Rosana Herminia Scola

A missense mutation in the Kv1.1 voltage-gated potassium channel–encoding gene KCNA1 is linked to human autosomal dominant hypomagnesemia

Primary hypomagnesemia is a heterogeneous group of disorders characterized by renal or intestinal magnesium (Mg2+) wasting, resulting in tetany, cardiac arrhythmias, and seizures. The kidney plays an essential role in maintaining blood Mg2+ levels, with a prominent function for the Mg2+-transporting channel transient receptor potential cation channel, subfamily M, member 6 (TRPM6) in the distal convoluted tubule (DCT). In the DCT, Mg2+ reabsorption is an active transport process primarily driven by the negative potential across the luminal membrane. Here, we studied a family with isolated autosomal dominant hypomagnesemia and used a positional cloning approach to identify an N255D mutation in KCNA1, a gene encoding the voltage-gated potassium (K+) channel Kv1.1. Kv1.1 was found to be expressed in the kidney, where it colocalized with TRPM6 along the luminal membrane of the DCT. Upon overexpression in a human kidney cell line, patch clamp analysis revealed that the KCNA1 N255D mutation resulted in a nonfunctional channel, with a dominant negative effect on wild-type Kv1.1 channel function. These data suggest that Kv1.1 is a renal K+ channel that establishes a favorable luminal membrane potential in DCT cells to control TRPM6-mediated Mg2+ reabsorption.

Congenital Myasthenic Syndrome: A Brief Review

Congenital myasthenic syndromes comprise heterogeneous genetic diseases characterized by compromised neuromuscular transmission. Congenital myasthenic syndromes are classified as presynaptic, synaptic, or postsynaptic, depending on the primary defects location within the neuromuscular junction. Presynaptic forms are the rarest, affecting an estimated 7-8% of patients; synaptic forms account for approximately 14-15% of patients; and the remaining 75-80% are attributable to postsynaptic defects. Clinical manifestations vary by congenital myasthenic syndrome subtype. Electrophysiologic, morphologic, and molecular descriptions of various forms of congenital myasthenic syndromes have led to an enhanced understanding of clinical manifestations and disease pathophysiology. Although congenital myasthenic syndromes are indicated by clinical manifestations, family history, electrophysiologic studies, and responses to acetylcholinesterase inhibitors, overlap in some presentations occurs. Therefore, genetic testing may be necessary to identify specific mutations in CHAT, COLQ, LAMB2, CHRNA, CHRNB, CHRND, CHRNE, CHRNG, RAPSN, DOK7, MUSK, AGRN, SCN4A, GFPT1, or PLEC1 genes. The identification of congenital myasthenic syndromes subtypes will prove important in the treatment of these patients. Different drugs may be beneficial, or should be avoided because they are ineffective or worsen some forms of congenital myasthenic syndromes. We explore the classification, clinical manifestations, electrophysiologic features, genetics, and treatment responses of each congenital myasthenic syndrome subtype.

A retrospective clinical study of the treatment of slow-channel congenital myasthenic syndrome

Slow-channel congenital myasthenic syndrome (CMS) is a rare subtype of CMS caused by dominant “gain of function” mutations in the acetylcholine receptor. Clinically, the cervical and forearm extensor muscles seem to be preferentially weaker; and conventional treatment with anticholinesterases fails to improve symptoms. In contrast, open channel blockers such as fluoxetine and quinidine have been shown to be of benefit. The objectives of our study were to provide further insight into the clinical features of slow-channel CMS and evaluate response to recommended therapy. We carried out a retrospective clinical follow up study of 15 slow-channel CMS patients referred to the Munich CMS Centre. Detailed clinical data were collected by clinicians involved in the care of each patient, with a particular focus on response and tolerability to recommended therapy. Patients varied widely as regard onset of symptoms, severity of disease and mutations involved. Patients received up to four different medications and some had none. Our results strengthen previous reported findings in terms of clinical phenotype variability and the poor response to pyridostigmine. Although treatment with fluoxetine was beneficial in most patients, a number of our patients suffered significant adverse effects that hindered optimum dose titration or led to treatment cessation. Slow-channel CMS is rare and exhibits distinct clinical and genetic characteristics. Our study suggests that fluoxetine, despite being effective in most patients, can be associated with significant side effects, thus reducing treatment effectiveness in clinical practice.

A clinical epidemiological study of 251 cases of amyotrophic lateral sclerosis in the south of Brazil

OBJECTIVE To study the clinical forms of amyotrophic lateral sclerosis (ALS) and the possible presence of risk factors in order to verify if there is any difference between cases in Paraná, Brazil. METHOD We studied 251 cases, all of which fulfilled the diagnosis criteria proposed in El Escorial (WFN). Between 1977 and 2004, 157 male and 94 female patients were examined. RESULTS 220 cases were classified as ALS-Spinal Onset (ALS-SO), 24 as ALS-Bulbar Onset (ALS-BO) and 7 as Familial ALS. The mean age at time of evaluation was 54.4+/-12.3 years, and symptoms had started 17.9+/-15.7 months previously. In the group studied, statistical relationships were found between heavy occupations and males; previous surgeries and females; ALS-BO and dysphagia and dysarthria in females; and ALS-SO and males, cramps, weakness, muscle atrophy, hypertonia, increased deep tendon reflex and abnormal gait. CONCLUSION The average age at time of evaluation was lower than that registered in the literature but similar to the Brazilian series. Domestic work and heavy occupations appear to be related to precocious perception of the symptoms by interference with daily functions. The socioeconomically higher classes seek medical care early. There was no relationship with exposure to toxic agents or trauma.OBJETIVO: Estudar as formas clinicas de esclerose lateral amiotrofica (ELA) e possiveis fatores de risco, a fim de verificar se existem diferencas entre os casos do Parana, Brasil. METODO: Estudamos 251 casos entre 1977 e 2004, que preencheram os criterios propostos em El Escorial (WFN), sendo 157 do sexo masculino e 94 do feminino. RESULTADOS: Foram classificados como ELA de inicio espinhal (ELA-IE) 220 casos, ELA de inicio bulbar (ELA-IB) 24 casos e 7 casos como ELA familiar. A idade media na avaliacao foi 54,4±12,3 anos cujos sintomas iniciaram 17,9 ±15,7 meses antes. Foram encontradas relacoes estatisticas entre ocupacao que demandam esforcos fisicos com homens; cirurgias previas com mulheres; ELA-IB, disfagia e disartria, mulheres; ELA-IE, homens, câimbras, fraqueza, atrofia muscular, hipertonia, aumento de reflexos profundos e marcha anormal. CONCLUSAO: A idade media na epoca da avaliacao foi menor que a registrada na literatura, mas similar as series brasileiras. Trabalhos domesticos e ocupacoes que demandam esforcos fisicos estao relacionados com a percepcao precoce dos sintomas pelas inferencias com as funcoes diarias. As classes socio-economicas melhores situadas procuram atendimento medico mais cedo. Nao foram encontradas relacoes com a exposicao a agentes toxicos e traumatismos.

NMO-IgG positive neuromyelitis optica in a patient with myasthenia gravis but no thymectomy

Here we report on a 44-year old woman presenting with both myasthenia gravis (MG) and neuromyelitis optica (NMO). MRI showed transverse myelitis extending from C2 to T4, multifocal demyelinating lesions in the supratentorial white matter, and left optic neuritis. Serological analysis demonstrated antibodies to acetylcholine receptors as well as NMO-IgG. To our knowledge, this is the first case of NMO-IgG positive NMO in a patient with MG but no history of thymectomy or immunosuppression.

Cervical dystonia: clinical and therapeutic features in 85 patients

We studied patients with cervical dystonia (CD) to determine clinical features and response to botulinum toxin A (BoNT/A). Patients were submitted to clinical, laboratory and neuroimaging evaluation. BoNT/A was injected locally in 81 patients using electromyographic guidance. Four patients who had had previous treatment were considered to be in remission. The average ages at onset of focal dystonia and segmental dystonia were greater than for generalized dystonia (p<0.0003). The severity of the abnormal head-neck movements were more severe among the patients with generalized dystonia (p<0.001). Pain in the cervical area was noted in 59 patients. It was not possible to determine the etiology of the disease in 62.3% of patients. Tardive dystonia was the most common secondary etiology. A major improvement in the motor symptoms of CD and pain was observed in patients following treatment with BoNT/A. The tardive dystonia subgroup did not respond to the treatment. Dysphagia was observed in 2.35% of the patients.

Study comparing the stroke unit outcome and conventional ward treatment: a randomized study in Joinville, Brazil

BACKGROUND AND PURPOSE To assess the impact of a stroke unit (SU) on acute phase treatment when compared to a conventional general ward treatment (GW). METHOD Seventy-four patients with acute stroke were randomized between a SU and conventional general ward (GW). We compared both groups regarding the length of hospital stay, lethality and functional and clinical status within 6 months, using the Scandinavian scale and Barthel index. RESULTS Thirty-five and thirty-nine patients were allocated at SU and GW, respectively. Lethality on the 10th day at SU and GW achieved 8.5% and 12.8% respectively (p= 0.41), whereas 30-days mortality rates achieved 14.2% and 28.2% (p= 0.24), 17.4% and 28.7% on the 3rd month (p= 0.39), and 25.7% and 30.7% on the 6th month (p= 0.41). Thirty-day survival curve achieved 1.8 log rank (p= 0.17), with a trend for lower lethality in the SU. In order to save one death in 6 months in SU, NNT (the number need to treat) was 20; to get one more home independent patient NNT was 15. No significant difference was found between the length of hospital stay and morbidity. CONCLUSION No significant benefit was found in SU patients compared to GW group. However,an evident benefit in absolute numbers was observed in lethality, survival curve and NNT in thirty days period after stroke. Further collaborative studies or incresead number of patients are required to define the role of SU.

Myasthenia gravis : a retrospective study comparing thymectomy to conservative treatment

Objectives– To study the effectiveness of thymectomy (TY) in a group of patients with myasthenia gravis compared to a group of patients submitted to conservative treatment (CT) at a similar clinical stage. Methods – Among 153 patients with myasthenia gravis, we paired 28 patients who underwent TY, with 28 cases under CT. The following data were analyzed: gender, age, and age at the beginning of symptoms, illness duration, follow‐up time and type of medical treatment. There was no statistical difference between these 2 groups. The mean time for TY was 2.5 (0.2‐13) years after the onset of the disease. The cases were evaluated through a functional scale at the beginning and at the end of the study. Results – We found complete remission in 15 cases (TY 6, CT 9), improved (normal life with or without minimal symptoms and with or without medication) 9 cases (TY 8, CT 1), improved with partial control and minimal limitation 32 cases (TY 14, CT 18), and poor control 2 cases (TY 2). No death was found in this group. Conclusion – There was no statistical difference between the conservative treatment and thymectomy groups, regarding remission or improvement. Furthermore TY done in the first year of the disease or latter, did not change the ®naloutcome.

Pure neural leprosy: diagnostic value of the polymerase chain reaction.

Pure neural leprosy (PNL) is often difficult to diagnose when acid‐fast bacilli (AFB) cannot be detected. We undertook the present study to evaluate use of the polymerase chain reaction (PCR) in diagnosing PNL. Fifty‐eight patients (41 men and 17 women) suspected of pure neural leprosy (PNL) were examined. Patients were classified as borderline tuberculoid (BT, 40 cases) and polar tuberculoid (TT, 18 cases) types. Nerve biopsy was performed and was positive for AFB in 20 patients (all BT patients), i.e., 34.5% of total cases. DNA was extracted from the nerve biopsy samples and amplified using PCR for a specific repeated sequence of DNA from Mycobacterium leprae. PCR analysis was positive in the nerve samples from 29 patients (50%), 27 of the BT type, and 2 of the TT type patients. Further, PCR analysis was positive in 14 of 38 cases that were negative for AFB by nerve biopsy, of which 12 were of the BT type and 2 the TT type. PCR analysis proved to be a useful method to investigate pure neural leprosy, enabling confirmation of the diagnosis in more than a third of the cases that were negative for AFB by nerve biopsy. Muscle Nerve 2006

Diagnosis of dermatomyositis and polymyositis: a study of 102 cases

UNLABELLED Patients with dermatomyositis (DM) or polymyositis (PM) were studied retrospectively. The patients were divided into four groups: definite PM 24, probable PM 19, definite DM 34 and mild-early DM 25 cases. PM patients complained more often proximal muscle weakness [p <0.01]. DM patients complained more arthralgia [p <0.05], dysphagia [p <0.03] and weight loss [p <0.04]. Five patients had a malignant neoplasm and 9 had other connective-tissue disease. DM presented higher ESR than PM [p <0.002]. PM presented more significant increase in creatine kinase (CK) [p <0.02] and in alanine aminotransferase (ALT) [p <0.001] levels. Electromyography showed myopathic pattern in 76%. Muscle biopsy was the definitive test. Perifascicular atrophy was more frequent in definite DM than in mild-early DM group [p <0.03]. CONCLUSION A small association with connective-tissue diseases and neoplasms was found. DM and PM are clinically different. DM presents systemic involvement affecting the skin, developing more severe arthralgia, dysphagia and weight loss and presenting higher values of ESR. PM presents a restricted and more significant involvement of muscles generating more weakness complaints and higher levels of serum muscle enzymes.