Clinical Neurophysiological Evaluation for Simple Motor Tics

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.

The Human Tic Detector: An automatic approach to tic characterization using wearable sensors

OBJECTIVE

Current rating scales for Tourette syndrome (TS) are limited by recollection bias or brief assessment periods. This proof-of-concept study aimed to develop a sensor-based paradigm to detect and classify tics.

METHODS

We recorded both electromyogram and acceleration data from seventeen TS patients, either when voluntarily moving or experiencing tics and during the modified Rush Video Tic Rating Scale (mRVTRS). Spectral properties of voluntary and tic movements from the sensor that captured the dominant tic were calculated and used as features in a support vector machine (SVM) to detect and classify movements retrospectively.

RESULTS

Across patients, the SVM had an accuracy, sensitivity, and specificity of 96.69 ± 4.84%, 98.24 ± 4.79%, and 96.03 ± 6.04%, respectively, when classifying movements in the test dataset. Furthermore, each patient's SVM was validated using data collected during the mRVTRS. Compared to the expert consensus, the tic detection accuracy was 85.63 ± 15.28% during the mRVTRS, while overall movement classification accuracy was 94.23 ± 5.97%.

CONCLUSIONS

These results demonstrate that wearable sensors can capture physiological differences between tic and voluntary movements and are comparable to expert consensus.

SIGNIFICANCE

Ultimately, wearables could individualize and improve care for people with TS, provide a robust and objective measure of tics, and allow data collection in real-world settings.

The utility of Jerk-locked back averaging technique in diagnosis of generalized myoclonic epilepsy with normal scalp EEG: A case report

RATIONALE

The diagnosis of myoclonic epilepsy and the classification of generalized or partial type may be challenging, especially when the scalp electroencephalogram (EEG) is normal. In such situation, how to apply another electrophysiological technique to begin the diagnosis and classification? The utility of Jerk-locked back averaging technique has been described in our case.

PATIENT CONCERNS

A Chinese patient (male, 21 years old) presented with frequent unilateral or bilateral shoulder-jerking. He has an epilepsy history of complex partial seizure (CPS) or secondary tonic-clonic seizure (sGTCS) for 10 years.

DIAGNOSIS

After admission, scalp EEG was performed with the normal result when the patient showed the jerks. According to the patient's clinical presentation, we suspected myolconic seizure, but there was lack of objective evidence. Then we used Jerk-locked back averaging technique to help begin the diagnosis. A bilateral-symmetrical time-locked, evoked cortical averaging potential that preceded the jerk has been found. So the jerks were considered as cortical origin and generalized myoclonic seizure was confirmed.

INTERVENTIONS

So in this situation, we added another antiepileptic drug of Levetiracetam (1500 mg/24 h).

OUTCOMES

One week later, the jerk seizure had disappeared, and in the following visit, he had an improved prognosis with decreased seizure frequency.

LESSONS

Generalized polyspike-slow wave in EEG was common to see in myoclonic seizure and can help to make the classification. However, it should not dissuade clinicians from the diagnosis of myoclonic epilepsy with normal scalp EEG. Under this condition, we may apply other electrophysiological technique such as Jerk-locked back averaging technique, to give objective evidence to verify the cortical origin.