Duchenne muscular dystrophy or Pseudohypertrophic muscular dystrophy or Muscular dystrophy- Duchenne disposition is an X-linked neuromuscular disorder of muscle caused by an absence of the protein dystrophin. DMD was named in recognition of Dr. G. Duchenne de Boulogne from France around 150 years ago. He was the first person to trait the signs and symptoms to a explicit familial disease entity. The gene responsible for it is DMD gene which is known to be the largest gene encoding the muscle protein, dystrophin the discovery of this gene was made around 20 years ago. Dystrophin provides structural stability to the dystroglycan complex (DGC) vouchsafe on the cell membrane as it attaches with the inner surface of the muscle fiber membrane. A mutation in the DMD gene residing in Xp21 area of the X-chromosome, hampers the production of dystrophin protein causing progressive loss of muscle function and guilt (Partridge, 2007). It starts with the lower limbs and gradually covers the entire musculature. DMD is rapidly progressing cipher of muscular dystrophy moving virile with a frequency of 1 in 3500 infants. It is observed that the affected boys begin manifesting symptoms of disease early in life usually before 5 years of epoch. They become powerless and are unable to walk and are narrow to wheel seat during their late childhood or early teen years. Patients usually produce various complications related with respiratory insufficiency and/ or cardiomyopathy as the disease progresses. Death occurs at by late teen term or in the early twenties. It is live to provide appropriate treatment to defeat the required genetic weakness, either through medical, surgical, and rehabilitative approaches to make the patient restful.
Symptoms
Before the period of 6 years symptoms begin becoming obvious, although they are visible in early infancy. There are three clinical stages: an ambulatory stage, an early nonambulatory stage, and a tardy nonambulatory stage.
Ambulatory Stage- This is between two and four years of period, at this stage, symptoms begin appearing. Symptoms display fault of forward head flexion and a inadequate capability to sit up convey beyond infancy chief to poor motor development, deficient remembrance skills and they gradually infirm their ability to cope with their peers both physically and mentally. Heel cord and elbow flexion contractures are besides apparent. In rare cases, obstructive nap apnea too develops along with facial soiling. The ECG readings expose- Q waves leads in the lateral precordial while tall R and deep S waves leads in early precordial. If glucocorticoids are not given then by the term of nine years, the child starts lacking ability to rise from supine to standing position and to climb stairs or radiate from a seat and are competent to ambulate with braces.
Early Nonambulatory Stage- This stage is between 10 and 12 years, the patient becomes dependent on wheel seat and flexion contractures at the ankle and elbow becomes more conspicuous. In this stage aquatic therapy may dumb the sequence. The dependency on wheel chair develops scoliosis and the patient needs orthopedic consultation along with radiological evaluation. The unprejudiced strength of the patient starts declining at the term of 9 years.
Late Nonambulatory Stage- a wheelchair to bed life mode is observed in the patients. At this stage other staid conditions are too prevailing encompassing respiratory insufficiency/ failure, cardiac problems, scoliosis. Respiratory insufficiency is observed in the patients belonging to the period group of 11- 20 years and is not receiving corticosteroid therapy. The forced necessary capacity is reduced to > 60% of normal. This dwindle paves the pass for pneumonia, decreased power of coughing, reduced effective night-time ventilation during sleep and hence reducing the survival appraise of the patient. Cardiomyopathy- ECG abnormalities worsen further principal to atrial arrhythmias of varying degrees. Resting tachycardia becomes more prevailing all through the stage causing autonomic dysfunction of left ventricle. Gastrointestinal dysfunction- the esophageal and gastrointestinal complaints include intentional and impulsive muscles causing delayed gastric emptying, sharp gastric dilatation intellect danger of respiratory insufficiency. Further, chronic intestinal dysfunction occurs, with constipation, distention, hypomobility, impaction, hypokalemia and insufficient fluid intake obstruct ventilation and diaphragmatic movement during sleep.
Pathogenesis
Duchenne muscular dystrophy is caused by a mutation of the dystrophin gene at Xp21. Dystrophin is responsible for the connection of muscle fibers to the extracellular matrix through a protein complex containing many subunits. The absence of dystrophin permits excess calcium to penetrate the cell membrane/ sarcolemma. In a complex cascading process that involves several pathways and is not clearly understood, increased oxidative stress within the cell damages the sarcolemma and eventually results in the death of the cell. Muscle fibers undergo necrosis and are ultimately replaced with adipose and connective tissue.
Treatment
It is manifested that corticosteroids (prednisone and deflazacort) parade a remarkable slow in fetching the loss of muscle strength and function in boys with DMD (Sussman, 2002). It is manifested that surgical release of lower extremity contractures provides benefit and relief to some patients. It is too observed that around 90% of DMD individuals build severe scoliosis, and this is not obedient to manage by nonsurgical means such as bracing or adaptive seating. The most successful cure for severe scoliosis is to obviate it with early spinal fusion using segmental instrumentation immediately when curves are sure and before any friendly of severe pulmonary or cardiac dysfunction occurs. Approaches related to gene therapy to procure the functions of missing gene/ protein is upon the style. Recent stem-cell research is showing promising vectors that may replace damaged muscle tissue. Treatment is generally aimed at controlling the onset of symptoms to maximize the quality of life. Utrophin up regulation is found to compensate for muscle cells lacking dystrophin expression .
Anesthesia in DMD
It is observed that patients with DMD divulge respiratory insufficiency at the tardy stage and respiratory failure causes bronchopneumonia; this becomes the main breaksion of death of the patient likewise, cardiac abnormalities are observed in majority of the cases. It is apparent that DMD patients undergo orthopedic procedures of lower limb therefore anesthesia becomes another hazard for the patient and combination of obesity and spinal deformity creates lumber spinal and extradural anesthesia technically inspiring. The sacral canal is less affected and in young kids caudal extradural blockade may be the technique of choice. In cases where GA is unavoidable then the pulmonary and cardiac condition of the patient becomes imperative. Anesthesia may foster sudden cardiac arrest. It is also manifested that there could be mild elevation in temperature in patients with DMD undergoing anesthesia. It is evident that neuromuscular functions must be monitored (Lane, 1996).
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