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WEST SYNDROME

 

 

INFANTILE SPASMS

Also called West Sd. (From Dr. West who described it on his own son in the late 19th century.)

 

Definition:             1. Seizures of a particular type

                                2. Psychomotor retardation

                                3. EEG (Hypsarrhythmia)

 

                1. The Seizures:  Sudden, bilateral, symetrical, contractions of  

                                TRUNC

                                NECK

                                EXTREMITIES

 They involve the  Flexors muscles groups (“Syndrome des spasmes en flexions”) also sometime   Mixed Flexors/extensors muscles or Extensors muscles groups only (less frequently) .

                              The seizures consist of an abrupt initial contraction followed by more sustained contraction.

 A cry may be heard ; unilaterality  or asymetry are also possible. A laughter, flushing, nystagmus can also be seen.

                                A key feature is that the seizures are  REPETITIVE every 5 to 30 seconds, there can be repeated sometimes a 100 times.

                                This type of seizures may lasts 1 - 2 years, up to 5-10 years

                 2. Psychomotor Retardation/Deterioration: Initially may only be perceived as simple developmental delay. Often the neurological status is already abnormal before the onset of Psychomotor Retardation/Deterioration or delay. Sometimes a loss of social smile, or a loss of interests will lead to the  child being labelled as blind as the presenting complain.

                 3. The EEG is TYPICAL : There is HYPSARRHYTHMIA. But hypsarhythmia is not the sole EEG pattern. (NB Hypsarrhythmia is a EEG pattern not to be used as a synonymous to Infantile Spasms). It is an ICTERICAL pattern observed in the AWAKE state.

                                NB: O. Dulac from Paris (France) has shown the probable  FOCAL onset of the seizures which are very rapidly SECONDARILY generalized.

                 The diagnosis is CLINICAL 1. Spasms

                                                                  2. Repetitive

                                                                  3. Clusters

often on awakening.

                                 In the differential diagnosis one must think of  1. Benign Myoclonus of early infancy  2. Early true Myoclonic Epilepsy ( but is briefer more saccadic and not repeated)  3. The Lennox-Gastaut .

                Etiologies: The West syndrome can be symptomatic of a central nervous system malformation as in the Tuberous Sclerosis condition (TS), or cryptogenic (the cause remaining then unknown).

                 Incidence .24 to.42 / 1000. It occurs  in children less than a year old. Maximum onset is at 3 to7 months

                                                   Males>Females 2:1

                There is a family history of seizures in  6% to 17% of the children.

  

SYMTOMATIC 75-90%

CRYPTOGENIC 10-25%

Dysgenetic

TS, Down’s syndrome, Corpus callosus agenesis, cortical dysplasias.

?

Hypoxic/Ischemic

Pre,Peri,Post natal

?

Infectious

« T O R C H »Toxoplasmosis

Rubella, CMV herpes...

?

Hemorrhagic/trauma

 

?

Metabolic/Toxic

PKU, Urea cycle, NH4, Leigh’s VitB6 def, Hypoglycemia degenerative disorders, lead

?

         

                Treatment:  Mogadon ( Nitrazepam )

                                     Frisium ( Clobazam )

                                     Rivotril ( Clonazepam )

                                     Depakene/Epival ( Valproic Acid )

                                     Vigabatrine in association with Carbamazepine.

                                     ACTH 20 to 40 units / day IM. Some 10 to 180 units                               

                                     Prednisone 2 to 10 mg/kg/day

                                     HydroCortisone 5-20

                                     DexaMethasone .3-.5

                                     Vitamin B6

All these medications have been shown to have some benefit. Streroids are used for a minimum of 3 to 8 WEEKS up to 6 to 10 months. Other anticonvulsants such as Vigabatrine may be used much longer.

                Usually helps within 1 week, ++ if cryptogenic relapses in 30% after d/c ACTH.

 

                                Mental outcome: almost invariably leads to mental deficiency if Symptomatic; this outcome is improved to 30-40% incidence of mental deficiency in case of Cryptogenic West syndrome.

 

                Prognosis:  Mortality 20%.  Survivors have sensory defects, CP in 50%

                                             Mental retardation in 80% (severe in 50%)

                                               Lennox-Gastaut Syndrome

 

                                THE EARLIER THE INFANTILE SPASMS APPEAR THE LESS FAVORABLE THE PROGNOSIS IS.


                ACTH and other steroid medications, used in the treatment of infantile spasms has major side effects which include:

                cardiomyopathy

                hypertension

                electrolytes imbalance

                depression of the immune system

                cataract

                transient brain atrophy

                Cushingoid appearance

                osteoporosis                                                                                                         .

2 infants have been reported to have developed reversible massive enlargement of both adrenal glands during treatment with ACTH, one with infantile spasms, and the second with opsoclonus and cerebellar encephalopathy. The first child was treated with ACTH 80 units IM for 3 weeks followed by 40 units every other day for 14 days. When the adrenal enlargement was detected, ACTH was tapered off, and the adrenal enlargement rapidly disappeared. See: Liebling MS; Pediat Radiol 23:454-456, Oct 1993.

 

Vigabatrine/Carbamazepine association seems to be the preferred treatment in case of symptomatic West particularly when associated with TS. The side effects are infrequent but recent reports of visual field defects associated with Vigabatrine have made this drug less widely used.

 

Vitamin B6 is used particularly extensively in Japan. There seems to be a similar response rate than with other therapeutic protocols.