M. de Carvalho

Motor‐axonal polyneuropathy associated with hepatitis C virus

The association between hepatitis C virus (HCV) infection, the presence of mixed cryoglobulinemia and peripheral neuropathy is well‐documented ( Apartis et al., 1996 ). HCV is the chief cause of essential mixed cryoglobulinemia (type II cryoglobulinemia) with cryoglobulins present in up to half of patients with HCV infection ( Akriviadis et al., 1997 ). More recently it has been stated that peripheral polyneuropathy may be associated with HCV chronic infection without mixed cryoglobulinemia ( Lidove et al., 2001 ).

Finite element studies of the mechanical behaviour of the diaphragm in normal and pathological cases

The diaphragm is a muscular membrane separating the abdominal and thoracic cavities, and its motion is directly linked to respiration. In this study, using data from a 59-year-old female cadaver obtained from the Visible Human Project, the diaphragm is reconstructed and, from the corresponding solid object, a shell finite element mesh is generated and used in several analyses performed with the ABAQUS 6.7 software. These analyses consider the direction of the muscle fibres and the incompressibility of the tissue. The constitutive model for the isotropic strain energy as well as the passive and active strain energy stored in the fibres is adapted from Humphreys model for cardiac muscles. Furthermore, numerical results for the diaphragmatic floor under pressure and active contraction in normal and pathological cases are presented.

Lesion of the deep palmar branch of the ulnar nerve : causes and clinical outcome

AIM OF THE STUDY We aim to describe the clinical and neurophysiological characteristics of a group of patients with a clinical diagnosis of deep palmar branch lesion of the ulnar nerve. We report the clinical and neurophysiological outcome. POPULATION AND METHOD Eleven patients (six males, mean age: 52 years) were included prospectively. Neurophysiological studies were performed in all patients at diagnosis and longitudinally in five. RESULTS Occupational trauma was the cause of the nerve lesion in seven patients, neuritis was diagnosed in one and an idiopathic lesion was the final diagnosis in two. In 10 patients, conservative management with interruption of repetitive trauma led to a progressive full recovery. Hand weakness was progressive in one patient who underwent surgical intervention with a diagnosis of ganglion compression, whose removal caused gradual improvement. Neurophysiological studies confirmed severe deep branch lesion, but in four a mild proximal lesion of the ulnar nerve at the wrist was identified. Follow-up neurophysiological studies confirmed the rapid resolution of the lesion. CONCLUSION Conservative management should be the first option in patients with deep palmar branch lesion of the ulnar nerve, in particular in patients with a work-related lesion. Electromyography has a central role in diagnosis.

Erythropoietin and amyotrophic lateral sclerosis: Plasma level determination

Abstract In amyotrophic lateral sclerosis (ALS), respiratory muscle weakness causes ventilatory insufficiency and tissue hypoxia, which induces a number of metabolic pathways, and in particular increases erythropoietin (EPO) synthesis. EPO is a glycoprotein with neuroprotective properties that stimulates erythropoiesis. Here, EPO plasma level in a large population of ALS patients, with and without respiratory failure, was measured. Plasma EPO level of patients with ALS (n = 98), controls with other neuromuscular diseases (n = 58) and healthy controls (n = 20) has been quantified by ELISA. No significant difference was found between ALS patients and the two control groups. EPO level was not different between bulbar- and spinal-onset patients and was not correlated with disease duration or functional impairment. However, in the ALS group EPO level was higher in females (p = 0.0006) and correlated positively with age (p = 0.006). The subgroup of ALS patients with respiratory failure had higher plasma levels of EPO compared with ALS patients with preserved respiratory function (p = 0.016), but short-term non-invasive ventilation did not change EPO level. In conclusion, EPO levels were found to be significantly higher in ALS patients with respiratory impairment representing preservation of this homeostatic mechanism.

Motor excitability measurements: The influence of gender, body mass index, age and temperature in healthy controls

STUDY AIMS The technique of threshold tracking to test axonal excitability gives information about nodal and internodal ion channel function. We aimed to investigate variability of the motor excitability measurements in healthy controls, taking into account age, gender, body mass index (BMI) and small changes in skin temperature. MATERIALS AND METHODS We examined the left median nerve of 47 healthy controls using the automated threshold-tacking program, QTRAC. Statistical multiple regression analysis was applied to test relationship between nerve excitability measurements and subject variables. RESULTS Comparisons between genders did not find any significant difference (P>0.2 for all comparisons). Multiple regression analysis showed that motor amplitude decreases with age and temperature, stimulus-response slope decreases with age and BMI, and that accommodation half-time decrease with age and temperature. CONCLUSION The changes related to demographic features on TRONDE protocol parameters are small and less important than in conventional nerve conduction studies. Nonetheless, our results underscore the relevance of careful temperature control, and indicate that interpretation of stimulus-response slope and accommodation half-time should take into account age and BMI. In contrast, gender is not of major relevance to axonal threshold findings in motor nerves.

Added value of electromyography in the diagnosis of myopathy: A consensus exercise

OBJECTIVE Currently, neurologists may primarily rely on blood biomarkers, muscle biopsy, MRI, and genetics in the diagnostic work-up of suspected myopathy. Using expert consensus as diagnostic reference standard, this study addressed the added value of electrodiagnostic medicine (EDX) in diagnosis of myopathies. METHODS One hundred ninety-four EDX evaluations of patients with a peer-review consensus diagnosis of myopathy were collected by seven European centres. Each patient was given three different consensus diagnoses: (1) the EDX diagnosis solely based on EDX results, (2) the pure clinical diagnosis based on all available information except EDX results, and (3) the final diagnosis including EDX and all additional information. The myopathies were grouped as muscular dystrophy (45), inflammatory myopathy (46), other aetiology (36) or unknown aetiology (67). RESULTS Higher diagnostic probabilities for myopathy were seen in the final diagnosis compared to the pure clinical diagnosis (p<0.001). Adding EDX information increased the diagnostic probability of myopathy in 67 patients (34.4%). The greatest increase was seen for myopathies of unknown aetiology. CONCLUSIONS EDX has a major impact in the diagnosis of myopathies of unknown aetiology. In genetically or biopsy proven myopathies, EDX generally supports the diagnosis. SIGNIFICANCE EDX is still a useful tool in the diagnostic work-up of most patients with suspected myopathy.

P21-17 Early detection of small-fiber neuropathy in familial amyloid polyneuropathy patients

Objective: Acquired neuromyotonia is an immune-mediated syndrome of peripheral nerve hyperexcitability presenting clinically by muscle twitching, cramps and stiffness and hyperhidrosis. Sensory symptoms are less common and include numbness and tingling. Methods: Case report of a 53 year old Chinese-Malaysian woman who presented with sensory symptoms of cold allodynia suggestive of smallfibre sensory polyneuropathy. Results: Madam LCC, known diabetic presented with polyarthralgia, lethargy and painful sensation of her hands and feet when immersed in cold water or in an air-conditioned room. She continuously wore gloves at work to keep warm. There were no features of Raynaud phenomenon. There was hyperhidrosis and mild muscle stiffness. Clinically, there was no rash, muscle wasting or myokymia. Muscle power was normal. Reflexes were absent in the lower extremities. Sensation to pain and propioception were normal. Investigations showed ESR, 31 mm/hr; positive ANA, 1:1280, homogeneous; anti-dsDNA antibody, 1149 iu/L (normal <200). She did not fulfil the ACR criteria for SLE. Nerve conduction studies were normal but needle EMG showed spontaneous myokymic and neuromyotonic discharges. Anti-VGKC antibody was 5150 pM (normal <100). Acetylcholine receptor antibody was positive, 0.65 nmol/L (normal <0.25) but CT thorax showed no thymoma. She had no clinical or EMG features of myasthenia gravis. She was diagnosed to have acquired neuromyotonia with undifferentiated connective tissue disease. Initial treatment with oral prednisolone, azathioprine and carbamazepine did not show significant improvement of symptoms. However, after intravenous immunoglobulin at a dose of 0.4 g/kg body wt/day for 5 days, her symptoms improved with reduction of the allodynia, hyperhidrosis and muscle stiffness. Conclusions: We report a patient with acquired neuromyotonia and undifferentiated connective tissue disease presenting cold allodynia illustrating the hyperexcitability the small sensory nerve fibres. The response to IVIG suggests that the symptoms are not due to diabetes mellitus which was present in the patient.

Transcutaneous spinal direct current stimulation of the lumbar and sacral spinal cord: a modelling study

OBJECTIVE Our aim was to perform a computational study of the electric field (E-field) generated by transcutaneous spinal direct current stimulation (tsDCS) applied over the thoracic, lumbar and sacral spinal cord, in order to assess possible neuromodulatory effects on spinal cord circuitry related with lower limb functions. APPROACH A realistic volume conductor model of the human body consisting of 14 tissues was obtained from available databases. Rubber pad electrodes with a metallic connector and a conductive gel layer were modelled. The finite element (FE) method was used to calculate the E-field when a current of 2.5 mA was passed between two electrodes. The main characteristics of the E-field distributions in the spinal grey matter (spinal-GM) and spinal white matter (spinal-WM) were compared for seven montages, with the anode placed either over T10, T8 or L2 spinous processes (s.p.), and the cathode placed over right deltoid (rD), umbilicus (U) and right iliac crest (rIC) areas or T8 s.p. Anisotropic conductivity of spinal-WM and of a group of dorsal muscles near the vertebral column was considered. MAIN RESULTS The average E-field magnitude was predicted to be above 0.15 V m-1 in spinal cord regions located between the electrodes. L2-T8 and T8-rIC montages resulted in the highest E-field magnitudes in lumbar and sacral spinal segments (>0.30 V m-1). E-field longitudinal component is 3 to 6 times higher than the ventral-dorsal and right-left components in both the spinal-GM and WM. Anatomical features such as CSF narrowing due to vertebrae bony edges or disks intrusions in the spinal canal correlate with local maxima positions. SIGNIFICANCE Computational modelling studies can provide detailed information regarding the electric field in the spinal cord during tsDCS. They are important to guide the design of clinical tsDCS protocols that optimize stimulation of application-specific spinal targets.

Muscular cramp: causes and management

Muscular cramp is a common symptom in healthy people, especially among the elderly and in young people after vigorous or peak exercise. It is prominent in a number of benign neurological syndromes. It is a particular feature of chronic neurogenic disorders, especially amyotrophic lateral sclerosis. A literature review was undertaken to understand the diverse clinical associations of cramp and its neurophysiological basis, taking into account recent developments in membrane physiology and modulation of motor neuronal excitability. Many aspects of cramping remain incompletely understood and require further study. Current treatment options are correspondingly limited.

Hereditary amyloidosis related to transthyretin V30M: disease progression in treated and untreated patients

Hereditary amyloidosis related to transthyretin V30M (hATTR V30M) is a progressive length‐dependent sensorimotor axonal neuropathy. We aimed to compare the disease progression of treated [liver transplantation (LT) or tafamidis] versus untreated patients with hATTR V30M.