Operculoinsular cortectomy

Operculoinsular cortectomy

Operculoinsular cortectomy for refractory epilepsy is a relatively safe therapeutic option but temporary neurological deficits after surgery are frequent. A study of Bouthillier et al. highlighted the role of frontal/parietal opercula resections in postoperative complications. Corona radiata ischemic lesions are not clearly related to motor deficits. There were no obvious permanent neurological consequences of losing a part of an epileptic insula, including on the dominant side for language. A low complication rate can be achieved if the following conditions are met: 1) microsurgical technique is applied to spare cortical branches of the middle cerebral artery; 2) the resection of an opercula is done only if the opercula is part of the epileptic focus; and 3) the neurosurgeon involved has proper training and experience 1).


The goal of a study of Bouthillier et al. of the Sainte-Justine University Hospital CenterMontrealQuebecCanada, was to document seizure control outcome after operculoinsular cortectomy in a group of patients investigated and treated by an epilepsy team with 20 years of experience with this specific technique.

Clinical, imaging, surgical, and seizure control outcome data of all patients who underwent surgery for refractory epilepsy requiring an operculoinsular cortectomy were retrospectively reviewed. Tumors and progressive encephalitis cases were excluded. Descriptive and uni- and multivariate analyses were done to determine seizure control outcome and predictors.

Forty-three patients with 44 operculoinsular cortectomies were studied. Kaplan-Meier estimates of complete seizure freedom (first seizure recurrence excluding auras) for years 0.5, 1, 2, and 5 were 70.2%, 70.2%, 65.0%, and 65.0%, respectively. With patients with more than 1 year of follow-up, seizure control outcome Engel class I was achieved in 76.9% (mean follow-up duration 5.8 years; range 1.25-20 years). With multivariate analysis, unfavorable seizure outcome predictors were frontal lobe-like seizure semiology, shorter duration of epilepsy, and the use of intracranial electrodes for invasive monitoring. Suspected causes of recurrent seizures were sparing of the language cortex part of the focus, subtotal resection of cortical dysplasia/polymicrogyria, bilateral epilepsy, and residual epileptic cortex with normal preoperative MRI studies (insula, frontal lobe, posterior parieto-temporal, orbitofrontal).

The surgical treatment of operculoinsular refractory epilepsy is as effective as epilepsy surgery in other brain areas. These patients should be referred to centers with appropriate experience. A frontal lobe-like seizure semiology should command more sampling with invasive monitoring. Recordings with intracranial electrodes are not always required if the noninvasive investigation is conclusive. The complete resection of the epileptic zone is crucial to achieving good seizure control outcome 2).


In 2017 Bouthillier et al. published twenty-five patients underwent an epilepsy surgery requiring an operculoinsular cortectomy: mean age at surgery was 35 y (9-51), mean duration of epilepsy was 19 y (5-36), 14 were female, and mean duration of follow-up was 4.7 y (1-16). Magnetic resonance imaging of the operculoinsular area was normal or revealed questionable nonspecific findings in 72% of cases. Investigation with intracranial EEG electrodes was done in 17 patients. Surgery was performed on the dominant side for language in 7 patients. An opercular resection was performed in all but 2 patients who only had an insulectomy. Engel class I seizure control was achieved in 80% of patients. Postoperative neurological deficits (paresis, dysphasia, alteration of taste, smell, hearing, pain, and thermal perceptions) were frequent (75%) but always transient except for 1 patient with persistent mild alteration of thermal and pain perception. 3).

References

1)

Bouthillier A, Weil AG, Martineau L, Létourneau-Guillon L, Nguyen DK. Operculoinsular cortectomy for refractory epilepsy. Part 2: Is it safe? J Neurosurg. 2019 Sep 20:1-11. doi: 10.3171/2019.6.JNS191126. [Epub ahead of print] PubMed PMID: 31597116.
2)

Bouthillier A, Weil AG, Martineau L, Létourneau-Guillon L, Nguyen DK. Operculoinsular cortectomy for refractory epilepsy. Part 1: Is it effective? J Neurosurg. 2019 Sep 20:1-10. doi: 10.3171/2019.4.JNS1912. [Epub ahead of print] PubMed PMID: 31629321.
3)

Bouthillier A, Nguyen DK. Epilepsy Surgeries Requiring an Operculoinsular Cortectomy: Operative Technique and Results. Neurosurgery. 2017 Oct 1;81(4):602-612. doi: 10.1093/neuros/nyx080. PubMed PMID: 28419327.

Vagus Nerve Stimulation outcome

Vagus Nerve Stimulation outcome

Evidence for long-term efficacy is still limited.

The true outcome of long-term VNS is difficult to assess in real-world practice. The effect may be overestimated due to confounding factors, particularly the common introduction of novel AEDs and the natural course of the disorder. Patients without perceived benefit from long-term VNS should not routinely remain on treatment and be subject to undue generator re-implantations 1).


Kawai et al. report the overall outcome of a national, prospective registry that included all patients implanted in Japan. The registry included patients of all ages with all seizure types who underwent VNS implantation for drug-resistant epilepsy in the first three years after approval of VNS in 2010. The registry excluded patients who were expected to benefit from resective surgery. Efficacy analysis was assessed based on the change in frequency of all seizure types and the rate of responders. Changes in cognitive, behavioural and social status, quality of life (QOL), antiepileptic drug (AED) use, and overall AED burden were analysed as other efficacy indices. A total of 385 patients were initially registered. Efficacy analyses included data from 362 patients. Age range at the time of VNS implantation was 12 months to 72 years; 21.5% of patients were under 12 years of age and 49.7% had prior epilepsy surgery. Follow-up rate was >90%, even at 36 months. Seizure control improved over time with median seizure reduction of 25.0%, 40.9%, 53.3%, 60.0%, and 66.2%, and responder rates of 38.9%, 46.8%, 55.8%, 57.7%, and 58.8% at three, six, 12, 24, and 36 months of VNS therapy, respectively. There were no substantial changes in other indices throughout the three years of the study, except for self/family-accessed QOL which improved over time. No new safety issues were identified. Although this was not a controlled comparative study, this prospective national registry of Japanese patients with drug-resistant epilepsy, with >90% follow-up rate, indicates long-term efficacy of VNS therapy which increased over time, over a period of up to three years. The limits of such trials, in terms of AED modifications and during follow-up and difficulties in seizure counting are also discussed 2).


VNS can affect the voice and reduced vocal cord motion on the implantation side with secondary supraglottic muscle tension. Otolaryngologists are not only capable of performing VNS implantation, but can also manage surgical complications, assess laryngeal side effects and treat them as needed 3).


VNS implantation may render patients with some forms of cortical dysgenesis (parietooccipital polymicrogyriamacrogyria) seizure-free. Patients with unilateral IEDs and earlier implantation achieved the most benefit from VNS 4).

References

1)

Brodtkorb E, Samsonsen C, Jørgensen JV, Helde G. Epilepsy patients with and without perceived benefit from vagus nerve stimulation: A long-term observational single center study. Seizure. 2019 Sep 19;72:28-32. doi: 10.1016/j.seizure.2019.09.004. [Epub ahead of print] PubMed PMID: 31563121.
2)

Kawai K, Tanaka T, Baba H, Bunker M, Ikeda A, Inoue Y, Kameyama S, Kaneko S, Kato A, Nozawa T, Maruoka E, Osawa M, Otsuki T, Tsuji S, Watanabe E, Yamamoto T. Outcome of vagus nerve stimulation for drug-resistant epilepsy: the first three years of a prospective Japanese registry. Epileptic Disord. 2017 Sep 1;19(3):327-338. doi: 10.1684/epd.2017.0929. PubMed PMID: 28832004.
3)

Al Omari AI, Alzoubi FQ, Alsalem MM, Aburahma SK, Mardini DT, Castellanos PF. The vagal nerve stimulation outcome, and laryngeal effect: Otolaryngologists roles and perspective. Am J Otolaryngol. 2017 Jul – Aug;38(4):408-413. doi: 10.1016/j.amjoto.2017.03.011. Epub 2017 Apr 4. PubMed PMID: 28390806.
4)

Ghaemi K, Elsharkawy AE, Schulz R, Hoppe M, Polster T, Pannek H, Ebner A. Vagus nerve stimulation: outcome and predictors of seizure freedom in long-term follow-up. Seizure. 2010 Jun;19(5):264-8. doi: 10.1016/j.seizure.2010.03.002. Epub 2010 Apr 1. PubMed PMID: 20362466.

Stereoelectroencephalography guided radiofrequency thermocoagulation

Stereoelectroencephalography guided radiofrequency thermocoagulation

stereoelectroencephalography.jpg

Indications

Concerns about the impact of open surgery for drug-resistant mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) have driven interest in minimally invasive techniques. Stereoelectroencephalography guided radiofrequency thermocoagulation (SEEG guided RF-TC) offers an alternative choice but with currently limited efficacy. Fan et al. developed a procedure for optimally extended thermocoagulation lesions and investigated the efficacy and safety of MTLE-HS in a preliminary observational study. Optimized SEEG-guided RF-TC is a promising complementary option for the treatment of MTLE-HS 1).


Despite the increasing number of studies reporting results of stereo-electroencephalography (SEEG)-guided radiofrequency-thermocoagulation (SEEG-guided RF-TC) in the treatment of patients with drug-resistant focal epilepsy, the exact efficacy of this approach remains unclear. The seizure-freedom rate varies greatly across studies and the factors associated with efficacy have not been formally investigated.

All prospective or retrospective studies reporting efficacy and/or safety of SEEG-guided RF-TC in patients with drug-resistant focal epilepsy were included. The primary outcome was the seizure-free rate 1 year after the procedure. Secondary outcomes were (1) the responder rate 1 year after the procedure and (2) the proportion of patients with permanent neurologic deficit 1 year after the procedure. Each outcome was assessed in all patients and in 4 groups of patients defined by the etiology of epilepsy. Each outcome was pooled using inverse variance weighting, logit transformation of proportion, and a random-effects model.

No prospective study was identified and a total of 6 retrospective studies, reporting efficacy and safety data of 296 patients, were included. The pooled rate of permanent neurologic deficit was 2.5% (95% confidence interval [CI] 1.2%-5.3%), without heterogeneity across studies. In contrast, both the seizure-free and responder rates varied greatly across studies, and statistical heterogeneity was high. The pooled seizure-free and responder rates were 23% (95% CI 8%-50%) and 58% (95% CI 36%-77%), respectively. Both for the seizure-free and responder rates, the greatest efficacy was observed in patients with periventricular nodular heterotopia and the lowest in patients with normal magnetic resonance imaging (MRI) findings.

SEEG-guided RF-TC is a safe procedure with low risk of complications. In contrast, the level of evidence regarding its efficacy remains low. Better identification of factors associated with seizure outcome are needed 2).

Case series

From June 2016 to August 2017, twenty-two patients were selected for the present study. They met the criteria of unilateral MTLE-HS after noninvasive evaluation and then underwent implantation of a combination of SEEG electrodes to form a high-density focal stereo-array, including one electrode along the long axis of amygdalohippocampal complex and three orthogonal electrodes to widely sample mesial temporal structures. A unilateral epileptogenic zone of mesial temporal structures was confirmed in these 21 patients. SEEG-guided bipolar coagulations were performed between two contiguous contacts of the same electrode, or between two adjacent contacts of different electrodes.

Surgical procedures were well tolerated, with no related complications. At the follow-up of 12 months, 20 patients (95.2%) experienced a >90% decrease in seizure frequency and 16 patients (76.2%) were free of disabling seizures (Engel class I). Among them, eight (38.1%) were classified as Engel class Ia and the other eight (38.1%) as Engel class Ib. Four others (19%) had rare disabling seizures (Engel class II). Only one (4.8%) experienced an Engel class III outcome.

Optimized SEEG-guided RF-TC is a promising complementary option for the treatment of MTLE-HS 3).

References

1) , 3)

Fan X, Shan Y, Lu C, An Y, Wang Y, Du J, Wang D, Wei P, Fisher RS, Wang Y, Ren L, Zhao G. Optimized SEEG-guided radiofrequency thermocoagulation for mesial temporal lobe epilepsy with hippocampal sclerosis. Seizure. 2019 Aug 30;71:304-311. doi: 10.1016/j.seizure.2019.08.011. [Epub ahead of print] PubMed PMID: 31521052.
2)

Bourdillon P, Cucherat M, Isnard J, Ostrowsky-Coste K, Catenoix H, Guénot M, Rheims S. Stereo-electroencephalography-guided radiofrequency thermocoagulation in patients with focal epilepsy: A systematic review and meta-analysis. Epilepsia. 2018 Dec;59(12):2296-2304. doi: 10.1111/epi.14584. Epub 2018 Oct 21. PubMed PMID: 30345535.
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