Anterior temporal lobectomy (ATL)

Anterior temporal lobectomy (ATL)

Anterior temporal lobectomy for mesial temporal sclerosis is a very effective measure to control seizures, and the probability of being seizure-free is approximately 70-90%. However, 30% of patients still experience seizures after surgery.

In neurosurgery there are several situations that require transgression of the temporal cortex. For example, a subset of patients with temporal lobe epilepsy require surgical resection (most typically, en-bloc anterior temporal lobectomy). This procedure is the gold standard to alleviate seizures but is associated with chronic cognitive deficits. In recent years there have been multiple attempts to find the optimum balance between minimising the size of resection in order to preserve cognitive function, while still ensuring seizure freedom. Some attempts involve reducing the distance that the resection stretches back from the temporal pole, whilst others try to preserve one or more of the temporal gyri. More recent advanced surgical techniques (selective amygdalohippocampectomy) try to remove the least amount of tissue by going under (sub-temporal), over (trans-Sylvian) or through the temporal lobe (middle-temporal), which have been related to better cognitive outcomes. Previous comparisons of these surgical techniques focus on comparing seizure freedom or behaviour post-surgery, however there have been no systematic studies showing the effect of surgery on white matter connectivity. The main aim of this study, therefore, was to perform systematic ‘pseudo-neurosurgery’ based on existing resection methods on healthy neuroimaging data and measuring the effect on long-range connectivity. We use anatomical connectivity maps (ACM) to determine long-range disconnection, which is complementary to existing measures of local integrity such as fractional anisotropy or mean diffusivity. ACMs were generated for each diffusion scan in order to compare whole-brain connectivity with an ‘ideal resection’, nine anterior temporal lobectomy and three selective approaches. For en-bloc resections, as distance from the temporal pole increased, reduction in connectivity was evident within the arcuate fasciculusinferior longitudinal fasciculusinferior frontooccipital fascicle, and the uncinate fasciculus. Increasing the height of resections dorsally reduced connectivity within the uncinate fasciculus. Sub-temporal amygdalohippocampectomy resections were associated with connectivity patterns most similar to the ‘ideal’ baseline resection, compared to trans-Sylvian and middle-temporal approaches. In conclusion, we showed the utility of ACM in assessing long-range disconnections/disruptions during temporal lobe resections, where we identified the subtemporal resection as the least disruptive to long-range connectivity which may explain its better cognitive outcome. These results have a direct impact on understanding the amount and/or type of cognitive deficit post-surgery, which may not be obtainable using local measures of white matter integrity 1).

Anterior temporal lobectomy (ATL) with amygdalohippocampectomy (ATLAH) has been shown to be more efficacious than continued medical therapy in a randomized, controlled trial 2).

Minimally invasive approaches to treating MTLE might achieve seizure freedom while minimizing adverse effects.

Anterior temporal lobectomy as described by Penfield and Baldwin 3). is the most established neurosurgical procedure for temporal lobe epilepsy, for those in whom anticonvulsant medications do not control epileptic seizures.

It consists in the complete removal of the anterior portion of the temporal lobe of the brain.

Knowledge of the temporomesial region, including neurovascular structures around the brainstem, is essential to keep this procedure safe and effective 4).

The techniques for removing temporal lobe tissue vary from resection of large amounts of tissue, including lateral temporal cortex along with medial structures, to more restricted anterior temporal lobectomy (ATL) to more restricted removal of only the medial structures (selective amygdalohippocampectomy, SAH).

Limits of resection

The measurements are made along the middle temporal gyrus.

Dominant temporal lobe: Up to 4-5 cm may be removed

Non Dominant: 6- 7 cm.


Nearly all reports of seizure outcome following these procedures indicate that the best outcome group includes patients with MRI evidence of mesial temporal sclerosis (hippocampal atrophy with increased T-2 signal.) The range of seizure-free outcomes for these patients is reported to be between 80 and 90%, which is typically reported as a sub-set of data within a larger surgical series.

Open surgical procedures such as ATL have inherent risks including damage to the brain (either directly or indirectly by injury to important blood vessels), bleeding (which can require re-operation), blood loss (which can require transfusion), and infection. Furthermore, open procedures require several days of care in the hospital including at least one night in an intensive care unit. Although such treatment can be costly, multiple studies have demonstrated that ATL in patients who have failed at least two anticonvulsant drug trials (thereby meeting the criteria for medically intractable temporal lobe epilepsy) has lower mortality, lower morbidity and lower long-term cost in comparison with continued medical therapy without surgical intervention.

The strongest evidence supporting ATL over continued medical therapy for medically refractory temporal lobe epilepsy is a prospective, randomized trial of ATL compared to best medical therapy (anticonvulsants), which convincingly demonstrated that the seizure-free rate after surgery was ~ 60% as compared to only 8% for the medicine only group.

Furthermore, there was no mortality in the surgery group, while there was seizure-related mortality in the medical therapy group. Therefore, ATL is considered the standard of care for patients with medically intractable mesial temporal lobe epilepsy.

Surgical resection is the gold standard treatment for drug-resistant focal epilepsy, including mesial temporal lobe epilepsy (MTLE) and other focal cortical lesions with correlated electrophysiological features. Anterior temporal lobectomy with amygdalohippocampectomy (ATLAH) has been shown to be more efficacious than continued medical therapy in a randomized, controlled trial 5).

The most common surgical procedure for the mesial temporal lobe is the standard anterior temporal resection or what is commonly called the anterior temporal lobectomy. There are, however, a number of other more selective procedures for removal of the mesial temporal lobe structures (amygdala, hippocampus, and parahippocampal gyrus) that spare much of the lateral temporal neocortex. Included in these procedures collectively referred to as selective amygdalohippocampectomy are the transsylvian, subtemporal, and transcortical (trans-middle temporal gyrus) selective amygdalohippocampectomy 6).

The ATL group scored significantly worse for recognition of fear compared with selective amygdalohippocampectomy (SAH) patients. Inversely, after SAH scores for disgust were significantly lower than after ATL, independently of the side of resection. Unilateral temporal damage impairs facial emotion recognition (FER). Different neurosurgical procedures may affect FER differently 7).

Outcome

Functional MRIResting state fMRIdiffusion tensor imaging modalities can be used effectively, in an additive fashion, to predict functional reorganization and cognitive outcome following anterior temporal lobectomy 8).

Complications

see Anterior temporal lobectomy complications.

Case series

Of 1214 patients evaluated for surgery in the epilepsy Center of Faculdade de Medicina de São Jose do Rio Preto (FAMERP), a tertiary Brazilian epilepsy center, 400 underwent ATL for MTS. Number and type of auras was analyzed and compared with Engel Epilepsy Surgery Outcome Scale for outcome.

Analyzing the patients by the type of aura, those who had extratemporal auras had worst result in post-surgical in Engel classifcation. While mesial auras apparently is a good prognostic factor. Patients without aura also had worse prognosis. Simple and multiple aura had no difference. In order to identify the most appropriate candidates for ATL, is very important to consider the prognostic factors associated with favorable for counseling patients in daily practice 9).


Boucher et al. compared preoperative vs. postoperative memory performance in 13 patients with selective amygdalohippocampectomy (SAH) with 26 patients who underwent ATL matched on side of surgery, IQ, age at seizure onset, and age at surgery. Memory function was assessed using the Logical Memory subtest from the Wechsler Memory Scales – 3rd edition (LM-WMS), the Rey Auditory Verbal Learning Test (RAVLT), the Digit Span subtest from the Wechsler Adult Intelligence Scale, and the Rey-Osterrieth Complex Figure Test. Repeated measures analyses of variance revealed opposite effects of SAH and ATL on the two verbal learning memory tests. On the immediate recall trial of the LM-WMS, performance deteriorated after ATL in comparison with that after SAH. By contrast, on the delayed recognition trial of the RAVLT, performance deteriorated after SAH compared with that after ATL. However, additional analyses revealed that the latter finding was only observed when surgery was conducted in the right hemisphere. No interaction effects were found on other memory outcomes. The results are congruent with the view that tasks involving rich semantic content and syntactical structure are more sensitive to the effects of lateral temporal cortex resection as compared with mesiotemporal resection. The findings highlight the importance of task selection in the assessment of memory in patients undergoing TLE surgery 10).

Case reports

Georgia country is a Caucasian low- to a middle-income country with a remarkable effort to deal with epileptic diseases, but without an appropriate epilepsy surgery program. To address the needs for such a service in this country, two joint German-Georgian projects were initiated in 2017 and 2019. In the framework of these projects, a productive exchange program involving German and Georgian experts was undertaken in the past two years. This program included training and mentoring for Georgian clinical colleagues, as well as a joint case conferences and workshops with the aim of optimizing presurgical diagnostics and preparing for an epilepsy surgery program in Georgia. Finally, a postsurgical medium- and long-term follow-up scheme was organized as the third component of this comprehensive approach. As a result of the efforts, the first patients underwent anterior temporal lobectomy and all of them remain seizure-free up to the present day. Hence, epilepsy surgery is not only feasible but also already available in Georgia. In a report, Dugladze et al. aimed to share their experiences in the initiation and implementation of surgical epilepsy intervention in Georgia and illustrate the recent endeavor and achievements 11).

References

1)

Busby N, Halai AD, Parker GJM, Coope DJ, Lambon Ralph MA. Mapping whole brain connectivity changes: The potential impact of different surgical resection approaches for temporal lobe epilepsy. Cortex. 2018 Nov 17;113:1-14. doi: 10.1016/j.cortex.2018.11.003. [Epub ahead of print] PubMed PMID: 30557759.
2) , 5)

Wiebe S, Blume WT, Girvin JP, Eliasziw M. A randomized, controlled trial of surgery for temporal-lobe epilepsy. N Engl J Med. 2001;345(5):311–318.
3)

PENFIELD W, BALDWIN M. Temporal lobe seizures and the technic of subtotal temporal lobectomy. Ann Surg. 1952 Oct;136(4):625-34. PubMed PMID: 12986645; PubMed Central PMCID: PMC1803045.
4)

Schaller K, Cabrilo I. Anterior temporal lobectomy. Acta Neurochir (Wien). 2016 Jan;158(1):161-6. doi: 10.1007/s00701-015-2640-0. Epub 2015 Nov 23. PubMed PMID: 26596998.
6)

Wheatley BM. Selective amygdalohippocampectomy: the trans-middle temporal gyrus approach. Neurosurg Focus. 2008 Sep;25(3):E4. doi: 10.3171/FOC/2008/25/9/E4. Review. PubMed PMID: 18759628.
7)

Wendling AS, Steinhoff BJ, Bodin F, Staack AM, Zentner J, Scholly J, Valenti MP, Schulze-Bonhage A, Hirsch E. Selective amygdalohippocampectomy versus standard temporal lobectomy in patients with mesiotemporal lobe epilepsy and unilateral hippocampal sclerosis: post-operative facial emotion recognition abilities. Epilepsy Res. 2015 Mar;111:26-32. doi: 10.1016/j.eplepsyres.2015.01.002. Epub 2015 Jan 16. PubMed PMID: 25769370.
8)

Osipowicz K, Sperling MR, Sharan AD, Tracy JI. Functional MRI, resting state fMRI, and DTI for predicting verbal fluency outcome following resective surgery for temporal lobe epilepsy. J Neurosurg. 2016 Apr;124(4):929-37. doi: 10.3171/2014.9.JNS131422. Epub 2015 Sep 25. PubMed PMID: 26406797.
9)

da Cruz Adry RAR, Meguins LC, Pereira CU, da Silva Júnior SC, de Araújo Filho GM, Marques LHN. Auras as a prognostic factor in anterior temporal lobe resections for mesial temporal sclerosis. Eur J Neurol. 2018 Jun 28. doi: 10.1111/ene.13740. [Epub ahead of print] PubMed PMID: 29953714.
10)

Boucher O, Dagenais E, Bouthillier A, Nguyen DK, Rouleau I. Different effects of anterior temporal lobectomy and selective amygdalohippocampectomy on verbal memory performance of patients with epilepsy. Epilepsy Behav. 2015 Oct 12;52(Pt A):230-235. doi: 10.1016/j.yebeh.2015.09.012. [Epub ahead of print] PubMed PMID: 26469799.
11)

Dugladze T, Bäuerle P, Kasradze S, et al. Initiating a new national epilepsy surgery program: Experiences gathered in Georgia [published online ahead of print, 2020 Jul 1]. Epilepsy Behav. 2020;111:107259. doi:10.1016/j.yebeh.2020.107259

A brief review of technical nuances of functional hemispherotomy

Join us today, Monday, at noon EST for a brief review of technical nuances of functional hemispherotomy.

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Based on the request of the residents and faculty, the Atlas will start a series of Virtual Operating Room live lectures every Mon at noon EST. During each session, one procedure will be reviewed using an HD video broadcasting platform while the participants can chat their questions. Virtual reality technology will be utilized for the OR setup and the surgical video will be reviewed. Space is limited to the first 300 participants.

Virtual OR webconference info: cohen.omnovia.com/room1 Use the Google Chrome browser, login as attendee and download the Flash Player. A strong Internet connection is required for these HD presentations.

Aaron Cohen-Gadol, MD, MSc, MBA
Indiana University Department of Neurosurgery
CEO, The Neurosurgical Atlas

Epilepsy surgery

Epilepsy surgery

see also Pediatric Epilepsy Surgery.

Technology

Dorfer et al. emphasized the role of the technological progress in changing the landscape of epilepsy surgery and provides a critical appraisal of robotic applications, laser interstitial thermal therapyintraoperative imaging, wireless recording, new neuromodulation techniques, and high-intensity focused ultrasound. Specifically, (a) it relativizes the current hype in using robots for stereoelectroencephalography (SEEG) to increase the accuracy of depth electrode placement and save operating time; (b) discusses the drawback of laser interstitial thermal therapy (LITT) when it comes to the need for adequate histopathologic specimen and the fact that the concept of stereotactic disconnection is not new; © addresses the ratio between the benefits and expenditure of using intraoperative magnetic resonance imaging (MRI), that is, the high technical and personnel expertise needed that might restrict its use to centers with a high caseload, including those unrelated to epilepsy; (d) soberly reviews the advantages, disadvantages, and future potentials of neuromodulation techniques with special emphasis on the differences between closed and open-loop systems; and (e) provides a critical outlook on the clinical implications of focused ultrasound, wireless recording, and multipurpose electrodes that are already on the horizon. This outlook shows that although current ultrasonic systems do have some limitations in delivering acoustic energy, the further advance of this technique may lead to novel treatment paradigms. Furthermore, it highlights that new data streams from multipurpose electrodes and wireless transmission of intracranial recordings will become available soon once some critical developments will be achieved such as electrode fidelity, data processing, and storage, heat conduction as well as rechargeable technology. A better understanding of modern epilepsy surgery will help to demystify epilepsy surgery for the patients and the treating physicians and thereby reduce the surgical treatment gap 1).

Indications

Epilepsy surgery indications.

Pre-surgical evaluation

Epilepsy surgery pre-surgical evaluation.

Techniques

Resective epilepsy surgery.

Hemispherectomy.

Magnetic resonance guided laser induced thermal therapy for epilepsy.

Temporal lobe epilepsy surgery

Vagus nerve stimulation for drug resistant epilepsy.

Neuromodulation

Several palliative neuromodulation treatment modalities are currently available for adjunctive use in the treatment of medically intractable epilepsy. Over the past decades, a variety of different central and peripheral nervous system sites have been identified, clinically and experimentally, as potential targets for chronic, nonresponsive therapeutic neurostimulation. Currently, the main modalities in clinical use, from most invasive to least invasive, are anterior thalamus deep brain stimulation, vagus nerve stimulation, and trigeminal nerve stimulation. Significant reductions in seizure frequency have been demonstrated in clinical trials using each of these neuromodulation therapies 2).

see Vagus nerve stimulation for drug resistant epilepsy.


see Epilepsy surgery in India.

The current practice under which patients with refractory epilepsy are surgically treated is based mainly on the identification of specific cortical areas, mainly the epileptogenic zone, which is believed to be responsible for generation of seizures. A better understanding of the whole epileptic network and its components and properties is required before more effective and less invasive therapies can be developed.

Epilepsy surgery is constantly researching for new options for patients with refractory epilepsy.

see Magnetic resonance guided laser induced thermal therapy for epilepsy

Despite significant underutilization of surgical treatment for drug-resistant epilepsy, no studies have quantified patient desire for surgery within a representative population.

An online survey was administered to all clients connected with a core epilepsy community access center. It obtained information about demographics, clinical characteristics, knowledge of epilepsy surgery, and interest in receiving surgery before and after receiving risk/benefit information about it.

Of 118 potential respondents, 48 (41%) completed the questionnaire, of which 67% had failed more than two AEDs and 78% experienced seizures in the past year. Eleven ( 26%) were uninterested in receiving surgery at baseline, and this decreased significantly to 7 (16%) following knowledge translation regarding the benefits (p = 0.001). Significance was lost with subsequent complication rate information despite fewer respondents still being uninterested compared to baseline (20% vs. 26%). Having experienced seizures within the past month was correlated with being interested in or undecided regarding surgery at baseline and following all steps of knowledge translation. Subjects had conservative views regarding the benefits of surgery and largely overestimated the risks.

A significant portion of those with active epilepsy in the community do not desire surgical treatment. Passive knowledge translation regarding the risks and benefits enhanced optimistic attitudes and mobilized interest within a subset of participants. Preexisting views regarding the risks of surgery were exaggerated, and analysis suggests that these views can be modified with information about the benefits of surgery. However, exaggerated risk perceptions return following crude descriptions of the risks, underlying the importance of sensitive counseling from primary care physicians 3).


In Epilepsy surgery where resective surgery is not indicated, deep brain stimulation (DBS) may be an effective alternative. The majority of available literature targets the thalamic nuclei (anterior; centromedian), subthalamic nucleus, hippocampus, and cerebellum.

Data show DBS may be a safe and effective treatment option for refractory epilepsy 4).

Surgery is a safe and effective option for some patients, however the opportunity exists to develop less invasive and more effective surgical options. To this end, multiple minimally invasive, image-guided techniques have been applied to the treatment of epilepsy. These techniques can be divided into thermoablative and disconnective techniques. Each has been described in the treatment of epilepsy only in small case series. Larger series and longer follow up periods will determine each option’s place in the surgical armamentarium for the treatment of refractory epilepsy but early results are promising 5).

Outcome

see Epilepsy Surgery outcome.

Books

Engel J Jr, Van Ness PC, Rasmussen T, Ojemann LM: Outcome with respect to epileptic seizures, in Engle J Jr (ed): Surgical Treatment of the Epilepsies, ed 2. New York: Raven Press, 1993, pp 609–621

Case series

Epilepsy surgery case series.

References

1)

Dorfer C, Rydenhag B, Baltuch G, Buch V, Blount J, Bollo R, Gerrard J, Nilsson D, Roessler K, Rutka J, Sharan A, Spencer D, Cukiert A. How technology is driving the landscape of epilepsy surgery. Epilepsia. 2020 Mar 29. doi: 10.1111/epi.16489. [Epub ahead of print] PubMed PMID: 32227349.
2)

Krishna V, Sammartino F, King NK, So RQ, Wennberg R. Neuromodulation for Epilepsy. Neurosurg Clin N Am. 2016 Jan;27(1):123-131. doi: 10.1016/j.nec.2015.08.010. Epub 2015 Oct 24. Review. PubMed PMID: 26615114.
3)

Zuccato JA, Milburn C, Valiante TA. Balancing health literacy about epilepsy surgery in the community. Epilepsia. 2014 Sep 23. doi: 10.1111/epi.12791. [Epub ahead of print] PubMed PMID: 25251908.
4)

Klinger NV, Mittal S. Clinical efficacy of deep brain stimulation for the treatment of medically refractory epilepsy. Clin Neurol Neurosurg. 2015 Nov 14;140:11-25. doi: 10.1016/j.clineuro.2015.11.009. [Epub ahead of print] Review. PubMed PMID: 26615464.
5)

Bandt SK, Leuthardt EC. Minimally Invasive Neurosurgery for Epilepsy Using Stereotactic MRI Guidance. Neurosurg Clin N Am. 2016 Jan;27(1):51-8. doi: 10.1016/j.nec.2015.08.005. Epub 2015 Oct 24. Review. PubMed PMID: 26615107.
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