Sympathetic Skin Response Latency Research Articles

Novel neurophysiological evidence for preserved pain habituation across chronic pain conditions

ObjectiveThe present study aimed to investigate whether subjective and objective measures of pain habituation can be used as potential markers for central sensitization across various chronic pain patients. MethodsTwo blocks of contact-heat stimuli were applied to a non-painful area in 93 chronic pain patients (low back pain, neuropathic pain, and complex regional pain syndrome) and 60 healthy controls (HC). Habituation of pain ratings, contact-heat evoked potentials (CHEP), and sympathetic skin responses (SSR) was measured. ResultsThere was no significant difference in any measure of pain habituation between patients and HC. Even patients with apparent clinical signs of central sensitization showed no reduced pain habituation. However, prolonged baseline CHEP and SSR latencies (stimulation block 1) were found in patients compared to HC (CHEP: Δ-latency = 23 ms, p = 0.012; SSR: Δ-latency = 100 ms, p = 0.022). ConclusionGiven the performed multimodal neurophysiological testing protocol, we provide evidence indicating that pain habituation may be preserved in patients with chronic pain and thereby be of limited use as a sensitive marker for central sensitization. These results are discussed within the framework of the complex interactions between pro- and antinociceptive mechanism as well as methodological issues. The prolonged latencies of CHEP and SSR after stimulation in non-painful areas may indicate subclinical changes in the integrity of thermo-nociceptive afferents, or a shift towards antinociceptive activity. This shift could potentially affect the relay of ascending signals. SignificanceOur findings challenge the prevailing views in the literature and may encourage further investigations into the peripheral and central components of pain habituation, using advanced multimodal neurophysiological techniques.

The Electrophysiological Evaluation of Small Fiber Neuropathy in Symptomatic Patients with Vitamin B12 Deficiency before and after Treatment

ABSTRACT Background: Small fiber neuropathy (SFN) leads to sensory and autonomic dysfunction by affecting small-diameter myelinated A-delta and unmyelinated C fibers, with vitamin B12 deficiency identified as one of its causes. Objectives: To achieve early diagnosis of SFN in patients with vitamin B12 deficiency and to illustrate the impact of vitamin B12 replacement therapy using noninvasive electrophysiological tests. Materials and Methods: Patients aged 18 to 65 with vitamin B12 deficiency experiencing neuropathic pain or autonomic symptoms were included. A control group consisted of asymptomatic, healthy volunteers with normal B12 levels. Neurological examinations, cutaneous silent period (CSP), sympathetic skin response (SSR), and cardiovascular autonomic tests (R-R interval variability during the Valsalva maneuver [RRIV-VM] and standing [RRIV-S]) were performed at admission and six months later. Patients received 1000 mcg cyanocobalamin intramuscularly daily for one week, weekly for one month, and monthly for three months. Results: The final analyses included 25 patients and 25 controls. At admission, patients had significantly longer CSP and SSR latencies compared to controls (P = 0.047, P < 0.001) and shortened CSP durations (P = 0.043). The SSR amplitude was lower in patients but not significantly (P = 0.823). Post-treatment, CSP latency, CSP duration, and SSR latency significantly improved (P < 0.001, P = 0.002, P < 0.001). Positive symptoms and autonomic symptoms improved significantly after treatment (P = 0.039, P = 0.016). The number of patients with neuropathic pain significantly decreased (P = 0.008). Conclusion: CSP latency, CSP duration, and SSR latency are effective, non-invasive, and cost-effective screening tests for diagnosing SFN in individuals with B12 deficiency. These tests are also valuable for monitoring the progression of SFN following vitamin B12 replacement therapy. The study supports the use of these noninvasive electrophysiological tests to enhance early diagnosis and treatment efficacy in SFN associated with vitamin B12 deficiency.

Desensitizing the autonomic nervous system to mitigate anti-GD2 monoclonal antibody side effects.

Anti-GD2 monoclonal antibodies (mAbs) have shown to improve the overall survival of patients with high-risk neuroblastoma (HR-NB). Serious adverse events (AEs), including pain, within hours of antibody infusion, have limited the development of these therapies. In this study, we provide evidence of Autonomic Nervous System (ANS) activation as the mechanism to explain the main side effects of anti-GD2 mAbs. Through confocal microscopy and computational super-resolution microscopy experiments we explored GD2 expression in postnatal nerves of infants. In patients we assessed the ANS using the Sympathetic Skin Response (SSR) test. To exploit tachyphylaxis, a novel infusion protocol (the Step-Up) was mathematically modelled and tested. Through confocal microscopy, GD2 expression is clearly visible in the perineurium surrounding the nuclei of nerve cells. By computational super-resolution microscopy experiments we showed the selective expression of GD2 on the cell membranes of human Schwann cells in peripheral nerves (PNs) significantly lower than on NB. In patients, changes in the SSR were observed 4 minutes into the anti-GD2 mAb naxitamab infusion. SSR latency quickly shortened followed by gradual decrease in the amplitude before disappearance. SSR response did not recover for 24 hours consistent with tachyphylaxis and absence of side effects in the clinic. The Step-Up protocol dissociated on-target off-tumor side effects while maintaining serum drug exposure. We provide first evidence of the ANS as the principal non-tumor target of anti-GD2 mAbs in humans. We describe the development and modeling of the Step-Up protocol exploiting the tachyphylaxis phenomenon we demonstrate in patients using the SSR test.

Epilepsy's effect on cardiac rhythm and the autonomic nervous system.

Sudden unexpected death in epilepsy is the most common cause of death in young patients with epilepsy. The aim of this study was to evaluate changes in interictal electrocardiogram parameters and sympathetic skin responses as markers of autonomic dysfunction in patients with epilepsy and to determine their effects on the type and duration of epilepsy, frequency of seizures, and responses to treatment. A total of 97 patients with epilepsy and 94 healthy controls were recruited. We recorded their clinical and demographic characteristics and analyzed sympathetic skin response latency and amplitude, electrocardiogram recordings, and seven cardiac rhythm parameters: P-wave duration, PR segment, QRS duration, QT interval, QT interval distribution, Tpe duration, and Tpe/QT interval ratio. P-wave durations, T-wave durations, QT and QT interval durations, and Tpe and sympathetic skin response latency were significantly longer among patients with epilepsy than the controls, and their heart rate was significantly lower. However, sympathetic skin response latency and heart rate were negatively correlated, and T-wave duration, QT duration, QT interval duration, and Tpe were positively correlated. Our results from interictal electrocardiograms indicate clinically significant arrhythmias among patients with epilepsy and the correlation of such arrhythmias with sympathetic skin responses. Thus, noninvasive tests that evaluate the autonomic system should be used to predict the risk of sudden unexpected death in epilepsy among patients with epilepsy.

Evaluation of sympathetic skin response for early diagnosis and follow-up of diabetic peripheral neuropathy in children

BackgroundThe morbidity of type 1 diabetes mellitus (T1DM) in children is increasing and diabetic peripheral neuropathy (DPN) is one of the main microvascular complications of T1DM. The aim of this study was to explore sympathetic skin response (SSR) characteristics in children with T1DM and analyze the value of early diagnosis and follow-up in T1DM complicated with DPN.MethodsOur prospective study enrolling 85 participants diagnosed with T1DM and 30 healthy controls (HCs) in the Children’s Hospital of Hebei Province from 2017 to 2020. Compared the outcomes of SSR and nerve conduction study (NCS) in T1DM, and evaluated the variations in SSR and NCS of different durations, as well as changes after six months of therapy.ResultsSSR latency of T1DM group showed statistical difference as compared to HCs (p < 0.05). The SSR test was more sensitive than the NCS test in the early diagnosis of T1DM with DPN (p < 0.05). The abnormal rates of SSR and NCS in long duration of disease were higher than those in short duration of disease (p < 0.05). Among 65 participants with diabetic neuropathy, the onset latencies of SSR were shortened and the NCS were improved after treatment (p < 0.05).ConclusionsSSR could provide the accurate early diagnosis and follow-up of pediatric diabetic peripheral neuropathy.

Sympathetic skin response (SSR) in pediatric Guillain-Barré syndrome.

In the present study, sympathetic skin response (SSR) characteristics were explored in children with Guillain-Barré syndrome (GBS) and the value of early diagnosis and prognostic evaluation in GBS complicated by autonomic dysfunction (AD) was evaluated. A total of 25 children with GBS and 30 healthy controls (HCs) were enrolled in this prospective study. SSR findings for the two groups were compared. SSR and nerve conduction study (NCS) results were compared among patients with GBS, and differences in clinical characteristics between the groups with abnormal and normal SSR were analyzed. Within the GBS group, six patients (24%) required mechanical ventilation, 17 patients (66.7%) had AD, 18 patients (72%) had an abnormal SSR, and 13 patients (52%) had AD combined with SSR abnormalities. There was a statistically significant difference in SSR latency in the lower limbs between the GBS group and HCs (P < 0.05). There was no statistically significant difference between SSR and NCS results in the acute phase of GBS (P > 0.05), and there was no significant difference in the rate of AD or in Hughes functional grade at nadir between the groups with abnormal and normal SSR (P>0.05). However, there was a statistically significant difference between the results of SSR and NCS tests during the recovery phase (P = 0.003). Abnormal SSR mainly occurred in cases of the acute inflammatory demyelinating polyradiculoneuropathy (AIDP) subtype. In addition, SSR was abnormal in all pediatric GBS patients with poor prognosis 1 month after onset of symptoms. Two-thirds of the children with GBS have AD. SSR could be used for early diagnosis and follow-up of GBS and may also be helpful in evaluating disease severity and short-term prognosis.

Substantiating the Therapeutic Effects of Simultaneous Heat Massage Combined with Conventional Physical Therapy for Treatment of Lower Back Pain: A Randomized Controlled Feasibility Trial

There are various therapeutic options for the conservative management of lower back pain (LBP). A combination of two or more treatment options may be more effective in the clinical management of non-specific LBP. In this study, we compared the effects of simultaneous heat massage with conventional physical therapy in patients with subacute LBP. A single-center randomized controlled trial in which 40 participants with LBP were allocated to one of two groups: a heat massage group (HMG) and physical therapy group (PTG). The HMG received simultaneous heat massage therapy using a mechanical device (CGM MB-1401, Ceragem, Republic of Korea). The PTG received conventional physical therapy. Both groups received 40 min of therapy once daily, five times a week, for a total of four weeks. Changes in serum cortisol, epinephrine (EP), and norepinephrine (NE) were assessed. The outcomes were measured using the pain numeric rating scale (PNRS), the Oswestry disability index (ODI), the Roland-Morris disability questionnaire (RMDQ), the short-form McGill pain questionnaire (SF-MPQ), the multidimensional fatigue inventory (MFI-20), the Beck depression inventory (BDI), surface EMG (sEMG), and sympathetic skin response (SSR) at baseline (PRE), at 2 (2 W) and 4 weeks (4 W) following the intervention. The serum EP and NE levels in the HMG decreased after treatment. The PNRS, ODI, RMDQ, and SF-MPQ scores improved without significance in both groups. The BDI score showed improvement in the HMG before the PTG. The MFI-20 score improved in both groups, but the results were better in the HMG than in the PTG at 4 W. All the activities of sEMG were significantly decreased in both groups. However, the improvement of the %MVIC in the HMG was better than that in the PTG at 4 W. The SSR latency on sEMG decreased while the amplitude increased in the HMG at 2 W and 4 W, respectively. Following 4 weeks of combined therapies, heat massage was not superior to conventional physical therapy alone. Both treatments were shown to be effective in improving LBP and pain-related disability. However, heat massage was shown to have a better effect on the control of autonomic nerve function and underlying moods.

Evaluation of peripheral nerve involvements in patients with familial Mediterranean fever.

The aim of this study was to evaluate possible peripheral and autonomic nerve involvement in familial Mediterranean fever (FMF) patients with nerve conduction studies, sympathetic skin response (SSR) and RR interval variability (RRIV). The comparative case series was conducted with 76 participants between November 2017 and December 2018. Forty-six FMF patients, [12 with amyloidosis (5 males, 7 females; mean age: 44.7±13.9 years) and 34 without amyloidosis (14 males, 20 females; mean age: 35.9±8.7 years)], and 30 healthy volunteers (11 males, 19 females; mean age: 38.4±10 years) were included in this study. Nerve conduction parameters, SSR latency and amplitude from palmar and plantar responses, and RRIV at rest and deep breathing were studied in all the subjects. Neuropathic symptoms of the patient group were evaluated using the survey of autonomic symptoms scale and the neuropathy disability score. Nerve conduction studies of the patient group revealed polyneuropathy in seven (15.21%) patients and carpal tunnel syndrome in six (13.04%) patients. The mean amplitudes of SSR measured from the soles were significantly lower than the control group (p=0.041). The mean values of RRIV during rest and hyperventilation were lower in the patient group compared to the control group, but no statistically significant difference was found (p=0.484, p=0.341). We detected that the prevalence of carpal tunnel syndrome in our patient population (13.04%) was higher than in the general population. Most of the changes in the range of parameters of SSR and RRIV determined in the patient group did not reach statistical significance, suggesting subclinical dysautonomia in FMF patients.

Assessment of Cutaneous Parameters and Sympathetic Skin Response as a Non-Invasive Complementary Diagnostic Tool in Psoriasis: An Exploratory Study.

Various diagnostic tools are used to assess cutaneous psoriasis, but most of it were subjective. Sympathetic skin response (SSR), skin PH and temperature objectively measure the skin barrier functions that could aid clinicians to evaluate accurately and predict skin disease incidence even before the onset of clinical symptoms. The study's objective was to assess the utility of cutaneous parameters (skin temperature and pH) and SSRs influencing psoriatic patients' diagnosis management and treatment compared to controls. A total of 40 healthy participants and 40 psoriasis patients aged 18 to 65 years were recruited for this study. SSR, skin temperature and pH were assessed. The psoriasis disability index (PDI) was recorded from all the patients. Data analysis was carried out using SPSS version 20.0. The results shows significantly increased skin temperature, prolonged SSR latency (bilaterally) and decreased SSR amplitude (bilaterally) among patients affected with psoriasis compared to control subjects. There is a positive correlation between SSR latency with PDI and a negative correlation between SSR amplitude and PDI in psoriasis patients. SSR reveals sympathetic sudomotor dysfunction and increased skin temperature in psoriasis. Furthermore, there is a link between increased SSR latency and PDI, which shows that local nervous system impairment significantly contributes to the inflammatory process in psoriasis. Thus, SSR can be used as a complementary tool for the early identification and assessment of epidermal barrier integrity in psoriasis patients, along with the clinician's standard protocols.

Evaluation of Neuromuscular Functions in Hashimoto’s Thyroiditis

Hashimoto’s thyroiditis is the most prevalent autoimmune thyroid disease with an increasing incidence. Although the exact causes and pathogenesis of Hashimoto’s thyroiditis are not yet fully understood, the literature indicates complex interactions of immunologic, genetic, environmental, and epigenetic factors. It generally leads to hypothyroidism which can cause neuromuscular problems including neuropathy and myopathy. Data on neuromuscular functions of Hashimoto’s thyroiditis patients are relatively underreported and not up to date.The current observational study aimed to evaluate neuromuscular functions and sympathetic skin responses (SSR) in patients with Hashimoto’s thyroiditis and compare them with healthy participants. In total, 50 patients (25 females, 25 males; mean age, 31.6±4.9 years; range: 25-40 years) including 33 euthyroid, 10 with subclinical hypothyroidism, and 7 with hypothyroidism were included. The control group consisted of 50 healthy individuals (25 females, 25 males; mean age: 31.5±5.1 years; range, 25-40 years). Nerve conduction studies, repetitive nerve stimulation, SSRs and F wave recordings were performed in all participants. There were significant differences in the mean SSR latency and amplitude both in the upper extremities (p&amp;lt;0.001 and p=0.013, respectively) and in the lower extremities (p=0.008 and p=0.002, respectively) in the comparison groups. There was a significant difference in comparison groups regarding needle electroneuromyography (EMG) tests (p=0.012) and 14% of the patients showed myogenic EMG findings. In addition, a significant correlation was found between EMG findings and anti-TPO levels in the Hashimoto’s thyroiditis patients (r=0.453; p=0.001). No significant differences were found in the nerve conduction studies, routine EMG tests, repetitive nerve stimulations or F wave recordings between patients and control groups. Hashimoto’s thyroiditis, can cause negative influences on the proper functioning of neuromuscular systems. SSR, and electrophysiological tests may be beneficial for early detection and investigation of neuromuscular abnormalities in these patients.

A Temporospatial Study of Sympathetic Skin Response and Electroencephalogram in Oral Mucosa Thermal Perception.

ObjectiveTo investigate the temporospatial changes in sympathetic skin response (SSR) and electroencephalogram (EEG) under thermal stimuli and to draw a topographic map of SSR threshold temperature of the oral mucosa.Materials and MethodsA total of 40 healthy volunteers (24 men, 16 women, mean age of 23 ± 3) were enrolled. Thermal stimuli were applied to the 35 partitions of oral mucosa starting from 36°C at the gradience of 1°C and the lowest temperature evoked SSR was defined as SSR threshold temperature. SSR and EEG signals at 45, 48, 51, and 54°C were then recorded synchronously.ResultsThe SSR threshold temperature increased from the anterior areas to the posterior areas. No significant difference between bilateral corresponding areas or between genders was observed. The SSR amplitude value increased from 45 to 54°C in the same area, while the highest value was recorded on the tip of the tongue and decreased backwardly from the anterior area. There were significant differences in latency of SSR between the tip of the tongue and the molar areas of the oral cavity (p < 0.05). Reduction in the alpha frequency band was observed after thermal stimuli, and there were statistical differences between baseline and thermal stimuli in all four degrees of temperatures (p < 0.05).ConclusionThe result of the experiment revealed that the autonomic and central nervous system (CNS) played important roles in thermal perception of oral mucosa and could be helpful for better understanding of pathological mechanism of burning mouth syndrome (BMS).

Autonomic Function Tests, Heart Rate Variability, and Electrophysiological Evaluation in Patients With a Primary Episodic Headache: An Observational Study.

Cranial autonomic symptoms are typically associated with the trigeminal autonomic cephalalgias and also present in substantial cases of migraine. Autonomic nervous system dysfunctions are also been reported in headache disorders and postulated to promote headache attacks. This study was aimed to evaluate the parasympathetic and sympathetic autonomic functions tests in patients with a episodic primary headache and to investigate, if any, electrophysiological abnormalities in the blink reflex test and sympathetic skin response test in these patients. In this cross-sectional study, a total of 100 patients, 50 patients each of migraine and tension-type headache attending the neurology OPD and fulfilling the diagnostic criteria of headache disorders were enrolled. Autonomic functions tests were performed in the Department of Physiology, whereas electrophysiological tests were powered by the Editorial Manager and ProduXion Manager from Aries Systems Corporation performed in the Department of Neurology. Significant association ( P < 0.05) was observed in "blood pressure response to sustained handgrip" (sympathetic activity) and "heart rate response to Valsalva maneuver" (parasympathetic activity) among patients with migraine. Although the mean sympathetic skin response latency of patients with migraine was within the normal range, it was significantly prolonged in comparison with the control group. "Blood pressure response to sustained handgrip" and "heart rate variability" were found to be significantly ( P < 0.05) different in patients with a tension-type headache. The blink reflex test was observed to be normal in all patients with a headache. Patients with migraine showed a significant dysautonomia in category three of the Ewing battery for autonomic functional disability. Autonomic functional abnormality, both sympathetic and parasympathetic, does exist in patients with a primary episodic headache.

Autonomic dysfunction in amyotrophic lateral sclerosis: A neurophysiological and neurosonology study.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder affecting upper and lower motor neurons. Some ALS patients exhibit concomitant nonmotor signs, and thus ALS is considered a multisystem disorder. The aim of this study is to investigate autonomous nervous system involvement in ALS. We investigated 21 ALS patients and 28 age-matched controls. ALS patients were assessed for disease severity with the Revised-ALS Functional Rating Scale (ALSFSR) and for the presence of autonomic symptoms with the Composite Autonomic Symptom Score scale. Sympathetic nervous system was evaluated by sympathetic skin response (SSR) and parasympathetic nervous system by ultrasonography of vagus nerve (VN) at the level of the thyroid gland. SSR latencies were shorter and SSR amplitudes were higher in controls compared to ALS patients. The cross-sectional area (CSA) of the VN was significantly smaller in ALS patients (mean CSA right/left: 1.73±0.62 mm2 /1.47±0.53 mm2 ) compared to controls (mean CSA right/left: 2.91±0.79 mm2 /2.30±0.80 mm2 ), right: p <. 001, left: p <. 001. There was a significant negative correlation between disease duration and CSA of left-VN (r = -0.493, p = .023). This correlation was attenuated between disease duration and CSA of right-VN (r = -0.419, p = .059). ALSFSR-R was positively correlated to CSA of right-VN (p = .006, r = 0.590). CSA of VN did not correlate with bulbar involvement. This study confirms the presence of autonomic dysfunction in ALS patients and provides evidence of VN atrophy that correlates with disease severity and duration and is independent of bulbar involvement. Degeneration of dorsal nucleus neurons of the VN is hypothesized.

The First Electropysiological Abnormality In New-onset DM: Autonomic Tests

Conventional nerve conduction studies (NCS) are used in the electrodiagnosis of diabetic neuropathy. The aim of our study was to investigate diabetic small fiber neuropathy in newly diagnosed type 2 diabetes mellitus (DM) patient group by using autonomic tests. Our study was conducted on 49 patients (24 female, 25 male) who were newly diagnosed with type 2 DM in the last 3 months and a control group of 25 volunteers. In addition to conventional NCS, sympathetic skin response (SSR) and RR interval variability (RRIV) tests were performed. The mean upper limb SSR latency of the patient group was more prolonged than that of the control group, whereas the mean lower limb SSR amplitude of the patient group was lower than that of the control group (p=0.002, p<0.001; respectively). The mean resting (R) and deep inspiration (D) RRIV values of the patient group were lower than that of the control group (p=0.037, p<0.001; respectively). In the patient group, the mean R-RRIV and D-RRIV values were found to be positively correlated with the lower limb SSR amplitude (r=0.006, r=0.011; respectively). The mean R-RRIV and D-RRIV change rate of the patient group (D-R)/R was found to be lower than that of the control group (p=0.002). In our study, we showed that autonomic function tests were impaired in newly diagnosed type 2 DM patients who were found not to have diabetic polyneuropathy by standard electrophysiological study. These findings suggest that standard electrophysiological tests are not sufficient in the early stages of the disease.

Interictal autonomic dysfunction in patients with epilepsy

BackgroundAutonomic nervous system (ANS) symptoms are frequently present in people with epilepsy (PwE). They are generally more prominent when they originate from the temporal lobe. We aim to investigate the alterations of autonomic functions during the interictal period in patient with temporal lobe epilepsy (TLE) and idiopathic generalized epilepsy (IGE) using heart-based tests, blood pressure (BP)-based tests and sympathetic skin response (SSR). Forty-eight PwE with disease duration ranging from 2 to 15 years and 51 healthy individuals were studied. Long-term electroencephalography (EEG) monitoring, the heart rate variability (HRV) during normal breathing, deep breathing, Valsalva maneuver and standing, BP responses during standing, to isometric hand grip and to mental arithmetic, and the SSR was recorded for all participants.Results31 patients with TLE and 17 with IGE showed lower RR-IV values during deep breathing, Valsalva maneuver and standing, but not during rest, impaired BP responses during standing, isometric hand grip, and mental arithmetic. Also, prolonged SSR latencies. Within PwE group, no difference was noticed between males and females, nor between the left and right temporal lobes.ConclusionAbnormal autonomic (sympathetic and parasympathetic) regulatory functions suggest that epilepsy may alter the autonomic function and this is not only in TLE but rather in IGE too. These autonomic changes are irrespective of the localization of epilepsy between the two hemispheres. The ANS changes in epileptic patients, particularly those with autonomic symptoms, confirm that electrophysiologic measures of autonomic function may be of value in preventing sudden unexpected death in epilepsy.

Electrophysiological findings in patients with restless legs syndrome

BackgroundRestless legs syndrome (RLS) manifests as an urge to move the body to relieve the discomfortable sensations, primarily when resting, sitting, laying down, or sleeping. Diagnosis of RLS relies on clinical criteria, and the immobilization test was the only instrumental tool with equivocal results. ObjectivesTo assess different electrophysiological findings in patients with RLS, and compare the diagnostic values of these parameters in the diagnosis of RLS. Methods30 patients with primary RLS and 30 controls who were matched for age and gender were studied. Participant's demographics, laboratory findings, and electrophysiological test, namely nerve conduction studies (NCS), cutaneous silent period (CSP), H reflex and sympathetic skin response (SSR), F-wave latency, amplitude, F-wave duration (FWD), and the ratio between FWD and duration of the corresponding compound muscle action potential (FWD/CMAPD) were analyzed. ResultsNone of the patients showed altered NCS data. FWD of upper (12.37 ± 2.77 ms) and lower limb (21.71 ± 5.24 ms) were significantly longer in patients. Also, FWD/CMAP duration of the upper (1.03 ± 0.2) and lower limb (2.02 ± 0.55) was longer in patients. Likewise, they exhibited delayed CSP latency from TA (110.62 ± 13.73 ms) and APB (77.35 ± 12.16 ms) whereas the CSP duration from TA and APB was decreased (37.36 ± 11.59 ms; 42.55 ± 7.97 ms, respectively). The SSR latency was not different, and right-sided H reflex amplitude (5.07 ± 3.98 mV) and H/M ratio (0.65 ± 1.81) were significantly increased in the patient group. ConclusionThe data suggest that there may be a dysfunction of the inhibitory/excitatory circuits at a spinal level; and no pathology in the peripheral nerves. The unilateral difference of H reflex amplitude and H/M ratio may suggest asymmetrical central inhibitory dysfunction. Further prospective studies with larger cohorts are now needed to evaluate the pathophysiology of RLS with different neurophysiological assessment tools.

Neurophysiological and ultrasonographic comparative study of autonomous nervous system in patients suffering from fibromyalgia and generalized anxiety disorder.

Fibromyalgia (FM) and generalized anxiety disorder (GAD) share common clinical features: they both affect women more than men, their diagnosis is based solely on clinical criteria, and some of the symptoms such as anxiety, aches and muscle tension, sleep disorders, and cognitive dysfunction occur in both diseases. For both conditions, an underlying dysregulation of the autonomic nervous system (ANS) has been proposed. The aims of this study were to investigate ANS dysfunction in FM and GAD and compare them with controls. Sympathetic skin response (SSR) from palm and sole and cross-sectional area (CSA) of bilateral vagus nerves (VN) were measured in 28 healthy controls, 21 FM patients, and 24 GAD patients. CSA of VN was significantly smaller in FM patients (right: 1.97 ± 0.74mm2, left: 1.75 ± 0.65 mm2) and GAD patients (right: 2.12 ± 0.97mm2, left: 1.71 ± 0.86 mm2) compared to controls (right: 3.21 ± 0.75 mm2, left: 2.65 ± 1.13 mm2, p < 0.001, but did not differ between the two patient groups. SSR parameters were similar between patients and controls. SSR latency correlated to clinical scales (FM Widespread Pain Index) in the FM group (r = 0.515, p = 0.02 and r = 0.447, p = 0.05) for the upper and lower limbs respectively, but no other correlation between clinical and neurophysiological parameters was identified. This study confirms similar ANS abnormalities in FM and GAD that fairly distinguish them from controls and support the hypothesis of a common pathophysiological substrate underlying both conditions.

Peripheral Nerve Conduction And Sympathetic Skin Response Are Reliable Methods to Detect Diabetic Cardiac Autonomic Neuropathy.

AimThis study aimed to investigate the role of nerve conduction studies (NCS) and sympathetic skin response (SSR) in evaluating diabetic cardiac autonomic neuropathy (DCAN).MethodsDCAN was diagnosed using the Ewing test combined with heart rate variability analysis. NCS and SSR were assessed by electrophysiological methods. The association between NCS/SSR and DCAN was assessed via multivariate regression and receiver-operating characteristic analyses.ResultsThe amplitude and conduction velocity of the motor/sensory nerve were found to be significantly lower in the DCAN+ group (all P < 0.05). A lower amplitude of peroneal nerve motor fiber was found to be associated with increased odds for DCAN (OR 2.77, P < 0.05). The SSR amplitude was lower while the SSR latency was longer in the DCAN+ group than in the DCAN– group. The receiver-operating characteristic analysis revealed that the optimal cutoff points of upper/lower limb amplitude of SSR to indicate DCAN were 1.40 mV (sensitivity, 61.9%; specificity, 66.3%, P < 0.001) and 0.85 mV (sensitivity, 66.7%; specificity, 68.5%, P < 0.001), respectively. The optimal cutoff points of upper/lower limb latency to indicate DCAN were 1.40 s (sensitivity, 61.9%; specificity, 62%, P < 0.05) and 1.81 s (sensitivity, 69.0%; specificity, 52.2%, P < 0.05), respectively.ConclusionsNCS and SSR are reliable methods to detect DCAN. Abnormality in the peroneal nerve (motor nerve) is crucial in predicting DCAN. SSR may help predict DCAN.

Peripheral nervous system electrodiagnostic abnormalities in predominantly Hispanic Multiple Sclerosis patients

BackgroundPeripheral nervous system (PNS) abnormalities in Multiple Sclerosis (MS) have been reported in case reports and small case series over the past several decades. Little is known, however, about the prevalence of electrodiagnostic abnormalities in patients with MS, including not only demyelinating neuropathies such as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) but also axonal peripheral neuropathy and sympathetic dysfunction. MethodsThis is an observational, cross-sectional study with the objective of identifying the prevalence of the electrodiagnostic abnormalities in predominantly Hispanic MS patients in Miami, Florida. Electrodiagnostic data including nerve conduction study (NCS), electromyography (EMG) and sympathetic skin response (SSR) information was prospectively collected in 18 patients (16 females; 43.7±15.2 years) with a diagnosis of MS compared to 18 healthy (16 females; 39.9±11 years), age- and height-matched controls. The study was offered to all-comers in the MS Clinic over a period of 3 months, regardless of clinical suspicion for an underlying neuropathic process, in an effort to estimate the prevalence of abnormalities. Demographic data including age, sex, race/ethnicity was evaluated in addition to MS-specific characteristics including MS subtype, duration of disease, duration of therapy, clinical symptoms and laboratory data. ResultsThere were no significant differences in baseline characteristics of patients and controls for age (p=0.4) and height (164.0±6.4 vs 162.3±4.6 centimeters; p=0.3). The mean disease duration was 106±27 months (median 107 months; range 5-336 months). The mean Expanded Disability Status Scale (EDSS) was 2.4±1.87 (median: 2.5; range 1.0-6.5). The ethnicity of patients (15 Hispanic, 3 non-Hispanic) and controls (13 Hispanic, 5 non-Hispanic; p=0.56) was similar. The frequency of electrophysiological axonal polyneuropathy (PN) was 77.8% (14/18 patients), and 85.6% of these patients had clinical sensory symptoms. Interestingly, 1 patient had previously unrecognized CIDP. All 18 patients displayed prolonged SSR latencies consistent with autonomic dysfunction. Thirteen patients (72.2%) reported autonomic symptoms such as bladder abnormalities and blood pressure fluctuations. ConclusionThe prevalence of electrodiagnostic abnormalities, especially axonal polyneuropathy, in the MS population may be higher than traditionally considered. The relationship between axonal polyneuropathy and central axonopathy in the context of neurodegeneration in MS should be further explored. Analytic studies may identify common symptomatic and pathophysiologic etiologies to further understanding and potentially guide treatment of MS subtypes with PNS involvement.

Combined Effects of Extracorporeal Shockwave Therapy and Integrated Neuromuscular Inhibition on Myofascial Trigger Points of Upper Trapezius: A Randomized Controlled Trial.

Objective To investigate the combined effect of extracorporeal shockwave therapy (ESWT) and integrated neuromuscular inhibition (INI) on myofascial trigger points in the upper trapezius.MethodsSixty subjects aged 18–24 years old with active myofascial trigger points in the upper trapezius were studied. Participants were assigned randomly to either group A who received ESWT one session/week, group B who received INI three sessions/week, or group C who received ESWT in addition to INI. All groups completed 4 weeks of intervention. The following main outcome measures were evaluated at baseline and after 4 weeks of intervention: pain intensity, functional disability, pressure pain threshold (PPT), sympathetic skin response (SSR), and neuromuscular junction response (NMJR).ResultsWithin-group analysis revealed a significant decline in visual analog scale (VAS), Arabic neck disability index (ANDI), and NMJR and incline in PPT and SSR latency post-intervention (p<0.001). Multiple comparison analysis showed a substantial difference between the groups, while the major changes favored group C (p<0.05).ConclusionCombined treatment with ESWT and INI for treating myofascial trigger points in the upper trapezius is more effective than using only one of the two approaches in terms of clinical, functional, and neurophysiological aspects.