Segmental Spinal Myoclonus After a Cervical Transforaminal Epidural Steroid Injection

Diagnostic Utility of Clinical Neurophysiology in Jerky Movement Disorders: A Review from the MDS Clinical Neurophysiology Study Group

BACKGROUND

Myoclonus and other jerky movement disorders are hyperkinetic disorders, the diagnosis of which heavily relies on clinical neurophysiological testing. However, formal diagnostic criteria are lacking, and recently the utility and reliability of these tests have been questioned.

OBJECTIVE

The aim of this review was to assess the utilization of clinical neurophysiology testing to identify possible gaps and boundaries that might guide the development of new methods for a more precise diagnosis and in-depth understanding of myoclonus.

METHODS

We reviewed electrophysiological features of cortical myoclonus, subcortical myoclonus (ie, myoclonus associated with dystonia, brainstem myoclonus), excessive startle reflex, spinal myoclonus (ie, spinal segmental and propriospinal myoclonus), peripheral myoclonus and mimics of myoclonus of peripheral origin (hemifacial spasm, minipolymyoclonus, myokymia), functional jerky movements, chorea, and tics.

RESULTS

Electrophysiological features that support the recognition of myoclonus subtypes, such as muscle burst duration, muscle pattern of activation, measures of cortical excitability, or movement-related cortical potentials, have been identified. These significantly contribute to the diagnosis of jerky movement disorders, but their reliability is uncertain. Despite the significant advancements, several unresolved questions persist. Factors contributing to this include the absence of systematic neurophysiological assessment and standardized methods, alongside the limited number of patients investigated using these techniques.

CONCLUSION

Although clinical neurophysiology remains the "gold standard" for defining and diagnosing myoclonus, our review highlighted the need to enhance the quality and reliability of neurophysiological testing in jerky movement disorders. Further studies including larger cohorts of patients recruited from different centers, employing standardized and optimized electrophysiological techniques, are warranted.

Spinal segmental myoclonus following ultrasound-guided suprascapular nerve block: A case report

Herein, we reported a case of spinal myoclonus following an ultrasound-guided suprascapular nerve block. A 58-year-old male patient who had a diagnosis of calcific tendinitis inside the right supraspinatus tendon received a right suprascapular nerve block (3 mL of 2% prilocaine mixed with 2 mL of 1% lidocaine) under the guidance of ultrasound. Sudden, painless, and involuntary movements began in the upper extremity 10 min after the intervention. Three months after the injection, the involuntary movements were entirely stopped. Involuntary, painless, and brief muscle jerks may be suggestive of myoclonus after interventions with local anesthetics.

2. Cervical radicular pain

INTRODUCTION

Cervical radicular pain is pain perceived in the upper limb, caused by irritation or compression of a cervical spine nerve, the roots of the nerve, or both.

METHODS

The literature on the diagnosis and treatment of cervical radicular pain was retrieved and summarized.

RESULTS

The diagnosis is made by combining elements from the patient's history, physical examination, and supplementary tests. The Spurling and shoulder abduction tests are the two most common examinations used to identify cervical radicular pain. MRI without contrast, CT scanning, and in some cases plain radiography can all be appropriate imaging techniques for nontraumatic cervical radiculopathy. MRI is recommended prior to interventional treatments. Exercise with or without other treatments can be beneficial. There is scant evidence for the use of paracetamol, nonsteroidal anti-inflammatory drugs, and neuropathic pain medications such as gabapentin, pregabalin, tricyclic antidepressants, and anticonvulsants for the treatment of radicular pain. Acute and subacute cervical radicular pain may respond well to epidural corticosteroid administration, preferentially using an interlaminar approach. By contrast, for chronic cervical radicular pain, the efficacy of epidural corticosteroid administration is limited. In these patients, pulsed radiofrequency treatment adjacent to the dorsal root ganglion may be considered.

CONCLUSIONS

There is currently no gold standard for the diagnosis of cervical radicular pain. There is scant evidence for the use of medication. Epidural corticosteroid injection and pulsed radiofrequency adjacent to the dorsal root ganglion may be considered. [Correction added on 12 June 2023, after first online publication: The preceding sentence was corrected.].

Spinal segmental myoclonus following spinal surgery

A 44-year-old male was admitted with L5/S1 spondylodiscitis complicated by a posterior epidural abscess that was compressing the thecal sac with severe narrowing of the canal and compression of the cauda equine. He underwent computed tomography (CT) guided drainage followed by L5/S1 decompression laminectomy and was started on a 6-week course of intravenous antibiotics with good response. He remained well and afebrile with inflammatory markers showing improvement. During this period, he developed intermittent myoclonic movements of right lower limb with severe pain over the back radiating to the gluteal region which hindered his rehabilitation potential. He was diagnosed with spinal segmental myoclonus based on clinical findings and history of recent spinal surgery. He was successfully treated with a course of clonazepam and continues to make functional improvements during his rehabilitation program.

Acute on chronic cervical myelopathy causing cervical segmental myoclonus in a high-level wheelchair athlete: a case report

INTRODUCTION

This is a 20-year-old wheelchair athlete with history of caudal regression syndrome and cervical canal stenosis who developed spinal segmental myoclonus following routine intubation for an elective procedure.

CASE PRESENTATION

This patient is a 20-year-old man with history of caudal regression syndrome and chronic cervical stenosis. He is a high-level wheelchair racer and paralympic hopeful. This patient initially presented 18 months prior with shoulder abduction weakness. He was found to have cervical stenosis at C4, C5 on MRI. Neurosurgical treatment was not needed at that time as symptoms resolved. On this encounter, he presented for an elective urologic surgical procedure. Glidescope intubation was performed with notable cervical extension. In the Post Anesthesia Care Unit, the patient began experiencing twitching movements in his pectoral muscles bilaterally as well as left deltoid and biceps. His findings were consistent with myoclonus due to his cervical myelopathy. He was initially started on levetiracetam, but experienced dizziness. His symptoms were finally controlled with clonazepam. Neurosurgery performed cord decompression and fusion with resolution of his symptoms.

DISCUSSION

There are few cases of myoclonus secondary to myelopathy documented in literature. The current recommended treatments, levetiracetam and/or benzodiazepines, were successful in managing the myoclonus in this patient. However, cord decompression is necessary to avoid progression of myelopathic symptoms. In conclusion, myoclonus can be a presenting symptom of myelopathy and warrants further investigation, especially in patients with known spinal cord or vertebral pathology.