Simultaneous Motor and Visual Intraoperative Neuromonitoring in Asleep Parietal Lobe Surgery: Dual Strip Technique

Devika Rajashekar; Jose Pedro Lavrador; Prajwal Ghimire; Hannah Keeble; Lauren Harris; Noemia Pereira; Sabina Patel; Ahmad Beyh; Richard Gullan; Keyoumars Ashkan; Ranjeev Bhangoo; Francesco Vergani

doi:10.3390/jpm12091478

Simultaneous Motor and Visual Intraoperative Neuromonitoring in Asleep Parietal Lobe Surgery: Dual Strip Technique

Devika Rajashekar, Jose Pedro Lavrador, Prajwal Ghimire^*, Hannah Keeble, Lauren Harris, Noemia Pereira, Sabina Patel, Ahmad Beyh, Richard Gullan, Keyoumars Ashkan, Ranjeev Bhangoo, Francesco Vergani

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

4 Citations (Scopus)

Abstract

Background: The role played by the non-dominant parietal lobe in motor cognition, attention and spatial awareness networks has potentiated the use of awake surgery. When this is not feasible, asleep monitoring and mapping techniques should be used to achieve an onco-functional balance. Objective: This study aims to assess the feasibility of a dual-strip method to obtain direct cortical stimulation for continuous real-time cortical monitoring and subcortical mapping of motor and visual pathways simultaneously in parietal lobe tumour surgery. Methods: Single-centre prospective study between 19 May–20 November of patients with intrinsic non-dominant parietal-lobe tumours. Two subdural strips were used to simultaneously map and monitor motor and visual pathways. Results: Fifteen patients were included. With regards to motor function, a large proportion of patients had abnormal interhemispheric resting motor threshold ratio (iRMTr) (71.4%), abnormal Cortical Excitability Score (CES) (85.7%), close distance to the corticospinal tract—Lesion-To-Tract Distance (LTD)—4.2 mm, Cavity-To-Tract Distance (CTD)—7 mm and intraoperative subcortical distance—6.4 mm. Concerning visual function, the LTD and CTD for optic radiations (OR) were 0.5 mm and 3.4 mm, respectively; the mean intensity for positive subcortical stimulation of OR was 12 mA ± 2.3 mA and 5/6 patients with deterioration of VEPs > 50% had persistent hemianopia and transgression of ORs. Twelve patients remained stable, one patient had a de-novo transitory hemiparesis, and two showed improvements in motor symptoms. A higher iRMTr for lower limbs was related with a worse motor outcome (p = 0.013) and a longer CTD to OR was directly related with a better visual outcome (p = 0.041). At 2 weeks after hospital discharge, all patients were ambulatory at home, and all proceeded to have oncological treatment. Conclusion: We propose motor and visual function boundaries for asleep surgery of intrinsic non-dominant parietal tumours. Pre-operative abnormal cortical excitability of the motor cortex, deterioration of the VEP recordings and CTD < 2 mm from the OR were related to poorer outcomes.

Original language	English
Article number	1478
Journal	Journal of Personalized Medicine
Volume	12
Issue number	9
DOIs	https://doi.org/10.3390/jpm12091478
Publication status	Published - Sept 2022

Keywords

corticospinal tract
intra-operative neuro-monitoring
optic radiations
parietal lobe
subdural strip electrodes
tractography
transcranial magnetic stimulation

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10.3390/jpm12091478

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@article{52a34214ad8a456e95bc72adf016e3e7,

title = "Simultaneous Motor and Visual Intraoperative Neuromonitoring in Asleep Parietal Lobe Surgery: Dual Strip Technique",

abstract = "Background: The role played by the non-dominant parietal lobe in motor cognition, attention and spatial awareness networks has potentiated the use of awake surgery. When this is not feasible, asleep monitoring and mapping techniques should be used to achieve an onco-functional balance. Objective: This study aims to assess the feasibility of a dual-strip method to obtain direct cortical stimulation for continuous real-time cortical monitoring and subcortical mapping of motor and visual pathways simultaneously in parietal lobe tumour surgery. Methods: Single-centre prospective study between 19 May–20 November of patients with intrinsic non-dominant parietal-lobe tumours. Two subdural strips were used to simultaneously map and monitor motor and visual pathways. Results: Fifteen patients were included. With regards to motor function, a large proportion of patients had abnormal interhemispheric resting motor threshold ratio (iRMTr) (71.4%), abnormal Cortical Excitability Score (CES) (85.7%), close distance to the corticospinal tract—Lesion-To-Tract Distance (LTD)—4.2 mm, Cavity-To-Tract Distance (CTD)—7 mm and intraoperative subcortical distance—6.4 mm. Concerning visual function, the LTD and CTD for optic radiations (OR) were 0.5 mm and 3.4 mm, respectively; the mean intensity for positive subcortical stimulation of OR was 12 mA ± 2.3 mA and 5/6 patients with deterioration of VEPs > 50% had persistent hemianopia and transgression of ORs. Twelve patients remained stable, one patient had a de-novo transitory hemiparesis, and two showed improvements in motor symptoms. A higher iRMTr for lower limbs was related with a worse motor outcome (p = 0.013) and a longer CTD to OR was directly related with a better visual outcome (p = 0.041). At 2 weeks after hospital discharge, all patients were ambulatory at home, and all proceeded to have oncological treatment. Conclusion: We propose motor and visual function boundaries for asleep surgery of intrinsic non-dominant parietal tumours. Pre-operative abnormal cortical excitability of the motor cortex, deterioration of the VEP recordings and CTD < 2 mm from the OR were related to poorer outcomes.",

keywords = "corticospinal tract, intra-operative neuro-monitoring, optic radiations, parietal lobe, subdural strip electrodes, tractography, transcranial magnetic stimulation",

author = "Devika Rajashekar and Lavrador, {Jose Pedro} and Prajwal Ghimire and Hannah Keeble and Lauren Harris and Noemia Pereira and Sabina Patel and Ahmad Beyh and Richard Gullan and Keyoumars Ashkan and Ranjeev Bhangoo and Francesco Vergani",

note = "Publisher Copyright: {\textcopyright} 2022 by the authors.",

year = "2022",

month = sep,

doi = "10.3390/jpm12091478",

language = "English",

volume = "12",

journal = "Journal of Personalized Medicine",

publisher = "Multidisciplinary Digital Publishing Institute (MDPI)",

number = "9",

}

TY - JOUR

T1 - Simultaneous Motor and Visual Intraoperative Neuromonitoring in Asleep Parietal Lobe Surgery

T2 - Dual Strip Technique

AU - Rajashekar, Devika

AU - Lavrador, Jose Pedro

AU - Ghimire, Prajwal

AU - Keeble, Hannah

AU - Harris, Lauren

AU - Pereira, Noemia

AU - Patel, Sabina

AU - Beyh, Ahmad

AU - Gullan, Richard

AU - Ashkan, Keyoumars

AU - Bhangoo, Ranjeev

AU - Vergani, Francesco

PY - 2022/9

Y1 - 2022/9

N2 - Background: The role played by the non-dominant parietal lobe in motor cognition, attention and spatial awareness networks has potentiated the use of awake surgery. When this is not feasible, asleep monitoring and mapping techniques should be used to achieve an onco-functional balance. Objective: This study aims to assess the feasibility of a dual-strip method to obtain direct cortical stimulation for continuous real-time cortical monitoring and subcortical mapping of motor and visual pathways simultaneously in parietal lobe tumour surgery. Methods: Single-centre prospective study between 19 May–20 November of patients with intrinsic non-dominant parietal-lobe tumours. Two subdural strips were used to simultaneously map and monitor motor and visual pathways. Results: Fifteen patients were included. With regards to motor function, a large proportion of patients had abnormal interhemispheric resting motor threshold ratio (iRMTr) (71.4%), abnormal Cortical Excitability Score (CES) (85.7%), close distance to the corticospinal tract—Lesion-To-Tract Distance (LTD)—4.2 mm, Cavity-To-Tract Distance (CTD)—7 mm and intraoperative subcortical distance—6.4 mm. Concerning visual function, the LTD and CTD for optic radiations (OR) were 0.5 mm and 3.4 mm, respectively; the mean intensity for positive subcortical stimulation of OR was 12 mA ± 2.3 mA and 5/6 patients with deterioration of VEPs > 50% had persistent hemianopia and transgression of ORs. Twelve patients remained stable, one patient had a de-novo transitory hemiparesis, and two showed improvements in motor symptoms. A higher iRMTr for lower limbs was related with a worse motor outcome (p = 0.013) and a longer CTD to OR was directly related with a better visual outcome (p = 0.041). At 2 weeks after hospital discharge, all patients were ambulatory at home, and all proceeded to have oncological treatment. Conclusion: We propose motor and visual function boundaries for asleep surgery of intrinsic non-dominant parietal tumours. Pre-operative abnormal cortical excitability of the motor cortex, deterioration of the VEP recordings and CTD < 2 mm from the OR were related to poorer outcomes.

AB - Background: The role played by the non-dominant parietal lobe in motor cognition, attention and spatial awareness networks has potentiated the use of awake surgery. When this is not feasible, asleep monitoring and mapping techniques should be used to achieve an onco-functional balance. Objective: This study aims to assess the feasibility of a dual-strip method to obtain direct cortical stimulation for continuous real-time cortical monitoring and subcortical mapping of motor and visual pathways simultaneously in parietal lobe tumour surgery. Methods: Single-centre prospective study between 19 May–20 November of patients with intrinsic non-dominant parietal-lobe tumours. Two subdural strips were used to simultaneously map and monitor motor and visual pathways. Results: Fifteen patients were included. With regards to motor function, a large proportion of patients had abnormal interhemispheric resting motor threshold ratio (iRMTr) (71.4%), abnormal Cortical Excitability Score (CES) (85.7%), close distance to the corticospinal tract—Lesion-To-Tract Distance (LTD)—4.2 mm, Cavity-To-Tract Distance (CTD)—7 mm and intraoperative subcortical distance—6.4 mm. Concerning visual function, the LTD and CTD for optic radiations (OR) were 0.5 mm and 3.4 mm, respectively; the mean intensity for positive subcortical stimulation of OR was 12 mA ± 2.3 mA and 5/6 patients with deterioration of VEPs > 50% had persistent hemianopia and transgression of ORs. Twelve patients remained stable, one patient had a de-novo transitory hemiparesis, and two showed improvements in motor symptoms. A higher iRMTr for lower limbs was related with a worse motor outcome (p = 0.013) and a longer CTD to OR was directly related with a better visual outcome (p = 0.041). At 2 weeks after hospital discharge, all patients were ambulatory at home, and all proceeded to have oncological treatment. Conclusion: We propose motor and visual function boundaries for asleep surgery of intrinsic non-dominant parietal tumours. Pre-operative abnormal cortical excitability of the motor cortex, deterioration of the VEP recordings and CTD < 2 mm from the OR were related to poorer outcomes.

KW - corticospinal tract

KW - intra-operative neuro-monitoring

KW - optic radiations

KW - parietal lobe

KW - subdural strip electrodes

KW - tractography

KW - transcranial magnetic stimulation

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U2 - 10.3390/jpm12091478

DO - 10.3390/jpm12091478

M3 - Article

AN - SCOPUS:85138658822

VL - 12

JO - Journal of Personalized Medicine

JF - Journal of Personalized Medicine

IS - 9

M1 - 1478

ER -

Simultaneous Motor and Visual Intraoperative Neuromonitoring in Asleep Parietal Lobe Surgery: Dual Strip Technique

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