Congenital Myopathies Follow-up

Updated: Mar 11, 2019
  • Author: Matthew Harmelink, MD; Chief Editor: Amy Kao, MD  more...
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Follow-up

Further Outpatient Care

Follow-up and outpatient care depends on disease severity. In children, or a newly diagnosed patient, more frequent visits, such as every 3–6 months, can be considered. For older patients or those with milder disease, at least yearly visits are warranted.

At each visit care should be directed based on the exact needs of the patient but should also involve assessments of the following:

  • Muscle function

  • Contractures

  • Ability to perform activities of daily living

  • Cardiopulmonary function

For patients requiring more than one provider, consider a multidisciplinary approach.

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Further Inpatient Care

Inpatient care is directed at specific needs. Often infants or neonates will have a longer inpatient stay after birth. Additionally, given the weak respiratory muscles, admission may be warranted as needed.

In patients with neuromuscular weakness the method of supportive care and methods of extubating differ from patients without muscle weakness.  This often presents as different supportive settings, more frequent interventions by the respiratory therapist, and, in some cases, extubating the patient to non-invasive support regardless of how well they were doing on the ventilator. As such, consultation with a pulmonologist or critical care specialist who is experienced in caring for patients with neuromuscular disease is often warranted.

While ill, there are certain medications that should be avoided due to their muscle relaxant properties. While not an absolute contraindication, a patient;s underlying muscle weakness has the potential to significantly worsen when exposed to these medications.

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Complications

Patients with central core disease (CCD) (less frequently with multicore disease) are inclined to develop malignant hyperthermia. However, since the precise diagnosis may not be known, precautions should be taken in all patients with a presumed diagnosis of congenital myopathy. General anesthesia usually triggers a full-blown episode, but excessive heat, neuroleptic drugs, alcohol, or infections may trigger milder episodes.

If surgery is required, these patients (and their relatives) should avoid inhaled anesthetics (except nitrous oxide) and succinylcholine.

Signs and symptoms of malignant hyperthermia include the following:

  • Elevated pCO2

  • Muscle rigidity

  • Tachycardia

  • Hemodynamic instability

  • Hyperventilation

  • Cyanosis

  • Lactic acidosis

  • Fever

  • Hyperkalemia

  • Hypercalcemia

  • Myoglobinuria

  • Death may result from pulmonary edema, coagulopathy, ventricular fibrillation, cerebral edema, or renal failure

Appropriate treatment includes the following:

  • Stopping inhalational anesthetics or succinylcholine

  • Hyperventilating the patient with 100% oxygen

  • Administering dantrolene up to 10 mg/kg

  • Providing bicarbonate for metabolic acidosis

  • Cooling the patient

  • Monitoring for arrhythmias and hyperkalemia

  • Maintaining urine output over 2 mL/kg/h

  • Avoiding calcium antagonists and beta-blockers

  • Monitoring in an ICU for 24–48 hours

Cardiac involvement can occur in patients with congenital myopathies, especially nemaline myopathy, CCD, and multiminicore disease.

Pulmonary insufficiency can occur in any form of congenital myopathy that presents with severe neonatal hypotonia. It is more common or more severe in nemaline myopathy, X-linked and autosomal myotubular/centronuclear myopathy, multiminicore disease, and reducing body myopathy. This is especially important to assess before surgery since postoperative respiratory failure can occur.

Skeletal deformities, including contractures and scoliosis, are common in patients with most of the congenital myopathies.

Obstetric complications during childbirth are uncommon in mothers with congenital myopathy. However, neonatal complications can include polyhydramnios; decreased fetal movements; or complications related to fetal distress, abnormal presentation, failure to progress, or prematurity.

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Patient Education

Genetic counseling is often helpful to assist patients with family-planning decisions. However, definitive prenatal diagnosis is only possible if a disease-causing mutation has been identified. Genetic counseling is especially important for families of patients with CCD to avoid unexpected cases of malignant hyperthermia in asymptomatic relatives.

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