How do seizures affect the prognosis of Sturge-Weber syndrome (SWS)?

Updated: Dec 26, 2018
  • Author: Masanori Takeoka, MD; Chief Editor: George I Jallo, MD  more...
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The incidence of epilepsy in patients with SWS is 75-90%. Seizures result from cortical irritability caused by cerebral angioma, through mechanisms of hypoxia, ischemia, and gliosis. Dual pathology, such as microgyria, also may be present, which also contributes to epileptogenesis. Seizures may be intractable in some patients.

Garcia et al reported that a child with SWS could have an early normal neurologic course, with a seizure as the presenting manifestation of a neurologic problem. [18]

In a survey of cases identified by the Sturge-Weber Foundation, [8] seizures occurred in 136 of 171 patients, with the age of onset ranging from birth to 23 years and the median age of onset being 6 months. About 75% of the patients had onset during the first year of life; 86%, before age 2 years; and 95%, before age 5 years. Seizures occurred in 71% of those with unilateral and 87% of those with bilateral disease.

Bebin and Gomez, from the Mayo Clinic, reported that seizures occurred in 80% of patients with SWS (72% with unilateral involvement vs 93% with bilateral involvement), with the median age of onset being 8.5 months in patients with unilateral PWS and 4 months in patients with bilateral PWS. [37]

Oakes reported seizures in 24 (80%) of 30 patients with SWS, with a mean age of onset of 6 months. [38]

Bebin and Gomez reported an earlier onset of seizures in patients with bilateral involvement (mean ages of seizure onset were 6 months with bilateral disease and 24 months with unilateral disease). [37] Pascual-Castroviejo et al showed that patients with more frequent seizures tended to have an earlier seizure onset (mean seizure onset at age 5-6 months compared with a mean onset at age 2 years in those with less severe involvement). [39]

Pascual-Castroviejo et al reported seizures in 32 (80%) of 40 patients. Seizures began during a febrile illness in 10 patients (31%; fever could be a precipitant at any age), while infantile spasms occurred in 2 patients (6%). [39]

Developmental delay

In the patients reported by the Sturge-Weber Foundation, 50% had complete control and 39% had partial control of seizures with medications. Those with a later age of seizure onset had a lower incidence of developmental delay and fewer special educational needs.

The onset of seizures prior to age 2 may suggest a greater chance of refractory epilepsy and mental retardation. [1] Patients with refractory seizures are more likely to have mental retardation, since those individuals have more extensive brain involvement.

In a report by Sujansky and Conradi, using data obtained through the Sturge-Weber Foundation, [24] overall developmental delay occurred in 97 (58%) of 168 patients with SWS. Early developmental delay, however, occurred in 71% of patients with seizures and in only 6% of those without seizures. Patients with a later seizure onset also had a lower incidence of developmental delay and fewer special education needs.

However, even with seizure onset within the first year, Erba and Cavazzuti reported satisfactory control in 50% of patients, with 30% of patients being seizure free for at least 2 years. Among the other patients, 17% had an average of 1 seizure per month, and 33% were considered to have poorly controlled seizures, defined as greater than 1 seizure per week. [40] Therefore, early seizures may not predict either the severity of subsequent epilepsy or severe mental retardation.

Maria et al divided their patients into 2 groups by age for a longitudinal study—those aged 1-3 years versus those aged 10-22 years—and found no difference in clinical outcomes with early onset seizures. [22]

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