eMedicine Specialties > Physical Medicine and Rehabilitation > Disorders of the Motor Unit

Kugelberg Welander Spinal Muscular Atrophy: Treatment & Medication

Author: Joyce L Oleszek, MD, Assistant Professor, Department of Physical Medicine and Rehabilitation, University of Colorado at Denver Health Sciences Center, The Children's Hospital of Denver
Coauthor(s): Stephanie E Vallee, MS, Certified Genetic Counselor, Dartmouth-Hitchcock Medical Center, Children's Hospital at Dartmouth; Michael Dichiaro, MD, Chief Resident, Department of Physical Medicine and Rehabilitation, University of Colorado at Denver Health Sciences Center; Mary Louise Caire, MD, Consulting Staff, Department of Physical Medicine and Rehabilitation, Wise Regional Medical Center; Stephen Kishner, MD, Residency Program Director, Professor of Clinical Medicine, Department of Medicine, Section of Physical Medicine and Rehabilitation, Louisiana State University School of Medicine
Contributor Information and Disclosures

Updated: Jul 29, 2008

Treatment

Rehabilitation Program

Physical Therapy

Spinal muscular atrophy (SMA) has no known cure; thus, most care for the patient with SMA is focused on symptomatic control and preventative rehabilitation.¹⁴ Maintaining the patient's joint mobility is very important, because the goal is to decrease the incidence of contractures. Plantar flexion contractures are the most common.

Ankle-foot orthotics worn at night may help to provide prolonged, passive stretching to prevent worsening of ankle plantar flexion contractures.

Stretching and strength training in patients under the care of an experienced physical therapist are very important components of the preventative rehabilitation approach. For school-age patients, a physical therapist can provide consultation regarding appropriate or adaptive physical education activities.

Aquatic therapy is an excellent way to maintain mobility, strength, and flexibility.

Because of the progressive weakness associated with SMA, patients may require the full-time use of a wheelchair. For these patients, there are multiple assistive devices available that enable them to maintain a level of independence. Patients are encouraged to use manual wheelchairs rather than electric ones, when possible, to maintain cardiovascular fitness and upper body strength.

Occupational Therapy

The occupational therapist plays an essential role in addressing the individual needs of patients with spinal muscular atrophy. Occupational therapy is useful for teaching the patient ways to increase his/her independence in activities of daily living (ADL). Fine motor skills may be affected by fatigue. Affected school-age patients may benefit from an occupational therapy consultation that addresses keyboarding and other ways to avoid fatigue from upper extremity activities in the classroom.

Patients may eventually require the use of a wheelchair on a full-time basis. In addition, multiple assistive devices are available that enable patients to maintain a higher level of independence.

Speech Therapy

Patients with spinal muscular atrophy may require consultation with a speech therapist if dysphagia is present or diet modification is needed.

Medical Issues/Complications

• Orthopedic¹⁵ - A few studies have shown that scoliosis is a major problem in half of the patients with spinal muscular atrophy (SMA) type III. However, scoliosis occurs less frequently in patients with SMA type III than it does in persons with type II, and it is not as severe. Routine radiography should be performed, and the patient may require a thoracolumbar sacral orthosis (TLSO) or may need surgery. Spinal orthoses have been shown to assist in containing the spinal deformity until instrumentation and fusion can be performed, if necessary.
  
  Hip subluxation is also common. One author reports 50% of patients with SMA type III have hip subluxation or dislocation, with rare improvement in function from surgical reduction.
• Respiratory - Pulmonary disease is the major cause of morbidity and mortality in patients with SMA types I and II and in a small portion of persons with SMA type III.^6,7,8 The presence of expiratory muscle weakness that is greater than inspiratory muscle weakness, with relative sparing of the diaphragm, leads to impaired cough, hypoventilation during sleep, chest wall underdevelopment, and the potential for recurrent infections. One author found that in SMA type III, pulmonary function was preserved until age 13 years, and that by age 17 years, pulmonary function decreased to 79%.
  
  Pulmonary function tests can be performed, with forced vital capacity (FVC) as the best predictor of respiratory reserve; these tests should be done on a regular basis. Treatments may include noninvasive ventilation, including intermittent positive pressure ventilation, bilevel positive airway pressure ventilation, and negative pressure ventilation. Infections should be treated aggressively with antibiotics, mucolytics and bronchodilators, oxygen, chest PT and postural drainage, and a cough-assist machine.
• Sleep disorders - Questions regarding sleep hygiene and fatigue should be addressed. Patients with SMA type III frequently report fatigue. One case report described a 46-year-old man with SMA type III whose increasing daytime fatigue caused by nocturnal snoring and apnea resolved with nighttime use of continuous positive airway pressure with a nasal mask.¹⁶ Another case report documented the coexistence of sleep-disordered breathing and dilated cardiomyopathy in a 53-year-old patient with SMA type III.¹⁷ Similarly, symptoms were virtually eliminated with nighttime use of continuous positive airway pressure via nasal mask. Sleep studies can be used to screen for nocturnal hypoventilation.
• Contractures - Contractures are usually mild as long as patients remain ambulatory.
• Dysphagia

Surgical Intervention

• If scoliosis develops in a patient with spinal muscular atrophy, spinal instrumentation and fusion may be necessary.¹⁸ Some upper extremity function can be lost after fusion.
• Tendon lengthenings may be needed to improve joint position.

Consultations

• Genetic counseling for spinal muscular atrophy (SMA) - Parents, patients, and extended family members may benefit from genetic counseling. Carrier detection relies on determining the number of exon 7 – containing SMN1 gene copies present in an individual. SMA carrier testing, a polymerase chain reaction – based dosage assay, is available on a limited clinical basis. For a number of reasons, test results can be difficult to interpret and should be provided in the context of formal genetic counseling.
• Vocational rehabilitation counseling - This type of counseling may be beneficial to facilitate the transition from secondary school to postsecondary education or for vocational planning.

Medication

Numerous treatment trials for spinal muscular atrophy (SMA) have been described or are currently underway.¹⁹ Medications being studied for upregulation of SMN2 protein production or for increase of exon 7 inclusion include phenylbutyrate, valproic acid, suberoylanilide hydroxamic acid, and hydroxyurea. The neuroprotective medications being investigated, including gabapentin and riluzole, are thought to provide protection from oxidative stress. Albuterol has been studied for its trophic/anabolic effects. Exercise therapy in rats has shown modest improvement in survival and modest decrease in motor neuron loss. Treatment with stem cells is also an area undergoing further study.

A single study from the Russian literature in 1980 suggested that lithium may have a role in slowing the disease progression, but this has not been corroborated. Further studies are needed to investigate this.²⁰

A study using thyrotropin-releasing hormone as a treatment for SMA types II and III in children showed promising results. More studies are warranted to further investigate this possible treatment.²¹

Merlini and colleagues performed a multicenter, randomized, controlled trial of gabapentin versus no treatment in 120 patients with SMA type II or III for 12 months.²² A significant improvement in lower extremity, maximum, voluntary isometric contraction was seen.

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