Clinical Neurophysiology Practice最新文献

Objective

We present a retrospective cross-sectional review of the electrodiagnostic (EDX) referral and diagnostic patterns in patients with suspected neuromuscular conditions at a tertiary hospital in Ethiopia.

Methods

Between 2016 and 2019, 313 patients were evaluated at the EDX lab in Tikur Anbessa Specialised Hospital, Addis Ababa, Ethiopia. In our patients, nerve conduction study and when appropriate needle electromyography was done. Demographic and clinical data were extracted from a digital registry.

Results

Polyneuropathy (19.8%), carpal tunnel syndrome (12.1%), and lumbosacral radiculopathy (9.9 %) were the top three reasons for EDX referral in Ethiopia. Among them, polyneuropathy was the most frequent electrodiagnosis, where diffuse axonal and demyelinating subtypes accounted for 54% and 18.8%, respectively. Guillain-Barre syndrome was suspected in 18 patients and 15 had EDX confirmed motor axon polyneuropathy while three patients had demyelinating variant. Although a quarter (26.2%) of the referrals had a normal EDX, abnormal test results were significantly associated with weakness (95% CI: 3.29–7.04, p < 0.001), bound to wheelchair (95% CI: 1.86–2.87, p = 0.01) and having a specific diagnosis at time of referral (95% CI: 2.53–4.68, p = 0.007).

Conclusions

Diffuse and entrapment neuropathies were the main reasons for electrodiagnosis test referrals in Ethiopia. Also, motor axonal variant was the most common type of inflammatory polyneuropathy diagnosed with EDX.

Significance

Proper patient evaluation and documentation significantly improves the diagnostic yield and cost-effectiveness of EDX testing in a resource-poor countries like Ethiopia. This might be achieved through educating medical students, residents, and other care providers on the basics of EDX and its indications for correct use in the clinical care.

Objective

Stimulated skin wrinkling test (SSW) has been launched as a non-invasive diagnostic procedure. However, no normative age dependent values have been reported that can be applied in clinical practice. The objectives of the study were to (1) collect age-dependent normative values according to the 5-point scale assessment for the SSW, to (2) determine reliability scores for the obtained norm values, and to (3) introduce a new digital method for SSW assessment, the Digit Wrinkle Scan© (DWS©) for detection of wrinkles in a more quantitative manner.

Methods

Firstly, 82 healthy participants were included, divided in 5 age groups. The participants underwent SSW using lidocaine and prilocaine topical cream. Secondly, 35 healthy participants were included to test whether the DWS© could be a novel manner to assess the grade of wrinkling quantitatively. We determined the inter-observer reliability of both methods. Also, the intra-observer reliability was calculated for the DWS©.

Results

We found a decrease in normative values over age. The inter-observer reliability of assessment by the 5-point scale method was moderate after SSW (Cohen’s k: 0.53). Results of the DWS© indicate that total wrinkle length per mm² showed moderate to good agreement for the 4th and 5th digits after SSW, and a low agreement for the other digits.

Conclusions

Age-dependent normative values were obtained according to the 5-point scale, but its clinical application is doubtful since we found a moderate inter-observer reliability. We introduced the DWS© as a possible new method in order to quantify the grade of wrinkling.

Significance

We found unsatisfactory reliability scores, which hampers its usefulness for clinical practice.

Background

Functional neurological disorders represent conditions without a readily identifiable origin or laboratory-supported diagnostic. We report a case of functional neurological disorder, presenting with muscle weakness with alterations in F-waves on the affected side.

Case report

A retrospective case review of a patient seen in clinic. Electrophysiological evaluation included nerve conduction studies, including recording of F-waves in lower limbs, and needle EMG. A patchy sensory loss and unilateral muscle weakness of the left lower limb persisted nine days after a 40-year-old female patient developed bilateral lower limb weakness following a laparoscopic surgery. MRI was negative for radicular compression, myelopathy, or lumbosacral plexopathy. F-waves of the peroneal and tibial nerves on the left were absent or of reduced persistence and amplitude compared to the asymptomatic right side.

Significance

The observation of unilateral alterations of F-wave parameters could be interpreted as an asymmetrical decrease of alpha motor neuron excitability on L4 – S2 segments. In the absence of peripheral nervous system dysfunction or a structural lesion, the results here suggest a central control dysfunction or point to a more complex peripheral role. Further research is necessary to determine the frequency of these findings in a larger group of patients while incorporating other late responses, such as H (Hoffman) reflex, and measures of cortical excitability.

This review is part of the series on the clinical neurophysiology of movement disorders. It focuses on Parkinson’s disease and parkinsonism. The topics covered include the pathophysiology of tremor, rigidity and bradykinesia, balance and gait disturbance and myoclonus in Parkinson’s disease. The use of electroencephalography, electromyography, long latency reflexes, cutaneous silent period, studies of cortical excitability with single and paired transcranial magnetic stimulation, studies of plasticity, intraoperative microelectrode recordings and recording of local field potentials from deep brain stimulation, and electrocorticography are also reviewed. In addition to advancing knowledge of pathophysiology, neurophysiological studies can be useful in refining the diagnosis, localization of surgical targets, and help to develop novel therapies for Parkinson’s disease.

This paper presents results from the first survey of training and education undertaken by the Europe-Middle East-Africa (EMEAC), the Latin America (LAC) and the Asia-Oceania (AOC) Chapters of the International Federation of Clinical Neurophysiology (IFCN). The survey was conducted initially by the EMEAC in 2012 and updated in 2016, 2019, and 2020. It had the following categories: status of specialty and training in member country (21 questions), competency and accreditation (12 questions), practice and concerns (23 questions). An abbreviated version of the survey was conducted by the LAC and AOC in 2018–2019.

Clinical neurophysiology (CN) was a single specialty in a minority of member societies’ countries: 8/33 EMEAC, 2/12 AOC and 2/10 LAC. In others it was usually a subspecialty of neurology. Training periods in CN were split fairly evenly between 1, 2, 3, 4 and 5 years in EMEAC, while neurology takes 4 to 5 years. In the AOC, neurology training was for 3 to 4 years and CN for up to 2 years. In LAC a majority of countries trained for 2 to 3 years in both neurology and CN. An exit exam was performed in 16/30 EMEAC respondents, 8/12 in the AOC and 3/10 in the LAC.

Competence was considered to require a wide range of numbers of tests performed under supervision, from <250 to >750 in EMEAC and AOC, with the EMEAC tending to require more. The main concerns were in recruitment and workload in EMEAC, training in AOC and the need for more recognition of the specialty in some countries within the LAC.

This survey, the first across the three chapters, revealed considerable differences in training durations and numbers of tests performed for competence between national societies.

Objective

We investigated how clinical neurophysiological testing can help distinguish tremor and myoclonus and their subtypes.

Methods

We retrospectively analysed clinical and neurophysiological data from patients who had undergone polymyography (EMG + accelerometry) to diagnose suspected tremor or myoclonus. We show a systematic approach, which includes contraction pattern, rhythm regularity, burst duration and evidence of cortical drive.

Results

We detected 773 patients in our database, of which 556 patients were ultimately diagnosed with tremor (enhanced physiological tremor n = 169, functional tremor n = 140, essential tremor n = 90, parkinsonism associated tremor n = 64, cerebellar tremor n = 19, Holmes tremor n = 12, dystonic tremor n = 8, tremor not further specified n = 9), 140 with myoclonus and 23 with a combination of tremor and myoclonus. Polymyography confirmed the presumptive diagnosis in the majority of the patients and led to a change of diagnosis in 287 patients (37%). Conversions between diagnoses of tremor and myoclonus occurred most frequently between enhanced physiological tremor, essential tremor, functional tremor and cortical myoclonus.

Conclusions

Neurophysiology is a valuable additional tool in clinical practice to differentiate between tremor and myoclonus, and can guide towards a specific subtype.

Significance

We show how the stepwise neurophysiological approach used at our medical center aids the diagnosis of tremor versus myoclonus.

Objective

The goal of this study was to investigate the diagnostic utility of electric source imaging (ESI) in the presurgical evaluation of children with focal cortical dysplasia (FCD) and to compare it with other imaging techniques.

Methods

Twenty patients with epilepsy onset before 18 years, surgically treated focal epilepsy with a minimal follow-up of 2 years, and histologically proven FCD were retrospectively selected. All patients underwent MRI, positron emission tomography (PET), and 16 patients also had ictal single-photon emission computed tomography (iSPECT). ESI, using EEG with 64 electrodes or more (HD-ESI), was performed in all 20 patients. We determined sensitivity, specificity and accuracy of ESI, and compared its yield to that of other imaging techniques.

Results

Twelve patients were seizure-free post-operatively (60%). Among all patients, highest localization accuracy (80%) was obtained with ESI, followed by PET and iSPECT (75%). When results from ESI and SPECT were concordant 100% of patients achieved Engel I outcome. If ESI and PET showed concordant localization, 90% of patients achieved postoperative seizure freedom.

Conclusions

Our findings demonstrate that HD-ESI allows accurate localization of the epileptogenic zone in patients with FCD.

Significance

In combination with other imaging modalities, ESI helps with planning a more accurate surgery and therefore, the chances of postoperative seizure control are higher. Since it is based on EEG recordings, it does not require sedation, which is particularly interesting in pediatric patients. ESI represents an important imaging tool in focal epilepsies due to cortical dysplasia, which might be difficult to detect on standard imaging.

Myoclonus and other jerky movements form a large heterogeneous group of disorders. Clinical neurophysiology studies can have an important contribution to support diagnosis but also to gain insight in the pathophysiology of different kind of jerks. This review focuses on myoclonus, tics, startle disorders, restless legs syndrome, and periodic leg movements during sleep. Myoclonus is defined as brief, shock-like movements, and subtypes can be classified based the anatomical origin. Both the clinical phenotype and the neurophysiological tests support this classification: cortical, cortical-subcortical, subcortical/non-segmental, segmental, peripheral, and functional jerks. The most important techniques used are polymyography and the combination of electromyography-electroencephalography focused on jerk-locked back-averaging, cortico-muscular coherence, and the Bereitschaftspotential. Clinically, the differential diagnosis of myoclonus includes tics, and this diagnosis is mainly based on the history with premonitory urges and the ability to suppress the tic. Electrophysiological tests are mainly applied in a research setting and include the Bereitschaftspotential, local field potentials, transcranial magnetic stimulation, and pre-pulse inhibition. Jerks due to a startling stimulus form the group of startle syndromes. This group includes disorders with an exaggerated startle reflex, such as hyperekplexia and stiff person syndrome, but also neuropsychiatric and stimulus-induced disorders. For these disorders polymyography combined with a startling stimulus can be useful to determine the pattern of muscle activation and thus the diagnosis. Assessment of symptoms in restless legs syndrome and periodic leg movements during sleep can be performed with different validated scoring criteria with the help of electromyography.

Objective

To determine the prevalence and characteristics of normal variants in EEG recordings in a large cohort, and provide readers with typical examples of all normal variants for educational purposes.

Methods

Using the SCORE EEG system (Standardized Computer-Based Organized Reporting of EEG), we prospectively extracted EEG features in consecutive patients. In this dataset, we analyzed 3050 recordings from 2319 patients (mean age 38.5 years; range: 1–89 years).

Results

The distribution of the normal variants was as follows: sharp transients 19.21% (including wicket spikes), rhythmic temporal theta of drowsiness 6.03%, temporal slowing of the old 2.89%, slow fused transients 2.59%, 14-and 6-Hz bursts 1.83%, breach rhythm 1.25%, small sharp spikes 1.05%, 6-Hz spike and slow wave 0.69% and SREDA 0.03%.

Conclusions

The most prevalent normal variants are the sharp transients, which must not be over-read as epileptiform discharges.

Significance

EEG readers must be familiar with the normal variants to avoid misdiagnosis and misclassification of patients referred to clinical EEG recordings.