Transient neonatal myasthenia gravis

Transient neonatal myasthenia gravis is occurring in 10-15% of infants born to women with myasthenia gravis.The symptoms appear a few hours after the birth in two thirds of babies and usually disappear within 18 days. The amount of AChR antibodies in mothers body is not relevant, neonatal myasthenia gravis is reported in infants with mothers with no antibodies against acetylcholine receptors. The prognosis has improved very much lately due to timely thymus removal and a lot of young women suffering from MG is in clinical remission without medicaments.

Symptoms:

feeble cry, weakened mimic muscles               95%

sucking difficulties                                               87%

generalised weakness, hypotonia                     65%

involvment of breathing muscles                        65%

ptosis,strabismus                                               15%

Every baby of myasthenic mother must be monitored at least 3 – 4 days after the birth!!!

Treatment:

Monitoring, physostigmine, neostygmine injected intramuscularly or subcutaneously (0.04-0.05mg/kg),used 10 to 20 mins before feeding or  tablets put into nasogastric probe (0.5mg/kg), used 30 to 40mins before feeding. An optimal dosage is in 3-4 hours interval.The dose is decreased when symptoms are subsiding. In the majority of infants the condition resolves spontaneously.

Juvenile myasthenia gravis

Juvenile myasthenia gravis is a rare disorder acquired in childhood.Most patients present the same symptoms like the adult form. The diagnosis and the treatment is the same. It most frequently affects patients age 5-6 (mainly girls) but the symptoms of MG were recorded even in one year old patient (1case in The Czech Republic).

Most patients have ptosis and diplopia. More advanced cases may also have bulbar problems and limb weakness. Left untreated, the disease may progress to myasthenic crisis. The consensus on the benefit of thymectomy is still unclear. Several studies address thymectomy in children with generalized weakness and conclude that thymectomy is generally effective and has a higher percentage of remission than medical therapy.

Congenital myasthenic syndrome

Congenital myasthenic syndrome (CMS) is an inherited neuromuscular disorder caused by defects in genes that are necessary to make various proteins of the neuromuscular junction. Onset is usually at or near birth, but can manifest in children or adults.Symptoms of CMS include muscles weakness and fatigue of upper and lower limbs wih walking difficulty, droopy eyelids, double vision (vetsinou s uplnou obrnou okohybnych svalu), slurred speach,difficulty chewing and swallowing and respiratory problems. Due to molecular genetics development are new types of neuromusculars disorders constantly detected. These abnormalities  are classified into three categories: presynaptic, postsynaptic and synaptic.

In these pictures are shown different situations of neuromuscular transmission: normally, Myasthenia gravis and different types of CMS.

The diagnostic is carried out by neurological examination, looking for a similar diagnosis in blood relatives, electrophysiology test, molecular genetic test,eventually  muscle biopsy.