Neurophysiology of Atypical Parkinsonian Syndromes: A Study Group Position Paper.

Atypical parkinsonian syndromes (APs) are characterized by parkinsonian features combined with additional motor and non-motor signs and symptoms. Neurophysiological studies have contributed to clarifying differences and similarities between APs and idiopathic Parkinson's disease (PD) and to unravel specific pathophysiological features of APs. A comprehensive and updated evaluation of the potential clinical utility of the available neurophysiological tools in APs is, however, currently needed.

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.

Global Perceptions and Utilization of Clinical Neurophysiology in Movement Disorders.

Background: Clinical neurophysiology (CNP) involves the use of neurophysiological techniques to make an accurate clinical diagnosis, to quantify the severity, and to measure the treatment response. Despite several studies showing CNP to be a useful diagnostic tool in Movement Disorders (MD), its more widespread utilization in clinical practice has been limited.

Objectives: To better understand the current availability, global perceptions, and challenges for implementation of diagnostic CNP in the clinical practice of MD.

Cortical mechanisms of sensory trick in cervical dystonia.

Patients with cervical dystonia (CD) often show an improvement in dystonic posture after sensory trick (ST), though the mechanisms underlying ST remain unclear. In this study, we aimed to investigate the effects of ST on cortical activity in patients with CD and to explore the contribution of motor and sensory components to ST mechanisms. To this purpose, we studied 15 CD patients with clinically effective ST, 17 without ST, and 14 healthy controls (HCs) who mimicked the ST.

How to Do an Electrophysiological Study of Myoclonus.

Diagnosing and characterizing myoclonus can be challenging. Many authors agree on the need to complement the clinical findings with an electrophysiological study to characterize the movements. Besides helping to rule out other movements that may look like myoclonus, electrophysiology can help localize the source of the movement.

Diagnostic Neurophysiologic Biomarkers for Task-Specific Dystonia.

Background: Task-specific dystonia (TSD) is a challenging clinical diagnosis with no objective diagnostic biomarkers.

Objective: The objective of this study was to test 2 neurophysiologic variables using transcranial magnetic stimulation as potential diagnostic biomarkers for TSD.

Methods: We tested (1) cortical silent period (CSP) and (2) dorsal inferior parietal lobule-motor cortex (dIPL-M1) physiologic connectivity in 9 patients with the writer's cramp form of TSD and 12 healthy volunteers on 2 separate sessions.

In vivo assessment of neurodegeneration in Spinocerebellar Ataxia type 7.

Spinocerebellar Ataxia type 7 (SCA7) is a neurodegenerative disease characterized by progressive cerebellar ataxia and retinal degeneration. Increasing loss of visual function complicates the use of clinical scales to track the progression of motor symptoms, hampering our ability to develop accurate biomarkers of disease progression, and thus test the efficacy of potential treatments. We aimed to identify imaging measures of neurodegeneration, which may more accurately reflect SCA7 severity and progression.

Myoclonus: An Electrophysiological Diagnosis.

Background: Many different movement disorders have similar "jerk-like" phenomenology and can be misconstrued as myoclonus. Different types of myoclonus also share similar phenomenological characteristics that can be difficult to distinguish solely based on clinical exam. However, they have distinctive physiologic characteristics that can help refine categorization of jerk-like movements.

The role of the inferior parietal lobule in writer's cramp.

Humans have a distinguishing ability for fine motor control that is subserved by a highly evolved cortico-motor neuronal network. The acquisition of a particular motor skill involves a long series of practice movements, trial and error, adjustment and refinement. At the cortical level, this acquisition begins in the parieto-temporal sensory regions and is subsequently consolidated and stratified in the premotor-motor cortex.

How to do an electrophysiological study of tremor.

The electrophysiological characterization of hand tremors is a useful method to complement the history and physical exam of tremor patients. Our article describes the methodology (recording, processing and interpretation) used in a diagnostic/phenotypic hand tremor study conducted in our lab at the Human Motor Control Section of the National Institute of Neurological Disorders and Stroke (NINDS), at the National Institutes of Health. The necessary equipment includes two one-axis accelerometers and four-channel electromyography (EMG).

A novel exaggerated "spino-bulbo-spinal like" reflex of lower brainstem origin.

Background: Many different oligosynaptic reflexes are known to originate in the lower brainstem which share phenomenological and neurophysiological similarities.

Objective: To evaluate and discuss the differences and aberrancies among these reflexes, which are hard to discern clinically using neurophysiological investigations with the help of a case report.

Methods: We describe the clinical and neurophysiological assessment of a young man who had a childhood history of opsoclonus-myoclonus syndrome with residual mild ataxia and myoclonic jerks in the distal extremities presenting with subacute onset total body jerks sensitive to sound and touch (in a limited dermatomal distribution), refractory to medications.

Objective predictors of 'early tolerance' to ventral intermediate nucleus of thalamus deep brain stimulation in essential tremor patients.

Objective: To identify pre-operative clinical and computerized spiral analysis characteristics that may help ascertain which patients with Essential Tremor (ET) will exhibit 'early tolerance' to ventral intermediate nucleus of thalamus (Vim) deep brain stimulation (DBS).

Methods: Identification of comparative characteristics of defined cases of 'early tolerance' versus patients with sustained satisfactory response treated with Vim DBS surgery for medically-refractory ET, based on retrospective chart review by a clinician blinded to the findings of computerized spiral analysis.

Results: Statistically significant differences in two spiral analysis indices, SWVI and DoS, were found in the dominant upper limbs of patients who developed 'early tolerance', whereas the clinical characteristics were not significantly different.

Evidence already exists for motor system reorganization in CRPS.

Complex regional pain syndrome (CRPS) is a disabling condition that is usually preceded by trauma or surgical procedure. Involvement of the motor system is a well-known phenomenon in CRPS, though the pathophysiologic mechanisms of motor system affliction in CRPS are poorly understood. Graded motor imagery (GMI) has been proposed to be one of the therapeutic interventions to help improve pain and other disabling symptoms associated with CRPS, though the benefits noted are modest and inconsistent.

Cervical angina: an overlooked source of noncardiac chest pain.

Cervical angina has been widely reported as a cause of chest pain but remains underrecognized. This series demonstrates the varied clinical presentation of patients with cervical angina, the delay in diagnosis, and the extensive cardiac examinations patients with this condition typically undergo prior to a definitive diagnosis. Recognition of this condition in patients with acute chest pain requires a high index of suspicion and an awareness of the common presenting features and clinical findings of cervical angina.