EEG Frequency Correlates with α2-Receptor Density in Parkinson's Disease.

INTRODUCTION: Increased theta and delta power and decreased alpha and beta power, measured with quantitative electroencephalography (EEG), have been demonstrated to have utility for predicting the development of dementia in patients with Parkinson's disease (PD). Noradrenaline modulates cortical activity and optimizes cognitive processes. We claim that the loss of noradrenaline may explain cognitive impairment and the pathological slowing of EEG waves. Here, we test the relationship between the number of noradrenergic α2 adrenoceptors and changes in the spectral EEG ratio in patients with PD. METHODS: We included nineteen patients with PD and thirteen healthy control (HC) subjects in the study. We used positron emission tomography (PET) with [11C]yohimbine to quantify α2 adrenoceptor density. We used EEG power in the delta (δ, 1.5-3.9 Hz), theta (θ, 4-7.9 Hz), alpha (α, 8-12.9 Hz) and beta (ß, 13-30 Hz) bands in regression analyses to test the relationships between α2 adrenoceptor density and EEG band power. RESULTS: PD patients had higher power in the theta and delta bands compared to the HC volunteers. Patients' theta band power was inversely correlated with α2 adrenoceptor density in the frontal cortex. In the HC subjects, age was correlated with, and occipital background rhythm frequency (BRF) was inversely correlated with, α2 adrenoceptor density in the frontal cortex, while occipital BRF was inversely correlated with α2 adrenoceptor density in the thalamus. CONCLUSIONS: The findings support the claim that the loss or dysfunction of noradrenergic neurotransmission may relate to the parallel processes of cognitive decline and EEG slowing.

Cortical somatosensory evoked potential amplitudes and clinical outcome after cardiac arrest: a retrospective multicenter study.

OBJECTIVE: Bilaterally absent cortical somatosensory evoked potentials (SSEPs) reliably predict poor outcome in comatose cardiac arrest (CA) patients. Cortical SSEP amplitudes are a recent prognostic extension; however, amplitude thresholds, inter-recording, and inter-rater agreement remain uncertain. METHODS: In a retrospective multicenter cohort study, we determined cortical SSEP amplitudes of comatose CA patients using a standardized evaluation pathway. We studied inter-recording agreement in repeated SSEPs and inter-rater agreement by four raters independently determining 100 cortical SSEP amplitudes. Primary outcome was assessed using the cerebral performance category (CPC) upon intensive care unit discharge dichotomized into good (CPC 1-3) and poor outcome (CPC 4-5). RESULTS: Of 706 patients with SSEPs with median 3 days after CA, 277 (39.2%) had good and 429 (60.8%) poor outcome. Of patients with bilaterally absent cortical SSEPs, one (0.8%) survived with CPC 3 and 130 (99.2%) had poor outcome. Otherwise, the lowest cortical SSEP amplitude in good outcome patients was 0.5 µV. 184 (42.9%) of 429 poor outcome patients had lower cortical SSEP amplitudes. In 106 repeated SSEPs, there were 6 (5.7%) with prognostication-relevant changes in SSEP categories. Following a standardized evaluation pathway, inter-rater agreement was almost perfect with a Fleiss' kappa of 0.88. INTERPRETATION: Bilaterally absent and cortical SSEP amplitudes below 0.5 µV predicted poor outcome with high specificity. A standardized evaluation pathway provided high inter-rater and inter-recording agreement. Regain of consciousness in patients with bilaterally absent cortical SSEPs rarely occurs. High-amplitude cortical SSEP amplitudes likely indicate the absence of severe brain injury.

Common patterns of EEG reactivity in post-anoxic coma identified by quantitative analyses.

OBJECTIVE: Description of typical kinds of EEG reactivity (EEG-R) in post-anoxic coma using a quantitative method. METHODS: Study of 101 out-of-hospital cardiac arrest patients, 71 with good outcome (cerebral performance category scale ≤ 2). EEG was recorded 12-24 hours after cardiac arrest and four noxious, one auditory, and one visual stimulation were applied for 30 seconds each. Individual reference intervals for the power in the delta, theta, alpha, and beta bands were calculated based on six 2-second resting epochs just prior to stimulations. EEG-R in consecutive 2-second epochs after stimulation was expressed in Z-scores. RESULTS: EEG-R occurred roughly equally frequent as an increase or as a decrease in EEG activity. Sternal rub and sound stimulation were most provocative with the most pronounced changes as an increase in delta activity 4.5-8.5 seconds after stimulation and a decrease in theta activity 0.5-4.5 seconds after stimulation. These parameters predicted good outcome with an AUC of 0.852 (95 % CI: 0.771-0.932). CONCLUSIONS: Quantitative EEG-R is a feasible method for identification of common types of reactivity, for evaluation of stimulation methods, and for prognostication. SIGNIFICANCE: This method provides an objective measure of EEG-R revealing knowledge about the nature of EEG-R and its use as a diagnostic tool.

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.

[EEG diagnosticsof non-convulsive status epilepticus in critically ill patients].

Critically ill patients are at high risk of non-convulsive status epilepticus (NCSE). As clinical signs of NCSE are subtle and unspecific, EEG is necessary to make the diagnosis. This is a review of the terminology for EEG reporting and the criteria for NCSE in critically ill patients. We discuss the newly proposed ictal-interictal continuum, and how caution is needed when assessing EEG criteria in order to avoid both over- and undertreatment. Finally, we discuss how specific EEG findings, in combination with clinical information, can help infer treatment decision and need for continuous EEG monitoring.

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.

Gold Coast diagnostic criteria increase sensitivity in amyotrophic lateral sclerosis.

OBJECTIVE: This study evaluates diagnostic accuracy of the proposed 'Gold Coast' (GC) diagnostic criteria for amyotrophic lateral sclerosis (ALS). METHODS: Five European centres retrospectively sampled consecutive patients referred for electromyography on suspicion of ALS. Patients were classified according to the GC criteria, the revised El Escorial (rEE) criteria and the Awaji (AW) criteria without and with the 'Possible' category (+ Poss). Reference standard was ALS confirmed by disease progression at follow-up. RESULTS: Of 404 eligible patients 272 were diagnosed as ALS, 94 had mimicking disorders, 35 were lost for follow-up, and three had insufficient data. Sensitivity for the GC criteria was 88.2% (95% CI: 83.8-91.8%), which was higher than for previous criteria, of which the AW + Poss criteria reached the highest sensitivity of 77.6% (95% CI: 72.2-82.4%) (p < 0.001). Specificity was high for all criteria. The increase in sensitivity for the GC criteria was mainly due to the inclusion of 28 patients with progressive muscular atrophy (PMA). CONCLUSIONS: The simpler GC criteria increase the sensitivity, primarily due to considering PMA as a form of ALS with high specificity preserved. SIGNIFICANCE: This validation study supports that GC criteria should be used in clinical practice and may be used for inclusion in trials.

Automatic continuous EEG signal analysis for diagnosis of delirium in patients with sepsis.

OBJECTIVE: In critical care, continuous EEG (cEEG) monitoring is useful for delirium diagnosis. Although visual cEEG analysis is most commonly used, automatic cEEG analysis has shown promising results in small samples. Here we aimed to compare visual versus automatic cEEG analysis for delirium diagnosis in septic patients. METHODS: We obtained cEEG recordings from 102 septic patients who were scored for delirium six times daily. A total of 1252 cEEG blocks were visually analyzed, of which 805 blocks were also automatically analyzed. RESULTS: Automatic cEEG analyses revealed that delirium was associated with 1) high mean global field power (p < 0.005), mainly driven by delta activity; 2) low average coherence across all electrode pairs and all frequencies (p < 0.01); 3) lack of intrahemispheric (fronto-temporal and temporo-occipital regions) and interhemispheric coherence (p < 0.05); and 4) lack of cEEG reactivity (p < 0.005). Classification accuracy was assessed by receiver operating characteristic (ROC) curve analysis, revealing a slightly higher area under the curve for visual analysis (0.88) than automatic analysis (0.74) (p < 0.05). CONCLUSIONS: Automatic cEEG analysis is a useful supplement to visual analysis, and provides additional cEEG diagnostic classifiers. SIGNIFICANCE: Automatic cEEG analysis provides useful information in septic patients.

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.

Post resuscitation prognostication by EEG in 24 vs 48 h of targeted temperature management.

OBJECTIVE: To test if prognostic performance is affected by prolonged targeted temperature management (TTM) in comatose out-of-hospital cardiac arrest patients using two recently proposed EEG pattern classification models. METHODS: In this sub-study of the "Target Temperature Management for 48 vs. 24 hand Neurologic Outcome after Out-of-Hospital Cardiac Arrest: A Randomized Clinical Trial", EEGs of 20-30 min duration were collected 24 h and 48 h after reaching the target temperature of 33 ±â€¯1 °C. We classified EEGs according to two EEG classification models by Westhall et al. ("highly malignant", "malignant" and "benign") and Hofmeijer et al. ("unfavorable", "intermediate" and "favorable"). We tested prognostic ability against 6 months functional outcome using the Cerebral Performance Category score. RESULTS: We recorded EEGs in 120 patients at 24 h and in 44 patients at 48 h. We found no difference in specificities or sensitivities of the two models between the two TTM groups (all p-values >0.19) or in prognostication at 24 h compared to 48 h (all p-values >0.13), except for the presence of EEG reactivity favoring prognostication at 24 h (p < 0.001). Being classified in the "benign" or "favorable" category was strongly associated with good outcome with specificities of 100% (90-100) and 97% (85-100) for the Westhall and Hofmeijer models respectively. CONCLUSIONS: We found no difference in the prognostic performance of the two studied EEG classification models during prolonged TTM for 48 h compared to standard duration, nor between EEG classification performed at 24 h versus 48 h after reaching target temperature. The two models performed best in good outcome prediction.

Large inter-rater variability on EEG-reactivity is improved by a novel quantitative method.

OBJECTIVE: To assess inter-rater agreement on EEG-reactivity (EEG-R) in comatose patients and compare it with a quantitative method (QEEG-R). METHODS: Six 30-s stimulation epochs (noxious, visual and auditory) were performed during EEG on 19 neurosurgical and 11 cardiac arrest patients. Six experts analysed EEGs for reactivity using their habitual methods. QEEG-R was defined as present if ≥2/6 epochs were reactive (stimulation/rest power ratio exceeding noise level). Three-months patient outcome was assessed by the Cerebral Performance Category Score (CPC) dichotomized in good (1-2) or poor (3-5). RESULTS: Agreement among experts on overall EEG-R varied from 53% to 83% (κ: 0.05-0.64) and reached 100% (κ: 1) between two QEEG-R calculators. For the experts, absence of EEG-R yielded sensitivities for poor outcome between 40-85% and specificities between 20-90%, for QEEG-R sensitivity was 40% (CI: 23-68%) and specificity 100% (CI: 69-100%). CONCLUSIONS: There is a large inter-rater variation among experts on EEG-R assessment in comatose patients. QEEG-R is a promising objective prognostic parameter with low inter-rater variation and a high specificity for prediction of poor outcome. SIGNIFICANCE: Clinicians should be cautious when using the traditional, qualitative method, in particular in end-of-life decisions. Implementation of the quantitative method in clinical practice may improve reliability of reactivity assessments.

Noradrenergic Deficits in Parkinson Disease Imaged with 11C-MeNER.

Degeneration of noradrenergic neurons may underlie the disabling nonmotor symptoms in patients with Parkinson disease (PD). Quantification of the loss of noradrenergic neurons by means of neuroimaging has been limited by the lack of radioligands that are selective for noradrenergic neurotransmission. The radioligand (S,S)-11C-2-(α-(2-methoxyphenoxy)benzyl)morpholine (11C-MeNER) is a highly selective inhibitor of noradrenaline transporters, and PET studies suggest that this radioligand is suitable for quantitative neuroimaging of noradrenergic deficits in human brain in vivo. In the present investigation, we used PET with 11C-MeNER to map the density of noradrenaline transporters in groups of patients with PD and age-matched healthy controls. Methods: After administration of 11C-MeNER, 15 nondemented patients with PD and 10 healthy subjects underwent 90-min dynamic PET. We determined 11C-MeNER binding potential relative to nondisplaceable binding potential (BPND) by multilinear analysis, simplified reference tissue model 2, and multilinear reference tissue model 2. Results: Metabolism of 11C-MeNER did not differ between groups. The simplified reference tissue model 2 and the multilinear reference tissue model 2 were used to determine 11C-MeNER BPND11C-MeNER BPND was reduced in the PD group compared with the control subjects, with regionally significant declines in the thalamus and nucleus ruber. Tremor was associated with higher tracer binding in the PD group on multivariate regression analysis. Conclusion: To our knowledge, this was the first specific quantification of noradrenergic denervation in PD patients in vivo. In agreement with predictions from determinations in vitro, we discovered a decline of noradrenergic projections in vivo in brain of PD patients.

The Nature of EEG Reactivity to Light, Sound, and Pain Stimulation in Neurosurgical Comatose Patients Evaluated by a Quantitative Method.

EEG reactivity (EEG-R) is regarded as an important parameter in coma prognosis but knowledge is sparse on the nature of EEG changes due to different kinds of stimulation and their prognostic significance. EEG-R was quantified in a study of 39 comatose neurosurgical patients. Six 30-second standardized visual, auditory, and painful stimulations were applied. EEG-R in the delta, theta, alpha, and beta band was normalized in z-scores as the power of a stimulation epoch relative to average power of 6 resting epochs. Outcome measure was 3 months Glasgow Outcome Scale. Increase in EEG activity was related to poor outcome, was more common (13.4% of tests), and grew continuously during the 30-second stimulation epoch. Decrease in EEG activity was related to good outcome, was rarer (2.5%), and peaked around 15 seconds. Pain was the most provocative stimulation (20.4%) followed by sound (8.7%) and eye-opening (6.7%). Discrimination between good (n = 6) and poor (n = 33) outcome was best in the theta and alpha bands for pain stimulation in the first 10-20 seconds and for sound stimulation in the first 5 to 10 seconds, eye-opening did not discriminate. Increase in activity predicted poor outcome with a high specificity 100% (CI = 52%-100%) and a modest sensitivity of 39% (CI = 23%-58%). Decrease in activity predicted good outcome with a high specificity of 100% (CI = 87%-100%) and a modest sensitivity of 33% (CI = 6%-76%). This quantitative study reveals new knowledge about the nature of EEG-R, which contribute to the development of more reliable and objective clinical procedures for outcome prediction.

Quantitative sensory testing and structural assessment of sensory nerve fibres in amyotrophic lateral sclerosis.

OBJECTIVE: In this prospective study, involvement of sensory nerve fibres in ALS patients was assessed using functional and structural measures in the form of quantitative sensory testing (QST) and skin and nerve biopsies. METHODS: Thirty-two ALS patients and 32 healthy subjects were evaluated with a QST battery comprising thresholds of mechanical detection, mechanical pain, vibration detection, cold detection, warm detection, heat pain, and pinprick sensation. Skin biopsies were evaluated in 31 ALS patients by intraepidermal nerve fibre density (IENFD) and axonal swelling ratios, and growth-associated protein 43 (GAP-43) antibody staining. Sural nerve biopsies were evaluated using teased fibre analysis in eight patients. RESULTS: Mean values for QST parameters and IENFD in ALS patients were within normal range. However, the patients had increased axonal swelling ratios and GAP-43 antibody staining was negative in all patients. CONCLUSIONS: Although QST and IENFD were affected in only a small subset of ALS patients, the axonal swellings observed in all patients indicate that the affection is more frequent, and suggests that IENFD count may not be sufficient. The negative GAP-43 staining suggested an insufficiency of regeneration in small sensory nerve fibres.

Reversible median nerve impairment after three weeks of repetitive work.

Objectives The aim of this study was to evaluate the development of impaired median nerve function in relation to hand-intensive seasonal work. We hypothesized that at end-season, median nerve conduction would be impaired and then recover within weeks. Methods Using nerve conduction studies (NCS), we examined median nerve conduction before, during, and after engaging in 22 days of mink skinning. For a subgroup, we used goniometry and surface electromyography to characterize occupational mechanical exposures. Questionnaire information on symptoms, disability, and lifestyle factors was obtained. Results The study comprised 11 male mink skinners with normal median nerve conduction at pre-season (mean age 35.7 years, mean number of seasons with skinning 8.9 years). Mink skinning was characterized by a median angle of wrist flexion/extension of 16º extension, a median velocity of wrist flexion/extension of 22 °/s, and force exertions of 11% of maximal voluntary electrical activity. At end-season, mean distal motor latency (DML) had increased 0.41 ms (P<0.001), mean sensory nerve conduction velocity (SNCV) digit 2 had decreased 6.3 m/s (P=0.004), and mean SNCV digit 3 had decreased 6.2 m/s (P=0.01); 9 mink skinners had decreases in nerve conduction, 5 fulfilled electrodiagnostic criteria and 4 fulfilled electrodiagnostic and clinical criteria (a positive Katz hand diagram) for carpal tunnel syndrome (CTS). Three to six weeks post-season, the changes had reverted to normal. Symptom and disability scores showed corresponding changes. Conclusions In this natural experiment, impaired median nerve conduction developed during 22 days of repetitive industrial work with moderate wrist postures and limited force exertion. Recovery occurred within 3-6 weeks post-season.

Laser and somatosensory evoked potentials in amyotrophic lateral sclerosis.

OBJECTIVE: Mild involvement of sensory nerves has been reported in previous studies in ALS patients. In this study, we assessed sensory pathways in ALS patients using laser evoked potentials (LEPs) and somatosensory evoked potentials (SSEPs). METHODS: We recruited 18 ALS patients and 31 healthy subjects. Neodymium-doped yttrium aluminium perovskite (Nd:YAP)-laser was used to evoke LEPs in upper (UE) and lower (LE) extremities. N1 and N2P2 potentials were obtained from contralateral insular cortex (T3 or T4) and vertex (Cz), respectively. Median SSEPs were recorded from C3' or C4' and tibial SSEPs from Cz'. RESULTS: Compared to controls, ALS patients had longer N2 and P2 latencies, and smaller N2P2 amplitudes in both UE- and LE-LEPs (p<0.05), and longer latencies for median and tibial SSEPs (p<0.05). LEPs and SSEPs were abnormal in 72.2% and 56.6% patients, respectively. CONCLUSIONS: Cortical potentials showed that A-beta or A-delta sensory fibres, or both, were impaired in more than half of the ALS patients. SIGNIFICANCE: The findings support that ALS is a multi-systemic disorder involving, although to a lesser degree, other systems than the motor.

Involvement of distal sensory nerves in amyotrophic lateral sclerosis.

INTRODUCTION: The diagnostic criteria for amyotrophic lateral sclerosis (ALS) require normal sensory nerve conduction studies (NCS) or abnormal NCS only in the presence of neuropathy of identified etiology. In this study, we investigated the presence and extent of involvement of Aß sensory fibers in ALS. METHODS: Distal sensory NCS [antidromic dorsal sural (DS) and orthodromic medial plantar (MP)] and conventional sensory NCS (unilateral median sensory and bilateral sural nerves) were performed in 16 definite and 2 probable ALS patients (based on Awaji criteria) and 31 controls. RESULTS: Abnormal conventional sensory NCS were found in 8 (44.4%) ALS patients and 1 (3.2%) control subject (P = 0.002), whereas abnormal distal sensory NCS were found in 12 (66.7%) ALS patients and 3 (9.6%) controls (P < 0.0001). CONCLUSION: Distal sensory NCS were more often abnormal than conventional sensory NCS in ALS. Muscle Nerve 54: 1086-1092, 2016.

Contact Heat Evoked Potentials (CHEPs) in Patients with Mild-Moderate Alzheimer's Disease and Matched Control--A Pilot Study.

OBJECTIVE: Clinical studies have found that patients with Alzheimer's disease report pain of less intensity and with a lower affective response, which has been thought to be due to altered pain processing. The authors wished to examine the cerebral processing of non-painful and painful stimuli using somatosensory evoked potentials and contact heat evoked potentials in patients with Alzheimer's disease and in healthy elderly controls. DESIGN: Case-control study SETTING AND SUBJECTS: Twenty outpatients with mild-moderate Alzheimer's disease and in 17 age- and gender-matched healthy controls were included METHOD: Contact heat evoked potentials and somatosensory evoked potentials were recorded in all subjects. Furthermore, warmth detection threshold and heat pain threshold were assessed. Patients and controls also rated quality and intensity of the stimuli. RESULTS: The authors found no difference on contact heat evoked potential amplitude (P = 0.59) or latency of N2 or P2 wave (P = 0.62 and P = 0.75, respectively) between patients and controls. In addition, there was no difference in regard to pain intensity scores or pain quality. The patients and controls had similar warmth detection threshold and heat pain threshold. Somatosensory evoked potentials, amplitude, and latency were within normal range and similar for the two groups. CONCLUSIONS: The findings suggest that the processing of non-painful and painful stimuli is preserved in patients with mild to moderate Alzheimer's disease.