Abstracts

RATIONALE: Among individuals with epilepsy who are cognitively challenged (IQs of [lt]75), intractability is a problem in up to 45% of patients. Evaluation of treatment success may be difficult to assess secondary to multiple medical problems, behavioral problems and communication difficulties. Families, guardians and care staff have been reluctant to pursue invasive aggressive thrapies including the VNS, and have requested data regarding how this population fares in order to make treatment decisions. After review of our findings, readers should be able to discuss how patients with multiple retardation respond to and tolerate VNS therapy.
METHODS: All our adult patients with IQs [lt]75 implanted with the VNS between 11/97 and 04/02 were retrospectively reviewed. History, seizure frequency and severity, medications, post-op course, generator settings, reports of Quality of Life (QOL) measures, and alertness were tabulated.
RESULTS: Fifty patients between the ages of 19-52 years were implanted under general anesthesia: 19 were mild/borderline (MB), 10 moderate (MO), 21 severe/profound (SP). Seven batteries have been replaced; one turned off. There were three uncomplicated superficial post-op skin infections. One had prolonged hoarseness for several months post-implant. There were no serious complications. Staff/families trained/learned how to use the magnet without problems. Two patients died 2+ years after implant: 1 SP with SUDEP and 1 MO with aspiration pneumonia/sepsis. Medications were not held constant through the time periods. Duty-cycles used were [dsquote]Routine[dsquote] (5 min off/30 sec on) in 24% MB, 20% MO, 42% SP. [dsquote]Intermediate[dsquote] cycles were used in 29% MB, 50% MO, 5% SP. [dsquote]Rapid[dsquote] cycles (7 sec on/1 min or less off) were used in 47% MB, 40% MO, 47% SP. Fifty-percent of the whole group had at least a 50% decrease in seizure frequency. Four-percent became seizure-free; 20% [gt]75% decrease, 26% had 50-75% decrease. Twelve-percent had no clear change; 24% had such variable rates of seizure occurence that the response rate was not clear (variability). In the MB group 71% had [gt]50% and 17% had variability. In MO group 40% had [gt]50% response and 40% had variability. In SP group [gt]52% had [gt]50% response and 21% had variability. In 44% seizures were described as shorter, less intense, having shorter postictal recovery times, or were improved by use of the magnet. Alertness was improved in 71% MB, 60% MO, 65% SP.
CONCLUSIONS: Patients with mental retardation of any severity who have refractory epilepsy can benefit from VNS with decreased frequency and severity of seizures at rates equivalent to the general refractory population, tolerate the procedure and the stimulations well, and also achieve improved alertness, including other factors contributing to improved QOL.
(Disclosure: Grant - VNS Research Study Grant (ongoing))