Case Study One:
Case report:
A five-year-old girl with staring spells that worsened after treatment
Anthony R. Riela, M.D.
Practicing Physician
Texas Child Neurology
Plano, Texas
Brenda G. is a five-year-old girl from a suburb of Dallas who presented with a history of staring in her first year of school. These staring spells consisted of interruptions of activity and staring spells that lasted about 30-40 seconds. Initially, these spells occurred a couple of times a week. Sometimes, she would recover quickly and go back to what she was doing before the episode. Other times, she was confused for 5-10 seconds, after which she would return to her previous activity. After she experienced these spells for two months in school, her teachers thought that she had Attention Deficit disorder. Eventually, these spells came to the attention of her pediatrician.
Brenda's history was otherwise uneventful. She was the product of a full-term pregnancy and had no problems around the perinatal period. Her development was normal and she was doing fine in kindergarten. While the staring spells were first noticed in the beginning of her kindergarten year, they may have been present earlier. Her pediatrician saw her about three months into the school year. He considered the possibility of a seizure disorder and did an EEG, which showed a normal background, but also a kind of asymmetric spike and wave pattern, predominantly on the left side. During sleep, the focal spikes sometimes generalized, but there were frequent, independent left and right spikes in the frontal area.
The physician who read the EEG was an adult neurologist. He thought the pattern was consistent with seizures and suggested that these may be complex partial seizures. Brenda was started on carbamazapine. Initially, she appeared to have improved somewhat on medication, but continued to have occasional staring spells.
A blood test to check carbamazepine level showed it to be on the low side, so her dose was increased. After the dose increase, the number of staring spells increased. The blood level was re-checked and shown to be still low, so it was raised again. At this time, her serum carbamazepine level was about 6 µg/mL (therapeutic range: 4-12 µg/mL).
Because Brenda kept having staring spells and the drug level remained low, the dose was raised a third time. Surprisingly, her spells worsened. Sometimes they lasted a minute or more and were associated with longer periods of confusion afterwards. Then she started having new spells, where she would fall to the floor in an apparent drop attack. As the family described it, she would suddenly "get limp." After having been on an anticonvulsant about 6 or 8 weeks, her situation had noticeably worsened. In effect, she had so many staring spells and drop attacks that she became non-functional. She had trouble eating and eventually ended up in the emergency department. That's when we saw her for the first time.
On exam, we found that she was encephalopathic, with many staring events. We put her in our epilepsy monitoring unit, where we found was she was having very frequent spike-and-wave discharges. It was not the classic 3Hz spike-and-wave; it was a little slower, at 2-3Hz and, although generalized, it was slightly asymmetric, with more activity on the left side.
While she was being monitored, Brenda had several seizures. While she was still in the monitoring unit, we stopped the carbamazepine, and the EEG improved. She developed the classic, 3Hz, spike-and-wave pattern of absence epilepsy, but the EEG was still a little asymmetric. We started her on Depakote® Sprinkle (divalproex sodium coated particles in capsules), titrated to 125 mg t.i.d. Soon after discharge, she improved but still had occasional staring spells.
However, when she came for follow up in three weeks, we learned that her seizures had stopped about the third or fourth day after leaving the hospital, which was a little over a week after stopping the carbamazepine. Since then, she has been seizure-free. When we first evaluated her, we couldn't assess her mental status because she was so encephalopathic. As it turned out, her mental status was normal after her seizures were controlled.
Discussion
This scenario is not an unusual one. Brenda probably has classic absence, but atypical features led to an initial misdiagnosis. Her first EEG did not show the classic bilaterally synchronous and symmetrical, 3Hz, spike-and-slow-wave pattern. The adult neurologist who read the EEG found the pattern, which was somewhat asymmetrical and frontally predominant, to be more consistent with complex partial seizures (CPS). He prescribed carbamazepine, an appropriate agent for CPS, but inappropriate for absence.
There is a lesson here that applies to any patient with poorly controlled seizures. No matter how long ago the diagnosis was established, it is frequently very useful to go back to "square one" and re-establish the diagnosis. With Brenda, our suspicions were raised by her history of worsening seizures on carbamazepine; indeed, the degree of worsening seemed to be dose-related. There have also been reports in the literature of carbamazepine-related drop attacks. It seemed very probable that the initial diagnosis of CPS was wrong and that her treatment was responsible for her worsening condition. Our experience with Brenda in the epilepsy monitoring unit confirmed our suspicions, and Brenda was discharged on Depakote® Sprinkle, a first-line drug for absence seizures.
What about the drop attacks? Were they atonic seizures or a drug-related manifestation of absence? As Kiffin Penry showed with his early video studies of absence seizures, our conception of absence seizures as simply staring spells is too limited. He demonstrated that only about 10% of absence seizures consist of stares only. Most include other features, such as automatisms, increased muscle tone or, as in Brenda's case, a loss of tone. So it is most likely that the drop attacks were a manifestation of her absence brought out by carbamazepine.
Brenda has been followed for a year and a half and is still seizure-free. A follow-up EEG six months after discharge was normal. After she has been seizure-free for about two years, we will take another look at her EEG and, if it remains normal, attempt to withdraw her medication. Typically, we taper the drug over a two- to four-week period as soon as school lets out, so we have the summer to see if any relapses occur. About two-thirds of children with absence epilepsy will remain seizure-free after drug withdrawal. In summary, Brenda's prognosis is excellent.
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