Dysembryoplastic neuroepithelial tumour and mixed DNET-ganglioglioma: seizure outcome following surgery

Review of seizure outcomes after surgical resection of dysembryoplastic neuroepithelial tumors

Dysembryoplastic neuroepithelial tumors (DNETs) are rare tumors that present with seizures in the majority of cases. We report the results of a review of seizure freedom rates following resection of these benign lesions. We searched the English literature using PubMed for articles presenting seizure freedom rates for DNETs as a unique entity. Patient demographics, tumor characteristics, and operative variables were assessed across selected studies. Twenty-nine articles were included in the analysis. The mean age at surgery across studies was a median of 18 years (interquartile range 11-25 years). The mean duration of epilepsy pre-operatively was a median 7 years (interquartile range 3-11 years). Median reported gross-total resection rate across studies was 79% (interquartile range 62-92%). Authors variously chose lesionectomy or extended lesionectomy operations within and across studies. The median seizure freedom rate was 86% (interquartile range 77-93%) with only one study reporting fewer than 60% of patients seizure free. Seizure outcomes were either reported at 1 year of follow-up or at last follow-up, which occurred at a median of 4 years (interquartile range 3-7 years). The number of seizure-free patients who discontinued anti-epileptic drugs varied widely from zero to all patients. Greater extent of resection was associated with seizure freedom in four studies.

Systematic review and case series of neuropsychological functioning after epilepsy surgery in children with dysembryoplastic neuroepithelial tumors (DNET)

RATIONALE

The purposes of this study were to 1) conduct a review of neuropsychological (NP) outcomes after epilepsy surgery for DNET and 2) present pre/post-surgical NP results from a series of children with DNET.

METHODS

First, a systematic literature review was conducted with specific inclusion criteria. Second, a review of DNET surgical patients seen at two tertiary-care hospitals using reliable change methods of NP functioning was conducted.

RESULTS

Of 300 citations retrieved, 7 studies met criteria. Studies reported low average to average pre-surgical IQ. Engel Class I outcome was approximately 85%.

CASE SERIES

Thirteen children completed pre/post-surgical NP assessments. Pre-surgically, children demonstrated low average to average functioning. Post-surgically, few patients showed reliable change. One-third of children demonstrated psychological improvement.

CONCLUSIONS

NP outcome following DNET has not been well-described. Children with DNET demonstrate low average to average NP functioning pre-surgically, good seizure outcome, and stable NP functioning post-surgically.

Composite ganglioglioma/dysembryoplastic neuroepithelial tumor: a clinicopathologic study of 8 cases

Ganglioglioma and dysembryoplastic neuroepithelial tumor are both low-grade glioneuronal neoplasms that most commonly occur in association with chronic epilepsy. Rare cases of tumors with composite features of ganglioglioma and dysembryoplastic neuroepithelial tumor have been reported. We retrospectively reviewed the clinicopathologic features of 8 composite tumors (7 were female; median age, 20 years). All patients had chronic epilepsy and had tumors in either the temporal or the frontal lobe. Six patients are currently seizure-free (follow-up: median, 90 months). All tumors were multinodular. Some nodules had distinct features of each tumor type (range, 5%-85% of the tumor). Seven tumors contained nodules with mixed features of both tumor types. Five of 7 evaluable tumors demonstrated adjacent focal cortical dysplasia (Palmini type I). Mitotic activity, vascular proliferation, or necrosis was not observed in any of the tumors. Three tumors demonstrated focal meningeal extension. Composite tumors commonly arise in the temporal lobe in young patients with chronic epilepsy; they appear to behave as a World Health Organization grade I neoplasm. Histologically, these multinodular tumors appear to maintain distinct areas with features of each tumor and foci where the 2 patterns are merged. A subset of composite tumors are associated with adjacent focal cortical dysplasia.

Surgical strategies and seizure control in pediatric patients with dysembryoplastic neuroepithelial tumors: a single-institution experience

OBJECTIVES

Dysembryoplastic neuroepithelial tumors (DNTs) are commonly associated with medically resistant epilepsy that usually starts in childhood. Presurgical workup and surgical strategies remain controversial. The authors present a study of long-term seizure outcome after noninvasive presurgical investigations and different surgical strategies were used in a series of pediatric patients.

METHODS

Twenty-four children who underwent operations at a single center between 1986 and 2006 were eligible for this retrospective study. The authors reviewed medical records including sex, age at seizure onset, age at surgery, seizure type and pharmacoresistance, lesion location, extent and complications of resection, histopathological findings, prescription of seizure and antiepileptic drugs, outcome, and tumor recurrence.

RESULTS

At the last follow-up examination (range 1-16 years after initial treatment, mean 6.7 years) 20 children (83.3%) were seizure free. The authors did not find the rundown phenomenon in any of the patients. Complete antiepileptic drug withdrawal was achieved in 12 children (50%). In 4 of 15 children with temporal DNTs, the lesionectomy alone failed to control seizures. These results could be explained by the wider epileptogenic zone. The only significant predictor for favorable seizure outcome was an absence of preoperative generalized seizures.

CONCLUSIONS

In children with extratemporal DNTs the results suggest that complete lesionectomy alone without invasive presurgical investigations are effective for long-term seizure control. For children with temporal DNTs not invading the amygdalohippocampal complex, extensive presurgical evaluations seem indicated. The absence of preoperative generalized seizures was associated with a better seizure outcome.

Long-term seizure outcome following surgery for dysembryoplastic neuroepithelial tumor

OBJECT

Resection of dysembryoplastic neuroepithelial tumor (DNET) is thought to result in favorable seizure outcome, but long-term follow-up data are scarce. The authors present a review of 18 patients who underwent surgical removal of a DNET: 12 via temporal lobectomy and six via lesionectomy.

METHODS

The mean long-term follow up was 10.8 years (median 10.4 years, range 7.8 to 14.8 years), and results obtained during this time period were compared with previously reported short-term (mean 2.7 years) seizure outcome data. In the current study, 66.7% patients had an Engel Class I outcome and 55.6% had an Engel Class IA outcome compared with 77.8% and 55.6%, respectively. Temporal lobectomy (Engel Class I, 83.3%; Engel Class IA, 66.7%) led to a better seizure outcome than lesionectomy (Engel Classes I and IA, 33.3%). Two patients (11.1%) required repeated operation and both had an incomplete lesionectomy initially.

CONCLUSIONS

Results indicated that complete resection of a DNET leads to a favorable seizure outcome, with epilepsy cure in those who had experienced early postoperative seizure relief. Long-term seizure outcome after surgery is predictable based on the result of short-term follow up.