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Year : 2020  |  Volume : 68  |  Issue : 3  |  Page : 586--587

Visual Memory in People with Epilepsy- The Neglected Front!!

Bhargavi Ramanujan, Manjari Tripathi 
 Department of Neurology, AIIMS, Delhi, India

Correspondence Address:
Dr. Manjari Tripathi
Neurology, AIIMS, Delhi
India




How to cite this article:
Ramanujan B, Tripathi M. Visual Memory in People with Epilepsy- The Neglected Front!!.Neurol India 2020;68:586-587


How to cite this URL:
Ramanujan B, Tripathi M. Visual Memory in People with Epilepsy- The Neglected Front!!. Neurol India [serial online] 2020 [cited 2020 Sep 28 ];68:586-587
Available from: http://www.neurologyindia.com/text.asp?2020/68/3/586/289020


Full Text



Cognitive impairment is known to occur in persons with epilepsy (PWE); certain aspects of cognition, like executive functions, language and memory may particularly be affected, as has been reported in the literature. This comorbidity may be a part of the primary syndrome of epilepsy or due to recurrent seizures interfering with the formation of new memories, or related to the antiepileptic medications being chronically consumed by these individuals. Memory deficits are well studied, particularly among people with temporal lobe epilepsies, drug-resistant epilepsies (DRE)- especially before and after temporal lobe surgeries in adults as well as in children.[1] However, most studies have assessed overall, autobiographic or verbal memory; few have assessed visual memory in the cohort of adults with epilepsy.

Visual memory is the ability to store what has been visually perceived and is thus different from verbal memory, which is the 'memory of words' or presented spoken material. The authors of the paper “Prevalence and Factors Influencing Visual Memory Dysfunction among Epilepsy Patients- A Single Center Study” have assessed visual memory among PWE, and have found that over a third of their subjects had 'extremely low' visual memory scores. They have also noted that certain factors, like older age, long duration of epilepsy, multiple antiepileptic drug-intake, combined focal and generalized epilepsy, may be predictive of lower visual memory in this cohort.[2]

Visual memory is traditionally known to be the function of the right medial temporal region, and may presumably be affected in PWE with seizure onset zones in this region. It would, therefore, be important to know the effect of right temporal lobe resection on memory. Sanyalet al. found that PWE with good seizure outcomes after right temporal lobectomy had significantly better overall memory scores compared to baseline. At the same time, those with poor seizure outcomes did not. However, they did not observe such a relationship in the case of left temporal lobe surgeries.[3]

Chaudharyet al., in their fMRI-based study, reported activation in right superior temporal gyrus, bilateral insula, and right cerebral parahippocampal gyrus, during a verbal memory task in persons with drug-resistant epilepsy after left temporal lobectomy, which was different from the activation before surgery- mostly unilateral.[4] This shows how the reorganization of cortical functions takes place, after a surgery to remove the epileptogenic zone, and how it may help lower the deficits incurred afterwards.

Barbaroet al. studied verbal memory among English-speaking PWE who underwent surgery (temporal lobectomy) in the language-dominant hemisphere. Nine (64%) patients who underwent stereotactic radiosurgery and 3 (43%) open anterior temporal lobectomy patients were spared from consistent deficits in verbal memory after surgery, on follow-up.[5] Even the mathematical prowess of a young man with special calendar-like skills and left mesial temporal sclerosis, that could be preserved as reported by Bajajet al. In this patient, left temporal lobectomy was planned after fMRI evaluation showed a bilateral representation of memory. The surgery did not result in any worsening of memory, which may, in fact, improve on long-term follow up.[6]

Therefore, memory – both verbal and visual, may be affected in all PWE. Several predictive factors could help epileptologists plan or prognosticate their risks of developing deficits.

References

1Dwivedi R, Ramanujam B, Chandra PS, Sapra S, Gulati S, Kalaivani M, Garg A, Bal CS, Tripathi M, Dwivedi SN, Sagar R, Sarkar C, Tripathi M. Surgery for Drug-Resistant Epilepsy in Children. N Engl J Med 2017;377:1639-47.
2Beh HC, Tan HJ, Hod R, Khoo CS, Mohamad K. Prevalence and Factors Influencing Visual Memory Dysfunction Among Epilepsy Patients— A Single Center Study. Neurol India 2020;68:581-5.
3Sanyal SK, Chandra PS, Gupta S, Tripathi M, Singh VP, Jain Set al. Memory and intelligence outcome following surgery for intractable temporal lobe epilepsy: Relationship to seizure outcome and evaluation using a customized neuropsychological battery. Epilepsy Behav 2005;6:147-55.
4a. Chaudhary K, Kumaran SS, Chandra SP, Wadhawan AN, Tripathi M. Mapping of cognitive functions in chronic intractable epilepsy: Role of fMRI. Indian J Radiol Imaging. 2014;24:51-6. b. Chaudhary K, Tripathi M, Chandra SP, Nehra A, Kumaran SS. Evaluation of memory in persons with mesial temporal lobe sclerosis: A combined fMRI and VBM study. J Biosci. 2020;45:74.
5Barbaro NM, Quigg M, Ward MM, Chang EF, Broshek DK, Langfitt JT,et al. Radiosurgery versus open surgery for mesial temporal lobe epilepsy: The randomized, controlled ROSE trial. Epilepsia 2018;59:1198-207.
6Bajaj J, Chaudhary K, Chandra PS, Ramanujam B, Girishan S, Doddamani R,et al. Left Temporal Lobectomy Using Functional MRI in a Math Genius: A Case Report. Neurol India 2020;68:170-2.