Perioperative fluctuations of lamotrigine serum levels in patients undergoing epilepsy surgery.
Some patients undergoing epilepsy surgery suffer from early postoperative seizures which may have a negative impact on later outcome. Factors contributing to these seizures have not to date been examined systematically. We hypothesized that reduction of postoperative serum levels of antiepileptic drugs (AED) may be one risk factor for early postoperative seizures.


METHODS
We retrospectively reviewed medical records from 20 patients treated with lamotrigine (LTG) who underwent epilepsy surgery between January 1997 and February 2004. Demographic data, anaesthesiological and surgical procedures, co-medication, and pre- as well as one or more postoperative LTG serum levels were evaluated.


RESULTS
We found a significant decrease in LTG serum levels, amounting to more than 20% (mean 46%, range 21.9-69.1%), in 16 of 20 patients (80%). Six patients (30%) suffered from seizures in the first 2 weeks after surgery. In three patients, postoperative seizures occurred isochronically with the LTG serum level nadir. The magnitude of the reduction in serum levels was not influenced by age, sex, duration of the operation, the type of anaesthetic drugs or the postoperative co-medication.


CONCLUSIONS
Reductions in LTG serum levels are a relevant contributing factor for early postoperative seizures. Postoperative alteration of the gastrointestinal motility and transient time leading to delayed absorption and reduced bioavailability of AED may be a major risk factor. Therefore, close monitoring of postoperative LTG serum levels is necessary and should lead to a temporary dose augmentation and/or anticonvulsant co-medication with benzodiazepines in case of a pronounced reduction of serum levels.
Paul
Friedemann
F
Department of Epileptology, Evangelisches Krankenhaus Königin Elisabeth Herzberge, Herzbergstrasse 79, D-10365 Berlin, Germany. friedemann.paul@charite.de
Veauthier
Christian
C
Fritz
Georg
G
Lehmann
Thomas-Nicolas
TN
Aktas
Orhan
O
Zipp
Frauke
F
Meencke
Heinz-Joachim
HJ
D000293:Adolescent; D000328:Adult; D000927:Anticonvulsants / Q000097:blood* / Q000627:therapeutic use; D004827:Epilepsy / Q000097:blood* / Q000188:drug therapy / Q000601:surgery; D005260:Female; D006801:Humans; D000077213:Lamotrigine; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D014227:Triazines / Q000097:blood* / Q000627:therapeutic use
D000927:Anticonvulsants; D014227:Triazines; D000077213:Lamotrigine