Conference Coverage
Of the 18 patients for whom six months of follow-up data were available, 12 had a lifetime psychiatric history. Postsurgical mood disorder occurred in 11 of the 18 patients. Mood disorder was mild for six patients, meaning that the symptoms remitted completely following a pharmacologic intervention. Mood disorder was severe for five patients, meaning that several pharmacologic interventions were required. Three patients had persistent mood disorder, meaning that the symptoms were present at the last follow-up.
A history of antidepressant therapy at the time of surgery did not protect patients against severe postsurgical psychiatric complications. Six patients were taking antidepressant medication at the time of surgery. Of the five patients with a severe postsurgical mood disorder, four had been on antidepressant medication before surgery. “If you have significant psychopathology, even if you are on antidepressant medication, you are likely to be at increased risk of having a worsening of your presurgical mood disorder [after surgery],” said Dr. Kanner.
Of the 11 patients with a postsurgical mood disorder, seven had a major depressive episode, three had a dysthymic episode, and one had a hypomanic episode. Three patients required hospitalization in an inpatient psychiatric unit, two of whom had severe suicidal ideation.
Furthermore, 10 of the 11 patients with a postsurgical mood disorder had a presurgical mood disorder. All five patients who met criteria for severe postsurgical mood disorder had a previous psychiatric history. All three patients with persistent mood disorders had a previous psychiatric history. Eight of the 11 patients with postsurgical mood disorder had a left ablation, and four of the five patients with severe mood disorder had a left-sided ablation. All three patients with persistent symptoms had a left-sided ablation.
Dr. Kanner and colleagues saw no clear relationship between postsurgical seizure outcome and postsurgical mood disorder. Patients with severe or persistent postsurgical mood disorder, however, tended not to have an Engel Class Ia outcome.
“We tell patients, ‘You need to be aware that you may experience an exacerbation or development of de novo symptoms of mood and anxiety, and if that happens, you need to let us know,’” said Dr. Kanner. “We can’t mess around with mesiotemporal structures or with the limbic system and not expect some kind of an expression in the mood and anxiety domains.” Neurologists who follow up their patients less frequently (eg, at three or six months) are more likely to miss acute psychiatric changes, he added.
Risk of Visual Field Cut
One of the 18 patients, a 24-year-old male with mesiotemporal sclerosis, had a visual field cut after surgery. He developed a right homonymous hemianopsia that partially recovered after five months.
A neurosurgery fellow analyzed the patient’s data and found that the volume of CSF in the choroidal fissure at the ablation site was significantly smaller than that in the 17 patients who did not have a visual field cut. In contrast, the number of ablations performed, the intensity of the coagulation, and the extent of the ablation did not explain the visual field cut. Damage to the lateral geniculate nucleus, rather than to the optic tracts, thus may account for this adverse event. “In patients with small CSF volume in the choroidal fissure, you may need to have a neurosurgeon change the direction of the probe and the intensity of the temperatures in the tail of the hippocampal formation,” said Dr. Kanner.
Patients May Prefer Laser Ablation
It is uncertain whether the rate of seizure freedom after laser ablation changes after one year, but the technique appeals to patients who have refused resection. “If you fail the first ablation, you can have a repeat ablation or you can always have a resection,” said Dr. Kanner.
—Erik Greb
