Genetic disorder characterized by distal, late-onset
myopathy. The presenting feature is in 89% of cases weakness and wasting of
the small muscle of the hands. Myotonia and sensory changes are not present. Does not involve the heart.
Swedish Distal Myopathy type; Welander Muscular Atrophy.
Welander distal myopathy is observed almost exclusively
in Sweden, where it was first described; more than 250 cases have been
Autosomal dominant inheritance. The gene
causing Welander myopathy has not yet been identified but is restricted to a
region of 2.4 cM on chromosome 2 (2p13).
Unknown, but the gene locus region overlaps with
those of Miyoshi myopathy and limb-girdle muscular dystrophy IIB, both of
which result from mutation in the dysferlin gene.
Levels of creatine kinase are normal to slightly
increased. The most prominent finding on light microscopy is that of rimmed
vacuoles and tubulofilamentous inclusions evidenced by ultrastructural
Distal myopathy with late onset (after age 40
years). The first symptom is clumsiness in performing fine motor skills with
the index finger and thumb. The weakness subsequently progresses to all the
finger extensor muscles, and atrophy of intrinsic hand muscles becomes
manifest after several years' duration. The weakness later extends to the
anterior muscles of the legs with inability to raise the forefoot
appropriately. No proximal weakness and no cardiomyopathy. Progression is
slow and does not affect life expectancy.
No literature about this condition
and anesthesia, but certain considerations must be made. Obtain complete
workup, including neurologic and motor milestones, family history, and
previous problems. Cardiac function should be assessed in light of
cardiomyopathic potential of other distal myopathy. ECG, echocardiography,
and/or cardiac catheterization may be appropriate. Other syndromic features
should be sought.
Cardiomyopathic cases (Welander/ Swedish
type) in general have greater implications for anesthesia. Patients
manifesting cardiomyopathy require cardiac monitoring depending on the
degree of disease.
Use extreme caution with thiopentone
and muscle relaxants; avoid respiratory depressant drugs.
Distal Myopathy Type I (MPD I): Late distal myopathy with small
hand muscle weakness and wasting. Also associated with a very slow
progressive cardiomyopathy. It is inherited as an autosomal dominant
Miyoshi Myopathy (Late-Onset Distal Muscular Dystrophy):
Characterized by onset between 16 and 20 years in 80% of cases, with
muscular involvement of lower legs and forearms; small muscles of the feet
and hands are relatively spared.
Inclusion Body Myopathy: Characterized by muscular dystrophy,
especially of the anterior tibial muscles. Although the hamstring and
tibialis anterior muscles are affected severely by early adulthood, the
quadriceps muscles are spared even in a late stage of the disorder.
Limb-Girdle Muscular Dystropy (LGMD): Genetically heterogeneous group
of inherited progressive muscular disorders that affect mainly the proximal
musculature (hip and shoulder). Several different types have been
identified; at least eight have autosomal recessive ...