Abnormality of Contingent Negative Variation Correlates with Parkinson's Disease Severity.

Objective: We sought to assess the influence of Parkinson's disease (PD) on contingent negative variation (CNV). Patients and Methods: This prospective study included 49 patients with PD (69.7±16.5; 35 male) and 35 age- and sex-matched controls. The PD cohort was subdivided, according to the Hoehn-Yahr Scale, Unified Parkinson's Disease Rating Scale (UPDRS), and UPDRS Part III, into 30 cases of uncomplicated PD and 19 cases of advanced PD. CNV was recorded over the frontal and central vertex with a linked bimastoid reference using a dual-stimulus paradigm with interstimulus intervals (ISIs) of 1.7 and 2.0 seconds. Results: In advanced PD, the amplitude of the late CNV over the central vertex was markedly reduced (p<0.005) at ISI of 1.7 seconds and correlated negatively with UPDRS (r=-0.32; p<0.003) and motor score (UPDRS Part III) (r=-0.45; p<0.002). Conclusion: Late CNV amplitude was significantly abnormal in PD and correlated with the severity of the motor manifestations.

Diagnosis of Myasthenia Gravis.

The diagnosis of autoimmune Myasthenia Gravis (MG) remains clinical and rests on the history and physical findings of fatigable, fluctuating muscle weakness in a specific distribution. Ancillary bedside tests and laboratory methods help confirm the synaptic disorder, define its type and severity, classify MG according to the causative antibodies, and assess the effect of treatment objectively. We present an update on the tests used in the diagnosis and follow-up of MG and the suggested approach for their application.

Optimization of spectral domain optical coherence tomography and visual evoked potentials to identify unilateral optic neuritis.

BACKGROUND: Optic neuritis is a common manifestation of multiple sclerosis and frequently the presenting sign. The diagnosis of MS is heavily based on MRI findings but the latter is relatively insensitive in detecting optic nerve lesions. Identification of optic nerve lesion using ancillary tools such spectral-domain optical coherence tomography (SDOCT) by measuring the retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL), and visual-evoked potentials latencies (VEP) may facilitate early diagnosis and treatment of multiple sclerosis. OBJECTIVE: To determine the optimal of SDOCT measures in RFNL and GCIPL and the VEP latency value for the identification of a prior symptomatic optic nerve lesion. METHODS: Thirty patients with diagnosed clinically with optic neuritis and fifty healthy control subjects were tested with SDOCT and VEP and the sensitivity, specificity, negative and positive predictive values of optimal values from healthy controls and optic neuritis patients were determined of for the identification unilateral optic nerve lesion. RESULTS: The inter-eye GCIPL difference of 3.5 µm is highly sensitive (100%) and specific (98%) in identifying unilateral optic nerve lesion, while lowest 5th percentile normal GCIPL threshold values of 71 µm was highly sensitive (100%) but less specific (83.3%). The inter-eye RNFL difference of 5.5 µm had a sensitivity of 70% and specificity of 90% in identifying optic nerve lesion while the lower 5th percentile normal RNFL value of 92.3 µm was poorly sensitive (40%). Finally, the 95th percentile normal VEP latency of 104.50 milliseconds had sensitivity of 80% and specificity of 76% in identifying optic nerve lesion. CONCLUSIONS: The inter-eye GCIPL difference is a powerful index for identifying unilateral optic nerve lesion, while the inter-eye RNFL difference and 95th percentile normal VEP latency had very good sensitivity and specificity. These measures can be useful in the evaluation of the first demyelinating event of MS and therefor can facilitate early diagnosis and therapy.

Sensitivity of visual evoked potentials and spectral domain optical coherence tomography in early relapsing remitting multiple sclerosis.

BACKGROUND: Visual evoked potentials and spectral-domain optical coherence tomography are common ancillary studies that assess the visual pathways from a functional and structural aspect, respectively. OBJECTIVE: To compare prevalence of abnormalities of Visual evoked potentials (VEP) and spectral-domain optical coherence tomography (SDOCT) in patients with relapsing remitting multiple sclerosis (RRMS). METHODS: A cross-sectional study of 100 eyes with disease duration of less than 5 years since the diagnosis. Correlation between retinal nerve fiber layer and ganglion-cell/inner plexiform layer with pattern-reversal visual evoked potentials amplitude and latency and contrast sensitivity was performed. RESULTS: The prevalence of abnormalities in pattern-reversal visual VEP was 56% while that of SOCT was 48% in all eyes. There was significant negative correlations between the average RNFL (r=-0.34, p=0.001) and GCIPL (r=-0.39, p<0.001) with VEP latency. In eyes with prior optic neuritis, a significant negative correlation was seen between average RNFL (r=-0.33, p=0.037) and GCIPL (r=-0.40, p=0.010) with VEP latency. CONCLUSIONS: We have found higher prevalence of VEP abnormalities than SCOCT in early relapsing-remitting multiple sclerosis. This suggests that VEP has a higher sensitivity for detecting lesions of the visual pathway in patients with early RRMS.

Sonography in carpal tunnel syndrome with normal nerve conduction studies.

INTRODUCTION: We assessed the yield of high-resolution ultrasonography (HRUS) in patients with clinically definite carpal tunnel syndrome (CTS) and normal nerve conduction studies (NCS). METHODS: This blinded, prospective, cross-sectional study involved 35 patients (60 hands) with clinically definite CTS and normal NCS, and 20 controls (40 hands). Cross-sectional area (CSAs) of the median nerve at the level of the pisiform bone and flexor retinaculum thickness (FRT) were measured. RESULTS: CSA was abnormal in 48.6% of patients (confidence interval 32.0-65.2%, P = 0.95). FRT was increased in only 34.3% (18.3-49.7%), but was independently abnormal in 2 patients. CSA abnormalities correlated with positive provocative tests and sensory loss. The HRUS changes were mild. CONCLUSIONS: HRUS confirms clinically diagnosed CTS in about half of the patients with normal NCS.

Single-fiber electromyography of facial and limb muscles in diabetic patients with or without neuropathy.

PURPOSE: In diabetic patients, single-fiber electromyography (SFEMG) is often abnormal in the limb muscles and is considered unreliable in diagnosis of synaptic disorders. We aimed to compare SFEMG abnormalities of frontalis muscle (FM) and extensor digitorum communis muscle in diabetic patients with neuropathy and without neuropathy. METHODS: Stimulation SFEMG of FM and extensor digitorum communis muscle was performed in matched groups of 30 diabetic patients with neuropathy and 20 diabetic patients without neuropathy. RESULTS: Single-fiber electromyography in the FM was abnormal in four diabetic patients with neuropathy and in one diabetic patient without neuropathy. Changes were rather mild. Extensor digitorum communis abnormalities were significantly more frequent-in 20 diabetic patients with neuropathy and in 7 diabetic patients without neuropathy (P < 0.001). We never observed a patient with abnormal FM but normal extensor digitorum communis muscle. CONCLUSIONS: In diabetes, FM exhibits rare and quite mild SFEMG changes. This muscle may be suitable for SFEMG in diabetic patients with clinical suspicion for synaptic disorder.

An adult patient with ocular myasthenia and unusually long spontaneous remission.

A male patient developed ocular myasthenia gravis (MG) at the age of 33. He was anti-acetylcholine receptor antibody (anti-AChR Ab) negative. He received cholinesterase blocker for 5 months and went into a complete clinical remission that lasted untreated for 17 years. He relapsed recently with ocular symptoms only. He is now anti-AChR Ab positive and SFEMG is abnormal in a facial muscle. The patient is controlled with steroids. He had one of the longest spontaneous remissions reported in the natural history of MG, particularly unusual for an adult with the disease.

Abnormal levels of serum anti-elastin antibodies in patients with symptomatic carotid stenosis.

BACKGROUND AND OBJECTIVE: A correlation between the levels of antibodies to alpha-elastin (alpha-AEAb) and tropoelastin (tropo-AEAb) and the corresponding peptide concentration is found in human serum in health and disease. Serum elastin peptide and anti-elastin antibodies (AEAb) levels are age-related and vary with the stages of atherosclerotic vascular damage. This study aims to determine if elastin metabolism (assessed by the ratio of tropo-AEAb to alpha-AEAb) differs in patients with symptomatic carotid stenosis versus subjects with asymptomatic stenosis. PATIENTS AND METHODS: Alpha-AEAb and tropo-AEAb were measured by ELISA in blood sera of 65 patients with ultrasound verified high-grade symptomatic carotid stenosis (resulting in stroke 1-7 days before measurement) compared to 51 patients with asymptomatic stenosis. RESULTS: Serum anti-alpha-elastin IgG levels are extremely increased in symptomatic versus asymptomatic carotid stenosis. The ratio of tropo-AEAb (reflecting elastin synthesis) to alpha-AEAb (a function of elastin degradation) was 3.7 in symptomatic stenosis versus 14.2 in asymptomatic stenosis (p<0.001). CONCLUSIONS: There is a significant difference in elastin metabolism in patients with symptomatic carotid stenosis versus asymptomatic stenosis. The ratio of tropo-AEAb to alpha-AEAb as an index of elastin synthesis/degradation proves useful in investigation of atherosclerotic lesions and may represent a new immunologic marker for carotid plaque destabilization.

Isolated severe median mononeuropathy caused by a jellyfish sting.

Neuropathies caused by jellyfish stings are extremely rare and poorly studied. A 20-year-old female patient was stung on the volar aspect of the right forearm by an unidentified species of jellyfish. Local cutaneous reaction was followed within few days by severe median mononeuropathy, involving the motor and sensory branches to the hand and forearm but sparing the palmar branch. The patient had neuropathic pain relieved by pregabaline. Electrodiagnostic studies confirmed a demyelinating lesion. Ultrasound and magnetic resonance imaging of the median nerve revealed uniform swelling with mild uptake of contrast along the forearm. Within 2 months, strength improved significantly, pain subsided, and numbness partially resolved. Literature review and discussion of the possible mechanisms and implications of this rare effect of marine animal envenomation is presented. Jellyfish sting may cause focal mononeuropathies most probably because of the local effects of the toxins.

Clinically definite ALS presenting weeks after mild electric injury: causality or coincidence?

Motor neuron syndromes including typical ALS develop very rarely after electrotrauma, with possible causality discussed but not confirmed. We report on a 44-year-old male who developed clinically definite ALS by the revised El Escorial criteria with onset weeks after mild electric injury. He presented with asymmetric upper limb amyotrophy and weakness beginning around the entry point of the current. Over 1 year he developed generalized wasting, weakness and fasciculations, including the bulbar and thoracic muscles, with prominent spasticity and pyramidal tract signs. Electrodiagnostic studies confirmed widespread denervation, very unstable neurogenic motor units in the bulbar, cervical, thoracic and lumbosacral segments with normal motor velocities and normal sensory parameters. This is a well-documented case of fast-progressive ALS that seems related to electric injury.

Iatrogenic femoral neuropathy: two cases and literature update.

Iatrogenic femoral neuropathy is an uncommon surgical or obstetric complication that may be underreported. It results from compression, stretch, ischemia, or direct trauma of the nerve during hip arthroplasty, self-retaining retractor use in pelvicoabdominal surgery, lithotomy positioning for anesthesia or labor, and other more rare causes. Decreasing incidence of this complication after abdominal and gynecologic surgery but increase in its absolute numbers after hip arthroplasty has emerged over the last decade. We describe two illustrative cases related respectively to lithotomy positioning and self-retaining retractor use. The variability in clinical presentation of iatrogenic femoral nerve lesions, some new insights in their diverse pathophysiology, and in the diagnostic and treatment options are discussed with an update from the literature.

Single-fiber electromyography of masseter muscle in myasthenia gravis.

Jitter after axonal microstimulation in the masseter muscle was studied in 30 consecutive patients (12 women) with myasthenia gravis (MG). Patients' mean age was 42.3 (12-75), median disease duration was 3 months (1-72), and onset was ocular (15 cases), oculobulbar (7), bulbar (6), or generalized (2). There were 23 newly-diagnosed patients. Nine cases developed purely ocular MG and 21 cases developed generalized MG. In the latter group, five subjects had a rapidly progressive course and 16 subjects had stable or well-controlled disease (MGFA grade 2-3). Six patients did not have circulating anti-acetylcholine receptor antibodies. Masseter single-fiber electromyography (SFEMG) was abnormal in 6 of 9 ocular MG patients and in all generalized cases (overall sensitivity 27 of 30 cases or 90%; confidence interval 79.3%-100.0% at P = 0.95). Masseter should be considered for SFEMG in diagnosis of MG, especially in cases with bulbar onset.

Stimulated jitter in the masseter muscle: normative values.

Nineteen healthy volunteers (median age, 25; range, 18-51 years) were enrolled in a study to obtain normative values for stimulated jitter in the masseter muscle. Axonal microstimulation was performed via a monopolar needle electrode introduced in the masseter 2-2.5 cm above the mandibular angle on the line connecting it with the lateral canthus. The recording single-fiber electromyography (SFEMG) electrode was inserted anteriorly in the twitching area of the muscle. The mean consecutive difference (MCD) values for the 426 endplates studied followed a distribution skewed to the left, with a minimum value of 4.3 micros, maximal 44.7 micros, and a maximum of distribution at 11 micros. Mean pooled MCD measured 16.0 micros, and the mean of mean MCD per study was 13.6 micros. The value of the 95th upper percentile for an individual fiber was 29.3 micros. We suggest an upper normal limit for mean MCD per study of 21 micros and upper normal limit of MCD for individual fibers of 30 micros. The stimulated jitter study of masseter muscle is easy and reliable.

False localising levels in spinal cord compression.

OBJECTIVE: To describe three cases with false localising levels illustrating the difficulty in clinical diagnosis of spinal cord compression. PATIENTS AND METHODS: Three patients (aged 53, 55 and 57 years) developed acute (in one) and subacute (in two) spinal cord syndrome with paraparesis, bladder symptoms and sensory levels suggesting lower thoracic or higher lumbar involvement. Imaging at suspected levels was normal. Follow-up investigations after a significant delay showed compression at higher levels (up to 11 segments). Diagnoses were surgically verified. In one patient who died, post mortem investigation discloseed a caudally situated artery of Adamkiewicz and absent vicarious vessels at T7-T8 that are usually present in such cases. CONCLUSIONS: The well known but rare phenomenon of false localizing sensory levels in spinal cord syndromes should be kept in mind. Its causes can lie in remote higher levels of compressive lesion or in vascular compromise due to variants of the blood supply.

Predictive value of median-SSEP in early phase of stroke: a comparison in supratentorial infarction and hemorrhage.

OBJECTIVE: To compare the prognostic value of median somatosensory evoked potentials (M-SSEP) changes in the early phase of supratentorial infarction and hemorrhage. MATERIAL AND METHODS: This study includes 130 patients (mean age 62+/-11.4 years, 43 women, large middle cerebral artery territory infarction in 36 patients, restricted/lacunar in 55, massive supratentorial hemorrhage in 10, small/medium size hemorrhage in 31). M-SSEP were recorded early (0-7 days in ischemia, 0-21 days in hemorrhage) and patients stratified into groups with absent, abnormal, normal response. Clinical state was determined by the Medical Research Council (MRC) scale, Barthel Index and Rankin score and followed for at least 6 months. RESULTS: Moderate prognostic correlation was established between N20-P25 amplitudes (r=0.34, p<0.05) and N20-P25 amplitude ratio (r=0.45, p<0.01) and Barthel Index at 6 months in patients with ischemic stroke. Moderate relationship (r=-0.34, p<0.05) exists also between N20-P25 ratio and Rankin score at 6 months in patients with small/medium size hemorrhage. In large infarctions and small/medium size cerebral hemorrhages correlations with all clinical indices of outcome are weak. In massive hemorrhage, only a weak correlation (r=-0.19, p<0.05) between amplitude ratio and Rankin score was found. The combination of initial MRC and N20-P25 amplitude ratio has 10% (in hemorrhage) to 15% (in infarction) greater prognostic value (p<0.05) than initial alone. CONCLUSIONS: M-SSEP have independent predictive value regarding functional recovery in ischemic stroke and small/medium size cerebral hemorrhage. Combined assessment of initial MRC and M-SSEP substantially improves prognosis in acute stroke.

Muscle hypertrophy with complex repetitive discharges in C-6 radiculopathy.

OBJECTIVE: To report on a case of post-denervation muscle hypertrophy in an unusual distribution. CASE REPORT: A 52-year-old patient with severe flaccid paraparesis after polio developed unilateral C-6 radiculopathy that resolved with conservative treatment. Within 2 years marked hypertrophy, stiffness and pain in the muscles in the affected myotome developed. EMG discovered abundant complex repetitive discharges (CRD) within hypertrophic muscles. On biopsy, true hypertrophy of muscle fibers and some group atrophy was found. Steroid treatment relieved the symptoms and significantly suppressed the CRD. The possible causative role of CRD for hypertrophy in partially denervated muscle is discussed.

Prognostic value of median and tibial somatosensory evoked potentials in acute stroke.

The predictive values of early somatosensory evoked potentials (SSEPs) for the functional outcome after stroke are investigated. Ninety-four stroke patients (mean age: 61.2, S.D.: 11.8) with CT confirmed diagnoses of middle cerebral artery (MCA) infarction in 71 and supratentorial intracerebral hemorrhage in 23. Median and tibial SSEPs were recorded within 3 days of onset. SSEP parameters were compared to motor (MRC) and functional ability (Barthel index) followed up at 1, 3, 6 and 12 months. Upper limb MRC remains the strongest single predictor of functional outcome, determining 54.3% of Barthel index value at 12 months. The highest predictive value among SSEP parameters has N20-P25 amplitude ratio-34.5%. Combined application of upper limb MRC and N20-P25 amplitude ratio provided significantly stronger prognostic information-66%. Combined assessment of SSEP parameters and muscle power in acute stroke considerably improves prediction of functional outcome.