Accurate identification of EEG recordings with interictal epileptiform discharges using a hybrid approach: Artificial intelligence supervised by human experts.

OBJECTIVE: To evaluate the diagnostic performance of artificial intelligence (AI)-based algorithms for identifying the presence of interictal epileptiform discharges (IEDs) in routine (20-min) electroencephalography (EEG) recordings. METHODS: We evaluated two approaches: a fully automated one and a hybrid approach, where three human raters applied an operational IED definition to assess the automated detections grouped into clusters by the algorithms. We used three previously developed AI algorithms: Encevis, SpikeNet, and Persyst. The diagnostic gold standard (epilepsy or not) was derived from video-EEG recordings of patients' habitual clinical episodes. We compared the algorithms with the gold standard at the recording level (epileptic or not). The independent validation data set (not used for training) consisted of 20-min EEG recordings containing sharp transients (epileptiform or not) from 60 patients: 30 with epilepsy (with a total of 340 IEDs) and 30 with nonepileptic paroxysmal events. We compared sensitivity, specificity, overall accuracy, and the review time-burden of the fully automated and hybrid approaches, with the conventional visual assessment of the whole recordings, based solely on unrestricted expert opinion. RESULTS: For all three AI algorithms, the specificity of the fully automated approach was too low for clinical implementation (16.67%; 63.33%; 3.33%), despite the high sensitivity (96.67%; 66.67%; 100.00%). Using the hybrid approach significantly increased the specificity (93.33%; 96.67%; 96.67%) with good sensitivity (93.33%; 56.67%; 76.67%). The overall accuracy of the hybrid methods (93.33%; 76.67%; 86.67%) was similar to the conventional visual assessment of the whole recordings (83.33%; 95% confidence interval [CI]: 71.48-91.70%; p > .5), yet the time-burden of review was significantly lower (p < .001). SIGNIFICANCE: The hybrid approach, where human raters apply the operational IED criteria to automated detections of AI-based algorithms, has high specificity, good sensitivity, and overall accuracy similar to conventional EEG reading, with a significantly lower time-burden. The hybrid approach is accurate and suitable for clinical implementation.

Clamping of the Aortic Arch Vessels During Normothermic Regional Perfusion After Circulatory Death Prevents the Return of Brain Activity in a Porcine Model.

BACKGROUND: The cerebral effect of clamping following normothermic regional perfusion (NRP) in donation after circulatory death (DCD) remains unknown. We investigated the effect of cerebral reperfusion during NRP and the preventive effect of clamping on brain function in a porcine model. METHODS: In 16 pigs, intracranial physiological parameters were recorded, including pressure, cerebral blood perfusion (CBF), temperature, and oxygen. Additionally, electroencephalography (EEG) and somatosensory evoked potentials (SSEPs) were used to assess brain function. The animals were cannulated for the heart-lung machine, and baseline measurements were performed before withdrawal from life support. After 8 min of mechanical asystole, the animals were randomly allocated to clamp (n = 8) or nonclamp (n = 8) of the aortic arch vessels. After 30 min of NRP, the animals were monitored for 3 h after weaning (AW). RESULTS: Intracranial measurements of CBF, oxygen, and temperature indicated successful occlusion of the arch vessels following NRP and AW in the clamp group versus the nonclamp group. In the clamp group, EEG was isoelectric and SSEPs were absent AW in all pigs. In the nonclamp group, EEG activity was observed in all 8 pigs, whereas SSEPs were observed in 6 of 8 pigs. Additionally, agonal respiratory movements in the form of gasping were observed in 6 of 8 pigs in the nonclamp group. CONCLUSIONS: Reperfusion of the brain during NRP led to a return of brain activity. Conversely, clamping of the arch vessels halted cerebral circulation, ensuring the permanent cessation of brain function and maintaining the determination of death in DCD.

Comparison of ultrasound with electrodiagnosis of scapular winging: A prospective case control study.

OBJECTIVE: Compare high-resolution ultrasound (HRUS) and electrodiagnostic examination (EDX) in the diagnostic workup of patients with scapulae alatae. METHODS: 27 patients with scapulae alatae and 41 healthy subjects (HS) and underwent a standardized clinical examination (CEX), EDX and HRUS. We measured the thickness of the serratus anterior (SER), rhomboid major and trapezius muscles and the diameter of the long thoracic (LTN), dorsal scapular and spinal accessory nerves (SAN). RESULTS: Twenty patients showed medial winging and six patients showed lateral winging on CEX. One patient had both lateral and medial winging. In patients with medial winging, the SER muscle was thinner and the LTN diameter was larger on the symptomatic side compared with the asymptomatic side and with the dominant side in HS. In this group, both EDX and HRUS detected abnormalities of SER muscle/ LTN with sensitivity of 65%, and with specificity of 100% and 57%, respectively. EDX and HRUS detected abnormalities of the trapezius muscle/ SAN with sensitivity of 60% and 40%, and specificity of 91%, and 86 % a, respectively. There was no significant difference between the two methods. CONCLUSION: HRUS can contribute to the diagnostic workup of scapulae alatae by demonstrating atrophy of muscles and enlargement in nerve diameter. SIGNIFICANCE: HRUS supplements EDX in the diagnostic workup of scapulae alatae.

[Intraoperative neuromonitoring during brain surgery].

Intraoperative neuromonitoring is a perioperative method, supplementary to stealth navigation and fluorescence microscopic imaging in brain surgery. It allows cortical and subcortical mapping, hence real time identification of eloquent brain areas through electrical stimulation of the cerebral cortex and subcortical areas. The method allows for functional guidance during both awake and asleep neurosurgery and aids in optimizing the extent of resection of the relevant pathology while preserving neurological function as summarised in this review.

The influence of the abundance and morphology of epileptiform discharges on diagnostic accuracy: How many spikes you need to spot in an EEG.

OBJECTIVE: The operational definition of interictal epileptiform discharges (IEDs) of the International Federation of Clinical Neurophysiology (IFCN) described six morphological criteria. Our objective was to assess the impact of pattern-repetition in the EEG-recording, on the diagnostic accuracy of using the IFCN criteria. For clinical implementation, specificity over 95% was set as target. METHODS: Interictal EEG-recordings of 20-minutes, containing sharp-transients, from 60 patients (30 with epilepsy and 30 with non-epileptic paroxysmal events) were evaluated by three experts, who first marked IEDs solely based on expert opinion, and then, independently from the first session evaluated the presence of the IFCN criteria for each sharp-transient. The gold standard was derived from long-term video-EEG recordings of the patients habitual paroxysmal episodes. RESULTS: Presence of at least one discharge fulfilling five criteria provided a specificity of 100% (sensitivity: 70%). For discharges fulfilling fewer criteria, a higher number of discharges was needed to keep the specificity over 95% (5 discharges, when only 3 criteria were fulfilled). A sequential combination of these sets of criteria and thresholds provided a specificity of 97% and sensitivity of 80%. CONCLUSIONS: Pattern-repetition and IED morphology influence diagnostic accuracy. SIGNIFICANCE: Systematic application of these criteria will improve quality of clinical EEG interpretation.

Neuromuscular ultrasound of the scapular stabilisers in healthy subjects.

OBJECTIVES: To obtain normative high-resolution ultrasound (HRUS) data for thickness of the serratus anterior, the trapezius and the rhomboid major muscles and diameter of their corresponding nerves, the long thoracic, the spinal accessory and the dorsal scapular nerve. Moreover, we aimed to examine intra- and inter-examiner agreement of the HRUS measurements. METHODS: We included 41 healthy subjects. Muscle thickness and nerve diameter were measured bilaterally, resulting in 82 ultrasound measurements for each structure. Normative data were calculated using regression equations for the lower limit of muscle thickness and upper limit of nerve diameter, taking into account various variables. For intra- and inter-examiner agreement, ten subjects underwent two extra ultrasound examinations and Bland-Altman plots were calculated. RESULTS: This normative data set showed significant correlations between decreasing muscle thickness with increasing age and height and increasing muscle thickness with increasing weight and with male sex. Muscle thickness was larger on the dominant side compared to the non-dominant side for the trapezius and rhomboid muscles, whereas the opposite was found for the serratus anterior muscle. For all nerves, significant correlations were found between decreasing nerve diameter with increasing age and height. Intra-examiner agreement was acceptable in all sites. Inter-examiner agreement was acceptable for all sites but one site for the serratus anterior muscle and long thoracic nerve, and not acceptable for five out of six sites for the trapezius muscle. CONCLUSION: This study provides HRUS normative data and intra- and inter-examiner agreement data for muscle thickness and nerve diameter for the muscles stabilizing the scapulae and their corresponding nerves. SIGNIFICANCE: The normative HRUS data reported may be useful in future studies investigating neuromuscular disorders.

Seizure detection using heart rate variability: A prospective validation study.

Although several validated seizure detection algorithms are available for convulsive seizures, detection of nonconvulsive seizures remains challenging. In this phase 2 study, we have validated a predefined seizure detection algorithm based on heart rate variability (HRV) using patient-specific cutoff values. The validation data set was independent from the previously published data set. Electrocardiography (ECG) was recorded using a wearable device (ePatch) in prospectively recruited patients. The diagnostic gold standard was inferred from video-EEG monitoring. Because HRV-based seizure detection is suitable only for patients with marked ictal autonomic changes, we defined responders as the patients who had a>50 beats/min ictal change in heart rate. Eleven of the 19 included patients with seizures (57.9%) fulfilled this criterion. In this group, the algorithm detected 20 of the 23 seizures (sensitivity: 87.0%). The algorithm detected all but one of the 10 recorded convulsive seizures and all of the 8 focal impaired awareness seizures, and it missed 2 of the 4 focal aware seizures. The median sensitivity per patient was 100% (in nine patients all seizures were detected). The false alarm rate was 0.9/24 h (0.22/night). Our results suggest that HRV-based seizure detection has high performance in patients with marked autonomic changes.

Neuromas and postamputation pain.

Postamputation stump and phantom pain are highly prevalent but remain a difficult condition to treat. The underlying mechanisms are not fully clarified, but growing evidence suggests that changes in afferent nerves, including the formation of neuromas, play an important role. The main objective of this cross-sectional study was to investigate whether ultrasound-verified neuroma swellings are more frequent in amputees with postamputation pain than in amputees without pain (primary outcome). Sixty-seven amputees were included. Baseline characteristics including the frequency and intensity of spontaneous stump and phantom pain were obtained, and sensory characteristics and evoked responses were assessed. A high-frequency ultrasound examination of the amputated extremity was performed to obtain information on the presence, size, and elasticity of swollen neuromas and pressure pain thresholds. Swollen neuromas were present in 53 (79.1%) of the 67 amputees included in the study, in 47 (82.5%) of 57 amputees with pain and in 6 (60.0%) of 10 amputees without pain (P = 0.2). No difference was found in stump pain intensity (P = 0.42) during the last week or in phantom pain intensity in the last month (P = 0.74) between amputees with and without swollen neuromas. Our findings suggest that it is not the presence of swollen neuromas itself that drives postamputation pain. However, changes in the transected nerve endings may still be crucial for driving postamputation pain because a positive Tinel sign was significantly more frequent in amputees with pain, irrespectively of the degree of neuroma swelling.

Latency-shift of intra-operative visual evoked potential predicts reversible homonymous hemianopia after intra-ventricular meningioma surgery.

OBJECTIVES: Intraoperative visual evoked potentials (VEPs) are used to monitor the function of optic radiation during neurosurgery with the P100 amplitude decrement as a predictor of post-operative visual deficit. However, there is currently no evidence of early VEP changes indicating reversible visual field affection. METHODS: In this case report, we used VEPs during surgery for a benign meningioma located in the atrium of the right lateral ventricle. The tumor was accessed through a transcortical approach via a two-centimeter corticotomy in the lateral aspect of the superior parietal lobule. We performed flash VEPs and simultaneous recordings of electroretinography alongside with multimodal intraoperative monitoring. RESULTS: We observed a significant and sustained unilateral latency shift of the P100 component of VEPs, while amplitudes temporarily dropped to 80% of baseline but recovered entirely at the end of surgery. After the operation, the patient had a left-sided lower-quadrant anopia, which recovered completely during the following three months. Diagnostic VEP with pattern reversal monocular full field stimulation at one month postoperatively showed normal latencies bilaterally. CONCLUSION: Our case indicates that the VEP (P100) latency may be a new and valuable indicator (in addition to VEP amplitude) of the visual pathways. SIGNIFICANCE: Monitoring VEPs may be useful to detect an imminent injury and a potentially reversible functional deficit.

Seizure detection based on heart rate variability using a wearable electrocardiography device.

OBJECTIVE: To assess the feasibility and accuracy of seizure detection based on heart rate variability (HRV) using a wearable electrocardiography (ECG) device. Noninvasive devices for detection of convulsive seizures (generalized tonic-clonic and focal to bilateral tonic-clonic seizures) have been validated in phase 2 and 3 studies. However, detection of nonconvulsive seizures still needs further research, since currently available methods have either low sensitivity or an extremely high false alarm rate (FAR). METHODS: In this phase 2 study, we prospectively recruited patients admitted to long-term video-EEG monitoring (LTM). ECG was recorded using a dedicated wearable device. Seizures were automatically detected using HRV parameters computed off-line, blinded to all other data. We compared the performance of 26 automated algorithms with the seizure time-points marked by experts who reviewed the LTM recording. Patients were classified as responders if >66% of their seizures were detected. RESULTS: We recruited 100 consecutive patients and analyzed 126 seizures (108 nonconvulsive and 18 convulsive) from 43 patients who had seizures during monitoring. The best-performing HRV algorithm combined a measure of sympathetic activity with a measure of how quickly HR changes occurred. The algorithm identified 53.5% of the patients with seizures as responders. Among responders, detection sensitivity was 93.1% (95% CI: 86.6%-99.6%) for all seizures and 90.5% (95% CI: 77.4%-97.3%) for nonconvulsive seizures. FAR was 1.0/24 h (0.11/night). Median seizure detection latency was 30 s. Typically, patients with prominent autonomic nervous system changes were responders: An ictal change of >50 heartbeats per minute predicted who would be responder with a positive predictive value of 87% and a negative predictive value of 90%. SIGNIFICANCE: The automated HRV algorithm, using ECG recorded with a wearable device, has high sensitivity for detecting seizures, including the nonconvulsive ones. FAR was low during the night. This approach is feasible in patients with prominent ictal autonomic changes.

A prospective study of high resolution ultrasound in brachial plexopathies - Correlation with electrophysiological measurements.

OBJECTIVES: To evaluate the diagnostic role of ultrasound in brachial plexopathies. METHODS: We included 59 healthy subjects (HS) and 42 patients consecutively referred with clinical suspicion of brachial plexopathy from October 2015 to May 2016. Patients underwent routine electrodiagnostic testing (EDx) as reference standard and a blinded standardised ultrasound examination of the brachial plexus as index test with cross-sectional area (CSA) as the ultrasound parameter of choice. RESULTS: Seventeen patients were diagnosed by EDx with brachial plexopathy, ten with mononeuropathies, and ten had normal EDx. Five had a cervical radiculopathy. In 11 (64%) out of the 17 patients with EDx diagnosed plexopathy, we found at least one abnormal level on ultrasound. Six (60%) out of ten normal EDx patients had a normal ultrasound examination at all levels. Ultrasound identified the same abnormal level(s) as EDx in eight (73%) of the 11 patients who had both abnormal EDx and ultrasound results. Mean CSA was higher in the plexopathy group compared to HS at the level of the C6 root (p = .022), the middle trunk (p = .027), and the medial cord (p = .003). CONCLUSION: Ultrasound examination showed abnormalities in patients with brachial plexopathies in good agreement with EDx. SIGNIFICANCE: Ultrasound may be an important supplement to electrodiagnostics in evaluating brachial plexopathies.

Segmental innervation of the Göttingen minipig hind body. An electrophysiological study.

The Göttingen minipig is being used increasingly in biomedical research. The anatomical structure of the porcine peripheral nervous system has been extensively characterized, but no equivalent to the dermatome map, which is so valuable in human neurophysiological research, has been created. We characterized the medullar segmental skin and muscle innervations of the minipig hind body, using neurophysiological methodology. Six adult minipigs underwent unilateral laminectomy from L2 to S3, exposing the nerve roots. The skin of the hind part of the body was divided into 36 predefined fields, based on anatomical landmarks for consistent reproducibility. We recorded the evoked potential in each exposed nerve root L2-S3 for cutaneous stimulation of each skin field, mapping the sensory innervation of the entire hind body. We subsequently recorded the motor response in seven predefined muscles during sequential stimulation of the L2-S3 nerve roots. We obtained a clear sensory evoked potential in the nerve roots during stimulation of the skin fields, allowing us to map the sensory innervation of the minipig hind body. Neurophysiological data from skin stimulation and muscle recordings enabled us to map the sensory innervation of the Göttingen minipig hind body and provide information about muscular innervation. The skin fields were sensory innervated by more than one root. The muscles each had one dominant root with minor contribution from neighboring roots. This is consistent with experimental data from human studies.

Diagnostic accuracy of the Salzburg EEG criteria for non-convulsive status epilepticus: a retrospective study.

BACKGROUND: Several EEG criteria have been proposed for diagnosis of non-convulsive status epilepticus (NCSE), but none have been clinically validated. We aimed to assess the diagnostic accuracy of the EEG criteria proposed by a panel of experts at the fourth London-Innsbruck Colloquium on Status Epilepticus in Salzburg, 2013 (henceforth called the Salzburg criteria). METHODS: We did a retrospective, diagnostic accuracy study using EEG recordings from patients admitted for neurological symptoms or signs to three centres in two countries (Danish Epilepsy Centre, Dianalund, Denmark; Aarhus University Hospital, Aarhus, Denmark; and Paracelsus Medical University, Salzburg, Austria). Participants were included from the Danish centres if they were aged 4 months or older, and from the Austrian centre if aged 18 years or older. Participants were sorted into two groups: consecutive patients under clinical suspicion of having NCSE (the clinical validation group) or consecutive patients with abnormal EEG findings but no clinical suspicion of NCSE (the control group). Two raters blinded to all other patient data retrospectively analysed the EEG recordings and, using the Salzburg criteria, categorised patients as in NCSE or not in NCSE. By comparing with a reference standard inferred from all clinical and para-clinical data, therapeutic response, and the final outcome, we calculated sensitivity, specificity, overall diagnostic accuracy, positive and negative predictive values, and inter-rater agreement for the Salzburg criteria. The reference standard was inferred by two raters who were blinded to the scorings of the Salzburg criteria. FINDINGS: We retrospectively reviewed EEG data from 220 patients. EEGs in the clinical validation group were recorded in 120 patients between Jan 1, and Feb 28, 2014 (Austria), and Aug 1, 2014, and Jan 31, 2015 (Denmark). EEGs in the control group were recorded in 100 patients between Jan 13 and Jan 22, 2014 (Austria) and Jan 12 and Jan 26, 2015 (Denmark). According to the reference standard, 43 (36%) of the 120 patients in the validation group had NCSE. In the validation cohort sensitivity was 97·7% (95% CI 87·9-99·6) and specificity was 89·6% (80·8-94·6); overall accuracy was 92·5% (88·3-97·5). Positive predictive value was 84·0% (95% CI 74·1-91·5) and negative predictive value was 98·6% (94·4-100). Three people in the control group (n=100) fulfilled the Salzburg criteria and were therefore false positives (specificity 97·0%, 95% CI 91·5-99·0; sensitivity not calculable). Inter-rater agreement was high for both the Salzburg criteria (k=0·87) and for the reference standard (k=0·95). Therapeutic changes occurred significantly more often in the group of patients fulfilling Salzburg criteria (42 [84%] of 50 patients) than in those who did not (11 [16%] of 70; p<0·0001). INTERPRETATION: The Salzburg criteria for diagnosis of NCSE have high diagnostic accuracy and excellent inter-rater agreement, making them suitable for implementation in clinical practice. FUNDING: None.

High-resolution ultrasound in ulnar neuropathy at the elbow: A prospective study.

INTRODUCTION: We examined the role of ultrasound in diagnosing and localizing ulnar neuropathy (UN) at the elbow. METHODS: Forty-one patients referred for UN and 43 healthy subjects were included. Cross-sectional area (CSA) of the ulnar nerve was measured by ultrasound at 5 locations across the elbow and at the wrist. Patients underwent near-nerve conduction studies (N-NCS). RESULTS: Ultrasound (US) had a sensitivity of 80.5%, N-NCS had a sensitivity of 70.7%, and combined sensitivity was 85.4% in diagnosing UN. Using N-NCS as a reference standard, US reached a sensitivity of 93.1% and a specificity of 50.0% in diagnosing UN, and a sensitivity of 77.3% and a specificity of 42.9% in localizing UN at the elbow. There was a reduction in mean CSA at 3-month follow-up. CONCLUSIONS: N-NCS and US are complementary methods and have the potential to increase the sensitivity for diagnosing and localizing UN at the elbow.

A new stratified risk assessment tool for whiplash injuries developed from a prospective observational study.

OBJECTIVES: An initial stratification of acute whiplash patients into seven risk-strata in relation to 1-year work disability as primary outcome is presented. DESIGN: The design was an observational prospective study of risk factors embedded in a randomised controlled study. SETTING: Acute whiplash patients from units, general practitioners in four Danish counties were referred to two research centres. PARTICIPANTS: During a 2-year inclusion period, acute consecutive whiplash-injured (age 18-70 years, rear-end or frontal-end car accident and WAD (whiplash-associated disorders) grades I-III, symptoms within 72 h, examination prior to 10 days postinjury, capable of written/spoken Danish, without other injuries/fractures, pre-existing significant somatic/psychiatric disorder, drug/alcohol abuse and previous significant pain/headache). 688 (438 women and 250 men) participants were interviewed and examined by a study nurse after 5 days; 605 were completed after 1 year. A risk score which included items of initial neck pain/headache intensity, a number of non-painful complaints and active neck mobility was applied. The primary outcome parameter was 1-year work disability. RESULTS: The risk score and number of sick-listing days were related (Kruskal-Wallis, p<0.0001). In stratum 1, less than 4%, but in stratum 7, 68% were work-disabled after 1 year. Early work assessment (p<0.0001), impact of the event questionnaire (p<0.0006), psychophysical pain measures being McGill pain questionnaire parameters (p<0.0001), pressure pain algometry (p<0.0001) and palpation (p<0.0001) showed a significant relationship with risk stratification. ANALYSIS: Findings confirm previous studies reporting intense neck pain/headache and distress as predictors for work disability after whiplash. Neck-mobility was a strong predictor in this study; however, it was a more inconsistent predictor in other studies. CONCLUSIONS: Application of the risk assessment score and use of the risk strata system may be beneficial in future studies and may be considered as a valuable tool to assess return-to-work following injuries; however, further studies are needed.

The risk assessment score in acute whiplash injury predicts outcome and reflects biopsychosocial factors.

STUDY DESIGN: One-year prospective study of 141 acute whiplash patients (WLP) and 40 acute ankle-injured controls. OBJECTIVE: This study investigates a priori determined potential risk factors to develop a risk assessment tool, for which the expediency was examined. SUMMARY OF BACKGROUND DATA: The whiplash-associated disorders (WAD) grading system that emerged from The Quebec Task-Force-on-Whiplash has been of limited value for predicting work-related recovery and for explaining biopsychosocial disability after whiplash and new predictive factors, for example, risk criteria that comprehensively differentiate acute WLP in a biopsychosocial manner are needed. METHODS: Consecutively, 141 acute WLP and 40 ankle-injured recruited from emergency units were examined after 1 week, 1, 3, 6, and 12 months obtaining neck/head visual analog scale score, number of nonpainful complaints, epidemiological, social, psychological data and neurological examination, active neck mobility, and furthermore muscle tenderness and pain response, and strength and duration of neck muscles. Risk factors derived (reduced cervical range of motion, intense neck pain/headache, multiple nonpain complaints) were applied in a risk assessment score and divided into seven risk strata. RESULTS: A receiver operating characteristics curve for the Risk Assessment Score and 1-year work disability showed an area of 0.90. Risk strata and number of sick days showed a log-linear relationship. In stratum 1 full recovery was encountered, but for high-risk patients in stratum 6 only 50% and 7 only 20% had returned to work after 1 year (P < 5.4 × 10). Strength measures, psychophysical pain measurements, and psychological and social data (reported elsewhere) showed significant relation to risk strata. CONCLUSION: The Risk Assessment score is suggested as a valuable tool for grading WLP early after injury. It has reasonable screening power for encountering work disability and reflects the biopsychosocial nature of whiplash injuries.

The role of botulinum toxin in management of pain: an evidence-based review.

PURPOSE OF REVIEW: In the present review we discuss the role of botulinum neurotoxins (BoNTs) in the management of different pain conditions, with evidence-based data on the toxins' efficacy on pain and its mechanisms. RECENT FINDINGS: Experimental in-vitro studies have reported promising results of a novel recombinant chimera of BoNT A and E that inhibits the calcitonin gene-related peptide exocytosis from brainstem sensory neurons. Animal studies in neuropathic pain rat models have reported an analgesic effect of BoNT A given after the neuropathic procedure and a bilateral antinociceptive effect to the unilateral noxious stimuli. There is a growing body of evidence that BoNTs are effective in myofascial pain syndrome, neuropathic pain, and joint pain. The pre-existing evidence that BoNTs are ineffective in migraine or other headache disorders has not yet been challenged. In other pain syndromes, studies published in the last review year have not contributed significantly in either demonstrating or invalidating the research that has so far proved inconclusive. SUMMARY: The role of BoNTs in management of pain is not yet well established. Larger studies in neuropathic pain, joint pain, and myofascial pain syndrome are needed to fully ascertain the role for BoNT therapy in those areas.

Electrophysiological characteristics of motor units and muscle fibers in trained and untrained young male subjects.

We hypothesized that the amplitudes of compound muscle action potentials (CMAPs) and interference pattern analysis (IPA) would be larger in trained subjects compared with untrained subjects, possibly due to hypertrophy of muscle fibers and/or increased central drive. Moreover, we hypothesized that the untrained muscle is less excitable compared with the trained muscle. An electromyographic (EMG) needle electrode was used to record the IPA at maximal voluntary effort. The CMAP was obtained by stimulating the musculocutaneous nerve and recording the brachial biceps muscle using surface electrodes. CMAPs were obtained by direct muscle stimulation (DMS) with two stainless-steel subdermal electrodes placed subcutaneously in the distal third of the muscle. Amplitudes of CMAP and IPA were significantly larger in trained subjects compared with untrained subjects. We found no differences between trained and untrained subjects in IPA power spectrum and turns per second or amplitude of the CMAPs obtained by DMS. Muscle fiber hypertrophy and/or altered central drive may account for our results, but there was no indication of changes in muscle fiber excitability.

Occurrence of myofascial pain in patients with possible carpal tunnel syndrome - a single-blinded study.

BACKGROUND: There exits some similarity between symptoms of carpal tunnel syndrome (CTS) and myofascial pain related to trigger points (TPs) in the infraspinatus muscle. AIM: The aim was to examine what proportion of patients referred with a clinical suspicion of CTS had myofascial pain in the infraspinatus muscles and how their occurrence was related to the outcome of nerve conduction studies (NCS). METHODS: We examined the occurrence of CTS and of TPs in infraspinatus muscles in a cohort of patients suspected for CTS and referred to the Department of Clinical Neurophysiology, Aarhus University Hospital from October 2003 to February 2004. Patients underwent electrodiagnostic studies of the median and ulnar nerves. Additional tests were performed if necessary. Patients were examined for TPs by a blinded examiner immediately after NCS. RESULTS: We included 335 patients (202 females; 133 males, mean age 46). Two hundred one patients (60%) had abnormal NCS indicating CTS. Fifteen patients (4%) had other electrodiagnostic abnormalities. One hundred nineteen patients (36%) had normal NCS. Forty nine percent (58 out of 119) of the subjects with normal NCS had TPs in the infraspinatus muscles whereas only 26% (53 out of 201) of the patients with abnormal NCS indicating CTS had TPs. Likewise, 26% (4 out of 15) of the patients with other electrodiagnostic abnormalities had TPs. CONCLUSIONS: Approximately one third of patients referred with a clinical suspicion of CTS had TPs in the infraspinatus muscles. This occurrence was higher in the group with normal NCS than in the group with abnormal NCS indicating CTS. When CTS is suspected clinically, physicians must be aware of TPs in the infraspinatus muscles as a possible cause of the symptoms; thus, NCS are important in these patients.