| 1. |
- Amandusson, Åsa
(författare)
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Comparison between adaptive and fixed stimulus paired-pulsetranscranial magnetic stimulation (ppTMS) in normal subjects
- 2017
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Ingår i: Clinical Neurophysiology Practice. - : Elsevier BV. - 2467-981X. ; , s. 91-97
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Tidskriftsartikel (refereegranskat)abstract
- ObjectivesPaired-pulse TMS (ppTMS) examines cortical excitability but may require lengthy test procedures and fine tuning of stimulus parameters due to the inherent variability of the elicited motor evoked potentials (MEPs) and their tendency to exhibit a ‘ceiling/floor effects’ in inhibition trials. Aiming to overcome some of these limitations, we implemented an ‘adaptive’ ppTMS protocol and compared the obtained excitability indices with those from ‘conventional’ fixed-stimulus ppTMS.MethodsShort- and long interval intracortical inhibition (SICI and LICI) as well as intracortical facilitation (ICF) were examined in 20 healthy subjects by adaptive ppTMS and fixed-stimulus ppTMS. The test stimulus intensity was either adapted to produce 500 μV MEPs (by a maximum likelihood strategy in combination with parameter estimation by sequential testing) or fixed to 120% of resting motor threshold (rMT). The conditioning stimulus was 80% rMT for SICI and ICF and 120% MT for LICI in both tests.ResultsThere were significant (p < 0.05) intraindividual correlations between the two methods for all excitability measures. There was a clustering of SICI and LICI indices near maximal inhibition (‘ceiling effect’) in fixed-stimulus ppTMS which was not observed for adaptive SICI and LICI.ConclusionsAdaptive ppTMS excitability data correlates to those acquired from fixed-stimulus ppTMS.SignificanceAdaptive ppTMS is easy to implement and may serve as a more sensitive method to detect changes in cortical inhibition than fixed stimulus ppTMS. Whether equally confident data are produced by less stimuli with our adaptive approach (as already confirmed for motor threshold estimation) remains to be explored.
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| 2. |
- Barkhaus, Paul E., et al.
(författare)
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Revisiting the compound muscle action potential (CMAP)
- 2024
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Ingår i: Clinical Neurophysiology Practice. - : Elsevier. - 2467-981X. ; 9, s. 176-200
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Tidskriftsartikel (refereegranskat)abstract
- 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. CO 2024 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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| 3. |
- Broman, N. Jaffer, et al.
(författare)
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Stimulus-induced EEG-patterns and outcome after cardiac arrest
- 2021
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Ingår i: Clinical Neurophysiology Practice. - : Elsevier BV. - 2467-981X. ; 6, s. 219-224
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Tidskriftsartikel (refereegranskat)abstract
- Objective: EEG is commonly used to predict prognosis in post anoxic coma. We investigated if stimulus-induced rhythmic, periodic or ictal discharges (SIRPIDs) add prognostic information after cardiac arrest. Methods: In the multicenter Targeted Temperature Management trial, routine-EEGs were prospectively recorded after rewarming (≥36 h). Presence and subtype of SIRPIDs and main EEG-pattern (benign, malignant, highly malignant) were retrospectively reported according to a standardised classification. Patients were followed up after 180 days. Poor outcome was defined as severe neurological disability or death (Cerebral Performance Category 3–5). Results: Of 142 patients, 71% had poor outcome and 14% had SIRPIDs. There was no significant difference in outcome between patients with and without SIRPIDs, even when subgrouped according to underlying main EEG-pattern. Comparing subtypes of SIRPIDs, 82% of patients with stimulus-induced periodic discharges had poor outcome compared to 44% of patients with stimulus-induced rhythmic delta activity, but the difference was not significant. Conclusions: In EEGs performed ≥36 h after cardiac arrest, SIRPIDs cannot be used to reliably predict poor outcome. Whether certain subtypes of SIRPIDs indicate worse prognosis needs further investigation. Significance: Categorising the main EEG-pattern has important prognostic implications, but assessment of late appearing SIRPIDs does not seem to add prognostic information.
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| 4. |
- Heldestad Lilliesköld, Victoria, et al.
(författare)
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Method-of-limits : Cold and warm perception thresholds at proximal and distal body regions
- 2018
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Ingår i: Clinical Neurophysiology Practice. - : Elsevier BV. - 2467-981X. ; 3, s. 134-140
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Thermal quantitative sensory testing with the 'Method-of-Limits' is an established rationale for detection of small nerve fiber dysfunction, but adequate reference values are crucial for such evaluations, regardless of the underlying cause. This study assessed reference data for cold- (CPT) and warm- (WPT) perception thresholds at both proximal and distal sites in eight body regions of the lower and upper extremities, all determined within the same test session for each subject.Methods: Seventy-five healthy subjects (aged 16-72 years) were tested according to the method-of-limit for CPT and WPT at the dorsum of the foot, the medial and lateral lower leg, the ventral thigh, the thenar eminence, the radial and ulnar part of the lower arm, and the anterior deltoid part of the upper arm.Results: Overall, thermal perception thresholds (TPT) varied with test location, but were higher in the lower than in the upper part of the body, also WPT were generally higher than CPT. TPT at the dorsum foot highly correlated with age, while inconsistent correlations were noted between TPT and age or height at other tested locations.Conclusion: This study describes for the first time reference values at eight defined body regions, at both proximal and distal sites.Significance: The report enables refined evaluations of general small nerve fiber function, as assessed by quantitative thermal sensory testing with the Method-of-Limits.
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| 5. |
- Lundström, Ronnie, et al.
(författare)
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Vibrotactile and thermal perception and its relation to finger skin thickness
- 2018
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Ingår i: Clinical Neurophysiology Practice. - : Elsevier BV. - 2467-981X. ; 3, s. 33-39
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Quantitative measurements of vibrotactile and thermotactile perception thresholds (VPT and TPT, respectively) rely on responses from sensory receptors in the skin when mechanical or thermal stimuli are applied to the skin. The objective was to examine if there is a relation between skin thickness (epidermis and dermis) and VPT or TPT. Methods: Perception thresholds were measured on the volar side of the fingertip on 148 male subjects, out of which 116 were manual workers exposed to hand-transmitted vibration and 32 were white-collar (office) workers. Skin thickness was measured using a high-frequency ultrasonic derma scanner system. Results: The difference in age, perception thresholds and skin thickness between manual and office workers was small and non-significant except for the perception of cold, which was decreased by vibration exposure. Skin thickness for both subgroups was mean 0.57 mm (range 0.25–0.93 mm). Increased age was associated with decreased perception of warmth and vibration. Lifetime cumulative exposure to vibration, but not age, was associated with decreased perception of cold. Conclusion: No association (p >.05) was found between finger skin thickness in the range of about 0.1–1 mm and vibration perception threshold for test frequencies from 8 to 500 Hz and thermotactile perception thresholds for warmth and cold. Increasing age was associated with reduced perception of vibration and warmth. Vibration exposure was associated with decreased perception of cold. Significance: Skin thickness is a factor that may affect the response from sensory receptors, e.g., due to mechanical attenuation and thermal insulation. Thus, to evaluate perception threshold measurements, it is necessary to know if elevated thresholds can be attributed to skin thickness. No previous studies have measured skin thickness as related to vibrotactile and thermotactile perception thresholds. This study showed no association between skin thickness and vibrotactile perception or thermotactile perception. © 2018 International Federation of Clinical Neurophysiology
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| 6. |
- Molin, Carl Johan, et al.
(författare)
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High-resistance strength training does not affect nerve cross sectional area – An ultrasound study
- 2017
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Ingår i: Clinical Neurophysiology Practice. - : Elsevier BV. - 2467-981X. ; 2, s. 163-169
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveThe aim was to study the effect of high-resistance strength training on peripheral nerve morphology, by examining properties of peripheral nerves as well as distal and proximal muscle thickness with ultrasound, comparing healthy individuals who perform and do not perform high-resistance strength training.MethodsNeuromuscular ultrasound was used to examine cross sectional area (CSA) of the median and musculocutaneous nerves, and muscle thickness of the abductor pollicis brevis muscle, biceps brachii muscle, quadriceps muscle and extensor digitorum brevis muscle, in 44 healthy individuals, of whom 22 performed regular high-resistance strength training.ResultsNo difference in nerve CSA was found between trained and untrained individuals although trained individuals had thicker biceps brachii muscles. The CSA of the median nerve in the forearm correlated with participants’ height and was significantly larger in men than women.ConclusionsIn this cohort, CSA of the median and musculocutaneous nerves was not affected by strength training, whereas gender had a prominent effect both on CSA and muscle thickness.SignificanceThis is the first study to examine the effect of high-resistance strength training on peripheral nerves with neuromuscular ultrasound.
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| 7. |
- Rostedt Punga, Anna, et al.
(författare)
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Botulinum toxin injections associated with suspected myasthenia gravis : An underappreciated cause of MG-like clinical presentation
- 2020
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Ingår i: Clinical Neurophysiology Practice. - : Elsevier BV. - 2467-981X. ; 5, s. 46-49
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Tidskriftsartikel (refereegranskat)abstract
- IntroductionThe application of botulinum toxin type A (BoNTA) is accelerating, and this includes the uncontrolled cosmetic use of the BoNTA. Diffusion of BoNTA can disturb neuromuscular transmission in several surrounding and distant muscles and result in clinical manifestations similar to myasthenia gravis (MG).Case presentationsWe report two cases of patients referred for neurophysiological evaluation of suspected MG. A 55-year-old female who experienced dysphagia, dysarthria, right-sided ptosis, and neck extensor muscle weakness; and a 46-year-old male who presented with episodic double vision and right-sided ptosis. Both had the history of previous BoNTA use for cosmetic purposes and for the treatment of migraine before the presentation of their symptoms. In both cases examination revealed normal RNS, quite remarkably increased jitter, and signs of denervation and reinnervation in muscles surrounding the injection sites. After extensive neurophysiological evaluations, the primary cause of their symptoms was found to be related to previous BoNTA injections rather than a primary neuromuscular transmission disorder. It could also be concluded that patients do not automatically inform their physicians about cosmetic BoNTA use and they may not be aware of the potential risks associated with BoNTA therapy.ConclusionsThe presented cases illustrate the neurophysiological findings in two patients with suspected MG after the use of BoNTA and emphasize the importance of inquiring about previous BoNTA injections and highlight that it is essential that patients are informed about possible side effects of BoNTA therapy.
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| 8. |
- Rostedt Punga, Anna, et al.
(författare)
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Keeping up appearances : Don't frown upon the effects of botulinum toxin injections in facial muscles
- 2023
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Ingår i: Clinical Neurophysiology Practice. - : Elsevier. - 2467-981X. ; 8, s. 169-173
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Forskningsöversikt (refereegranskat)abstract
- Aesthetic use of low doses of Botulinum toxin (BoNT) injections into the facial muscles has become a leading non-surgical aesthetic treatment worldwide to reduce facial wrinkles, including glabellar lines, forehead lines, and periorbital wrinkles. Within these aesthetic applications, BoNT injections intend to reduce and prevent wrinkles, and the recommended usage of 2 years is often exceeded, which may result in atrophy of the injected muscles. The long-term effects of BoNT injections in the facial muscles and the evidence of diffusion of BoNT to surrounding muscles are obvious pitfalls and challenges for clinical neurophysiologists in differential diagnosing neuromuscular transmission failures. Also, this is further complicated by the risk of developing side effects upon permanent chemical denervation of facial muscles, with less possibility for reinnervation.This review summarizes the known long-term effects of BoNT over time in different facial muscles and the use of objective electrophysiological measures to evaluate these. A better understanding of the longterm effects of BoNT is essential to avoid misdiagnosing other neuromuscular disorders.
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| 9. |
- Sandberg, Arne
(författare)
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Motor unit properties do not correlate between MUNIX and needle EMG in remote polio in the biceps brachii muscle
- 2023
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Ingår i: Clinical Neurophysiology Practice. - : Elsevier. - 2467-981X. ; 8, s. 24-31
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To compare the utility of MUNIX (motor unit number index) with needle EMG in characterizing motor unit (MU) properties in the biceps brachii (BB) muscle in subjects with remote polio.Methods: Thirty subjects suffering from remote polio were investigated with MUNIX and needle EMG, all with Macro EMG and 16 of these subjects with concentric needle EMGResults: Both MUNIX and the needle EMG methods showed abnormal results. Fiber density (FD) was the most sensitive parameter for showing signs of reinnervation. At a group level, the methods showed neurogenic findings, but there was no correlation between the results of the MUNIX and needle EMG investigations.Conclusions: Both MUNIX and needle EMG are valuable methods for measuring neurogenic involvement in the BB muscle. However, there was a lack of correlation between the MUNIX and needle EMG findings. The cause for this missing correlation may be multifactorial as there are several differences between the methods.Significance: The reason for the lack of correlation between the MUNIX and needle EMG results is discussed. By combining the needle and surface recorded methods one can obtain more information on the denervation and reinnervation process compared to using just one of the methods alone.
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| 10. |
- Törnquist, Alba Lucia, et al.
(författare)
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Visual evoked potentials after hematopoietic allogeneic stem cell transplantation in childhood
- 2017
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Ingår i: Clinical Neurophysiology Practice. - : Elsevier. - 2467-981X. ; 2, s. 67-71
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To study visual pathway pathology detected by visual evoked potentials (VEPs) in patients treated with hematopoietic stem cell transplantation (HSCT) in childhood and to determine the impact of adverse ocular findings, somatic diseases, and conditioning regimens on the VEP results.METHODS: Ophthalmological assessments including pattern VEPs were performed in 47 of 79 patients at a median age of 15 years (range 3-21 years) in median 6 years (1-17 years) after HSCT. Somatic data were extracted from medical records.RESULTS: Eight patients of 47 (17%) demonstrated pathological VEPs with prolonged latencies bilaterally (n = 3) or unilaterally (n = 5) at their latest VEP test at an age of 12-18 years. A subnormal visual acuity was present in 8/11 eyes with pathological VEPs: one eye had cataract, six eyes had cataract surgery where of two had developed secondary cataracts. One eye had residual retinopathy of prematurity. Pathological VEPs were associated with decreased visual acuity (p = 0.00019) but not linked to gender, malignant diagnosis or conditioning.CONCLUSION: VEP recordings showed an association with decreased visual acuity but no relationship with irradiation or chemotherapy in the present study.SIGNIFICANCE: VEP recordings might be of clinical value for children with an unexplained subnormal visual acuity undergoing HSCT.
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| 11. |
- Zimnowodzki, Simon, et al.
(författare)
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Emergence of F-waves after repetitive nerve stimulation
- 2020
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Ingår i: Clinical Neurophysiology Practice. - : ELSEVIER. - 2467-981X. ; 5, s. 100-103
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Absence of the F-wave may represent the inability of spinal motor neurons to be excited after periods of inactivity. Repetitive stimulation in an otherwise immobile patient acts as a voluntary movement therefore allowing for the production of an F-wave in a patient with previously demonstrated absent F-waves. Through this case report, we attempt to highlight that the absence of the F-wave may result from inexcitability of spinal motor neurons after reduced mobilization. Case: We present the case of a 48-year-old woman who had been hospitalized in an ICU setting for almost one month due to a subarachnoid hemorrhage, pancreatitis, and respiratory failure. An electromyogram and nerve conduction study (NCS) was performed for weakness in all four extremities. On routine NCS, her F-waves were absent, but after repetitive stimulation was performed, her F-waves appeared. Discussion: This may be further evidence that the absence of the F-wave may result from inexcitability of spinal motor neurons after immobilization or reduced mobility rather than true pathology of the peripheral nerve. The ability to recover F-waves after an initial absence could assist in differentiating between inexcitability of the anterior horn cell and proximal nerve conduction block. This case presentation is an attempt to show that repetitive nerve stimulation may prove to be a useful technique to restore F-waves in patients who are unable to voluntarily contract their muscles, which may help exclude certain pathologic processes. (C) 2020 International Federation of Clinical Neurophysiology. Published by Elsevier B.V.
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