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Open access

Intraoperative application of indocyanine green and temporary venous occlusion test to assess collateral flow during microvascular decompression for venous-related trigeminal neuralgia: illustrative case

Kentaro Fujimoto, Yosuke Akamatsu, Yasumasa Nishikawa, and Kuniaki Ogasawara

BACKGROUND

In microvascular decompression (MVD) for vein-related trigeminal neuralgia (TN), determining whether transection of the offending vein is safe can be challenging. Here, the authors present a case of vein-related TN successfully treated by sacrificing the offending vein on the basis of findings from indocyanine green (ICG) video angiography and a temporary venous occlusion test to assess the collateral flow of the offending vessel.

OBSERVATIONS

A 43-year-old man presented with TN, which had failed to respond to previous medical therapy. Gadolinium-enhanced magnetic resonance imaging (MRI) revealed that the transverse or superior petrosal vein was the offending vein. The patient underwent MVD. Because the transposition of the offending vein was anatomically challenging, a temporary vein occlusion test was performed using ICG video angiography. During and after temporary occlusion, bidirectional flow in the offending vein was observed, suggesting collateral flow even after vein occlusion. On the basis of these findings, the offending vein was transected, resulting in relief from pain without any complications. Postoperative MRI revealed no new lesions in the brainstem or the cerebellar hemisphere. The patient has been free from neuralgia for 6 months.

LESSONS

The temporary vein occlusion test under ICG video angiography was useful for evaluating collateral flow in the offending vein in TN.

Open access

Cervicothoracic ventral-dorsal rhizotomy for bilateral upper-extremity hypertonia in cerebral palsy: illustrative case

Ryan Kelly, Hanna R Kemeny, Sunny Abdelmageed, Robin Trierweiler, Tim Krater, Melissa A LoPresti, and Jeffrey S Raskin

BACKGROUND

Management of medically refractory limb-specific hypertonia is challenging. Neurosurgical options include deep brain stimulation, intrathecal baclofen, thalamotomy, pallidotomy, or rhizotomy. Cervical dorsal rhizotomy has been successful in the treatment of upper-extremity spasticity. Cervical ventral and cervical ventral-dorsal rhizotomy (VDR) has been used in the treatment or torticollis and traumatic hypertonia; however, the use of cervicothoracic VDR for the treatment of upper-extremity mixed hypertonia is not well described.

OBSERVATIONS

A 9-year-old girl with severe quadriplegic mixed hypertonia secondary to cerebral palsy (CP) underwent cervicothoracic VDR. Modified Ashworth Scale scores, provision of caregiving, and examination improved. Treatment was well tolerated.

LESSONS

Cervicothoracic VDR can afford symptomatic and quality of life improvement in patients with medically refractory limb hypertonia. Intraoperative positioning and nuances in surgical techniques are particularly important based on spinal cord position as modified by scoliosis. Here, the first successful use of cervicothoracic VDR for the treatment of medically refractory upper-limb hypertonia in a pediatric patient with CP is described.

Open access

Optimization of direct cortical stimulation using tibial versus median nerve sensory mapping during midline brain tumor resection: illustrative case

Denmark Mugutso, Charles Warnecke, Lee Eric Tessler, Christopher J Pace, and Marat V Avshalumov

BACKGROUND

During brain tumor resection, neurophysiological mapping and monitoring help surgeons locate, characterize, and functionally assess eloquent brain areas in real time. The selection of mapping and monitoring targets has implications for successful surgery. Here, the authors compare direct cortical stimulation (DCS) as suggested by median nerve (MN) with posterior tibial nerve (PTN) cortical sensory mapping (SM) during mesial lesion resection.

OBSERVATIONS

Recordings from a 6-contact cortical strip served to generate an MN and a PTN sensory map, which indicated the strip was anterior to the central sulcus. Responses exhibited an amplitude gradient with no phase reversal (PR). DCS, elicited through a stimulus probe or contact(s) of the strip, yielded larger responses from the corresponding sensory mapped limb; that is, PTN SM resulted in larger lower limb muscle responses than those suggested by MN SM.

LESSONS

SM of the MN and PTN is effective for localizing eloquent cortical areas wherein the PTN is favored in surgery for mesial cortical tumors. The recorded amplitude of the cortical somatosensory evoked potential is a valuable criterion for defining the optimal location for DCS, despite an absent PR. The pathway at risk dictates the specifics of SM, which subsequently defines the optimal location for DCS.

Open access

Bilateral and asymmetrical localization of language function identified by the superselective infusion of propofol in an epilepsy patient with a mild malformation of cortical development: illustrative case

Mayuko Otomo, Shin-ichiro Osawa, Kyoko Suzuki, Kazuo Kakinuma, Kazushi Ukishiro, Hiroyoshi Suzuki, Kuniyasu Niizuma, Norio Narita, Nobukazu Nakasato, and Teiji Tominaga

BACKGROUND

Atypical localization of language function can result in unexpected postsurgical deficits after cortical resection, but it is difficult to predict the risk in the presurgical evaluation. The authors experienced a rare case of the bilateral and independent existence of different components of language function identified by segmented evaluation of anatomical anterior and posterior language areas using the superselective infusion of propofol.

OBSERVATIONS

A 32-year-old right-handed female presented with drug-resistant epilepsy. Comprehensive epilepsy evaluation suggested that the epileptic foci involved the whole left frontal lobe but provided less evidence of structural abnormality. To estimate the extent of functional deterioration likely to be caused by an extended left frontal lobectomy, the authors evaluated segmented cortical function in the ipsi- and contralateral hemispheres by the superselective infusion of propofol into the branches of the intracranial artery. The results revealed bilateral and asymmetrical localization of language function because the patient presented with different components of aphasia in each hemisphere. Based on the authors’ assessment of her functional tolerance, an extended left frontal lobectomy was performed and resulted in neurological deficits within the anticipated range.

LESSONS

An accurate understanding of the correlations between vascular and functional anatomy and the highly specific evaluation of language function provides more advanced presurgical assessment, allowing more tailored planning of cortical resection.

Open access

Stereoelectroencephalography in the setting of a previously implanted responsive neural stimulation device: illustrative case

Dorian M Kusyk, Nicholas Blaney, Timothy Quezada, and Alexander C Whiting

BACKGROUND

Responsive neural stimulation (RNS) is a relatively novel procedure for drug-resistant epilepsy, which involves implantation of a device into the skull and brain. As more devices are implanted, there may be an increasing need to perform intracranial electrocorticography in implant patients with persistent seizures. Given the device location, imaging difficulties with implanted devices, and other technical hurdles, stereoelectroencephalography (SEEG) could be especially challenging. The authors describe the first reported SEEG investigation in a patient with an RNS device, highlighting the technical challenges and clinical data ascertained.

OBSERVATIONS

A 41-year-old male with drug-resistant epilepsy presented several years after a local surgeon had placed an RNS device with two electrodes in the bilateral parieto-occipital lobes. Because of inadequate seizure control, the patient was offered a repeat SEEG investigation to characterize his epilepsy better. Although more technically challenging than a traditional SEEG implantation, the SEEG investigation was successfully performed, which led to a confirmation of bilateral hippocampal seizure onset. The patient underwent repositioning of his RNS leads with a significant decrease in his seizure frequency.

LESSONS

Concurrent implantation of SEEG electrodes in a functioning RNS device can be safely performed and can augment our understanding of a patient’s seizures.

Open access

Radiofrequency thermocoagulation for the treatment of trigeminal neuralgia associated with a focal pontine lesion: illustrative case

Vadym Biloshytsky, Anna Skorokhoda, Inna Buvailo, and Maryna Biloshytska

BACKGROUND

Trigeminal neuralgia (TN) associated with a focal pontine lesion is a rare but challenging condition. The origin of the lesion, which does not fulfill the diagnostic criteria for multiple sclerosis, remains disputable. Pain in such conditions is often refractory to treatment, including microvascular decompression.

OBSERVATIONS

A 36-year-old female presented with a 3.5-year history of shooting pain in the right V2 distribution triggered by talking and chewing. She became less responsive to high-dose carbamazepine over time. Magnetic resonance imaging (MRI) revealed no neurovascular compression but an elongated lesion hyperintense on T2-weighted imaging and T2- fluid-attenuated inversion recovery and hypointense and nonenhancing on T1-magnetization prepared rapid gradient-echo imaging without restricted diffusion, hemorrhage, or supposed malformation along the right pontine trigeminal pathway (PTP). Two other similar lesions were found in the corpus callosum and left thalamus. All lesions were stable compared to MRI data obtained 2 years before. Cerebrospinal fluid contained no oligoclonal bands. Pain attacks ceased with right-sided gasserian radiofrequency thermocoagulation (RFTC), and at the 6-month follow-up, there was no recurrence.

LESSONS

In patients with TN, preoperative neuroimaging should assess for brainstem lesions along the PTP. RFTC can be considered a treatment option in medication-refractory TN associated with a focal pontine lesion.

Open access

Effects of ventro-oral thalamic deep brain stimulation in a patient with musician’s dystonia: illustrative case

Fauve Poncelet, Sara Smeets, Takaomi Taira, Veerle Visser-Vandewalle, Wim Vandenberghe, Jana Peeters, Tine Van Bogaert, and Bart Nuttin

BACKGROUND

Musician’s dystonia is a task-specific focal hand dystonia characterized by involuntary contraction of muscles while playing a musical instrument. Current treatment options are often insufficient.

OBSERVATIONS

We present the effects of ventro-oral thalamic deep brain stimulation in a patient with musician’s dystonia. The patient was a 67-year-old pianist with musician’s dystonia who underwent deep brain stimulation with the ventralis oralis anterior and posterior nuclei of the thalamus as targets. The Tubiana and Chamagne rating scale was used to evaluate the effects of stimulation. The outcome was evaluated independently by four clinicians in a blinded manner at 3 months postoperatively. There was a distinct reduction of symptoms during stimulation. At 15 months postoperatively, the beneficial effect remained. No lasting side effects were observed.

LESSONS

Further studies are warranted to evaluate the safety and long-term efficacy of this treatment modality.

Open access

Pterygoid venous plexus anastomosis in trigeminal percutaneous glycerol rhizotomy: illustrative case

Kevin Cordeiro, Jason Kim, Niall Buckley, Mark Kraemer, Conrad Pun, and Daniel Resnick

BACKGROUND

Percutaneous glycerol rhizotomy (PGR) is a common, effective, and relatively safe treatment for trigeminal neuralgia that is refractory to medical management. Anastomotic skull base venous anatomy should be considered when delivering percutaneous agents.

OBSERVATIONS

The authors report an anastomotic connection, not previously described in the literature, between the bilateral pterygoid venous plexuses upon air injection during PGR with computed tomography (CT) guidance for trigeminal neuralgia. Pertinent microsurgical and skull base venous anatomy is reviewed.

LESSONS

Anastomoses between the pterygoid venous plexuses present a potential passage for materials used during PGR to reach unintended contralateral neurovascular structures. The use of CT guidance may identify this anastomotic connection and decrease the likelihood of an aberrant flow of materials used during the PGR.

Open access

Utilization of three-dimensional fusion images with high-resolution computed tomography angiography for preoperative evaluation of microvascular decompression: patient series

Takamitsu Iwata, Koichi Hosomi, Naoki Tani, Hui Ming Khoo, Satoru Oshino, and Haruhiko Kishima

BACKGROUND

High-resolution computed tomography (CT), outfitted with a 0.25-mm detector, has superior capability for identifying microscopic anatomical structures compared to conventional CT. This study describes the use of high-resolution computed tomography angiography (CTA) for preoperative microvascular decompression (MVD) assessment and explores the potential effectiveness of three-dimensional (3D) image fusion with magnetic resonance imaging (MRI) by comparing it with traditional imaging methods.

OBSERVATIONS

Four patients who had undergone preoperative high-resolution CTA and MRI for MVD at Osaka University Hospital between December 2020 and March 2022 were included in this study. The 3D-reconstructed images and intraoperative findings were compared. One patient underwent conventional CTA, thus allowing for a comparison between high-resolution and conventional CTA in terms of radiation exposure and vascular delineation. Preoperative simulations reflected the intraoperative findings for all cases; small vessel compression of the nerve was identified preoperatively in two cases.

LESSONS

Compared with conventional CTA, high-resolution CTA showed superior vascular delineation with no significant change in radiation exposure. The use of high-resolution CTA with reconstructed 3D fusion images can help to simulate prior MVD. Knowing the location of the nerves and blood vessels can perioperatively guide neurosurgeons.

Open access

A new strategy for treating drug-resistant focal aware seizures: thalamic specific nuclei deep brain stimulation. Illustrative case

Osvaldo Vilela-Filho, Hélio F. Silva-Filho, Lissa C. Goulart, Paulo C. Ragazzo, and Francisco M. Arruda

BACKGROUND

Focal aware seizures (FASs) are relatively common and frequently pharmaco-resistant. If the seizure onset zone (SOZ) is in eloquent cortical areas, making resective surgery risky and inadvisable, deep brain stimulation (DBS) of the anterior nucleus of the thalamus, which is efficacious in less than half of the cases, has been the main alternative. New targets should be searched to address this deficiency. The present study aims to determine if DBS of different thalamic specific nuclei can modulate the abnormal electrical activity of the SOZ located in their respective cortical projection areas. Herein, the authors present the first patient in an ongoing trial.

OBSERVATIONS

A 60-year-old female patient presented with 25-year history of pharmaco-resistant focal aware visual seizures frequently evolving to focal impaired awareness seizures. The SOZ was in the right occipital lobe (positron emission tomography-computed tomography/video electroencephalography). Magnetic resonance imaging was normal. She underwent ipsilateral lateral geniculate nucleus (LGN) DBS procedure. After a 24-month follow-up, seizure frequency decreased by 97%, improving quality of life and daily functioning without complications.

LESSONS

This is the first time the LGN has been targeted in humans. The results support the hypothesis that led to this study. This strategy represents a paradigm shift in the way of treating pharmaco-resistant FASs not amenable to resective surgery.