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Muscular dystrophy
Dystrophia myotonica
Autosomal dominant, probably with
incomplete penetrance
Clinical features
- onset
at any age. Most patients 20-30 years
-
onset
dominated by weakness or myotonia or both
-
difficulty
releasing grip may present problems if delicate skills required. If manual
work involved weakness tends to be the greater problem
-
in
most cases arm flexors are myotonic and extensors are weak
-
frontal
baldness
-
loss
of facial expression
-
ptosis
-
marked
wasting of masseters and temporalis produces haggard wasted “hatchet”
face
-
cataracts
-
dysarthria
due to myotonia of tongue
-
sternomastoid
wasting is a prominent early feature. Produces swan neck
-
percussion
of tongue or thenar eminence produces dimpling and slow myotonic contraction
of muscle
Picture
Non-neurological features
-
gynaecomastia
-
gonadal
atrophy
-
cardiac
abnormalities: cardiomyopathy and conduction defects
-
motility
disorders of bowel and biliary tree
-
respiratory
infections common due to respiratory muscle involvement and occasional
abnormalities in immunoglobulins
-
many
patients have low IQ and dementia may occur
-
diabetes
mellitus due to end-organ unresponsiveness to insulin
-
±
nodular thyroid goitre
Diagnosis
Treatment
Anaesthetic management
Respiratory muscle weakness
-
respiratory function. should be
fully assessed pre-op. and respiratory depressants (eg thiopentone or
opioids) should be used with care.
-
there is increased sensitivity to
non depolarising muscle relaxants
-
elective IPPV may be required
-
post-op. care of the airway must be
meticulous because of muscle weakness
-
chest infections are common
-
elective ITU admission advisable
Cardiovascular effects
-
arrhythmias common
-
cardiomyopathy
Muscle spasm
-
may be provoked by depolarising
muscle relaxants or anti-cholinesterases, therefore avoid suxamethonium and
neostigmine
-
not abolished by non-depolarising
relaxants
CNS
- very sensitive to thiopentone with
50-100 mg causing apnoea
Duchenne muscular dystrophy
Sex linked recessive. Very rare female
cases reported
Clinical features
-
onset
between 3 and 10 years of age
-
most
die within 10 years of onset
-
initially
involves proximal muscles of legs. Later shoulder girdle and then extends
peripherally
-
contractures
occur early and are severe
-
loss
of reflexes except ankle jerks
-
diaphragm,
neck, extraocular and facial muscles very rarely involved
-
macroglossia
in some cases
-
pseudohypertrophy
of calves, occasionally deltoid and infraspinatus
-
bone
thinning, pathological #s, fatty infiltration of the heart and respiratory
infections are important complications
-
30%
have IQ <75
-
CPK
very high initially with a later fall into the normal range when atrophy is
severe
-
carrier
state may be detected by high CPK and EMG.
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