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Open access

Brainstem anesthesia during awake craniotomy: illustrative case

Yun Chen, Mei Sun, Hongmin Bai, Ruixin Yang, and Huan He

BACKGROUND

Awake craniotomy (AC) is performed to remove the lesions near or in eloquent areas, during which the patients are alert and without any airway instrument. Apnea is a severe complication in AC. Here, the authors describe a case of sudden apnea induced by unexpected local anesthesia of the brainstem during AC.

OBSERVATIONS

A 42-year-old male underwent AC for a large, recurrent, bilateral frontal lobe mass and experienced transient apnea and loss of brainstem reflexes during the surgery. The patient recovered spontaneous breath rhythm just a few minutes after the removal of a lidocaine cotton pledget, which was found near the patient’s midbrain. Then the patient awoke and cooperated to finish the surgery.

LESSONS

The administration of a local anesthetic subdurally in AC is common but risky. The scouring action of cerebral spinal fluid can spread those agents and cause unexpected brainstem anesthesia. A lower concentration of the anesthetic and keeping away from the cistern can make it safer.

Open access

The infundibulochiasmatic angle and the favorability of an endoscopic endonasal approach in type IV craniopharyngioma: illustrative case

Guilherme Finger, Maria Jose C Ruiz, Eman H Salem, Matthew D Marquardt, Kyle C Wu, Lucas P Carlstrom, Ricardo L Carrau, Luciano M Prevedello, and Daniel M Prevedello

BACKGROUND

Lesions located in the floor of the third ventricle are among the most difficult to access in neurosurgery. The neurovascular structures can limit transcranial exposure, whereas tumor extension into the third ventricle can limit visualization and access. The midline transsphenoidal route is an alternative approach to tumor invading the third ventricle if the tumor is localized at its anterior half and a working space between the optic apparatus and the pituitary infundibulum exists. The authors introduce the “infundibulochiasmatic angle,” a valuable measurement supporting the feasibility of the translamina terminalis endoscopic endonasal approach (EEA) for resection of type IV craniopharyngiomas.

OBSERVATIONS

Due to a favorable infundibulochiasmatic angle measurement on preoperative magnetic resonance imaging (MRI), an endoscopic endonasal transsellar transtubercular approach was performed to resect a type IV craniopharyngioma. At 2-month follow-up, the patient’s neurological exam was unremarkable, with improvement in bitemporal hemianopsia. Postoperative MRI confirmed gross-total tumor resection.

LESSONS

The infundibulochiasmatic angle is a radiological tool for evaluating the feasibility of EEA when resecting tumors in the anterior half of the third ventricle. Advantages include reduced brain retraction and excellent rates of resection, with minimal postoperative risks of cerebrospinal fluid leakage and permanent pituitary dysfunction.

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

Endoscopic endonasal repair of temporal lobe meningoencephalocele in the lateral recess of the sphenoid sinus, complicated by intracerebral hematoma: illustrative case

Rasim Agaev, Ekaterina Gormolysova, Anton Kalinovskiy, and Jamil Rzaev

BACKGROUND

Anomalies in the anatomical structure of the nasal cavity and paranasal sinuses often serve as a potential cause of spontaneous cerebrospinal fluid (CSF) leakage and may result in the development of a meningoencephalocele. In this report, the authors present a case of surgically treated intrasphenoidal meningoencephalocele attributed to the persistence of the lateral craniopharyngeal canal, which was further complicated by the occurrence of an intracerebral hematoma.

OBSERVATIONS

A temporal lobe meningoencephalocele located in the lateral recess of the sphenoid sinus was successfully managed using endoscopic endonasal transpterygoid repair (EETR). However, an intracerebral hematoma developed after resection of the meningoencephalocele, necessitating additional surgical interventions. Despite this complication, the patient exhibited a favorable clinical outcome after the surgical interventions.

LESSONS

This case highlights the potential risk of intracerebral hematoma associated with EETR of a lateral sphenoid sinus meningoencephalocele. A thorough examination of magnetic resonance imaging scans, especially identifying vascular structures, is crucial during surgical planning. This knowledge can help to prevent the occurrence of complications, including intracerebral hematoma.

Open access

Rare median and musculocutaneous nerve fusion with intraoperative electrical confirmation: illustrative case

Audrey Huang, Sima Vazquez, Jose Dominguez, Avinash Mohan, Jin Li, and Jared M Pisapia

BACKGROUND

Nerve transfer is a surgical technique in which a redundant or expendable fascicle is transferred or coapted to an injured nerve distal to the site of injury for the purpose of reinnervation. Successful nerve transfer is dependent on correct intraoperative identification of donor and recipient nerves.

OBSERVATIONS

An 8-year-old male was recommended for ulnar nerve fascicle to biceps branch of musculocutaneous nerve transfer to restore elbow flexion weakness after a demyelinating spinal cord injury. The biceps branch was identified approximately midway along the upper arm. Proximal musculocutaneous nerve stimulation induced hand movement and electromyography activity in the median nerve muscles. Neurolysis of the thickened proximal structure revealed fusion of the musculocutaneous and median nerves. Because of the proximity of the median and musculocutaneous nerves, median rather than ulnar nerve fascicles were used as donors for transfer.

LESSONS

The authors provide the first reported intraoperative finding of an anatomical variant in which the musculocutaneous nerve and median nerve were fused in the upper arm, confirmed through intraoperative electrical stimulation. Surgeons should be aware of this rare anatomical variant to ensure correct nerve identification when performing nerve transfers in the proximal upper extremity.

Open access

Middle meningeal artery pseudoaneurysm and pterygoid plexus fistula following percutaneous radiofrequency rhizotomy: illustrative case

Rahim Ismail, Derrek Schartz, Timothy Hoang, and Alexander Kessler

BACKGROUND

Percutaneous treatment for trigeminal neuralgia is a safe and effective therapeutic methodology and can be accomplished in the form of balloon compression, glycerol rhizotomy, and radiofrequency thermocoagulation. These procedures are generally well tolerated and demonstrate minimal associated morbidity. Moreover, vascular complications of these procedures are exceedingly rare.

OBSERVATIONS

We present the case of a 64-year-old female with prior microvascular decompression and balloon rhizotomy who presented after symptom recurrence and underwent a second balloon rhizotomy at our institution. Soon thereafter, she presented with pulsatile tinnitus and a right preauricular bruit on physical examination. Subsequent imaging revealed a middle meningeal artery (MMA) to pterygoid plexus fistula and an MMA pseudoaneurysm. Coil and Onxy embolization were used to manage the pseudoaneurysm and fistula.

LESSONS

This case illustrates the potential for MMA pseudoaneurysm formation as a complication of percutaneous trigeminal balloon rhizotomy, which has not been seen in the literature. Concurrent MMA-pterygoid plexus fistula is also a rarity demonstrated in this case.

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

Transvenous embolization for an intraosseous clival arteriovenous fistula via a proper access route guiding a three-dimensional fusion image: illustrative case

Yu Iida, Jun Suenaga, Nobuyuki Shimizu, Kaoru Shizawa, Ryosuke Suzuki, Shigeta Miyake, Taisuke Akimoto, Satoshi Hori, Kensuke Tateishi, Yasunobu Nakai, and Tetsuya Yamamoto

BACKGROUND

Intraosseous clival arteriovenous fistulas (AVFs), in which the shunt drains extracranially from the posterior and anterior condylar veins rather than from the cavernous sinus (CS), are rare. Targeting embolization of an intraosseous clival AVF is challenging because of its complex venous and skull base anatomy; therefore, a therapeutic strategy based on detailed preoperative radiological findings is required to achieve a favorable outcome. Here, the authors report the successful targeted embolization of an intraosseous clival AVF using an ingenious access route.

OBSERVATIONS

A 74-year-old woman presented with left-sided visual impairment, oculomotor nerve palsy, and right facial pain. A fusion image of three-dimensional rotational angiography and cone-beam computed tomography revealed a left CS dural AVF and a right intraosseous clival AVF. The shunt flow of the clival AVF drained extracranially from the posterior and anterior condylar veins via the intraosseous venous route. Transvenous embolization was performed by devising suboccipital, posterior condylar, and intraosseous access routes. The symptoms resolved after the bilateral AVFs were treated.

LESSONS

Accurate diagnosis and proper transvenous access based on detailed intraosseous and craniocervical venous information obtained from advanced imaging modalities are key to resolving intraosseous clival AVF.

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

Management of a challenging dura-embedded anterior inferior cerebellar artery loop during a retrosigmoid hearing-preserving vestibular schwannoma resection: microsurgical technique and operative video. Illustrative case

Jaime L. Martínez Santos, Robert C. Sterner, and Mustafa K. Başkaya

BACKGROUND

Anatomical variants of the anterior inferior cerebellar artery (AICA), such as an anomalous “AICA loop” embedded in the dura and bone of the subarcuate fossa, increase the complexity and risk of vestibular schwannoma resections. Classically, osseous penetrating AICA loops are the most challenging to mobilize, as the dura must be dissected and the surrounding petrous bone must be drilled to mobilize the AICA away from the surgical corridor and out of harm.

OBSERVATIONS

The authors present a rare case of a dura-embedded, osseous-penetrating AICA loop encountered during a hearing-preserving retrosigmoid approach in which they demonstrate safe and efficient microdissection and mobilization of the AICA loop without having to drill the surrounding bone.

LESSONS

Although preoperative recognition of potentially dangerous AICA loops has been challenging, thin-sliced petrous bone computed tomography scanning and high-quality magnetic resonance imaging can be useful in preoperative diagnosis. Furthermore, this report suggests that a retrosigmoid approach is superior, as it allows early intradural recognition and proximal vascular control and facilitates more versatile mobilization of AICA loops.