Peripheral Nerve Conduction Studies Research Articles

A Comparative Peripheral Nerve Conduction Study in Type-2 Diabetics with Symptoms of Polyneuropathy with Age and Sex Matched Normal Subjects

Background: Diabetes Mellitus is one among the diseases that affects peripheral nervous system and symptomatic Neuropathy in uncontrolled Diabetes is one of the commonest incapacitating complications. Electro diagnostic tests can be used to detect Diabetic Neuropathy at an early stage (before development of the signs or symptoms of Neuropathy). Nerve Conduction Study (NCS) is considered to be the most sensitive, reliable, non-invasive and objective means of investigations of Diabetic Polyneuropathy. Diabetic Neuropathy is curable, and hence if detected, the proper treatment can be instituted in early stages, which again, can give rise to good outcome. As the peripheral nerve has the ability to regenerate, line of treatment can be planned. Aims & Objectives: To compare and analyze the peripheral nerve conduction studies in symptomatic diabetic neuropathy cases with age and sex matched normal subjects emphasizing on use of Nerve conduction studies as a diagnostic approach to prevent Severe Neuropathy. Methods: The study group consists of 9 cases diagnosed with Diabetic neuropathy referred to our neurophysiology lab and control group consists of 9 age and sex matched normal subjects who are nondiabetic, healthy volunteers. Statistical analysis was done using unpaired t-test and 8 out of 9 cases considered for statistical analysis. Motor and Sensory nerve conduction studies conducted in both Upper (Median and Ulnar nerves) and Lower limbs (Tibial and Peroneal nerves) using bipolar surface electrodes with RMS EMG EP MARK-II machine. Results: There is a definite decrease in amplitude and nerve conduction velocities of both the sensory and motor components, axonal and demyelinating type significantly correlating with higher HBA1c levels. F minimum latencies of Median, Tibial and Peroneal nerves were increased possibly more of demyelinating type of Polyneuropathy. Conclusion: NCS being a simple, harmless, non-invasive and objective technique along with easy interpretation of results can be used routinely to evaluate the status of nerves in patients with Type 2 Diabetes Mellitus to prevent more disabling state at the earliest.

ID 369 – The effects of chronic arsenic exposure on somatosensory pathway

Objective From 1920 to 1962, a mining company at a small mountainous village called Toroku in Japan intermittently produced arsenic trioxide. Although many patients had severe whole-body surface and deep sensory disturbances, previous studies reported only slight axonal degeneration based on nerve conduction studies or sural nerve biopsy. Methods Subjects were six patients with chronic arsenic exposure in Toroku. All patients had moderate to severe whole-body surface and deep sensory impairments without any motor disturbances. Peripheral nerve conduction study and bilateral median nerve somatosensory evoked potentials were performed in all patients. Results In nerve conduction study, two patients showed mild decrease of sensory nerve action potentials. In somatosensory evoked potentials, the N9 was delayed in two patients. The N11 was not detected in any patients, while the P13/14 was detected only in two patients. The N20 was detected in all patients. Patients with chronic arsenic poisoning had a significantly longer central sensory conduction time (latency between N9 and N20) compared to normal subjects (p Conclusions Sensory disturbances in patients with chronic arsenic poisoning are related to not only peripheral neuropathy but also central nervous system impairment. Key message Chronic arsenic exposure may affect the central nervous system.

Sensory Ganglionopathy and the Blink Reflex: Electrophysiological Features.

Sensory ganglionopathy (SG) is characterised by asymmetrical sensory fibre degeneration, with the primary pathology occurring at the level of the dorsal root ganglion. It is seen in the context of autoimmune, paraneoplastic, and degenerative disorders. There is limited literature examining the electrophysiological correlate of the trigeminal ganglion and associated pathways, the blink reflex (BR), in cases of SG. Previous work has suggested that the BR is preserved in cases of SG associated with paraneoplasia. The local clinical neurophysiology database was searched for patients diagnosed with SG from peripheral nerve conduction studies in whom the BR was performed. Twenty-six patients were included in the final analysis. Sjögren's syndrome constituted the most common SG aetiology (8/26), followed by idiopathic cases (7/26) and paraneoplasia (5/26). BR abnormalities were seen in 9 of the 26 patients (34.6%) across all aetiologies. No patients reported sensory disturbance in the distribution of the trigeminal nerve, indicating that the changes noted are subclinical. Three patients showed abnormality of the R1 response; in the remaining six patients, only R2 responses were affected. Subclinical abnormalities of both R1 and R2 can be seen in the context of SG of varying aetiologies, including paraneoplasia. Performing the BR in patients with suspected of having SG may be helpful in providing additional evidence of patchy sensory fibre involvement that is characteristic of the disease.

Study of predictive value of capillaroscopic pattern and serum level of interleukin-17 in rheumatoid vasculitis patients

Objectives The aim of this study was to investigate nailfold capillaroscopic (NC) abnormalities and serum interleukin (IL)-17) level among rheumatoid arthritis (RA) patients with or without vasculitis. Patients and methods The study was carried on a group of RA Egyptian patients (n=40) who were diagnosed with RA based on ACR criteria. These 40 patients were further divided into two groups. Group 1 included RA patients with clinical signs of skin vasculitis and NC changes (n=6). Group 2 included RA patients with no clinical signs of skin vasculitis and no NC changes (n=34). All patients were subjected to demographic data collection, clinical examination, Disease Activity Score (DAS) 28 calculation, laboratory measurement (including erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor, antinuclear antibody, antineutrophil cytoplasmic antibody, anticyclic citrullinated peptide, and IL-17), and NC examination. In addition, group 1 (n=6) was further subjected to electrophysiological evaluation by peripheral nerve conduction studies. Results Significantly elevated levels of IL-17 and characteristic NC changes were seen in RA vasculitis patients. Conclusion Rheumatoid vasculitis is associated with significantly elevated levels of serum IL-17 and characteristic NC changes.

Impaired Awareness of Hypoglycemia in Adults With Type 1 Diabetes Is Not Associated With Autonomic Dysfunction or Peripheral Neuropathy.

Impaired awareness of hypoglycemia (IAH) is a risk factor for severe hypoglycemia in people with insulin-treated diabetes; autonomic neuropathy has been suggested to underlie its development. The aim was to evaluate a putative association between IAH and autonomic dysfunction using novel and sensitive measures of autonomic neural function. Sixty-six adults with type 1 diabetes were studied, 33 with IAH and 33 with normal awareness of hypoglycemia (NAH), confirmed by formal testing. Participants were matched for age, sex, and diabetes duration. Clinical and laboratory evaluations included extensive autonomic function testing, peripheral nerve conduction studies, and quantitative sensory testing. Composite abnormality Z scores were used for group comparisons. The IAH and NAH group had similar median (interquartile range) age of 48 (14.5) vs. 47 (14.5) years, diabetes duration of 30 (13.5) vs. 31 (13.5) years, and mean ± SD HbA1c 7.8 ± 2.2% vs. 8.1 ± 1.9%, respectively. The autonomic composite Z score did not differ between the two groups (mean difference -0.15, 95% CI -0.46, 0.16; P = 0.33), nor did the thermal detection (mean difference 0.15, 95% CI -0.31, 0.61; P = 0.51) or nerve conduction scores (mean difference 0.03, 95% CI -0.43, 0.49; P = 0.89). In adults with type 1 diabetes, IAH was not associated with autonomic dysfunction or peripheral neuropathy.

Clinical and electrophysiological study of peripheral and central neuromuscular changes in connective tissue diseases in children

IntroductionChildren with juvenile connective tissue diseases (JCTDs) may have a wide variety of clinical features ranging from fever or a simple arthritis to complex multisystem autoimmune diseases. Aim of the workTo study clinical and electrophysiological peripheral and central neuromuscular changes in children with connective tissue diseases. Patients and methodsThirty children with different JCTDs were enrolled. Clinical and neurological examination and laboratory investigations were done. Electrophysiological evaluation was performed and included: peripheral nerve conduction studies, late responses, somatosensory evoked potential and electromyography. ResultsTwenty patients had juvenile idiopathic arthritis (JIA) (66.7%), 8 patients had juvenile systemic lupus erythematosus (JSLE) (26.7%), one patient had juvenile systemic sclerosis (JSScl), and one patient had juvenile overlap syndrome (JSScl and polymyositis). Clinical neurologic abnormalities were present in 3 patients (ulnar neuropathy, median neuropathy and polymyositis). Electrophysiological abnormalities were detected in 18 patients (clinical in 3 and subclinical in 15 patients) and included ulnar entrapment neuropathy, median axonal neuropathy, demyelinating sensory motor polyneuropathy, deep peroneal nerve entrapment at the ankle (anterior tarsal tunnel syndrome), prolonged posterior tibial somatosensory evoked potential latency and prolonged H reflex latency not explained by peripheral neuropathy, increased H/M ratio and myopathic motor units. The most common electrophysiological abnormalities were present in patients with JSLE. ConclusionClinical neurological abnormalities are not common in JCTDs whereas subclinical neurological abnormalities are common findings. Juvenile systemic lupus erythematosus had the most common abnormalities among JCTDs. Polyneuropathy in JIA is commonly of demyelinating type. Entrapment neuropathy is less frequent than in adults.

Type 2 diabetes mellitus and microvascular complications 1 year after Roux-en-Y gastric bypass: a case-control study.

Aims/hypothesisWe aimed to examine the effects of bariatric surgery on microvascular complications in patients with type 2 diabetes using objective measures.MethodsProspective case–control study of 70 obese surgical patients with type 2 diabetes undergoing gastric bypass surgery matched for age, sex and duration of diabetes to 25 medical patients treated using international guidelines. Microvascular complications were assessed before and 12–18 months after intervention using urine albumin creatinine ratio (ACR) measurements, two-field digital retinal images and peripheral nerve conduction studies (in the surgical group only).ResultsUrine ACR decreased significantly in the surgical group but increased in the medical group. There were no significant differences between the surgical and medical groups in the changes in retinopathy. There were no changes in the nerve conduction variables in the surgical group.Conclusions/interpretationIn the short term, bariatric surgery may be superior to medical care in the treatment of diabetic nephropathy, but not retinopathy or neuropathy.

Electromyography in musculoskeletal pain: A reappraisal and practical considerations.

Background:Patients with musculoskeletal pain (MSP) and local tenderness in the back and extremities are frequently referred to electromyography (EMG) laboratory to assess the integrity of the spinal nerve roots, peripheral nerves, and skeletal muscles. When focal muscle weakness and anatomical sensory deficits are clinically evident, this procedure is almost always abnormal. In some situations, when the presenting symptoms consist of local pain and tenderness without neuromuscular deficits, its diagnostic utility becomes questionable as illustrated in the present study.Methods:EMG findings of 75 patients referred for evaluation of local MSP and tenderness in the neck and lower back and in the upper and lower extremities were reviewed. These patients were selected from a group of 200 patients referred for evaluation of unilateral local pain and tenderness in various parts of the body. All EMG procedures and clinical neurologic examination were performed by the author and all underwent magnetic resonance imaging of the affected parts of the body prior to the procedure. None of the 75 patients studied had concurrent medical disorders or had previous spinal root injuries or surgeries to the spine.Results:All 75 patients in this study showed normal EMG of the affected extremities and normal peripheral nerve conduction study. Those with herniated disc in the cervical or lumbar spine presenting with local pain and tenderness in the neck and lower back but without neurologic deficits or clear radicular symptoms, had normal study also. The remaining 125 patients excluded from the study, had various EMG and peripheral nerve abnormalities that can be attributed to concurrent medical disorders and previous injuries to the spinal roots.Conclusions:Use of EMG in the diagnosis of local MSP, unless associated with clinical neurologic deficits, almost always yields negative results. The utility of this procedure is limited to pathology in the motor unit. It cannot assess the function of the sensory components of the spinal roots, small-diameter sensory nerves, and the sensory innervation of the spine via sinuvertebral nerve. Therefore, if the motor unit is anatomically and physiologically intact, the procedure is of little value in the diagnosis of MSP. Likewise, peripheral nerve conduction study is likely to be normal unless clear neurologic deficits are present. The present study illustrates that a good history and meticulous neurologic examination should be an integral part of an ideal electrodiagnostic procedure.

10.4066/AMJ.2014.2123

We report the case of a 20-year-old male who presented to us with acute bilateral multiple cranial neuropathy in the form of bilateral total ophthalmoplegia and bulbar dysfunction. The patient had normal haematological and biochemical investigations, however, cerebrospinal fluid (CSF) analysis showed raised protein (96mg/dl) in the second week of illness. Peripheral nerve conduction studies and an MRI of the brain were normal. The patient showed gradual improvement after three weeks of supportive treatment. Considering the course of illness and the clinical and investigational profile, a diagnosis of an oculopharyngeal variant of Guillain-Barré syndrome (GBS) was made.

Peripheral Motor and Sensory nerve conduction studies in normal infants and children in Eastern India

Peripheral Motor and Sensory nerve conduction studies in normal infants and children in Eastern India

Visual evoked potentials for the evaluation of CNS impairment in type 1 diabetes in children

Central nervous system (CNS) impairment is common in diabetic patients even in the early stage of the disease and it could be associated with peripheral neuropathy. Nevertheless, less attention has been directed toward the chronic effects of diabetes on the CNS. The aim of the study was to investigate the changes of central nerve conduction in children with insulin-dependent diabetes mellitus prospectively using the visual evoked potentials (VEP) and to know how those results were related to clinical risk factors and parameters of peripheral nerve conduction studies (NCS). A total of 75 diabetics (29 males) aged 5-26 years (mean 14.3±4.7) underwent VEP and NCS annually for 5 years. For comparison, 52 healthy children were studied. Out of 75 patients, 25 patients completed annual studies for 5 years. The latencies of P100 were prolonged at the study entry when compared with controls (P< 0.001). Significant positive correlations were found between the VEP latency and the glycosylated hemoglobin level. The values of latency and amplitude were inversely related with the age of patients and the duration of the disease. The values of latency were not related with parameters of NCS. Only a few parameters of NCS were weakly associated with the amplitudes of P100. Poor glycemic control proved to be an important risk factor over 5 years as related to the development of subclinical central neural pathway abnormality. VEP could be considered as a valid noninvasive tool for detecting early diabetic central conduction abnormalities such as retinopathy or optic neuropathy.

AB0663 Neurological involvement in primary sjÖgren syndrome

BackgroundPrimary Sjögren Syndrome (pSS) is an autoimmune disorder characterized by a chronic lymphocytic and plasmacellular infiltration of exocrine glands and extraglandular features including both peripheral nervous system and central nervous...

3:38 PM Abstract No. 162 - A test of nerves. The incidence of neuropathy following sts sclerotherapy of venous malformations

Purpose Sclerotherapy is widely advocated as the treatment of choice for venous malformations (VMs). Several sclerotherapy agents are available and a range of risk factors are associated with their use. There are almost no examples of neuropathy resulting from sodium tetradecyl sulfate (STS) published in the literature. We report our experience of neuropathy as a complication of STS sclerotherapy. Materials and Methods All VM sclerotherapy procedures performed between 1999-2012 were reviewed. Standard technique was used with STS as foam, formed from a 1:1:2 mixture of iohexol contrast, air and 3% STS. At the time of treatment technical details were recorded for all procedures including needle size and insertion technique, number, location and classification of treated lesions, the volume and nature of sclerosant used and whether steroids or antibiotics were given. All nerve lesions were recorded. Routine follow-up included post-operative assessment, post discharge telephone call and outpatient clinic appointments. Results 847 procedures were performed. Motor and/or sensory nerve lesions occurred after 10 (1.2%) of 847 procedures. 7 of the 10 cases were in patients that had undergone at least 1 previous sclerotherapy procedure. Neuropathy was seen following treatment of 5 Puig type II lesions, 5 type III and a single type I lesion. Nerve lesions were managed according to clinical need including surgical consultant with a peripheral nerve specialist, physiotherapy and nerve conduction studies. Neuropathy improved in all cases with complete resolution in 7 and partial resolution in 3 patients of whom two required surgery. Conclusion Nerve injury is a rare complication of STS sclerotherapy and an important factor to consider when deciding to treat VMs. A degree of recovery was seen in most patients, but may be incomplete. The literature to date doesn't report neuropathy with STS but our series demonstrates that nerve injury can occur. We advocate active management of neuropathy with physiotherapy, nerve conduction studies and surgical consultation. Long-term follow up is recommended. The authors advocate sharing of clinical information of sclerotherapy complications, to enable prevention, appropriate management and prognostication of lesions.

Electrodiagnosis in Persons With Amyotrophic Lateral Sclerosis

Electrophysiology remains an important tool in the evaluation of patients presenting with signs and symptoms of motor neuron disease. The electrodiagnostic study should include peripheral nerve conduction studies and needle electromyography to both exclude treatable disease and gather evidence regarding a diagnosis of amyotrophic lateral sclerosis (ALS). The recent changes in the revised El Escorial criteria, recommended by the Awaji-shima consensus group, have increased the diagnostic significance of fasciculation potentials to equal that of fibrillation and positive sharp-wave potentials in the needle electromyography examination of patients suspected of having ALS. In addition, electrophysiologic evidence is now considered equivalent to clinical signs and symptoms in reaching a diagnostic certainty of ALS. These changes, strategies for the design, and implementation of an effective electrodiagnostic evaluation, in addition to electrophysiologic techniques and their relationship to the evaluation of a patient with ALS, are reviewed and discussed.

Spontaneous CSF Collection in the Cervical Spine may Cause Neurological Deficit and Intra-cranial Hypotension

Objective:a case is described of a spontaneously occurring cerebrospinal fluid collection in the ventral cervical spine which caused radiculopathy and spontaneous intracranial hypotension. Case:a sixty eight year old Caucasian man presented with a 2 year history of proximal upper limb weakness with a his-tory of trivial cervical trauma many years previously. Methods:the patient was investigated with blood tests for causes of peripheral neuropathy, nerve conduction and electro-myography studies, lumbar puncture and MRI of the brain and spine with contrast. Results:a cerebrospinal fluid collection was identified in the ventral cervical spinal cord causing mass effect associated with cord atrophy and there were signs of spontaneous intracranial hypotension on the MRI brain including subdural cere-brospinal fluid collections, meningeal enhancement and slumped posterior fossa. Conclusions:this is the first description of a spontaneous spinal fluid collection causing direct compression and cord sig-nal change, manifest as a motor deficit, with intracranial signs of spontaneous hypotension. Spinal imaging is recom-mended in cases of spontaneous intracranial hypotension and cerebrospinal fluid collections in the spine may rarely be a cause of radiculopathy in such cases.

Spinal charcot‐marie‐tooth disease: A reappraisal

Distal hereditary motor neuropathy (dHMN) is characterized by isolated distal muscle atrophy without sensory deficit. Nevertheless, clinical sensory loss has been reported despite preserved sensory nerve conduction in a few patients, thus differentiating these cases from the classical type 2 Charcot-Marie-Tooth disease (CMT2). We report 4 patients who presented with clinical sensory and motor neuropathy and normal peripheral sensory nerve conduction studies and were investigated with complete electrophysiological studies, including somatosensory evoked potentials (SEP). These patients had a clinical presentation of classical CMT with isolated axonal motor neuropathy suggestive of dHMN. Interestingly, tibial nerve SEPs showed abnormalities suggestive of proximal involvement of dorsal roots that may explain the clinical somatosensory disturbances. These cases support the concept of spinal CMT that should be recognized as an intermediate form between dHMN and CMT2. SEP recording was helpful in defining a more precise phenotype of spinal CMT.

Chronic immune sensory polyradiculopathy with cranial and peripheral nerve involvement

Chronic immune sensory polyradiculopathy (CISP) is a recently described restricted form of chronic inflammatory demyelinating polyradiculopathy (CIDP) [1]. It preferentially affects large myelinated fibres of the posterior roots, is associated with normal peripheral nerve conduction studies, and may respond to immunomodulatory treatment. We describe a patient with clinical features of CISP and additional cranial nerve involvement. A 61 year old woman presented with a 10 year relapsing-remitting neurological disorder. She initially presented with nausea, headache and photophobia followed by diplopia and unilateral ptosis consistent with an oculomotor nerve palsy. Intracranial CT, MRI, MRA, catheter angiography and CSF were all normal. Symptoms resolved over 18 months but an inflammatory cause was suspected after a relapse and treatment with 2 g/kg intravenous immunoglobulin (IVIg) was effective. Further relapses with additional poor balance, facial numbness and distal sensory symptoms responded promptly to IVIg. Intravenous methylprednisolone worsened her symptoms. Neurological examination revealed a partial right oculomotor nerve palsy. Pin prick sensation was reduced in a right trigeminal nerve distribution. Limb power was normal but reflexes were reduced in the upper limbs and absent in the lower limbs with flexor plantars. Romberg’s test was positive. Pin prick was reduced on the ulnar aspect of the right forearm and up to the mid-shins bilaterally. Vibration sense was reduced up to both ankles and proprioception impaired up to the right ankle. Examination after IVIg revealed that ophthalmoplegia, ptosis and a timed Romberg’s test had all improved. Systemic inflammatory/autoimmune blood tests were unremarkable and these included full blood count, ESR, CRP, ANA, ANCA, complement, rheumatoid factor, ENA, protein electrophoresis, immunofixation, acetylcholine receptor antibodies, immunoglobulins, ganglioside serology, lyme serology, treponemal serology and anti-neuronal antibodies. CSF was acellular with normal glucose and a raised protein level of 0.71 g/L (normal 0.15–0.65 g/L). Oligoclonal bands were absent. Neurophysiological data are presented in the appendix. In summary, the absolute values of all neurophysiological investigations listed were normal. However, the ulnar nerve SNAPs were significantly asymmetrical and the motor F-waves prolonged. Thermal thresholds were abnormal in the feet and right hand. Somatosensory evoked potentials were poorly formed in the right lower limb. Asymmetry of motor evoked potential latencies following cervical spine stimulation was consistent with a lesion distal to the intervertebral foramina. Electronic supplementary material The online version of this article (doi:10.1007/s00415-011-6326-0) contains supplementary material, which is available to authorized users.

Does Cervical Radiculopathy Have an Effect on Peripheral Nerve Conduction Studies? An Electrophysiological Evaluation

Background: Peripheral nerve neuropathies are more common in patients with cervical radiculopathy (CR) and a proximal lesion along an axon might predispose that nerve to injury at distal sites. To evaluate this hypothesis, the frequency of median nerve neuropathy at the wrist and the frequency of ulnar nerve neuropathy at the elbow were investigated in 80 patients with one-sided CR. Methods: The symptomatic and asymptomatic extremities were compared for the electrophysiological parameters of ulnar and median nerve conduction studies. The patients were divided into three diagnostic subgroups (C5/C6 radiculopathy, C7 radiculopathy and C8/Th1 radiculopathy), and ulnar nerve conduction studies were compared between symptomatic and asymptomatic extremities in each subgroup. Results: Although, the median and ulnar nerves are mainly derived from C8/Th1 roots, we did not observe an increased frequency of ulnar nerve involvement at the elbow (3.7% in symptomatic, 2.5% in asymptomatic extremities) while increased median nerve involvement was present at the wrist (27.5% in symptomatic, 12.5% in asymptomatic extremities). Conclusion: The electrophysiological data and the frequency of ulnar and median nerve neuropathy did not support an etiological association between CR and distal neuropathy. Significance: the association between CR and peripheral neuropathy is associational rather than causative.

Normal Motor Nerve Conduction Studies Using Surface Electrode Recording from the Supraspinatus, Infraspinatus, Deltoid, and Biceps

Proximal peripheral nerve conduction studies can provide useful information to the clinician. The difficulty of measuring the length of the proximal nerve as well as a frequent inability to stimulate at 2 points along the nerve adds a challenge to the use of electrodiagnosis for this purpose. The purpose of this article is to present normal values for the suprascapular, axillary, and musculocutaneous nerves using surface electrodes while accounting for side-to-side variability. Prospective, observational study. Patients were evaluated in outpatient, private practices affiliated with tertiary care systems in the United States and Malaysia. One hundred volunteers were recruited and completed bilateral testing. Exclusion criteria included age younger than 18 years; previous shoulder surgery/atrophy; symptoms of numbness, tingling, or abnormal sensations in the upper extremity; peripheral neuropathy; or presence of a cardiac pacemaker. Nerve conduction studies to bilateral supraspinatus, infraspinatus, deltoid, and biceps brachii muscles were performed with documented technique. Distal latency, amplitude, and area were recorded. Side-to-side comparisons were made. A mixed linear model was fit to the independent variables of gender, race, body mass index, height, and age with each recorded value. Distal latency, amplitude, area, and side-to-side variability of nerve conduction studies of the suprascapular, axillary, and musculocutaneous nerves with correlation to significant independent variables. Data are presented showing normal distal latency, amplitude, and area values subcategorized by clinically significant variables, as well as acceptable side-to-side variability. Increased height correlated with increased distal latency in all the nerves tested. Amplitudes were larger in the infraspinatus recordings from women, while the amplitudes from the biceps and deltoid were greater in men. A larger body mass index was associated with a smaller amplitude in the deltoid in men. No correlations were seen with age or race. Normative values for distal latency, amplitude, duration, and area were developed for proximal nerve conductions to the axillary, musculocutaneous, and suprascapular nerves. Simple surface electrode placement allows for easy reproduction of the authors' techniques. This is a useful standard to facilitate evaluation of these proximal peripheral nerves.

Relationship between clinical probability of carpal tunnel syndrome and neurophysiological studies

To determine the sensitivity and specificity of a series of clinical features and risk factors in carpal tunnel syndrome (CTS) and suggest a diagnostic measure to clinically estimate probability of disease. A prospective, cross-sectional study was performed of 100 patients consecutively referred to us for a neurophysiological evaluation of CTS. Patients were chronologically divided into two groups of 50 cases each (93 and 90 symptomatic hands respectively). Evaluation procedures included a clinical interview and physical examination to test for the classic signs of CTS, as well as comparative sensory peripheral median nerve conduction studies. The combined sensory index (CSI) was also determined and used as a reference tool to calculate the sensitivity and specificity of clinical features in the first group of patients and in the control group. Female gender, bilateral involvement and persistence of symptoms for 6 months or more were identified as risk factors. The pattern of critical clinical features associated with electrophysiological damage included numbness, nocturnal paresthesia and pain, symptoms in areas innervated by the median nerve, muscular weakness, positive Phalen maneuver or a positive Tinel's sign. On the basis of these results, we suggest a clinical model for estimating clinical probability prior to the electrophysiological test (PAT). A linear regression analysis found a significant association between PAT and CSI in the second group of patients (F[1.148] = 49.7; p < 0.000). PAT can be considered useful as diagnostic measure of the clinical features of CTS. Determinar la sensibilidad y la especificidad de los rasgos clínicos y los factores sociodemográficos en el síndrome del túnel carpiano (STC) y proponer una medida para estimar la probabilidad clínica de presentar la enfermedad. Se realizó un estudio prospectivo, descriptivo y transversal de 100 pacientes referidos para evaluación neurofisiológica de STC, divididos cronológicamente en dos grupos de 50 casos (93 y 90 manos sintomáticas, respectivamente). También fueron estudiados 30 sujetos sanos (60 manos asintomáticas). A todos se les realizó interrogatorio y examen físico, orientados al diagnóstico de STC, y estudios de conducción nerviosa periférica comparativos del nervio mediano; se determinó el índice sensorial combinado (ISC), el cual se utilizó como criterio de referencia para conocer la eficacia diagnóstica de los rasgos clínicos en el primer grupo de pacientes y en el grupo control. Se identificaron como factores sociodemográficos significativos: sexo femenino, tiempo de evolución de 6 meses o superior y afectación bilateral. Los rasgos clínicos de adormecimiento, dolor, parestesias nocturnas, localización de éstos en el territorio del nervio mediano, debilidad muscular, maniobra de Phalen o signo de Tinel positivos estuvieron significativamente asociados con alteraciones neurofisiológicas. A partir de estos resultados se propone la estimación de la probabilidad clínica anterior a la prueba diagnóstica (PAP). Un análisis de regresión lineal, efectuado en el segundo grupo de pacientes, mostró una asociación significativa entre PAP e ISC (F[1,148] = 49,7; p < 0,000). La PAP puede considerarse de utilidad como medida resumen de la presencia de rasgos clínicos significativos en el STC.