Myotonic Dystrophy

Tractography reveals diffuse white matter abnormalities in Myotonic Dystrophy Type 1

Cerebral involvement in Myotonic Dystrophy Type 1 (DM1) is well-established but not well characterized. This study applied new Diffusion Tensor Imaging (DTI) tractography to characterize white matter disturbance in adults with DM1. Forty-five participants with DM1 and 44 control participants had MRIs on a Siemens 3T TIM Trio scanner. Data were processed with TRActs Constrained by UnderLying Anatomy (TRACULA) and 7 tracts were evaluated. Bilateral disturbances in white matter integrity were seen in all tracts in participants with DM1 compared to controls. There were no right-left hemisphere differences. The resulting DTI metrics were correlated with cognitive functioning, particularly working memory and processing speed. Motor speed was not significantly correlated with white matter microstructural integrity and, thus, was not the core explanation for the working memory and processing speed findings. White matter integrity was correlated with important clinical variables including the muscular impairment rating scale (MIRS). CTG repeat length was moderately associated with white matter status in corticospinal tract and cingulum. Sleepiness (Epworth Sleepiness Scale) was moderately associated with white matter status in the superior longitudinal fasciculus and cingulum. Overall, the results add to an emerging literature showing widespread white matter disturbances in both early-onset and adult-onset DM1. Results suggest that further investigation of white matter pathology is warranted in DM1 and that non-invasive measures such as DTI have a potentially important clinical value in characterizing the status of individuals with DM1.

Diffusion tensor imaging reveals widespread white matter abnormalities in children and adolescents with myotonic dystrophy type 1

Diffusion tensor imaging was used to evaluate cerebral white matter in 16 patients (ages 9-18) with myotonic dystrophy type 1 compared to 15 matched controls. Patients with myotonic dystrophy showed abnormalities in mean diffusivity compared to controls in frontal, temporal, parietal, and occipital white matter and in all individual tracts examined. Whole cerebrum mean diffusivity was 8.6 % higher overall in patients with myotonic dystrophy compared to controls. Whole cerebrum fractional anisotropy was also abnormal (10.8 % low overall) in all regions and tracts except corticospinal tracts. Follow-up analysis of parallel and perpendicular diffusivity suggests possible relative preservation of myelin in corticospinal tracts. Correlations between Wechsler working memory performance and mean diffusivity were strong for all regions. Frontal and temporal fractional anisotropy were correlated with working memory as well. Results are consistent with earlier studies demonstrating that significant white matter disturbances are characteristic in young patients with myotonic dystrophy and that these abnormalities are associated with the degree of working memory impairment seen in this disease.

White matter abnormalities and neurocognitive correlates in children and adolescents with myotonic dystrophy type 1: a diffusion tensor imaging study

Diffusion tensor imaging was used to evaluate cerebral white matter in eight patients (ages 10-17), with myotonic dystrophy type 1 (3 congenital-onset, 5 juvenile-onset) compared to eight controls matched for age and sex. Four regions of interest were examined: inferior frontal, superior frontal, supracallosal, and occipital. The myotonic dystrophy group showed white matter abnormalities compared to controls in all regions. All indices of white matter integrity were abnormal: fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity. With no evidence of regional variation, correlations between whole cerebrum white matter fractional anisotropy and neurocognitive functioning were examined in the patients. Strong correlations were observed between whole cerebrum fractional anisotropy and full-scale intelligence and a measure of executive functioning. Results indicate that significant white matter abnormality is characteristic of young patients with myotonic dystrophy type 1 and that the white matter abnormality seen with neuroimaging has implications for cognitive functioning.

Upper airway calibre and impedance in patients with steinert's myotonic dystrophy

Myotonic dystrophy (MD) can be responsible for increased inspiratory muscle loading, the origin of which is debated, with some authors incriminating distal lesions and others central abnormalities. Using a recent non-invasive method based on single transient pressure-wave reflection analysis, we measured central airway calibre from the mouth to the carina and respiratory impedance in a group of adults with MD, a group of patients with sleep apnoea syndrome (SAS) but no neuromuscular disease, and a group of normal controls. All participants were awake during the measurements. We found no reduction in central airway calibre in the patients with the adult form of MD, as compared to the normal controls. These data suggest that MD may be associated with peripheral airway obstruction related to alterations in the elastic properties of the lung.

Sleep complaints in patients with myotonic dystrophy

The aim of this study was to document the clinical picture of excessive daytime sleepiness (EDS) and of other sleep disturbances, and to study the relationship of daytime sleepiness to anthropometric data, muscular impairment, and CTG trinucleotide repeat expansion in myotonic dystrophy type 1 (DM1). A total of 157 DM1 patients were surveyed using a modified version of the Sleep Questionnaire and Assessment of Wakefulness. Other measurements included muscular impairment rating and the size of the trinucleotide repeat. Factor analysis and reliability estimates were used to produce a daytime sleepiness scale with five items of the questionnaire. Thirty-eight healthy family members were studied as control subjects. It was found that EDS was present in 33.1% of DM1 patients. Severity of daytime sleepiness correlated with the degree of muscular impairment but not with age, gender, body mass index, age at onset of symptoms, duration of illness, and CTG repeat. DM1 patients reported a longer sleep period, a less restorative sleep, and more difficulty falling asleep, being alert in the morning and staying awake after meals than controls, but a similar incidence of narcolepsy auxiliary symptoms. Compared with DM1 patients without EDS, those with EDS reported greater hypnagogic hallucinations, and greater pain associated with nocturnal awakenings and in their legs upon morning awakenings. In sum, both DM1 patients with and without EDS exhibit characteristics of sleep duration and sleepiness comparable with those found in idiopathic hypersomnia. The severity of daytime sleepiness is weakly related to the extent of muscular impairment but not to CTG repeat.

Warm heart operation in a patient with myotonic dystrophy

Myotonic dystrophy is the most severe form of myotonic disorder. Hypothermia or hyperkalemia may cause generalized muscle contraction during heart operations. We successfully repaired an atrial septal defect and pulmonary stenosis in a patient with myotonic dystrophy using systemic normothermia with continuous normokalemic coronary perfusion. This is the second reported case of a patient with myotonic dystrophy who underwent a cardiac operation.

[Sural nerve biopsy in myotonic muscular dystrophy]

Twelve patients with myotonic dystrophy were studied to look for the involvement of the peripheral nervous system in this disease. All of them showed the main signs and symptoms of the disease. They did not have another causes to justify a polineuropathy. They were submitted to sural nerve biopsy with counting of myelinated fibers and histogram. Patients showed a reduction in the number of myelinated fibers and in two patients the histogram was unimodal. We concluded that polineuropathy may be another multisystemic manifestation of myotonic dystrophy.

Satoyoshi syndrome: an unusual postnatal multisystemic disorder

Satoyoshi syndrome is a rare disorder of unknown cause characterized by progressive, painful intermittent muscle spasms, malabsorption, alopecia, amenorrhea, and skeletal abnormalities mimicking a skeletal dysplasia. We describe a 19-year-old Caucasian woman with characteristic manifestations starting at age 9. The report of this patient confirms that this condition is not limited to the Asian population.

Anaesthesia for caesarean section in a patient with myotonic dystrophy receiving warfarin therapy

A 31-yr-old parturient with myotonic dystrophy and asthma presented for elective Caesarean section. The patient was receiving warfarin having had two previous episodes of thromboembolism. Anticoagulation was subsequently provided by heparin in the weeks prior to delivery. The combination of the patient's medical conditions and the continuing need for anticoagulation presented a considerable anaesthetic problem in planning anaesthesia and analgesia for both elective and emergency delivery. Heparin was discontinued on the day prior to surgery and restarted immediately after surgery. During surgery flowtron anti-embolitic boots were used. Warfarin therapy was recommenced on the seventh postoperative day. Anaesthesia for Caesarean section was provided using a combined spinal epidural technique using a separate needle, separate interspace method. Postoperative pain was relieved by using a continuous epidural infusion, transcutaneous nerve stimulation and diclofenac. No new neurological problems arose despite the use of epidural analgesia in the presence of heparin anticoagulation. This method of providing anaesthesia and postoperative analgesia without the use of opioids in an anticoagulated, asthmatic, myotonic parturient has not been described elsewhere.

Outcome of pregnancy in women with myotonic dystrophy and analysis of CTG gene expansion

Pregnancy outcome was investigated in 32 women with clinically obvious myotonic dystrophy. The results indicated that there are two groups of women, those whose children have the adult type of myotonic dystrophy and those whose children have the congenital type. The overall perinatal mortality was 14%. Polyhydramnios was an obvious sign of the congenital type. No subclinical gene carrier was found among the children. We conclude that prenatal diagnosis should be offered to women with myotonic dystrophy, particularly to those who have previously given birth to a child with the congenital type.

[Myotonic dystrophy: study of clinico-genetic correlation in a pair of relatives (father-son)]

We report the case of a child with myotonic dystrophy (DM) with symptoms beginning at the age of seven, whose genetic study showed an additional DNA fragment, greater than of his father, an asymptomatic carrier. The clinical and molecular analysis of this parent-child pair are probably the first described in Brazil, since the recent discovery of genetic abnormality in DM by American and European researchers, that explained the long-debated phenomenon of "anticipation" in this disease. The main advances in molecular genetics in DM and its correlation with increasing severity and earlier onset of the symptoms in successive generations of a family are commented briefly.

Myotonia of the respiratory muscles in myotonic dystrophy

Myotonic dystrophy is a muscle disorder in which there is a tendency to rapid shallow breathing and a reduced ventilatory response to chemical stimuli. Respiratory failure may occur when respiratory muscle weakness is not marked. One explanation proposed for these observations is that myotonia of the respiratory muscles reduces the compliance of the chest wall. However, direct electrical evidence of myotonia in the respiratory muscles with breathing is lacking. In 11 patients with myotonic dystrophy the scalene, sternocleidomastoid, a parasternal muscle, and a lateral intercostal muscle were studied using intramuscular bipolar wires. Five of the 11 patients had an elevated PaCO2. All patients had a FVC greater than 70% of predicted. Myotonia was sought with needle insertion, quiet tidal breathing, voluntary large breaths, and involuntary larger breaths with chemical stimulation. Two of the 11 patients demonstrated no myotonia. Myotonia on insertion of the needle was seen in four patients. Myotonia was rare in an isolated respiratory cycle during quiet breathing, and repetitive myotonia with consecutive breathing cycles was never noted. Voluntary big breaths produced myotonia in five patients, whereas chemically stimulated larger breaths produced myotonia in seven patients. In two of these seven patients, myotonic activity with consecutive respiratory cycles was seen at higher levels of ventilation. In conclusion, the rare occurrence of myotonia with tidal breathing would suggest myotonia in the muscles does not account for the respiratory failure and tachypneic breathing pattern found in myotonic dystrophy. Its occurrence at higher levels of ventilation may contribute to the reduced ventilatory response to chemical stimuli.

Progression of cardiac disease in Emery-Dreifuss muscular dystrophy

Emery-Dreifuss muscular dystrophy (EDMD) is a rare X-linked muscular dystrophy characterized by early contractures, progressive muscle weakness, and atrial arrhythmias. Recent reports suggest that there may be additional cardiac problems in affected males and that carrier females may also show ECG abnormalities. We restudied two large families with EDMD in order to determine the extent of these problems. We examined 10 affected males and interviewed 2 others. The 3 affected males less than 20 years old had no ECG changes. All affected men of 35 years or older had arrhythmias. One had more severe arrhythmias when asleep, indicating the usefulness of continuous 24-h ECG monitoring in the evaluation of males affected with EDMD. Two required pacemakers, 4 had already had a pacemaker placed, and 4 other affected men with pacemakers had died prior to this study. One affected man with a pacemaker developed ventricular bigeminy and another developed congestive heart failure. Thus of 10 affected males with pacemakers, 6 had additional cardiac symptoms and 4 have died. Males with EDMD may survive longer with a ventricular pacemaker, but this may increase the likelihood that they will develop cardiomyopathy and ventricular arrhythmias. Of 34 carrier females examined, 6 had arrhythmias typical of EDMD. Two required a pacemaker. The risk of arrhythmia increased with age. Results from one family should be extrapolated to another with caution, as there appears to be significant interfamilial variation. We suggest careful cardiologic follow-up of EDMD patients and regular cardiac evaluations for older carrier females.