Dr Anakha V Ajay Dr Vinayan( Dept of Pediatric neurology) DRCJayakumar AIMS , Kochi
One and half year old female child presented with drooping of both eyelids towards evening and after exertion of one month duration
This used to improve after rest .
She also had difficulty in getting up from sitting position.
She was born as second child of a non consanguineous parentage .
Anetenatally, there is history of decreased fetal movements towards the end of last trimester was present. She was, born term via normal vaginally with birth weight of 3.1kg and uneventful post natal history. She has milestones at appropriate age No significant family history .
Differentials considered were:
1.Congenital myasthenic syndrome 2Congenital muscular dystrophy.
3Congenital myopathies
4Metabolic myopathies
5Endocrine myopathies
6Neuro degenerative disorders
7Peripheral neuropathies
On examination, child alert with stable vitals
PICCLE were normal.
No clinically detectable neurocutaneous markers or congenital anomalies. All the cranial nerves were normal. But fatiguable ptosis was present.
Muscles were of nomal bulk with mild hypotonia and power of 4/5 with 2+ DTR, Plantar showing bilateral flexors.
Gait and sensory system were within normal limits.
Specific tests ` done:
Ptosis time was 25 seconds, arm abduction test>1 min possible, single breath count: counting>25, truncal muscle weakness present, neck flexor weakness present, neck extensors: strong sittups- possible.
Labs done showed normal counts,
Renal function
Liver function test.
Edrophonium test was done and was opined as myasthenia;
Acetyl choline receptor antibody test
(AcH R )antibody was negative.
She was started on pyridostigmine.
Nerve conduction study done showed evidence of postsynaptic neuromuscular junction disorder suggestive of myasthenia.
Serum acetyl choline antibody was negative.
Nerve conduction velocity (NCV )with repetitive nerve stimulation (RNS )revealed lower limb motor conduction study showed reduced (Compound muscle action potential) CMAP amplitude from right peroneal nerve.
RNS study showed significant decremental response from left facial nerves suggesting an evidence for post synaptic neuromuscular junction transmission defect.
Pyridostigmine dose was increased.
Child improved symptomatically and hence was planned to keep under regular follow up.
Congenital myasthenic syndrome(CMS) is a group of conditions characterized muscle weakness that worsens with physical exertion. It is inherited as autosomal recessive pattern., rarely as autosomal dominant pattern is seen.
The muscle weakness typically begins in early childhood but can also appear in late childhood adolescence or adulthood. Facial muscles including muscles that control the eyelids, muscle that move the eyes and muscles used for chewing and swallowing are most commonly affected. Some may have feeding difficulty and breathing trouble.
Development of motor skills such as crawling or walking may be delayed. Diagnosis of CMS can be made on the basis of onset at birth to early childhood, fatiguable weakness affecting especially the ocular and other cranial muscles, a positive family history and a decremental EMG response or an abnormal single fibre EMG.
Current therapies for CMS include cholineregic agonists, namely pyridostigmine and 3,4 diaminopyridine(3,4 DAP), long lived open channel blocker of AChR ion channel and adrenaline agonists
Ptosis before and after treatment.
Prognosis- CMS may or may not affect the life expectancy. If child is having mild symptoms, CMS wont have major effect on overall health, but can impact life expectancy if symptoms affect muscles that regulate your breathing.
TAKE HOME MESSAGE- As it is a rare genetic disorder affecting neuromuscular junction, with no cure, early diagnosis and ongoing management a specialized helath care team are crucial for optimizing outcomes and enhance patients well being.