s sign with Spinal Cord Stimulation
Dear Editor,
No specific treatment exists for Lhermitte’s sign or an electric shock-like sensation that extends down the spine and shoots into the limbs lasting just a few seconds elicited during movement of cervical spine, particularly flexion of the neck. This symptom has been reported in various medical-like cervical spondylosis, multiple sclerosis, vitamin B12 deficiency, and pernicious anemia [1,2]. Many times, this transient symptom is self-limiting and will resolve over a period of 6 months. However, for those patients whose symptoms are not so fortunate, few options are available. Pharmacological treatment is initially analgesics, short-course opioid medications, muscle relaxants, and tapering doses of oral steroids. Persistent symptoms may be improved with neuropathic pain medications like gabapentin, pregabalin, tricyclic antidepressants, clonazepam, baclofen, carbamazepine, amitriptyline, and phenytoin [3,4].
The following case report utilizes neuromodulation after all other conservative methods failed to provide pain relief for this patient. The patient is a 60-year-old man with a history of worsening chronic neck pain without incident and reported “electricity running down my back and legs” when turning his head downward. A magnetic resonance imaging (MRI) scan demonstrated severe spondylosis at
C5-6, a moderate degree of cervical stenosis, and a concern for development of myelopathy. As the thoracic and lumbar MRI was absent of disease, the patient’s neurosurgeon diagnosed the traveling electric shock pain down the patient’s legs as Lhermitte’s sign from cervical spondylosis. Due to the patient’s physical findings, the findings on MRI scan, and the concern for spinal cord injury over time, surgical intervention was recommended and performed (cervical disectomy, decompression, and interbody structural allograft fusion and plating at C5-6). Eight months’ status postsurgical intervention, he returned to his neurosurgeon complaining of returned neck pain and pain shooting down his neck traveling down his spine into bilateral legs electrical and brief. His symptoms were unbearable, as he complained of big jolts of electrical sensation and spasm in the leg awakening him from rest. Plain films of the cervical spine were obtained and demonstrated an absolutely normal alignment and excellent fusion at the level of the construct. Lumbar spine X-rays including flexion extension views failed to demonstrate any problem. In addition, these demonstrated no subluxation with flexion and extension maneuver.
He presented to our clinic as referred by his neurosurgeon for management of his currently prescribed opioid medication regimen and for consideration of interventional pain procedures. Neurontin was effective initially at 600 mg three times a day for about 6 weeks, but despite further titration, no further benefit was obtained. The patient began to complain of more persistent symptoms of burning and pain into his lower extremities. In collaboration with the patient’s neurosurgeon, a cervical and lumbar MRI was repeated. Findings showed with cervical MRI: Interval C5-6 fusion with interval decrease in posterior disc bulge, central canal stenosis, and neural foraminal narrowing at C5-6. Additional multilevel degenerative changes are similar to prior exam. Lumbar MRI: Multilevel degenerative changes in the lumbar spine, stable since prior examination with the exception of increased conspicuity of tiny annular tear at posterior aspect of L2-3 disc space. Provocative discogram was performed, and no further surgical intervention was warranted. Furthermore, trialed therapies included: lumbar epidural injections, sacroiliac joint injections, pregablin, amitriptyline, acetaminophen, ibuprofen, cyclobenzaprine, methylprednisolone, oxycodone, hydrocodone, physical therapy (before and after surgery), chiropractic care, and a transcutaneous electrical nerve stimulation unit. At this
point, spinal cord stimulation (SCS) was discussed with patient as no further cervical or lumbar surgeries were recommended.
The patient underwent a successful 2-day trial of percutaneous placement of two temporary 8-electrode epidural leads positioned at T9-T10-T11 after passing a psychosocial evaluation for an implantable device. Epidural access was gained with C-arm guidance at the T12-L1 and L1/L2 intervertebral space with two 14-gauge Tuohy needles after local infiltration. During the SCS trial, he reported greater than 75% improvement in his pain, rating his pain with stimulation at a 2 on the visual analog scale (VAS) and prior to his trial, an 8 on the VAS. He felt good pain control via stimulation in his bilateral lower extremities and also inadvertently reported the shooting pains in his neck and midback were absent despite neck movement, and he was able to sleep at night without awakening with jolting pains.
Four weeks later, the patient underwent implantation with permanent leads and a rechargeable generator that was capable of adjusting stimulation with position change. The postoperative course and the initiation of SCS after implantation were uneventful. The stimulator was programmed using a guarded electrode configuration with a pulse width of 450 microseconds and a rate of 60 Hz. The amplitude ranged from 1.5 to 2.3 V. The patient reported that the stimulation was present in his low back and legs, and covered 100% of his painful areas.
At 6-month follow-up visit, he continued to report significant pain relief and was removed from opioid therapy. He also reported other positive outcomes including the ability to return to social and recreational activities.
Discussion
Conventional spinal cord stimulation alleviates pain by stimulating nerve fibers in dorsal horn of the spinal cord. The resulting impulses in the fibers may inhibit the conduction of pain signals to the brain. The inhibition of pain transmission may be explained by the “gate-control theory” introduced by Melzack and Wall in 1965 [5,6]. This theory proposes that large-diameter afferent fibers via application of an externally applied electric field “closes the gate” of pain transmission. It may also block the pain by activation of descending antinocioceptive pathways. SCS causes somatic afferent inhibition of sensory processing in the spinal cord; it has shown to downregulate the effect on central nervous system excitability and involves several mechanisms including induction of separate supraspinal pathways. These supraspinal mechanisms comprising the anterior pretectal nucleus may initiate the inhibitory effect of SCS on pain-signaling transmission [7,8].
The mechanism of action of SCS and neuromodulation in general continues to be investigated as there may be a magnitude of ways in which neuromodulation affects pain transmission. SCS captured at the thoracic spine may be effective in treating pain in areas originating from the cervical spine. SCS activates spinal and supraspinal mechanisms causing suppressed activity of spinal neurons for 30 minutes after stimulation [7], limiting the total time of SCS and avoiding unnecessary paresthesias. Nevertheless, the patient felt paresthesias in the legs, but through the activation of supraspinal analgesic centers experienced pain relief not only in lower extremities, but also in the back and neck.
Summary
Presented here is a case of pain associated with Lhermitte’s sign, which was successfully improved with the use of spinal cord stimulation in the thoracic region. This technique may be a safe and effective treatment for patients experiencing Lhermitte’s symptoms regardless of the etiology who have not found relief with more conservative measures.
ALEXANDER E. YAKOVLEV , MD
Medical Director
ANGELA M. PARMENTIER , APNP
Nurse Practitioner
Comprehensive Pain Management of the Fox Valley, SC
Appleton, Wisconsin, USA
References
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