INFANTILE SPASMS (WEST SYNDROME)
DEFINITION:
An epileptic syndrome characterized by the triad of infantile
spasm (generalized seizures), hypsarrhythmia, and arrest of
psychomotor development at seizure onset.
EPIDEMIOLOGY:
- incidence: 0.7/100,000
- accounts for 28-30% of infants with epilepsy
- age of onset:
- 3 to 12 months with peak at 4-7 months
- risk factors:
- M > F
- family history of infantile spasms in 3-6% of cases
PATHOGENESIS:
- defined by the International Classification of Epilepsy as a
cryptogenic or symptomatic generalized epileptic syndrome
- symptomatic with etiology known or unknown
- generalized origin of seizure
2. Types of Infantile Spasms
- no evidence of CNS disorder
- normal psychomotor development, neurological exam, and
neuroradiologic studies
- unknown etiology
- 20% recurrence rate after anticonvulsant therapy
- mental retardation & other types of seizures found in 32%
of cases
- complete recovery in 68% of cases
2. Symptomatic (85-90%)
- evidence of brain damage
- psychomotor retardation, neurological deficits, abnormal
neuroradiologic imaging studies, previous seizure
- known etiologies:
- cerebral dysgenesis (tuberous sclerosis)
- HIE with PVL
- intrauterine infections (CMV)
- brain malformations (Aicardi syndrome, Lissencephy,
Hemimegancephaly)
- inborn errors of metabolism (PKU, nonketotic
hyperglycinemia)
2. Postnatal (25% of cases)
- cerebral hypoxic events
- head trauma (subdural hematoma, IVH)
- infections (HSV, meningoencephalitis)
- ? immunization (pertussis)
- 65% recurrence rate after anticonvulsant therapy
- mental retardation & other types of seizures found in
85% of cases
- complete recovery in only 15% of cases
CLINICAL FEATURES:
- flexion of neck, arms, and legs on to trunk
2. Extension (23%)
- extension of neck, arms, and legs on to trunk
3. Mixed (43%)
- flexion in some volleys and extension in others
2. Seizure Characteristics
- sudden onset of a tonic seizure that is bilateral and
symmetrical
- spasms may vary from massive contractions of large muscle
groups to contractions of only neck and abdominal muscles - a
patient may have more than one type of spasm
- tend to occur in clusters of 5-10 individual spasms
- may persist for minutes with brief intervals between each
spasm
- a cry may precede or follow the seizure
- may occur during sleep or when awake but tends to develop
while drowsy or immediately upon awakening
- mental retardation is found in 60-70% of patients at onset
of infantile spasms
- if spasms persist despite therapy, these seizures usually
replaced by other seizure type by age 5 years
- 30% of symptomatic patients progress to the Lennox-Gastaut
- Syndrome
INVESTIGATIONS:
- found in 66% of patients at onset of seizure disorder
- typical pattern
- very high amplitude slow waves (1-7 Hz) chaotically
mixed with sharp waves and spikes
- interictal trace shows complete or modified hypsarrhythmia
(asymmetrical and/or unilateral), and/or diffuse slow
wave-spikes at <3 Hz and/or burst suppression pattern -
background is always abnormal
2. Imaging Studies
- abnormal in 69% of patients
- focal atrophy (35%), congenital anomalies (19%),
generalized atrophy (15%)
MANAGEMENT:
- there is nonuniformity in regard to dosage and duration of
therapy
- 20 units IM daily for 2 weeks with increases to 30 and
then 40 units if seizure activity persists
- many SE: hyperglycemia, hypertension, electrolyte changes,
GI disturbances (bleeding, diarrhea), intercurrent infections,
transient brain shrinkage
- moniter CBC, lytes, urinalysis, stool for occult blood,
blood pressure
- add salt restricted and potassium-rich diet
2. Prednisone
- 2 mg/kg/day po q12h for 2-4 weeks
- control of seizures with ACTH or prednisone is expected in
about 70-75% of patients within a few weeks of therapy
2. Antiepileptic Medications
- clonazepam, valproic acid, nitrazepam, clobazam
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