Focal Muscular Atrophies Treatment & Management

Updated: Feb 20, 2018
  • Author: Sridharan Ramaratnam, MD, MBBS; Chief Editor: Helmi L Lutsep, MD  more...
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Treatment

Medical Care

Treatment of focal muscular atrophy (FMA) varies according to the cause. The common causes (eg, monomelic amyotrophy, PPMA, SMA) have no specific treatment.

When patients with these conditions have disability, the treatment consists of physical and occupational therapy and rehabilitation.

A report of increase in the SMN2 messenger RNA levels in vivo among 7 of 13 patients with spinal muscular atrophy treated with valproic acid raises possibilities of in vivo activation of causative genes in inherited diseases. [55]

Some of the therapeutic strategies that have been tested in SBMA, fall into four main categories: (i) gene silencing; (ii) protein quality control and/or increased protein degradation; (iii) androgen deprivation therapies using leuprorelin and dutasteride; and (iv) modulation of androgen receptor function. Various therapeutic strategies have been effective in transgenic animal models, and research is ongoing to translate these strategies into safe and effective treatment in humans. [56]

An open trial of clenbuterol among patients with spinal and bulbar muscular atrophy (SBMA) found significant and sustained increase in walking distance covered in 6 minutes and forced vital capacity between the baseline and the 12-month assessments (P< .001), suggesting class IV evidence that clenbuterol may be effective in improving motor function. [57]  A randomized trial found no significant effect of dutasteride on the progression of muscle weakness in SBMA. [58]

Counsel patients concerning the benign nature of the illness once the diagnosis is confirmed.

Treatment of PPMA

Trials with amantadine, high-dose steroids, human growth hormone, co-enzyme Q [56]  pyridostigmine [59] , modafanil [60] and bromocriptine all have been disappointing.

In a study of subcutaneous insulinlike growth factor-1 in 22 patients with PPMA, patients had enhanced recovery after fatiguing exercise. However, the treatment had no impact upon strength or exercise-induced fatigue.

Intravenous immunoglobulin probably has no beneficial effect on activity limitations but may have modest beneficial effect on muscle strength and pain. [61, 62, 63, 64, 65]

One trial with weak methods found that lamotrigine might be effective in reducing pain and fatigue, resulting in fewer activity limitations. Data from 2 single trials suggest that muscle strengthening of thumb muscles (very low-quality evidence) and static magnetic fields (moderate-quality evidence) are beneficial for improving muscle strength and pain, respectively, with unknown effects on activity limitations. These interventions, however, need further investigation.

Screening and treating patients for osteopenia or osteoporosis may be appropriate.

Treatment of multifocal motor neuropathy

IV immunoglobulins are effective and commonly used for treating patients with multifocal motor neuropathy.

Either high-dose cyclophosphamide or monthly plasma exchange followed by pulse IV cyclophosphamide has been found effective in patients who do not respond to IV immunoglobulins. These patients do not respond to prednisone or plasmapheresis alone.

Whether the presence of anti-GM1 antibody or its titer has any bearing on the response to therapy is controversial.

Inclusion body myositis does not respond well to immunosuppressive medication.

Immunosuppressive treatment with corticosteroids may benefit focal myositis and sarcoid myopathy.

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Surgical Care

Surgery has no role in FMA, except in rare instances in which FMA is secondary to a surgically treatable intraspinal or extraspinal lesion.

A randomized trial of 2 surgical techniques, namely anterior cervical discectomy decompression with autologous iliac crest bone grafting and internal plate fixation (DDF) or anterior cervical corpectomy, posterior longitudinal ligament resection, autologous iliac crest bone grafting, and internal plate fixation (CDF), for patients with monomelic amyotrophy followed up for 2 years revealed subjective and electrophysiological improvement in 60-65% of patients. Because of the benign nature of the illness, cervical collar treatment is the preferred treatment, while surgery could be an exceptional second-line alternative. If surgery is chosen, DDF carries lower procedural risk compared with CDF. [66]

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Consultations

When the diagnosis is uncertain, referral to a tertiary care center with expertise in neuromuscular disorders may be appropriate.

Consultation with a physical and occupational therapist may prove useful. Vocational rehabilitation training can be used when appropriate.

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