Electrophysiological study of neuromuscular junction in congenital myasthenic syndromes, congenital myopathies, and chronic progressive external ophthalmoplegia.

This study was designed to analyze the sensitivity, specificity, and accuracy of jitter parameters combined with repetitive nerve stimulation (RNS) in congenital myasthenic syndrome (CMS), chronic progressive external ophthalmoplegia (CPEO), and congenital myopathies (CM). Jitter was obtained with a concentric needle electrode during voluntary activation of the Orbicularis Oculi muscle in CMS (n = 21), CPEO (n = 20), and CM (n = 18) patients and in controls (n = 14). RNS (3 Hz) was performed in six different muscles for all patients (Abductor Digiti Minimi, Tibialis Anterior, upper Trapezius, Deltoideus, Orbicularis Oculi, and Nasalis). RNS was abnormal in 90.5% of CMS patients and in only one CM patient. Jitter was abnormal in 95.2% of CMS, 20% of CPEO, and 11.1% of CM patients. No patient with CPEO or CM presented a mean jitter higher than 53.6 µs or more than 30% abnormal individual jitter (> 45 µs). No patient with CPEO or CM and mild abnormal jitter values presented an abnormal decrement. Jitter and RNS assessment are valuable tools for diagnosing neuromuscular transmission abnormalities in CMS patients. A mean jitter value above 53.6 µs or the presence of more than 30% abnormal individual jitter (> 45 µs) strongly suggests CMS compared with CPEO and CM.

Clinical variability of early-onset congenital myasthenic syndrome due to biallelic RAPSN mutations in Brazil.

Mutations in RAPSN are an important cause of congenital myasthenic syndrome (CMS), leading to endplate acetylcholine receptor deficiency. We present three RAPSN early-onset CMS patients (from a Brazilian cohort of 61 CMS patients). Patient 1 and patient 2 harbor the mutation p.N88K in homozygosity, while patient 3 harbors p.N88K in compound heterozygosity with another pathogenic variant (p.V165M; c.493G ≥ A). At onset, patient 3 presented with more severe symptoms compared to the other two, showing generalized weakness and repeated episodes of respiratory failure in the first years of life. During adolescence, she became gradually less symptomatic and does not require medication anymore, presenting better long-term outcomes than patients 1 and 2. This case series illustrates the variability of RAPSN early-onset CMS, with patient 3, despite severe onset, revealing an almost complete reversal of myasthenic symptoms, not limited to apneic episodes. Moreover, it suggests that RAPSN CMS may be underdiagnosed in non-European countries.

A common CHRNE mutation in Brazilian patients with congenital myasthenic syndrome.

The most common causes of congenital myasthenic syndromes (CMS) are CHRNE mutations, and some pathogenic allelic variants in this gene are especially frequent in certain ethnic groups. In the southern region of Brazil, a study found the c.130dupG CHRNE mutation in up to 33% of families with CMS. Here, we aimed to verify the frequency of this mutation among individuals with CMS in a larger cohort of CMS patients from different areas of Brazil and to characterize clinical features of these patients. Eighty-four patients with CMS, from 72 families, were clinically evaluated and submitted to direct sequencing of the exon 2 of CHRNE. The c.130dupG mutation was found in 32 patients (23 families), with 26 patients (19 families, 26.3%) in homozygosis, confirming its high prevalence in different regions of Brazil. Among the homozygous patients, the following characteristics were frequent: onset of symptoms before 2 years of age (92.3%), little functional restriction (92.3%), fluctuating symptoms (100%), ocular muscle impairment (96.1%), ptosis (100%), limb weakness (88.4%), response to pyridostigmine (100%), facial involvement (77%), and bulbar symptoms (70.8%). The pretest probability of finding at least one allele harbouring the c.130dupG mutation was 38.1%. Selecting only patients with impaired eye movement together with limb weakness and improvement with pyridostigmine, the probability increases to 72.2%. This clinical pre-selection of patients is likely a useful tool for regions where CHRNE mutations have a founder effect. In conclusion, the CHRNE mutation c.130dupG leads to fairly benign natural course of the disease with relative homogeneity.

Hipertensão arterial, osteoporose, amenorreia e depressão como manifestações da síndrome de cushing acth-independente: evolução após adrenalectomia laparoscópica / Arterial hypertension, osteoporosis, amenorrhea, and depression as presentation of ACTH-independent Cushing's syndrome: follow-up after laparoscopic adrenalectomy

A síndrome de Cushing é caracterizada por excesso de glicocorticóides circulantes. Os tumores suprarrenais secretores de cortisol representam a principal causa desse distúrbio, dentre os quais adenomas, que correspondem a 65% dos casos. A apresentação clínica típica inclui obesidade centrípeta, fadiga, hipertensão arterial de difícil controle, osteoporose, distúrbios menstruais, hirsutismo, equimoses e estrias violáceas. Entretanto, casos de síndrome de Cushing subclínica vem sendo descritos com frequência crescente, o que faz com que essa doença ainda representardesafio diagnóstico na atualidade, pela capacidade de mimetizar outras entidades nosológicas, tais como síndrome metabólica, depressão e alcoolismo. Relata-se o caso de uma mulher de 27 anos, que vinha em tratamento de hipertensão arterial, osteoporose e depressão intensa antes do diagnóstico de síndrome de Cushing ACTH-independente,na qual o tratamento cirúrgico da doença de base resultou abrandamento significativo das comorbidades.

Cushing’s syndrome is characterized by an excess of circulating glucocorticoids. Cortisol-secreting adrenal tumors are the most common cause of endogenous ACTH-independent disease, with adrenal adenomas accounting for 65% of these cases. The typical clinical presentation includes centripetal obesity, fatigue, arterial hypertension, osteoporosis, menstrual disorders, hirsutism, easy bruising, and diffuse violaceous striae. However, subclinical Cushing´s syndrome is being described with growing frequency, still making this disease a diagnostic challenge, due to the ability to mimicother nosologic entities, such as the metabolic syndrome, depression and alcoholism. The authors report the case of a 27-year-old woman, who has been treated for hypertension, osteoporosis and depression before the diagnosis of ACTH-independent Cushing’s syndrome was established, and in whom the surgical treatment of the disease resulted in significant improvement of co-morbidities.