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

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 Scalefor 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 surgery10).

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.

UpToDate: Temporal horn entrapment

Temporal horn entrapment

Entrapment of the temporal horn, known as isolated lateral ventricle (ILV).

Temporal horn entrapment is a very rare kind of isolated focal non communicating hydrocephalus caused by obstruction at the trigone of the lateral ventricle, which seals off the temporal horn from the rest of the ventricular system 1) 2) 3).

A very thoughtful review of the literature in 2013 reported only 24 cases 4)

In 2017 Guive Sharifi et al published a Review of Literature http://www.jneuro.com/neurology-neuroscience/an-idiopathic-huge-trapped-temporal-horn-surgical-strategy-and-review-of-literature.pdf

Etiology

Obstruction around the trigone of the lateral ventricle caused by inflammations, tumors, infections, or after surgical processes. Most reports are unilateral and acquired.

Treatment

Standard treatment has not yet been established for this condition, and only a few cases have been reported in the literature.

Entrapped temporal horn syndrome secondary to obstructive neoplastic lesions is most frequently treated by surgical excision of the offending lesion.

Golpayegani et al., from the Department of Neurosurgery, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Department of Neurosurgery, Children’s Hospital Medical Center, Tehran University of Medical Sciences, TehranIran, reported in 2018 the first congenital case of huge bilateral temporal horn entrapment. A six-month-old boy was admitted with progressive intracranial hypertension who was managed with bilateral ventricular catheters and Y tube connected to one peritoneal catheter 5).


Zhang et al., reviewed their database to report their experience with endoscopic fenestration for treating entrapped temporal horn caused by atrial adhesions. All endoscopic operations performed from February 2015 to December 2016 were reviewed.

Three patients developed temporal horn entrapment after tumor resection. Fenestration was successful in all patients, with a subsequent stomy of the septum pellucidum. Follow-up magnetic resonance imaging 1 year later showed a patent reduction of the entrapped horn.

Endoscopic fenestration is an option in the treatment of entrapped temporal horns. However, more experience is required to recommend it as the treatment of choice 6).


Entrapment of the temporal horn, known as isolated lateral ventricle (ILV), is a rare type of noncommunicating focal hydrocephalus, and its standard treatment has not been established.

Hasegawa et al. report two cases of endoscopic surgery for ILV, and highlight the anatomical surgical nuances to avoid associated surgical risks.

The authors present two surgical cases with ILV treated by endoscopic surgery. The first patient with recurrent ILV, due to shunt malfunction, following the initial shunt placement for ILV. In the second patient, the ILV recurred due to choroid plexus inflammation caused by cryptococcal infection. Endoscopic temporal ventriculocisternostomy was effective in both cases. However, in the second case, the choroidal fissure was fenestrated, which led to cerebral infarction in the territory of the choroidal artery zone, attributed to damaging the branches of the choroidal segment of the anterior choroidal artery.

Endoscopic temporal ventriculocisternostomy is considered as a safe and less invasive procedure for treatment of symptomatic ILV. However, the technique is still associated with risks. To avoid complications, it is necessary to be familiar with the anatomy of the choroidal arteries and the pertinent endoscopic intraventricular orientation. Addtitionally, sufficient experience is required before it can be recommended as the treatment of choice 7).


A 76-year-old male presented with altered mental status and left-sided weakness. Noncontrast computed tomography of the head showed a right ganglionic intraparenchymal hemorrhage with resultant entrapment of the temporal horn. Using Robotic Stereotactic Assistance (ROSA), intrahematomal and intraventricular catheters were placed. The temporal horn was immediately decompressed, and the hematoma almost completely resolved with scheduled administration of intrathecal alteplase in the ensuing 48 hours postoperatively.

Frameless image-guided placement of intraparenchymal hematoma catheter using Robotic Stereotactic Assistance is safe and efficient 8)


Paredes et al., reviewed their cases of temporal horn entrapment treated between May 2013 and December 2014 and report their experience with endoscopic temporal ventriculocisternostomy. Four patients were identified (3 adults and 1 child) who underwent this treatment. In 3 patients, the condition developed after tumor resection, and in 1 patient it developed after resection of an arteriovenous malformation. In 1 patient, a recurrent trapped temporal horn developed and a refenestration was successfully performed. No procedure-related complications were observed, and all of the patients remained shunt-free at last follow-up (range 4-24 months). Endoscopic temporal horn ventriculocisternostomy is a safe and effective procedure for the treatment of symptomatic temporal horn entrapment in selected cases. However, there is little experience with the procedure to recommend it as the treatment of choice 9).


In 2015 Spallone et al., reported a case of a 58-year-old man who presented with pure Wernicke aphasia (never described before in the albeit rare cases of isolated temporal horn dilatation) that regressed completely following successful ventriculoperitoneal shunting 10).

Chen et al described in 2013 an alternate approach involving temporal horn to prepontine cistern shunting followed by radiosurgery of the offending lesion. This 41-year-old woman with a history of meningiomatosis presented with progressive, incapacitating headache. Magnetic resonance imaging (MRI) showed growth of a right trigone meningioma, causing entrapment of the right temporal horn. A ventricular catheter was placed using frame-based stereotaxy and image fusion computed tomography/MRI to connect the entrapped lateral ventricle to the prepontine cistern. The patient reported complete resolution of her symptoms after the procedure.

Postoperative MRI revealed decompression of the temporal horn. The trigonal meningioma was treated with stereotactic radiosurgery. The patient remained asymptomatic at the 2-year follow-up 11).

In 1992 two cases of entrapment of the temporal horn, computed tomography demonstrated the typical appearance of a comma-shaped homogeneous area isodense with water surrounded by a periventricular low-density area. The cause was probably choroid plexitis resulting in obstruction of the cerebrospinal fluid pathway at the atrium. External drainage followed by shunt emplacement was indicated 12).

Maurice-Williams and Choksey reported in 1986 three cases of temporal horn entrapment: A recurrent glioma, a previous tuberculous meningitisand surgical excision of an intracranial arteriovenous malformation which extended into the trigone. Shunting of the trapped temporal horn provided satisfactory treatment 13)

References

1)

Berhouma M, Abderrazek K, Krichen W, Jemel H (2009) Apropos of an unusual and menacing presentation of neurosarcoidosis: The space-occupying trapped temporal horn. Clin Neurol Neurosurg 111: 196-199.

2)

Bohl MA, Almefty KK, Nakaji P (2015) Defining a standardized approach for the bedside insertion of temporal horn external ventricular drains: Procedure development and case series. Neurosurgery 79: 296-304.

3)

Bruck W, Sander U, Blanckenberg P, Friede RL (1991) Symptomatic xanthogranuloma of choroid plexus with unilateral hydrocephalus. Case report. J Neurosurg 75: 324-327.

4)

Krähenbühl AK, Baldauf J, Gaab MR, Schroeder HW. Endoscopic temporal ventriculocisternostomy: an option for the treatment of trapped temporal horns. J Neurosurg Pediatr. 2013 May;11(5):568-74. doi: 10.3171/2013.2.PEDS12417. Epub 2013 Mar 22. PubMed PMID: 23521153.

5)

Golpayegani M, Salari F, Anbarlouei M, Habibi Z, Nejat F. Huge bilateral temporal horn entrapment: a congenital abnormality and management. Childs Nerv Syst. 2018 Jul 28. doi: 10.1007/s00381-018-3924-5. [Epub ahead of print] PubMed PMID: 30056473.

6)

Zhang B, Wang X, Li C, Li Z. Neuroendoscopic Fenestration for Entrapped Temporal Horn After Surgery: Report of 3 Cases. World Neurosurg. 2018 Apr;112:77-80. doi: 10.1016/j.wneu.2018.01.096. Epub 2018 Jan 31. PubMed PMID: 29371166.

7)

Hasegawa T, Ogiwara T, Nagm A, Goto T, Aoyama T, Hongo K. Risks of endoscopic temporal ventriculocisternostomy for isolated lateral ventricle: Anatomical surgical nuances. World Neurosurg. 2017 Nov 15. pii: S1878-8750(17)31959-9. doi: 10.1016/j.wneu.2017.11.036. [Epub ahead of print] PubMed PMID: 29155114.

8)

Alan N, Lee P, Ozpinar A, Gross BA, Jankowitz BT. Robotic Stereotactic Assistance (ROSA) Utilization for Minimally Invasive Placement of Intraparenchymal Hematoma and Intraventricular Catheters. World Neurosurg. 2017 Dec;108:996.e7-996.e10. doi: 10.1016/j.wneu.2017.09.027. Epub 2017 Sep 14. PubMed PMID: 28919568.

9)

Paredes I, Orduna J, Fustero D, Salgado JA, de Diego JM, de Mesa FG. Endoscopic temporal ventriculocisternostomy for the management of temporal horn entrapment: report of 4 cases. J Neurosurg. 2017 Jan;126(1):298-303. doi: 10.3171/2016.1.JNS152248. Epub 2016 Apr 15. PubMed PMID: 27081903.

10)

Spallone A, Belvisi D, Marsili L. Entrapment of the Temporal Horn as a Cause of Pure Wernicke Aphasia: Case Report. J Neurol Surg Rep. 2015 Jul;76(1):e109-12. doi: 10.1055/s-0035-1549225. Epub 2015 May 13. PubMed PMID: 26251784; PubMed Central PMCID: PMC4520970.

11)

Chen CC, Kasper EM, Zinn PO, Warnke PC. Management of entrapped temporal horn by temporal horn to prepontine cistern shunting. World Neurosurg. 2013 Feb;79(2):404.e7-10. doi: 10.1016/j.wneu.2011.02.025. Epub 2011 Nov 7. PubMed PMID: 22120406.

12)

Tsugane R, Shimoda M, Yamaguchi T, Yamamoto I, Sato O. Entrapment of the temporal horn: a form of focal non-communicating hydrocephalus caused by intraventricular block of cerebrospinal fluid flow–report of two cases. Neurol Med Chir (Tokyo). 1992 Apr;32(4):210-4. Review. PubMed PMID: 1378565.

13)

Maurice-Williams RS, Choksey M. Entrapment of the temporal horn: a form of focal obstructive hydrocephalus. J Neurol Neurosurg Psychiatry. 1986 Mar;49(3):238-42. PubMed PMID: 3958736; PubMed Central PMCID: PMC1028721.

UpToDate: Anterior temporal lobectomy complications

Anterior temporal lobectomy complications

Anterior temporal lobectomy is often complicated by quadrantanopia. In some cases this can be severe enough to prohibit driving, even if a patient is free of seizures. These deficits are caused by damage to Meyers loop of the optic radiation, which shows considerable heterogeneity in its anterior extent. This structure cannot be distinguished using clinical magnetic resonance imaging sequences.

Optic radiation tractography by DTI could be a useful method to assess an individual patient’s risk of postoperative visual deficit 1)2).

van Lanen et al., developed a score method for the assessment of postoperative visual field defects after temporal lobe epilepsy surgery and assessed its feasibility for clinical use. A significant correlation between VFD and resection size for right-sided ATL was confirmed 3).

Cranial nerve (CN) deficits following anterior temporal lobectomy (ATL) are an uncommon but well-recognized complication. The usual CNs implicated in post-ATL complications include the oculomotor nervetrochlear nerve, and facial nerves.

Injury to the trigeminal nerve leading to neuropathic pain are described in 2 cases following temporal lobe resections for pharmacoresistant epilepsy. The possible pathophysiological mechanisms are discussed and the microsurgical anatomy of surgically relevant structures is reviewed.4).

Complications

Dickerson et al., from the Department of Neurosurgery, University of Mississippi Medical Center, JacksonUSA report the third known case and first of diffuse vasospasm. A 48-year-old woman underwent a transcortical anterior left temporal lobectomy. Eleven days later, she had new-onset expressive aphasia with narrowing of the anterior, middle, and posterior cerebral arteries, and increased velocities via transcranial Doppler. She was treated with fluids, nimodipine, and permissive hypertension. At 6 months, her speech was near baseline. Cerebral vasospasm may represent a rare cause of morbidity after anterior temporal lobectomy; a literature review on the subject is presented 5).

References

1)

Borius PY, Roux FE, Valton L, Sol JC, Lotterie JA, Berry I. Can DTI fiber tracking of the optic radiations predict visual deficit after surgery? Clin Neurol Neurosurg. 2014 Jul;122:87-91. doi: 10.1016/j.clineuro.2014.04.017. Epub 2014 May 5. PubMed PMID: 24908224.
2)

James JS, Radhakrishnan A, Thomas B, Madhusoodanan M, Kesavadas C, Abraham M, Menon R, Rathore C, Vilanilam G. Diffusion tensor imaging tractography of Meyer’s loop in planning resective surgery for drug-resistant temporal lobe epilepsy. Epilepsy Res. 2015 Feb;110:95-104. doi: 10.1016/j.eplepsyres.2014.11.020. Epub 2014 Nov 27. PubMed PMID: 25616461.
3)

van Lanen RHGJ, Hoeberigs MC, Bauer NJC, Haeren RHL, Hoogland G, Colon A, Piersma C, Dings JTA, Schijns OEMG. Visual field deficits after epilepsy surgery: a new quantitative scoring method. Acta Neurochir (Wien). 2018 Jul;160(7):1325-1336. doi: 10.1007/s00701-018-3525-9. Epub 2018 Apr 5. PubMed PMID: 29623432; PubMed Central PMCID: PMC5995984.
4)

Gill I, Parrent AG, Steven DA. Trigeminal neuropathic pain as a complication of anterior temporal lobectomy: report of 2 cases. J Neurosurg. 2016 Apr;124(4):962-5. doi: 10.3171/2015.5.JNS15123. Epub 2015 Oct 30. PubMed PMID: 26517768.
5)

Dickerson JC, Hidalgo JA, Smalley ZS, Shiflett JM. Diffuse vasospasm after transcortical temporal lobectomy for intractable epilepsy. Acta Neurochir (Wien). 2018 Jul 10. doi: 10.1007/s00701-018-3606-9. [Epub ahead of print] PubMed PMID: 29987392.

Update: Mesial temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is a chronic neurological condition characterized by recurrent seizures (epilepsy) which originate in the temporal lobe of the brain. The seizures involve sensory changes, for example smelling an unusual odour that is not there, and disturbance of memory.

Mesial temporal lobe epilepsy with hippocampal sclerosis (mTLE-HS) is the most common type of focal epilepsy.

Etiology

The most common cause is mesial temporal sclerosis.
Water homeostasis has been shown crucial for regulation of neuronal excitability. The control of water movement is achieved through a family of small integral membrane channel proteins called aquaporins (AQPs). Despite the fact that changes in water homeostasis occur in sclerotic hippocampi of people with temporal lobe epilepsy (TLE) , the expression of AQPs in the epileptic brain is not fully characterised 1).
Soluble human epoxide hydrolase 2 is increased in both lateral and medial temporal tissues in temporal lobe epilepsy. Further studies should be conducted as inhibition of this enzyme has resulted in a significant decrease in or stopping of seizures and attenuated neuro-inflammation in experimental epilepsy models in the current literature 2).

Pathophysiology

In order to understand the pathophysiology of temporal lobe epilepsy (TLE), and thus to develop new pharmacological treatments, in vivo animal models that present features similar to those seen in TLE patients have been developed during the last four decades. Some of these models are based on the systemic administration of chemoconvulsants to induce an initial precipitating injury (status epilepticus) that is followed by the appearance of recurrent seizures originating from limbic structures.
Kainic acid and pilocarpine models, have been widely employed in basic epilepsy research. Their behavioral, electroencephalographic and neuropathologic features and response of these models to antiepileptic drugs and the impact they might have in developing new treatments are explained in the work of Lévesque et al. 3).


The transition to the ictal stage is accompanied by increasing global synchronization and a more ordered spectral content of the signals, indicated by lower spectral entropy. The interictal connectivity imbalance (lower ipsilateral connectivity) is sustained during the seizure, irrespective of any appreciable imbalance in the spectral entropy of the mesial recordings 4).

Diagnosis

Fractional anisotropy asymmetry (FAA) values can be potentially used to identify the seizures of origin of TLE and to help understand the relationship between fiber tracts with the side of seizure origin of TLE 5).
The area of predominant perifocal 18F positron emission tomography hypometabolism and reduced [11C]flumazenil (11C-FMZ) -binding on PETscans is currently considered to contain the epileptogenic zone and corresponds anatomically to the area localizing epileptogenicity in patients with temporal lobe epilepsy (TLE).

Complicactions

Drug resistant epilepsy is a major clinical challenge affecting about 30% of temporal lobe epilepsy (TLE) patients.
The reasons for failure of surgical treatment for mesial temporal lobe epilepsy (MTLE) associated with hippocampal sclerosis (HS) remain unclear.

Treatment

Surgery

see Temporal lobe epilepsy surgery.
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.
Surgical approaches for medically refractory mesial temporal lobe epilepsy (MTLE) that previously have been reported include anterior temporal lobectomy (ATL), transcortical selective amygdalohippocampectomy, transsylvian amygdalohippocampectomy, and subtemporal amygdalohippocampectomy.
Each approach has its advantages and potential pitfalls.

Anterior temporal lobectomy

Outcome

The extent of pre-surgical perifocal PET abnormalities, the extent of their resection, and the extent of non-resected abnormalities were not useful predictors of individual freedom from seizures in patients with TLE 6).

Case series

2017

Seizure, cognitive, and psychiatric outcomes were reviewed after 389 surgeries performed between 1990 and 2015 on patients aged 15-67 years at a tertiary center. Three surgical approaches were used: anterior temporal lobectomy (ATL; n = 209), transcortical selective amygdalohippocampectomy (SAH; n = 144), and transsylvian SAH (n = 36).
With an average follow-up of 8.7 years (range = 1.0-25.2), seizure outcome was classified as Engel I in 83.7% and Engel Ia in 57.1% of patients. The histological classification of HS was type 1 for 75.3% of patients, type 2 for 18.7%, and type 3 for 1.2%. Two factors were significantly associated with seizure recurrence: past history of status epilepticus and preoperative intracranial electroencephalographic recording. In contrast, neither HS type, the presence of a dual pathology, nor surgical approach was associated with seizure outcome. Risk of cognitive impairment was 3.12 (95% confidence interval = 1.27-7.70), greater in patients after ATL than in patients after transcortical SAH. A presurgical psychiatric history and postoperative cognitive impairment were associated with poor psychiatric outcome.
The SAH and ATL approaches have similar beneficial effects on seizure control, whereas transcortical SAH tends to minimize cognitive deterioration after surgery. Variation in postsurgical outcome with the class of HS should be investigated further 7).

2016

A certain number of patients suffer significant decline in verbal memory after hippocampectomy. To prevent this disabling complication, a reliable test for predicting postoperative memory decline is greatly desired. Therefore, Tani et al., assessed the value of electrical stimulation of the parahippocampal gyrus (PHG) as a provocation test of verbal memory decline after hippocampectomy on the dominant side.
Eleven right-handed, Japanese-speaking patients with medically intractable left temporal lobe epilepsy (TLE) participated in the study. Before surgery, they underwent provocative testing via electrical stimulation of the left PHG during a verbal encoding task. Their pre- and posthippocampectomy memory function was evaluated according to the Wechsler Memory Scale-Revised (WMS-R) and/or Mini-Mental State Examination (MMSE) before and 6 months after surgery. The relationship between postsurgical memory decline and results of the provocative test was evaluated.
Left hippocampectomy was performed in 7 of the 11 patients. In 3 patients with a positive provocative recognition test, verbal memory function, as assessed by the WMS-R, decreased after hippocampectomy, whereas in 4 patients with a negative provocative recognition test, verbal memory function, as assessed by the WMS-R or MMSE, was preserved.
Results of the present study suggest that electrical stimulation of the PHG is a reliable provocative test to predict posthippocampectomy verbal memory decline 8).

2001

Eighty patients with temporal lobe epilepsy were randomly assigned to surgery (40 patients) or treatment with antiepileptic drugs for one year (40 patients). Optimal medical therapy and primary outcomes were assessed by epileptologists who were unaware of the patients’ treatment assignments. The primary outcome was freedom from seizures that impair awareness of self and surroundings. Secondary outcomes were the frequency and severity of seizures, the quality of life, disability, and death.
At one year, the cumulative proportion of patients who were free of seizures impairing awareness was 58 percent in the surgical group and 8 percent in the medical group (P<0.001). The patients in the surgical group had fewer seizures impairing awareness and a significantly better quality of life (P<0.001 for both comparisons) than the patients in the medical group. Four patients (10 percent) had adverse effects of surgery. One patient in the medical group died.
In temporal-lobe epilepsy, surgery is superior to prolonged medical therapy. Randomized trials of surgery for epilepsy are feasible and appear to yield precise estimates of treatment effects 9).
1)

Salman MM, Sheilabi MA, Bhattacharyya D, Kitchen P, Conner AC, Bill RM, Woodroofe MN, Conner MT, Princivalle AP. Transcriptome analysis suggests a role for the differential expression of cerebral aquaporins and the MAPK signalling pathway in human temporal lobe epilepsy. Eur J Neurosci. 2017 Jul 17. doi: 10.1111/ejn.13652. [Epub ahead of print] PubMed PMID: 28715131.
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Ahmedov ML, Kemerdere R, Baran O, Inal BB, Gumus A, Coskun C, Yeni SN, Eren B, Uzan M, Tanriverdi T. Tissue Expressions of Soluble Human Epoxide Hydrolase-2 Enzyme in Patients with Temporal Lobe Epilepsy. World Neurosurg. 2017 Jun 29. pii: S1878-8750(17)31032-X. doi: 10.1016/j.wneu.2017.06.137. [Epub ahead of print] PubMed PMID: 28669871.
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Lévesque M, Avoli M, Bernard C. Animal Models of temporal Lobe Epilepsy Following Systemic Chemoconvulsant Administration. J Neurosci Methods. 2015 Mar 10. pii: S0165-0270(15)00091-6. doi: 10.1016/j.jneumeth.2015.03.009. [Epub ahead of print] PubMed PMID: 25769270.
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Vega-Zelaya L, Pastor J, de Sola RG, Ortega GJ. Disrupted Ipsilateral Network Connectivity in Temporal Lobe Epilepsy. PLoS One. 2015 Oct 21;10(10):e0140859. doi: 10.1371/journal.pone.0140859. eCollection 2015. PubMed PMID: 26489091.
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Li H, Xue Z, Dulay MF Jr, Verma A, Karmonik C, Grossman RG, Wong ST. Fractional anisotropy asymmetry and the side of seizure origin for partial onset-temporal lobe epilepsy. Comput Med Imaging Graph. 2014 Jul 2. pii: S0895-6111(14)00102-5. doi: 10.1016/j.compmedimag.2014.06.009. [Epub ahead of print] PubMed PMID: 25037096.
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Stanišić M, Coello C, Ivanović J, Egge A, Danfors T, Hald J, Heminghyt E, Mikkelsen MM, Krossnes BK, Pripp AH, Larsson PG. Seizure outcomes in relation to the extent of resection of the perifocal fluorodeoxyglucose and flumazenil PET abnormalities in anteromedial temporal lobectomy. Acta Neurochir (Wien). 2015 Sep 8. [Epub ahead of print] PubMed PMID: 26350516.
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Mathon B, Bielle F, Samson S, Plaisant O, Dupont S, Bertrand A, Miles R, Nguyen-Michel VH, Lambrecq V, Calderon-Garcidueñas AL, Duyckaerts C, Carpentier A, Baulac M, Cornu P, Adam C, Clemenceau S, Navarro V. Predictive factors of long-term outcomes of surgery for mesial temporal lobe epilepsy associated with hippocampal sclerosis. Epilepsia. 2017 Jun 28. doi: 10.1111/epi.13831. [Epub ahead of print] PubMed PMID: 28656696.
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Tani N, Kishima H, Khoo HM, Yanagisawa T, Oshino S, Maruo T, Hosomi K, Hirata M, Kazui H, Nomura KT, Aly MM, Kato A, Yoshimine T. Electrical stimulation of the parahippocampal gyrus for prediction of posthippocampectomy verbal memory decline. J Neurosurg. 2016 Nov;125(5):1053-1060. PubMed PMID: 26771851.
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Wiebe S, Blume WT, Girvin JP, Eliasziw M; Effectiveness and Efficiency of Surgery for Temporal Lobe Epilepsy Study Group. A randomized, controlled trial of surgery for temporal-lobe epilepsy. N Engl J Med. 2001 Aug 2;345(5):311-8. PubMed PMID: 11484687.
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