Depression in temporal lobe epilepsy surgery patients: an FDG-PET study.
OBJECTIVE
Depression is common in temporal lobe epilepsy (TLE) and after temporal lobectomy, and its etiology is obscure. In nonepileptic depression (including depression associated with other neurologic disorders), a consistent PET imaging finding is frontal lobe hypometabolism. Many TLE patients have hypometabolism involving frontal regions. Thus in data available from routine clinical assessments in an epilepsy surgery unit, we tested the hypothesis that the pattern of hypometabolism, particularly in the frontal lobe, may be associated with the depression seen in patients with TLE and TLE surgery.


METHODS
We studied 23 medically refractory TLE patients who underwent anterior temporal lobectomy and who had preoperative FDG-PET scanning. All patients had pre- and postoperative psychiatric assessment. By using statistical parametric mapping (SPM-99), patterns of hypometabolism were compared between patients who had a preoperative history of depression (n=9) versus those who did not (n=14) and between those in whom postoperative depression developed (n=13) versus those in whom it did not (n=10). A significant region of hypometabolism was set at p<0.001 for a cluster of >or=20 contiguous voxels.


RESULTS
Patients with a history of depression at any time preoperatively showed focal hypometabolism in ipsilateral orbitofrontal cortex compared with those who did not (t=4.64; p<0.001). Patients in whom depression developed postoperatively also showed hypometabolism in the ipsilateral orbitofrontal region (t=5.10; p<0.001).


CONCLUSIONS
Although this study is methodologically limited, and other explanations merit consideration, orbitofrontal cortex dysfunction, already implicated in the pathophysiology of nonepileptic depression, may also be relevant to the depression of TLE and temporal lobectomy.
Salzberg
Michael
M
Department of Psychiatry, St. Vincent's Hospital and University of Melbourne, Melbourne, Victoria, Australia. msalzber@bigpond.net.au
Taher
Taufik
T
Davie
Michael
M
Carne
Ross
R
Hicks
Rodney J
RJ
Cook
Mark
M
Murphy
Michael
M
Vinton
Anita
A
O'Brien
Terrence J
TJ
D000328:Adult; D038481:Anterior Temporal Lobectomy; D001931:Brain Mapping / Q000379:methods; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology; D003866:Depressive Disorder / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000378:metabolism; D004833:Epilepsy, Temporal Lobe / Q000000981:diagnostic imaging / Q000523:psychology / Q000601:surgery*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D005625:Frontal Lobe / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000503:physiopathology; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D049268:Positron-Emission Tomography / Q000706:statistics & numerical data*; D011183:Postoperative Complications / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000378:metabolism; D011300:Preoperative Care
D019788:Fluorodeoxyglucose F18