Nusinersen (trade name: Spinraza) is the only approved drug to treat spinal muscular atrophy. It is a 2’-O-methoxyethyl, phosphorothioate modified antisense oligonucleotide targeting intronic splicing silencer N1 which is administered directly to the central nervous system using an intrathecal injection. Developed by Ionis Pharmaceuticals and licensed to Biogen, nusinersen was approved by FDA in December 2016, becoming the first approved pharmacological treatment for SMA. It was approved by the European Commission in centralised procedure in June 2017.

Since the underlying genetic cause of SMA was identified in 1995, several therapeutic approaches have been proposed and investigated that primarily focus on increasing the availability of SMN protein in motor neurons. The main research directions are as follows:

Since December 2016, autosomal recessive proximal spinal muscular atrophy can be treated with nusinersen. No cure is known to any of the remaining disorders of the spinal muscular atrophies group. The main objective there is to improve quality of life which can be measured using specific questionnaires. Supportive therapies are widely employed for patients who often also require comprehensive medical care involving multiple disciplines, including pulmonology, neurology, orthopedic surgery, critical care, and clinical nutrition. Various forms of physiotherapy and occupational therapy are frequently able to slow down the pace of nerve degeneration and muscle wasting. Patients also benefit greatly from the use of assistive technology.

A 2006 study followed 223 patients for a number of years. Of these, 15 died, with a median age of 65 years. The authors tentatively concluded that this is in line with a previously reported estimate of a shortened life expectancy of 10-15 years (12 in their data).

In terms of the management of congenital muscular dystrophy the American Academy of Neurology recommends that the individuals

need to have monitoring of cardiac function, respiratory, and gastrointestinal. Additionally it is believed that therapy in speech, orthopedic and physical areas, would improve the persons quality of life.

While there is currently no cure available, it is important to preserve muscle activity and any available correction of skeletal abnormalities (as scoliosis).Orthopedic procedures, like spinal fusion, maintains/increases the individuals prospect for more physical movement.

Currently there is no cure for myotubular or centronuclear myopathies. Treatment often focuses on trying to maximize functional abilities and minimize medical complications, and involvement by physicians specializing in Physical Medicine and Rehabilitation, and by physical therapists and occupational therapists.

Medical management generally involves efforts to prevent pulmonary complications, since lung infections can be fatal in patients lacking the muscle strength necessary to clear secretions via coughing. Medical devices to assist with coughing help patients maintain clear airways, avoiding mucous plugs and avoiding the need for tracheostomy tubes.

Monitoring for scoliosis is also important, since weakness of the trunk muscles can lead to deviations in spinal alignment, with resultant compromise of respiratory function. Many patients with congenital myopathies may eventually require surgical treatment of scoliosis.

Duchenne muscular dystrophy is a rare progressive disease which eventually affects all voluntary muscles and involves the heart and breathing muscles in later stages. As of 2013, the life expectancy is estimated to be around 25, but this varies. With excellent medical care males are often living into their 30s.

In rare cases, people with DMD have been seen to survive into their forties or early fifties, with proper positioning in wheelchairs and beds, and the use of ventilator support (via tracheostomy or mouthpiece), airway clearance, and heart medications. Early planning of the required supports for later-life care has shown greater longevity for people with DMD.

Curiously, in the mdx mouse model of Duchenne muscular dystrophy, the lack of dystrophin is associated with increased calcium levels and skeletal muscle myonecrosis. The intrinsic laryngeal muscles (ILMs) are protected and do not undergo myonecrosis. ILMs have a calcium regulation system profile suggestive of a better ability to handle calcium changes in comparison to other muscles, and this may provide a mechanistic insight for their unique pathophysiological properties. The ILM may facilitate the development of novel strategies for the prevention and treatment of muscle wasting in a variety of clinical scenarios.

No cure for DMD is known, and an ongoing medical need has been recognized by regulatory authorities.

Treatment is generally aimed at controlling the onset of symptoms to maximize the quality of life which can be measured using specific questionnaires, and include:

- Corticosteroids such as prednisolone and deflazacort lead to short-term improvements in muscle strength and function up to 2 years. Corticosteroids have also been reported to help prolong walking, though the evidence for this is not robust.

- Randomised control trials have shown that β agonists increase muscle strength, but do not modify disease progression. Follow-up time for most RCTs on β agonists is only around 12 months, hence results cannot be extrapolated beyond that time frame.

- Mild, nonjarring physical activity such as swimming is encouraged. Inactivity (such as bed rest) can worsen the muscle disease.

- Physical therapy is helpful to maintain muscle strength, flexibility, and function.

- Orthopedic appliances (such as braces and wheelchairs) may improve mobility and the ability for self-care. Form-fitting removable leg braces that hold the ankle in place during sleep can defer the onset of contractures.

- Appropriate respiratory support as the disease progresses is important.

- Cardiac problems may require a pacemaker.

Comprehensive multidisciplinary care standards/guidelines for DMD have been developed by the Centers for Disease Control and Prevention, and were published in two parts in "The Lancet Neurology" in 2010.

In terms of the management of spinal and bulbar muscular atrophy, no cure is known and treatment is supportive. Rehabilitation to slow muscle weakness can prove positive, though the prognosis indicates some individuals will require the use of a wheelchair in later stages of life.

Surgery may achieve correction of the spine, and early surgical intervention should be done in cases where prolonged survival is expected. Preferred nonsurgical treatment occurs due to the high rate of repeated dislocation of the hip.

Prognosis depends on the individual form of MD. In some cases, a person with a muscle disease will get progressively weaker to the extent that it shortens lifespan due to heart and breathing complications. However, some of the muscle diseases do not affect life expectancy at all, and ongoing research is attempting to find cures and treatments to slow muscle weakness.

Currently, there is no cure for muscular dystrophy. In terms of management, physical therapy, occupational therapy, orthotic intervention (e.g., ankle-foot orthosis), speech therapy, and respiratory therapy may be helpful. Low intensity corticosteroids such as prednisone, and deflazacort may help to maintain muscle tone. Orthoses (orthopedic appliances used for support) and corrective orthopedic surgery may be needed to improve the quality of life in some cases. The cardiac problems that occur with EDMD and myotonic muscular dystrophy may require a pacemaker. The myotonia (delayed relaxation of a muscle after a strong contraction) occurring in myotonic muscular dystrophy may be treated with medications such as quinine.

Occupational therapy assists the individual with MD to engage in activities of daily living (such as self-feeding and self-care activities) and leisure activities at the most independent level possible. This may be achieved with use of adaptive equipment or the use of energy-conservation techniques. Occupational therapy may implement changes to a person's environment, both at home or work, to increase the individual's function and accessibility; furthermore, it addresses psychosocial changes and cognitive decline which may accompany MD, and provides support and education about the disease to the family and individual.

In terms of treatment for neuromuscular diseases (NMD), "exercise" might be a way of managing them, as NMD individuals would gain muscle strength. In a study aimed at results of exercise, in muscular dystrophy and Charcot-Marie-Tooth disease, the later benefited while the former did not show benefit; therefore, it depends on the disease Other management routes for NMD should be based on medicinal and surgical procedures, again depending on the underlying cause.

There is no known cure for Becker muscular dystrophy yet. Treatment is aimed at control of symptoms to maximize the quality of life which can be measured by specific questionnaires. Activity is encouraged. Inactivity (such as bed rest) or sitting down for too long can worsen the muscle disease. Physical therapy may be helpful to maintain muscle strength. Orthopedic appliances such as braces and wheelchairs may improve mobility and self-care.

Immunosuppressant steroids have been known to help slow the progression of Becker muscular dystrophy. The drug prednisone contributes to an increased production of the protein utrophin which closely resembles dystrophin, the protein that is defective in BMD.

The cardiac problems that occur with EDMD and myotonic muscular dystrophy may require a pacemaker.

The investigational drug Debio-025 is a known inhibitor of the protein cyclophilin D, which regulates the swelling of mitochondria in response to cellular injury. Researchers decided to test the drug in mice engineered to carry MD after earlier laboratory tests showed deleting a gene that encodes cycolphilin D reduced swelling and reversed or prevented the disease’s muscle-damaging characteristics. According to a review by Bushby, et al. if a primary protein is not functioning properly then maybe another protein could take its place by augmenting it. Upregulation of compensatory proteins has been done in models of transgenic mice.

The overall incidence of myotubular myopathy is 1 in 50,000 male live births. The incidence of other centronuclear myopathies is extremely rare, with there only being nineteen families identified with CNM throughout the world. The symptoms currently range from the majority who only need to walk with aids, from a stick to a walking frame, to total dependence on physical mobility aids such as wheelchairs and stand aids, but this latter variety is so rare that only two cases are known to the CNM "community".

Approximately 80% of males with a diagnosis of myotubular myopathy by muscle biopsy will have a mutation in MTM1 identifiable by genetic sequence analysis.

Many patients with myotubular myopathy die in infancy prior to receiving a formal diagnosis. When possible, muscle biopsy and genetic testing may still be helpful even after a neonatal death, since the diagnostic information can assist with family planning and genetic counseling as well as aiding in the accurate diagnosis of any relatives who might also have the same genetic abnormality.

The disease has only been identified as distinct from SMA recently, so research is still experimental, taking place mostly in animal models. Several therapy pathways have been devised which include gene therapy, whereby an "IGHMBP2" transgene is delivered to the cell using a viral vector; small-molecule drugs like growth factors (e.g., IGF-1 and VEGF) or olesoxime; and transplantation of healthy motor neurons grown "in vitro" from the patient's stem cells. Studies in amyotrophic lateral sclerosis are also considered helpful because the condition is relatively similar to SMARD1.

The progression of Becker muscular dystrophy is highly variable—much more so than Duchenne muscular dystrophy. There is also a form that may be considered as an intermediate between Duchenne and Becker MD (mild DMD or severe BMD).

Severity of the disease may be indicated by age of patient at the onset of the disease. One study showed that there may be two distinct patterns of progression in Becker muscular dystrophy. Onset at around age 7 to 8 years of age shows more cardiac involvement and trouble climbing stairs by age 20, if onset is around age 12, there is less cardiac involvement.

The quality of life for patients with Becker muscular dystrophy can be impacted by the symptoms of the disorder. But with assistive devices, independence can be maintained. People affected by Becker muscular dystrophy can still maintain active lifestyles.

One drug in test seemed to prevent the type of muscle loss that occurs in immobile, bedridden patients.

Testing on mice showed that it blocked the activity of a protein present in the muscle that is involved in muscle atrophy. However, the drug's long-term effect on the heart precludes its routine use in humans, and other drugs are being sought.

There is no known cure to DSMA1, and care is primarily supportive. Patients require respiratory support which may include non-invasive ventilation or tracheal intubation. The child may also undergo additional immunisations and offered antibiotics to prevent respiratory infections. Maintaining a healthy weight is also important. Patients are at risk of undernutrition and weight loss because of the increased energy spent for breathing. Physical and occupational therapy for the child can be very effective in maintaining muscle strength.

There is no published practice standard for the care in DSMA1, even though the Spinal Muscular Atrophy Standard of Care Committee has been trying to come to a consensus on the care standards for DSMA1 patients. The discrepancies in the practitioners’ knowledge, family resources, and differences in patient’s culture and/or residency have played a part in the outcome of the patient.

There is no cure for MMA. Treatment consists of muscle strengthening exercises and training in hand coordination. It has been proposed that the changes in this disease are from compression of the spinal cord in flexion due to forward shifting of the posterior dural sac. There have been treatments studies ranging from use of a cervical collar to anterior cervical fusion and posterior decompression.

Congenital dSMA has a relatively stable disease course, with disability mainly attributed to increased contractures rather than loss of muscle strength. Individuals frequently use crutches, knee, ankle, and/or foot orthoses, or wheelchairs. Orthopaedic surgery can be an option for some patients with severely impaired movement. Physical therapy and occupational therapy can help prevent further contractures from occurring, though they do not reverse the effects of preexisting ones. Some literature suggests the use of electrical stimulation or botulinum toxin to halt the progression of contractures.

Muscle atrophy can be opposed by the signaling pathways which induce muscle hypertrophy, or an increase in muscle size. Therefore, one way in which not exercise induces an increase in muscle mass is to down regulate the pathways which have the opposite effect.

β-hydroxy β-methylbutyrate (HMB), a metabolite of leucine which is sold as a dietary supplement, has demonstrated efficacy in preventing the loss of muscle mass in several muscle wasting conditions in humans, particularly sarcopenia. A growing body of evidence supports the efficacy of HMB as a treatment for reducing, or even reversing, the loss of muscle mass, muscle function, and muscle strength in hypercatabolic disease states such as cancer cachexia; consequently, it is recommended that both the prevention and treatment of sarcopenia and muscle wasting in general include supplementation with HMB, regular resistance exercise, and consumption of a high-protein diet. Based upon a meta-analysis of seven randomized controlled trials that was published in 2015, HMB supplementation has efficacy as a treatment for preserving lean muscle mass in older adults. More research is needed to determine the precise effects of HMB on muscle strength and function in this age group.

Since the absence of muscle-building amino acids can contribute to muscle wasting (that which is torn down must be rebuilt with like material), amino acid therapy may be helpful for regenerating damaged or atrophied muscle tissue. The branched-chain amino acids or BCAAs (leucine, isoleucine, and valine) are critical to this process, in addition to lysine and other amino acids.

In severe cases of muscular atrophy, the use of an anabolic steroid such as methandrostenolone may be administered to patients as a potential treatment. A novel class of drugs, called SARM (selective androgen receptor modulators) are being investigated with promising results. They would have fewer side-effects, while still promoting muscle and bone tissue growth and regeneration. These claims are, however, yet to be confirmed in larger clinical trials.

One important rehabilitation tool for muscle atrophy includes the use of functional electrical stimulation to stimulate the muscles. This has seen a large amount of success in the rehabilitation of paraplegic patients.

Congenital muscular dystrophies are autosomal recessively-inherited muscle diseases. They are a group of heterogeneous disorders characterized by muscle weakness which is present at birth and the different changes on muscle biopsy that ranges from myopathic to overtly dystrophic due to the age at which the biopsy takes place.

Inactivity and starvation in mammals lead to atrophy of skeletal muscle, accompanied by a smaller number and size of the muscle cells as well as lower protein content. In humans, prolonged periods of immobilization, as in the cases of bed rest or astronauts flying in space, are known to result in muscle weakening and atrophy. Such consequences are also noted in small hibernating mammals like the golden-mantled ground squirrels and brown bats.

Bears are an exception to this rule; species in the family Ursidae are famous for their ability to survive unfavorable environmental conditions of low temperatures and limited nutrition availability during winter by means of hibernation. During that time, bears go through a series of physiological, morphological and behavioral changes. Their ability to maintain skeletal muscle number and size at time of disuse is of significant importance.

During hibernation, bears spend four to seven months of inactivity and anorexia without undergoing muscle atrophy and protein loss. There are a few known factors that contribute to the sustaining of muscle tissue. During the summer period, bears take advantage of the nutrition availability and accumulate muscle protein. The protein balance at time of dormancy is also maintained by lower levels of protein breakdown during the winter time. At times of immobility, muscle wasting in bears is also suppressed by a proteolytic inhibitor that is released in circulation. Another factor that contributes to the sustaining of muscle strength in hibernating bears is the occurrence of periodic voluntary contractions and involuntary contractions from shivering during torpor. The three to four daily episodes of muscle activity are responsible for the maintenance of muscle strength and responsiveness in bears during hibernation.

The importance of correctly recognizing progressive muscular atrophy as opposed to ALS is important for several reasons.

- 1) the prognosis is a little better. A recent study found the 5-year survival rate in PMA to be 33% (vs 20% in ALS) and the 10-year survival rate to be 12% (vs 6% in ALS).

- 2) Patients with PMA do not suffer from the cognitive change identified in certain groups of patients with MND.

- 3) Because PMA patients do not have UMN signs, they usually do not meet the "World Federation of Neurology El Escorial Research Criteria" for “Definite” or “Probable” ALS and so are ineligible to participate in the majority of clinical research trials such as drugs trials or brain scans.

- 4) Because of its rarity (even compared to ALS) and confusion about the condition, some insurance policies or local healthcare policies may not recognize PMA as being the life-changing illness that it is. In cases where being classified as being PMA rather than ALS is likely to restrict access to services, it may be preferable to be diagnosed as "slowly progressive ALS" or "lower motor neuron predominant" ALS.

An initial diagnosis of PMA could turn out to be slowly progressive ALS many years later, sometimes even decades after the initial diagnosis. The occurrence of upper motor neurone symptoms such as brisk reflexes, spasticity, or a Babinski sign would indicate a progression to ALS; the correct diagnosis is also occasionally made on autopsy.

Spinal muscular atrophies (SMAs) are a genetically and clinically heterogeneous group of rare debilitating disorders characterised by the degeneration of lower motor neurons (neuronal cells situated in the anterior horn of the spinal cord) and subsequent atrophy (wasting) of various muscle groups in the body. While some SMAs lead to early infant death, other types permit normal adult life with only mild weakness.