Congenital Miopathies and Anesthesia
Lecturer Aneshtesiologist, Bj Wadia Children's Hosiptal, Parel, Mumbai, India
Vol. 3, N. 4, Settembre 2005
MYOPATHIES: Myopathies are primary diseases of striated muscles in which biochemical, morphological or neurophysiological changes occur singly or in combination. They are characterized by the description of the histologic lesion and the clinical and genetic picture. Congenital myopathies are mainly of 3 types:
Central core disease: It is a rare disorder. It is so named because of the metabolically inactive cores present in the muscle fibres. Patients have decreased fetal movements and breech presentation. They have hypotonia and delay in motor milestones with increased proximal weakness. In childhood, they have difficulty in climbing stairs and getting up from the floor. Legs are more affected than arms. Investigations reveal increased CPK levels. EMG shows myopathic pattern and muscle biopsy shows fibres with single or multiple central or eccentric discrete zones devoid of oxidative enzymes.
It is of 3 types:
1) Neonatal form: Presents with severe hypotonia and weakness at birth. Respiratory assistance may be required.
2) Late infancy - Early childhood: Presents with delayed milestones, marfanoid features (slender body habitus, long narrow face, high arched palate), scoliosis, club feet, progressive Ophthalmoplegia (may have ptosis) and varying degrees of extraocular muscle impairment.
3) Late childhood - Adult type: Present in the 2nd or 3rd decade with full extraocular muscle involvement (rarely ptosis). Scoliosis and clubfeet may be present.
*All myopathies may have varying degrees of cardiac involvement. Central core disease is especially prone to cardiomyopathies.
MUSCULAR DYSTROPHIES: It is a group of disorders of primary muscular atrophy of unknown cause. They are best characterised by the lack of any evidence of denervation and yet there is degeneration of the muscle fibres and increases in the content of fat and fibrous tissue in the muscle. They are commonly seen and have features similar to myopathies. The common one are discussed below:
Duchenne Muscular Dystrophy: It is an X-linked disorder also called pseudohypertrophic muscular dystrophy as the calf muscles appear large and bulky though they are weak. It presents at birth but becomes apparent at 3-5 years of age. Patients present with ‘Gowers manoeuvre' i.e. uses his hands to climb up himself. Contractures are common and fixed. Scoliosis develops over a period of time. Muscle weakness is progressive. Cardiac cause of death is uncommon but presents with cardiomyopathy and CCF may occur. Intellectual impairment is common. Investigations show CPK levels increased by 20-100 times of normal. EMG features are similar to those of myopathy. Muscle Biopsy shows groups of necrotic and regenerating fires.
Becker's Muscular Dystrophy: It is also an X-linked muscular disease. Patients present with proximal muscle weakness. They present between 5-15yrs of age. Mental retardation is more common. Average life span is upto 4th-5th decade.
Congenital Muscular Dystrophy: Children present at birth or in the first few months of life with hypotonia and proximal limb weakness. There is varying degrees of contracture seen at birth called arthrogyroposis. Death may ensue because of respiratory insufficiency early in life
TYPES OF SURGERIES REQUIRED IN THESE PATIENTS: These patients usually come for
ANAESTHESIA RELATED PROBLEMS: The various problems faced by us are:
MALIGNANT HYPERTHERMIA: Malignant hyperthermia is a syndrome of a chain reaction of signs, which include a greatly increased body metabolism, muscle rigidity and high fever. Death or brain damage may result from cardiac arrest, internal haemorrhage or failure of other body systems. As all these myopathies are prone to malignant hyperthermia, it is important to know which are its prime triggers. All volatile anaesthetics- Halothane, Isoflurane, enflurane, Desflurane and Sevoflurane are triggers for malignant hyperthermia, while nitrous oxide is NOT. Amongst muscle relaxants Succinylcholine is a potent trigger. Thus, for short surgeries it is safer to use total intravenous anaesthesia using
a) Propofol and fentanyl or
We thank Dr. Sunita Goel, Pediatric Oncall and Dr. Ira Shah for professional collaboration with our Journal.
Dario Galante, MD