Clinical Neurophysiology Practice最新文献

Background

Creutzfeldt-Jakob disease (CJD) is a devastating degenerative brain disorder caused by an abnormal isoform of a cellular glycoprotein which is known as the prion protein. A diagnosis of CJD is usually based on specific clinical signs, EEG and MRI findings, as well as the presence of the 14–3-3 protein in the cerebrospinal fluid. Although end-stage CJD usually has a typical clinical presentation, early symptoms may be variable.

Case presentation

We present an uncommon case of CJD which manifested with primary progressive aphasia, leading to an incorrect diagnosis of frontotemporal dementia. EEG performed eight months after symptom onset revealed focal periodic sharp wave complexes that later evolved into diffuse EEG abnormalities characteristic of CJD. Brain MRI also suggested the diagnosis of CJD. Later, the patient developed rapidly progressive dementia, visual symptoms, ataxia, extrapyramidal symptoms, followed by dysphagia and mutism, and died 34 months after disease onset.

Discussion and conclusion

PPA is a relatively uncommon first manifestation of CJD, occurring only in about 1% of all CJD cases. Our case is also remarkable because we were able to capture focal periodic sharp wave complexes at the stage of the CJD when aphasia was the only clinical manifestation. We demonstrate that both brain MRI and wake and sleep EEG should be a mandatory part of the diagnostic workup for patients presenting with primary progressive aphasia.

Objective

Vincristine, a widely used anticancer chemotherapy drug, may cause polyneuropathy (PNP), potentially resulting in permanent functional impairment. We characterized the occurrence and development of vincristine-induced neuropathy (VIPN) in early treatment of childhood leukemia.

Methods

This prospective study of 35 pediatric acute lymphoblastic leukemia (ALL) patients comprised systematic clinical and electrophysiological studies at both the time of diagnosis and at least one time point during the first months of treatment.

Results

After vincristine treatment, all patients had axonal sensorimotor PNP on electroneuromyography (ENMG) In 34/35 patients, the motor and in 24/35 the sensory responses were decreased. Interestingly, in 3 patients PNP was most prominent in the upper limb. However, some children had no PNP symptoms despite moderate ENMG findings, and not all clinical symptoms were correlated with abnormal ENMG.

Conclusions

Pediatric VIPN is a sensorimotor, predominantly motor axonal neuropathy. VIPN can be detected even in its early phase by ENMG, but it is difficult to detect by symptoms and clinical examination only.

Significance

Pediatric ALL patients treated with vincristine are at risk of developing VIPN. Since the clinical signs of PNP in acutely ill children are difficult to identify, VIPN can easily be overlooked if ENMG is not performed.

Objective

To determine if compression sites of the facial nerve correlate with immediate postoperative outcomes in patients with hemifacial spasm (HFS), and if changes in the waveform of abnormal muscle response (AMR) during microvascular decompression (MVD) for HFS can predict the postoperative course.

Methods

In this retrospective review, we evaluated 50 patients with HFS who underwent AMR monitoring during MVD. The ratios of amplitude and duration of AMR waveforms were computed by comparing baseline with final examinations. Vascular compression sites were categorized into four portions of the facial nerve. Postoperatively, we classified patients into two groups based on symptom relief as those whose symptoms disappeared immediately (DI group), and those whose symptoms disappeared gradually (DG group).

Results

The compression sites significantly correlated with postoperative outcomes at discharge (p < 0.001) but not with outcomes after 6 months of MVD. Lower duration ratios of AMRs from the mentalis muscle were significantly associated with an increased chance of classification into the DI group based on the results of multivariate logistic regression analysis (p = 0.017).

Conclusions

Relationship between compression sites and immediate outcomes could provide useful information to surgeons for predicting if symptoms will resolve over long term. Moreover, changes in AMRs recorded from the mentalis muscle could predict the postoperative course of HFS.

Significance

These findings can help surgeons evaluate the changes in AMR amplitude and duration during MVD for HFS.

Functional Motor Disorders are common and disabling. Clinical diagnosis has moved from one of exclusion of other causes for symptoms to one where positive clinical features on history and examination are used to make a “rule in” diagnosis wherever possible. Clinical neurophysiological assessments have developed increasing importance in assisting with this positive diagnosis, not being used simply to demonstrate normal sensory-motor pathways, but instead to demonstrate specific abnormalities that help to positively diagnose these disorders. Here we provide a practical review of these techniques, their application, interpretation and pitfalls. We also highlight particular areas where such tests are currently lacking in sensitivity and specificity, for example in people with functional dystonia and functional tic-like movements.

Objective

We searched for long-term peripheral nerve complications 10–15 years after Roux-en-Y gastric bypass surgery (RYGB), using a comprehensive nerve conduction study (NCS) protocol.

Methods

Patients (n = 175, mean age 52.0, BMI 35.2) and 86 community-controls (mean age 56.8, BMI 27.2) had NCS of one upper and lower limb. New abnormality scores from 27 polyneuropathy-relevant (PNP27s) and four carpal tunnel syndrome-relevant NCS-measures (CTS4s) were compared between groups with non-parametric statistics. Estimated prevalences were compared by 95 % confidence limits. The clinical neurophysiologist’s diagnosis was retrieved from hospital records (PNP-ncs, CTS-ncs, other).

Results

Abnormality score did not differ between RYGB and control groups (PNP27s: 1.9 vs 1.7, CTS4s: 0.7 vs 0.6, p > 0.29). BMI correlated weakly with CTS4s in patients (rho = 0.19, p = 0.01), and less with PNP27s (rho = 0.12, p = 0.12). Polyneuropathy (PNP-ncs) prevalence was 12 % in patients and 8 % in controls. CTS-ncs prevalence was 21 % in patients and 10 % in controls (p = 0.04).

Conclusions

NCS-based abnormality scores did not differ between patients 10–15 years after RYGB and community-recruited controls, neither for PNP nor CTS.

Significance

Long-term polyneuropathic complications from RYGB have probably been avoided by modern treatment guidelines. NCS-diagnosed CTS is common in overweight RYGB patients. RYGB-patients with significant neuropathic symptoms need clinical evaluation.

The compound muscle action potential (CMAP) is among the first recorded waveforms in clinical neurography and one of the most common in clinical use. It is derived from the summated muscle fiber action potentials recorded from a surface electrode overlying the studied muscle following stimulation of the relevant motor nerve fibres innervating the muscle. Surface recorded motor unit potentials (SMUPs) are the fundamental units comprising the CMAP. Because it is considered a basic, if not banal signal, what it represents is often underappreciated. In this review we discuss current concepts in the anatomy and physiology of the CMAP. These have evolved with advances in instrumentation and digitization of signals, affecting its quantitation and measurement.

It is important to understand the basic technical and biological factors influencing the CMAP. If these influences are not recognized, then a suboptimal recording may result. The object is to obtain a high quality CMAP recording that is reproducible, whether the study is done for clinical or research purposes.

The initial sections cover the relevant CMAP anatomy and physiology, followed by how these principles are applied to CMAP changes in neuromuscular disorders. The concluding section is a brief overview of CMAP research where advances in recording systems and computer-based analysis programs have opened new research applications. One such example is motor unit number estimation (MUNE) that is now being used as a surrogate marker in monitoring chronic neurogenic processes such as motor neuron diseases.

Background

Postictal generalized electrographic suppression (PGES) may be considered an electrophysiological marker associated with an increased risk of sudden unexplained death in epilepsy (SUDEP).

Case Presentation

A case study is presented whereby a young man with focal to bilateral tonic-clonic seizures exhibited PGES after two spontaneously-aborted seizures; yet, after a third benzodiazepine-aborted seizure, PGES was absent.

Conclusion

This suggests that acutely administered benzodiazepines may offer direct anti-suppressive effects to prevent PGES, potentially reducing SUDEP risk.

Objective

To investigate the relative sensitivity and agreement of caloric testing and video head impulse test (vHIT) across four groups of vestibular disorders.

Methods

Caloric and vHIT results of 118 patients with either Ménière’s disease, vestibular neuritis/labyrinthitis, vestibular migraine, or vestibular schwannoma were retrospectively analyzed. vHIT gain, gain asymmetry, and catch-up-saccades (≥100°/sec) were compared with reference limits of 91 controls.

Results

Abnormal caloric results and vHIT gain were recorded in 57.6 % and 33.1 % of patients, respectively. Consideration of all three measures increased vHIT sensitivity to 43.2 %, and concordance with caloric results improved from 66.1 % to 70.3 %. A significant interaction effect confirmed the relationship between tests depended on the diagnosis (p = 0.013). Vestibular migraine and vestibular neuritis/labyrinthitis produced similar results on both tests, usually normal and abnormal respectively. Vestibular schwannoma produced more caloric abnormalities than vHIT gain but not compared with catch-up-saccades and gain asymmetry; Ménière’s disease produced more caloric abnormalities than all vHIT measures. When vHIT was normal (all measures), a 37 % canal paresis was 90 % specific for Ménière’s disease.

Conclusions

Rates of vHIT catch-up-saccades and gain asymmetry can improve sensitivity and concordance with caloric testing, but this is disease-dependent.

Significance

vHIT outcome measures are complementary to the caloric test and each other.

Objectives

Intensive care unit acquired weakness (ICUAW) is a clinical diagnosis and an umbrella term for acquired weakness due to neuromuscular disorders such as critical illness myopathy (CIM) but also muscular inactivity/atrophy. Without a clear understanding of the distinct aetiology, it seems difficult to predict outcomes of ICUAW and to test and apply effective future treatments. The present study contrasts ICUAW with CIM and assesses the diagnostic and clinical relevance for affected patients.

Methods

Data from a previous prospective cohort study investigating critically ill COVID-19 patients was analysed in a retrospective fashion. Patients were examined ten days after intubation with clinical assessment, nerve conduction studies, electromyography and muscle biopsy. Mortality was assessed during critical illness and at three months after hospital discharge. ICUAW and CIM were diagnosed according to the current diagnostic guidelines.

Results

In this patient sample (n = 22), 92 % developed ICUAW, 55 % developed ICUAW and CIM, and 36 % had ICUAW but did not develop CIM. Overall, 27 % patients died during their stay in the intensive care unit. At three months after discharge, there were no further deaths, but in 14 % of patients the outcome was unknown. The diagnosis of CIM was more strongly associated with death during critical illness than ICUAW. No patient with ICUAW who did not fulfil the criteria for CIM died. Both clinical and electrophysiological criteria showed excellent sensitivity for CIM diagnosis, but only electrophysiological criteria had a high specificity. Determination of the myosin:actin ratio showed neither high sensitivity nor specificity for the diagnosis of CIM.

Conclusions

The results of the present study support that ICUAW is a non-specific clinical diagnosis of low predictive power with regard to mortality. Further, diagnosing “ICUAW” seems also of little research value for both exploring the aetiology and pathophysiology of muscle weakness in critically ill patients and for evaluating potential treatment effects. Thus, more specific diagnoses such as CIM are more appropriate. Within the different diagnostic criteria for CIM, electrophysiological studies are the most sensitive and specific examinations compared to clinical and muscle tissue assessment.

Significance

Avoiding an overarching diagnosis of “ICUAW” and instead focusing on specific diagnoses appears to have several relevant consequences: more precise diagnosis making, more accurate referral to aetiology and pathophysiology, improved outcome prediction, and development of more appropriate treatments.