Clinical Neurophysiology Practice最新文献

Background

Lance-Adams Syndrome (LAS) is a rare complication of successful cardiopulmonary resuscitation (CPR). It is a form of posthypoxic myoclonus characterized by action or intention myoclonus developing days to months after an hypoxic insult to the brain. LAS, especially early in a patient’s clinical course, can be challenging to diagnose. Electroencephalogram (EEG) pattern of midline spike-wave discharge associated with favorable prognosis. There is no consensus in treatment of LAS but use of various anti-epileptic medications has been documented in literature.

Case Presentation

In this case series, all of the patients presented after achieving return of spontaneous circulation (ROSC) and subsequently developed myoclonus. EEG findings beyond the initial hospitalization continued to show later showed changes consistent with LAS in three of the four patients. Different combinations of AEDs were used in the management of LAS with variable success and adverse effects.

Conclusion

Our cases highlight that the characteristic EEG pattern can be useful in the diagnosis of LAS and allow for better prognostication and management in patients with posthypoxic myoclonus. We reviewed the available literature to better understand the prevalence, mechanism, clinical presentation, diagnosis, and management of LAS.

Objective

A prospective ultrasound study to analyze nerve size and its modifying factors in type 1 and type 2 diabetes mellitus.

Methods

The cross-sectional areas (CSAs) of motor and sensory nerves in both upper and lower limbs were measured at 14 measurement points, using high resolution ultrasound in 26 patients with type 1 and 76 patients with type 2 diabetes, and in 50 control subjects. All diabetic patients underwent electrophysiological assessment to check for the presence of polyneuropathy.

Results

Significant mild/moderate diffuse nerve enlargement was demonstrated in type 2 diabetes, more pronounced at compression sites versus non-compression sites, and on the upper limbs versus lower limbs (p value for pooled DM2 v. control group: <0.001). In type 1 diabetes, nerve enlargement was found only at one compression site (median nerve wrist; p = 0.002). No significant difference was found between patients with or without polyneuropathy.

Conclusions

The primary predictors of nerve size in diabetes are anatomical location (i.e. compression sites versus non-compression sites, upper versus lower limbs) and type of diabetes. Changes occur before the electrophysiological signs of polyneuropathy are detected.

Significance

Nerve ultrasound may contribute to early recognition of the neuropathic complications of diabetes.

Objective

To determine the utility of widely used intraoperative neuromonitoring (IONM) alert criteria and intervention for predicting postoperative outcome following paediatric spinal surgery.

Methods

Retrospective analysis of somatosensory evoked potentials (SSEP) and motor evoked potentials (MEP) in consecutive cervical spine fixations. An intervention protocol followed amplitude-reductions in SSEPs (≥50 %) and/or MEPs (≥80 %). Alert breaches were reversed when SSEP/MEP amplitude was restored to > 50 %/20 % of baseline. Sensorimotor function was assessed preoperatively and 3-months postoperatively via the Modified McCormick Scale score (MMS). We explored associations between postoperative outcome, demographic/surgical and IONM variables.

Results

Forty-five procedures in 38 children (mean age:9 ± 4 years;55 % female) were monitored, 42 %of which breached alert criteria. Instrumentation (6/19,32 %) and hypotension (5/19,26 %) were common causes for alert and the majority (13/19,68 %) were reversed following intervention. There was an association between pre- and post-MMS and the type of breach (p = 0.002). All children with worse postoperative MMS (3/38,8%) had irreversible breaches.

Conclusions

IONM in this small sample accurately detected neurological injury. The majority of breaches reversed following an intervention protocol. Irreversible breaches frequently led to worse postoperative sensorimotor function.

Significance

An intervention protocol which reversed IONM alerts never resulted in postoperative worsening of sensorimotor function.

Objective

To investigate the optimal combination of somatosensory- and transcranial motor-evoked potential (SSEP/tcMEP) modalities and monitored extremities during clip reconstruction of aneurysms of the anterior cerebral artery (ACA) and its branches.

Methods

A retrospective review of 104 cases of surgical clipping of ruptured and unruptured aneurysms was performed. SSEP/tcMEP changes and postoperative motor deficits (PMDs) were assessed from upper and lower extremities (UE/LE) to determine the diagnostic accuracy of each modality separately and in combination.

Results

PMDs were reported in 9 of 104 patients; 7 LE and 8 UE (3.6% of 415 extremities). Evoked potential (EP) monitoring failed to predict a PMD in 8 extremities (1.9%). Seven of 8 false negatives had subarachnoid hemorrhage. Sensitivity and specificity in LE were 50% and 97% for tcMEP, 71% and 98% for SSEP, and 83% and 98% for dual-monitoring of both tcMEP/SSEP. Sensitivity and specificity in UE were 38% and 99% for tcMEP, and 50% and 97% for tcMEP/SSEP, respectively.

Conclusions

Combined tcMEP/SSEP is more accurate than single-modality monitoring for LE but is relatively insensitive for UE PMDs.

Significance

During ACA aneurysm clipping, multiple factors may confound the ability of EP monitoring to predict PMDs, especially brachiofacial hemiparesis caused by perforator insufficiency.

Objective

The relative refractory period (RRP) of motor axons is an important parameter in nerve excitability tests of the recovery cycle (RC). Abnormalities may have a site in the axonal membrane, the neuromuscular junction, or in a dysfunction of the muscle. We aimed in this study to determine the site of abnormality, using a modified protocol of the conventional RC test, whereby an additional supramaximal stimulus is added at the same interstimulus interval as in RC recordings (RCSM).

Methods

Twenty-four healthy subjects aged 37.8 ± 2.4 years (mean ± SE) were examined with median nerve excitability testing using RC and RCSM protocols at normal temperature (34.1 ± 0.2 °C). The recordings were repeated in 12 subjects after selective cooling of the thenar muscle (25.2 ± 0.7 °C) and in 12 subjects after cooling the nerve trunk at the wrist (24.9 ± 0.3 °C).

Results

After cooling the nerve, RRP measured with RC and RCSM were prolonged similarly (medians by 1.8 ms, and 2.1 ms respectively). In contrast, cooling the muscle prolonged RRP measured with RC (by 1.3 ms), but did not significantly prolong RRP measured with RCSM. RRPs measured by RC and RCSM were significantly different when cooling was at the muscle (P = 5.10^-4), but not when cooling was at the nerve (P = 0.57).

Conclusions

A difference between RC and RCSM indicates abnormal excitability distal to the axonal membrane under the stimulating electrode.

Significance

Combining RCSM with the conventional RC protocol should help to localize the site of abnormal neuromuscular refractoriness.

Objective

The split elbow sign is a clinical feature of amyotrophic lateral sclerosis (ALS), characterised by preferential weakness of biceps brachii muscle compared to triceps. A novel neurophysiological index, termed the split elbow index (SEI), was developed to quantify the split-elbow sign, and assess its utility in ALS.

Methods

Clinical and neurophysiological assessment was prospectively undertaken on 34 ALS patients and 32 ALS mimics. Compound muscle action potential (CMAP) amplitude was recorded from biceps brachii and triceps muscles from which the SEI was calculated using the following formula:

$\mathrm{SEI}=\frac{\mathrm{CMAPamplitudeBICEPSBRACHII}}{\mathrm{CMAPamplitudeTRICEPSBRACHII}}$

Results

The split elbow sign was significantly more common in ALS patients when compared to ALS mimic patients (P < 0.05). The SEI was significantly reduced in ALS patients when compared to ALS mimics (P < 0.01). This reduction was evident in spinal and bulbar onset ALS. A SEI cut-off value of ≤0.62 exhibited a sensitivity of 71% and specificity of 61%.

Conclusions

The split elbow sign is significantly more common in ALS patients, and was supported by a reduction in the SEI.

Significance

The SEI may be utilised as a surrogate biomarker of the split elbow sign in future ALS studies.

Objective

Video-polysomnography (VPSG) and prolonged video-EEG-monitoring (pVEEG-M) are neurophysiological investigation modalities. Depending on indication either is performed, but occasionally patients undergo both (during the same or separate stays). We sought to assess the reasons and potential benefits of dual diagnostic assessments with both modalities.

Methods

A retrospective chart-review was performed to identify patients who underwent both VPSG and pVEEG-M during the 10 year period between 2007 and 2017. One-hundred-nine patients were identified who had undergone both studies. Patients were grouped according to indication and outcome.

Results

One-hundred-nine patients had both, a VPSG and pVEEG-M, in 62 (56.9%) the studies were performed because of separate diagnoses independent from each other. In 47 patients (43.1%) investigation with both modalities was needed to clarify the suspected diagnosis or to refute differential diagnoses. Out of these 47, 11 (10.1% of the whole group) arrived a new final diagnosis whereas in 36 (33%) the primary diagnosis was corroborated with the second modality.

Conclusions

In the majority of cases VPSG plus pVEEG-M were indicated to diagnose or monitor different comorbid diseases (e.g. sleep-related breathing disorder and epilepsy). In the other cases, performing both modalities was useful to achieve a higher diagnostic accuracy or to refute differential diagnoses.

Significance

VPSG and pVEEG-M are neurophysiological investigations which complement each other, especially in case of two different comorbid diseases in a single patient, to rule out differential diagnosis or when a higher diagnostic certainty is seeked.

Background

Essential tremor (ET) is one of the most common movement disorders, and continuous deep brain stimulation (DBS) is an established treatment for medication-refractory cases. However, the need for increasing stimulation intensities, with unpleasant side effects, and DBS tolerance over time can be problematic. The advent of novel DBS devices now provides the opportunity to longitudinally record LFPs using the implanted pulse generator, which opens up possibilities to implement adaptive DBS algorithms in a real-life setting.

Methods

Here we report a case of thalamic LFP activity recorded using a commercially available sensing-enabled DBS pulse generator (Medtronic Percept PC).

Results

In the OFF-stimulation condition, a peak tremor frequency of 3.8 Hz was identified during tremor evoking movements as assessed by video and accelerometers. Activity at the same and supraharmonic frequency was seen in the frequency spectrum of the LFP data from the left vim nucleus during motor tasks. Coherence analysis showed that peripherally recorded tremor was coherent with the LFP signal at the tremor frequency and supraharmonic frequency.

Conclusion

This is the first report of recorded tremor-related thalamic activity using the electrodes and pulse generator of an implanted DBS system. Larger studies are needed to evaluate the clinical potential of these fully implantable systems, and ultimately pulse generators with sensing-coupled algorithms driving stimulation, to really close the loop.