Spinal magnetic resonance imaging artifacts in lumboperitoneal shunt surgery using adjustable valve implantation on the paravertebral spinal muscles.

BACKGROUND: Adjustable shunt valves that have been developed for managing hydrocephalus rely on intrinsically magnetic components ; thus, artifacts with these valves on magnetic resonance imaging (MRI) are inevitable. No studies on valve-induced artifacts in lumboperitoneal shunt (LPS) surgery have been published. Therefore, this study aimed to evaluate valve-induced artifacts in LPS. METHODS: We retrospectively reviewed all MRIs obtained between January 2023 and June 2023 in patients with an implanted Codman CERTAS Plus adjustable shunt valve (Integra Life Sciences, Princeton, New Jersey, USA). The valve was placed <1 cm subcutaneously on the paravertebral spinal muscle of the back, with its long axis perpendicular to the body axis. The scans were performed using a Toshiba Medical Systems 1.5 Tesla scanner. The in-plane artifact sizes were assessed as the maximum distance of the artifact from the expected region of the back. RESULTS: All spinal structures or spinal cords can be recognized, even with valve-induced artifacts. The median maximum valve-induced artifact distance on T1-weighted axial imaging was 25.63 mm (mean, 25.98 mm ; range, 22.24-30.94 mm). The median maximum valve-induced artifact distance on T2-weighted axial imaging was 25.56 mm (mean, 26.27 mm ; range, 21.83-29.53 mm). CONCLUSION: LPS surgery with adjustable valve implantation on paravertebral muscles did not cause valve-induced artifacts in the spine and spinal cord. We considered that LPS could simplify the postoperative care of these patients. J. Med. Invest. 71 : 154-157, February, 2024.

Delayed Diagnosis of Spinal Dural Arteriovenous Fistula: A Case Report and Scoping Review.

Spinal dural arteriovenous fistula (SDAVF) is among the most common arterial shunt diseases typically found in middle aged or older men. Herein, we aimed to clarify the reasons for misdiagnoses and delayed diagnoses of SDAVF, determine how these affect prognoses, and establish how they can be prevented. We conducted a PubMed/MEDLINE literature search using "spinal dural arteriovenous fistula", "delayed diagnosis", "late diagnosis", and "misdiagnosis" terms. We identified 18 articles, including 965 SDAVF cases. Patients were predominantly males (71.8-100.0%) (mean age: 53.5-71.0 years). Misdiagnoses rates varied (17.5-100.0%) and encompassed many conditions. The mean time between early manifestations and confirmed diagnosis was approximately 10-15 months and from the first radiologic image revealing dural arteriovenous fistula (DAVF) features to diagnosis was 9.2-20.7 months. Posttreatment outcomes showed a significant improvement in motor functions, gait, and micturition, particularly in patients exhibiting preoperative symptoms over a short period. SDAVF is frequently misdiagnosed or subject to delayed diagnosis, causing poor clinical outcomes. SDAVF symptoms including progressive lower-limb weakness, paresthesia, and vesicorectal dysfunction are indications for spinal magnetic resonance imaging with subsequent spinal angiography, wherein DAVF is evidenced by extensive T2 hyperintensity and flow-void abnormalities. We reported a representative case with delayed diagnosis.

Rare complication of lumboperitoneal shunt with distal catheter migration into the inguinal hernia sac in two adults: A case report.

Background: Despite the proven benefits of lumboperitoneal shunt (LPS) for idiopathic normal-pressure hydrocephalus, complications such as catheter migration remain a problem. Inguinal complications of the distal catheter are rare in adults, and their management is uncertain. Herein, we present two cases of distal catheter migration into the inguinal hernia sac after LPS in adults and recommend their management. Case Description: An 86-year-old man presented with inguinal swelling. In another 82-year-old man who did not show any improvement after LPS, shunt angiography revealed LPS dysfunction due to lumbar catheter occlusion and distal LPS catheter in the right inguinal hernia sac, and lumbar catheter reconstruction was performed. Both patients did not have any symptoms, except inguinal swelling, and were followed up. After 2 weeks and 4 days, the distal catheter moved into the peritoneal cavity. Conclusion: Inguinal complications due to the migration of the distal catheter into the inguinal hernia sac are rare in LPS because frequent movements of the distal catheter due to trunk rotation dislodge it from the inguinal hernia sac for a short period. Urgent surgery was not recommended because the catheter was moved in a short period and the patients did not wish to undergo hernia repair.

Surgical Treatment of Vertebral Compression Fracture in a Patient with Idiopathic Normal Pressure Hydrocephalus.

Idiopathic normal pressure hydrocephalus (iNPH) with gait disturbance can be effectively treated with a cerebrospinal fluid shunt. Furthermore, balloon kyphoplasty (BKP) is a successful minimally invasive treatment for osteoporotic vertebral compression fractures (VCFs). This case report presents the surgical management of an elderly patient with iNPH who presented after a VCF due to a fall. A 77-year-old woman who had been experiencing progressive gait disturbance for five years reported experiencing back pain one month after a fall. Imaging revealed a recent L1 VCF that did not compromise the spinal canal. Furthermore, the Mini-Mental State Examination results and the timed up-and-go test were 20 points and 17.96 seconds, respectively. Magnetic resonance imaging revealed ventriculomegaly with an Evans' index of 0.35. Her symptoms improved temporarily after a tap test, and she was diagnosed with probable iNPH. BKP was performed for VCFs, followed by the lumboperitoneal (LP) shunt placement for iNPH one month later. Following the operation, her symptoms improved without complications. After one month of performing BKP, an LP shunt would be placed to prevent shunt complications, such as infection and catheter-related neurological symptoms. Screening for iNPH in the elderly who present after VCFs due to a fall may identify iNPH patients who may benefit more from surgical treatments.

A case report of hydrocephalus due to diffuse villous hyperplasia of the choroid plexus: surgical treatment by combination a flexible videoscope with a rigid endoscope.

PURPOSE: Diffuse villous hyperplasia of the choroid plexus (DVHCP) and choroid plexus papilloma (CPP) are rare benign tumors usually diagnosed as a result of progressive hydrocephalus, especially in childhood. We present the case of a Japanese boy diagnosed with progressive hydrocephalus due to DVHCP. METHODS: Case: A 2-year and 3-month-old Japanese boy was found to have delayed motor development (equivalent to 1 year and 2 months old), an enlarged head circumference of 51 cm within + 1.5 standard deviation (S.D.), and incomplete closure of the anterior fontanel. The magnetic resonance imaging (MRI) showed lobular enlargement of the bilateral choroid plexuses extending from the trigone to the body and inferior horn of the lateral ventricle. The endoscopic choroid plexus coagulation surgery was performed to reduce the CSF formation rate. RESULTS: DVHCP was diagnosed both pathologically and clinically. Postoperatively, the patient progressed without complications, such as cerebrospinal fluid leakage. Although ventricular enlargement persisted, the anterior fontanel recessed, and the expansion of the head circumference stopped. CONCLUSION: Few cases of bilateral DVHCP and CPP have been reported in the literature. We encountered a case in which effective choroid plexus coagulation was performed for hydrocephalus due to DVHCP using less invasive endoscopic technique. It also represented an association between DVHCP and the gain of chromosome 9p.

A Case of Neonate with Split Cord Malformation Presenting with Hypoplasia of the Left Lower Extremity.

The frequency of split cord malformation (SCM) is approximately 1 in 5000 births; however, patients are rarely diagnosed with SCM in the neonatal period. Moreover, there have been no reports of SCM with hypoplasia of the lower extremities at birth. A 3-day-old girl was transferred to our hospital for a thorough examination of hypoplasia of the left lower extremity and lumbosacral abnormalities detected after birth. The spinal magnetic resonance imaging (MRI) revealed a split spinal cord in a single dural tube. Based on the MRI findings, the patient was diagnosed with SCM type II. Following discussions with the parents, pediatricians, neurosurgeons, psychologists, and social workers, we decided to perform untethering to prevent further neurological impairment after achieving a sufficient body weight. The patient was discharged on day 25 of life. Early diagnosis and intervention may improve the neurological prognosis in terms of motor function, bladder and bowel function, and superficial sensation; thus, clinicians should report infrequent findings that may lead to SCM diagnosis. SCM should be differentiated in patients with left-right differences in the appearance of the lower extremity, particularly in those with lumbosacral abnormalities.

Fact-Finding Survey of Treatment of Traumatic Brain Injury in Japan: Standardization of Care and Collaboration Between Neurosurgery and Emergency Departments.

BACKGROUND: Standardization of seamless treatment from prehospital injury care to initial injury and specialized care through collaboration among departments have been promoted in Japan since 2000. This survey was conducted to examine the current status of the system for treatment of traumatic brain injury (TBI) in Japan. METHODS: In February 2022, questionnaires on the treatment system and TBI care were sent to 869 facilities that participated in a training program held by the Japan Neurosurgical Society. Responses were received from 480 facilities (55.2%). These responses were compared with those in a similar survey performed in 2008. RESULTS: Among the responding facilities, 39.4% had neurosurgeons in emergency departments. Initial care for TBI was the responsibility of the neurosurgery department in 42.3% of the facilities, the emergency department in 26.0%, and jointly between these departments in 29.6%; and neurocritical care was managed by the neurosurgery department in 81.9%, the emergency department in 5.2%, and jointly in 12.1%. For patients with acute-phase TBI, intracranial pressure monitoring was performed in 72.1%. Active normothermia was performed in 86.0%, and decompressive craniectomy in 99.4%, as required. There was compliance with guidelines for treatment and management of TBI in 93.3%. CONCLUSIONS: Comparison with the 2008 results suggested role-sharing between 2 departments in TBI treatment is increasing. TBI treatment compliance with the guidelines was high. In-hospital mortality of Japanese patients with TBI has decreased since 2000. This may be due to the progress with standardization of TBI treatment and collaboration among departments in compliance with guidelines.

Hands-on neuroendovascular practice for nonselective undergraduate medical students increases interest and aspirations in pursuing neurosurgery as a specialization.

Background: The number of medical students aspiring to become neurosurgeons has decreased worldwide, mainly due to poor work-life balance among neurosurgeons; therefore, recruiting students for neurosurgery is essential to ensure the availability and appropriate quality of neurosurgical treatment. This study aimed to evaluate the efficacy of hands-on neuroendovascular practice for nonselective undergraduate medical students to determine whether this increases their interest in neurosurgery and contributes to their aspirations of becoming neurosurgeons. Methods: Hands-on neuroendovascular practice for mechanical thrombectomy was performed by undergraduate 5th-year medical students during their 2-week clinical rotation in the Department of neurosurgery at our university hospital between April 2021 and March 2023. After the neurosurgery practice, a questionnaire about their understanding of neurosurgery and aspirations for this specialization before and after the practice was anonymously completed by all students. Results: Overall, 153 students completed the questionnaire. Of these, 140 (91.5 %) showed increased interest in neurosurgery after participating in the hands-on practice. Through this practice, the number of students who considered neurosurgery as their first choice or one of their specialty choices increased from 8 (5.2%) to 12 (7.8%) (P = 0.3534) and from 19 (12.4%) to 52 (34.0%) (P < 0.0001), respectively. Furthermore, the number of students with no aspiration to become neurosurgeons decreased from 95 (62.1%) to 43 (28.1%) (P < 0.0001). Conclusion: Hands-on neuroendovascular practice for nonselective undergraduate medical students effectively increased their interest in neurosurgery specialization and their desire to become neurosurgeons. Therefore, this practice can help recruit medical students for neurosurgery specialization.

A Case of Suspected Radiation-Induced Meningioma That Developed 36 Years after Radiotherapy for a Suprasellar Tumor.

Recently, the improvements in the prognosis of childhood brain tumors have made it necessary to consider the risk of radiation-induced brain tumor development in long-term survivors. In this report, we describe a case of radiation-induced meningioma (RIM) treated surgically 36 years after radiotherapy. A 46-year-old woman, who underwent craniotomy for suprasellar germ cell tumor at 10 years of age with additional postoperative radiotherapy, was admitted to the emergency room with consciousness disturbance and right hemiplegia. One year earlier, magnetic resonance imaging (MRI) revealed a 1-cm diameter tumor in the left middle cranial fossa. This MRI showed an enlarged brain tumor in same lesion with clearly enhanced by gadolinium. A RIM located on a left sphenoid ridge with a fast growth rate was diagnosed, and the gross total removal was achieved by a left frontotemporal craniotomy. Histological diagnosis of atypical meningioma (World Health Organization grade II) was made. RIMs are frequently atypical, anaplastic meningiomas that have already been treated with radiotherapy, making additional postoperative radiotherapy difficult; the removal rate must be increased to achieve a good prognosis. In the case of long-term survivors after childhood radiotherapy, a strict follow-up with the occurrence of RIM in mind is necessary.

The development of a new, ultra-fine, and flexible neuroendoscope for intracranial observation.

Background: A neuroendoscope is a technical advance that allows surgeons to visualize certain regions of the brain that was previously inaccessible through the use of a surgical microscope. Several neuroendoscope designs have been implemented by other neurosurgeons over the past 5 years. The advantage of a neuroendoscope is the addition of a flexible and narrow tip that allows for safe entry into intracranial structures for clinical observation. However, there are some limitations to this approach. Here, we report the use of a modified angioscope as a newly developed neuroendoscope to be employed in observing intracranial structures. Methods: We report the use of an angioscope that is 1.8 mm in diameter and has both a thin and flexible tip. In this study, the angioscope was inserted into the lumen of an aspirator tube, and the tip of the device was placed at the intracranial area of intended observation area. Image findings were evaluated using an established in vivo goat brain model. Results: The angioscope was light in weight and maneuverable and could be reached and observed in the blind spot using a surgical microscope. From the cerebellopontine angle, the lower cranial nerves and trigeminal nerve could be observed, and from the cisterna magna, the floor of the fourth ventricle and the aqueduct could be seen. Conclusion: The angioscope is a useful instrument to observe intracranial locations safely and effectively even within a limited surgical field. Further modifications will be required to use the angioscope in various craniotomy procedures.

[Neuroendoscopic Third Ventriculostomy].

Endoscopy is essential in less invasive surgery and its use has widely expanded in almost all surgical specialties. This procedure has also been adopted for neurosurgery. It is now introduced in skull base surgery, expanded from endoscopic transsphenoidal surgery, to remove pituitary tumors, assisting tumor removal or removing a tumor only with the endoscope; spine surgery; and endoscopic third ventriculostomy(ETV). ETV is now accepted as a standard technique for treating noncommunicating hydrocephalus. Currently, 1067 neurosurgeons are certified by the Japan Society for Neuroendoscopy, and endoscopic surgery is recognized as a typical treatment option. This article describes the surgical procedure for ETV, a basic procedure for pediatric hydrocephalus. It is important to master intraventricular manipulation using the endoscope. Also, certain tips must be implemented before and after the endoscopic procedure to avoid complications. It is also necessary to emphasize the difference between adult cases, such as high risk of cerebrospinal fluid leakage in child cases. So that every single effort must be done to avoid this leak.

Abusive head trauma in Japan.

PURPOSE: Abusive head trauma (AHT) is a serious cause of morbidity and mortality in the pediatric population, especially in young infants. This review of the literature aimed to understand the characteristics of AHT in Japan. METHODS: PubMed and the Japanese database Ichuushi were searched to understand the differences in AHT between Japan and other countries. RESULTS: Shaking was identified as an uncommon cause of injury, while mothers were the most common perpetrator of pediatric AHT in Japan. Although uncommon in other countries, infantile subdural hematoma caused by an accidental slight head injury was reported in Japan. CONCLUSION: As in other countries, AHT is a major condition which pediatric neurosurgeons face in Japan. The mechanisms of injury and perpetrators of AHT seemed to differ slightly between western countries and Japan. Additionally, non-accidental infantile acute subdural hematoma was reported mainly in Japan. Therefore, further care and fair judgment is necessary when investigating child abuse in Japan.

Trigeminal neuropathy after tozinameran vaccination against COVID-19 in postmicrovascular decompression for trigeminal neuralgia: illustrative case.

BACKGROUND: Vaccines against coronavirus disease 2019 have a high level of efficacy and safety across all populations. However, numerous case series have been published on neurological disorders, including Bell's palsy, Guillain-Barre syndrome, transverse myelitis, and multiple sclerosis. The authors presented a case of trigeminal neuropathy after coronavirus vaccination in a patient who had undergone microvascular decompression (MVD) for trigeminal neuralgia (TN). OBSERVATIONS: A 77-year-old woman presented with acute trigeminal neuropathy after receiving a Pfizer-BioNtech vaccination (tozinameran) against severe acute respiratory syndrome coronavirus 2. The patient had undergone MVD for TN and the facial pain completely disappeared. One month later, she received the first injection of the tozinameran vaccine. Twelve hours after vaccination, she presented with numbness and pain induced by touching any place on the entire right face. No eruption was observed on her face. The serum herpes zoster virus antibodies were confirmed within the normal range. Magnetic resonance imaging revealed no abnormalities. The authors suspected a right trigeminal neuropathy after vaccination. Administration of carbamazepine and pregabalin improved TN but facial numbness persisted, especially in the mandibular division. LESSONS: The coronavirus is a possible etiology of secondary trigeminal neuropathy in the case of MVD for TN.

Small vestibular schwannoma presented with trigeminal neuralgia: illustrative case.

BACKGROUND: A vestibular schwannoma (VS) presenting with paroxysmal facial electric shock pain, that is, trigeminal neuralgia (TN), is relatively rare. Furthermore, TN is extremely rare in small VSs. OBSERVATIONS: Herein, the authors report the case of a 52-year-old woman with a complaint of right TN. Magnetic resonance (MR) imaging revealed a right VS of 12-mm diameter that compressed the trigeminal nerve. Although she did not report any hearing impairment, audiometry revealed decreased high-frequency range on the right side. The tumor was excised using the right retrosigmoid approach, and TN was confirmed to be caused by direct compression of the trigeminal nerve by the VS. Sufficient decompression of trigeminal nerve was done. The proximity of the trigeminal nerve root to the vestibular nerve root was the cause of TN. TN disappeared immediately after surgery, and there was no worsening of hearing impairment and facial paralysis. LESSONS: It is important to remember that TN may occur with direct tumor compression, even in small VSs. A preoperative 3-dimensional MR cisternogram/angiogram fusion image clearly showed direct tumor compression of the trigeminal nerve and the absence of responsible vessels, which was useful for surgical planning.

Unruptured aneurysm at bifurcation of super short middle cerebral artery mimicking duplicated middle cerebral artery aneurysm.

Background: Duplicated middle cerebral artery (DMCA) is a normal variation of the middle cerebral artery (MCA), and distinguishing DMCA from other arteries based only on the angiographical findings is sometimes difficult. Case Description: Preoperative angiography of a 60-year-old woman revealed two MCAs originating near the top of the right internal carotid artery and a 6-mm-sized aneurysm located between these two MCAs. The ipsilateral A1 segment of the anterior cerebral artery was not visualized due to hypoplasia. The patient was diagnosed with an unruptured aneurysm at the bifurcation between MCA and DMCA, preoperatively. However, during clipping surgery, the hypoplastic A1 segment was observed at approximately 2 mm proximal to the bifurcation of the MCA, indicating that these two MCAs were not "true" MCA and DMCA, but rather two normal MCA trunks bifurcated from the very short prebifurcation segment of M1. This difference in interpretation was due to the fact that the hypoplastic A1 was not visualized on preoperative examinations. The patient was discharged following the surgery without any neurological deficits. Conclusion: The distinction between DMCA and MCA trunks from the very short prebifurcation segment of MCA might be difficult, especially when the ipsilateral A1 segment is hypoplastic. Such an M1 with a length of 2-3 mm might be named super short M1. Thus, it is necessary to confirm the anatomy during aneurysm surgery.

In vivo goat brain model for neurosurgical training.

Background: Novice neurosurgeons require neurosurgical technique training, but the current method is demanding and time consuming. Therefore, it is crucial to perform training using an appropriate and informative method. In this report, we describe our attempts to provide training in neurosurgical techniques using goat in vivo brain model and to demonstrate the effectiveness of this model. Methods: Under general anesthesia, the surgery was performed on a male goat in the prone position. A midline liner skin incision was made in the scalp, six burr holes were drilled, a craniectomy was performed, and the dura was incised in an arcuate fashion. We attempted the interhemispheric approach and a retrosigmoid approach. Results: It was confirmed that common neurosurgical approaches are achievable in this model. Furthermore, anatomical structures such as nerves and blood vessels were similar to those of humans. Moreover, the goat brain was similar in color and texture to that of humans. Conclusion: Unlike a cadaver brain, in vivo brain requires hemostasis and careful dissection, which provides the surgeons a realistic experience of actual neurosurgery.

Recanalization for straight sinus thrombosis through combined mechanical thrombectomy: A case report.

Background: Systemic anticoagulation has been the standard treatment for cerebral venous sinus thrombosis (CVT). Although endovascular treatments, including mechanical thrombectomy (MT), have been reported to be effective for CVT, no clear evidence has been established. Case Description: A 51-year-old woman who had been administered oral contraceptive pills was transferred to our hospital with altered consciousness and disorientation. Computed tomography (CT) revealed a hyperdense signal in the straight sinus (StS), and CT angiography revealed a defect in the basal vein and StS, leading to a diagnosis of StS thrombosis. Although systemic anticoagulation through unfractionated heparin was performed, her neurological condition deteriorated, and venous ischemia was observed on CT the next day. She then underwent MT. Partial recanalization was achieved with an aspiration catheter and a stent retriever. Her neurological condition improved tremendously, and venous ischemia was reversed following MT. She was discharged 3 weeks later without neurological deficits with oral anticoagulant. Conclusion: This was a relatively rare case with CVT confined to StS. Immediate combined MT for StS thrombosis can improve venous circulation, make the venous ischemia reversible, and improve patient outcomes, even if it results in partial recanalization.

Intermediate nerve neuralgia developed during hemifacial spasm follow-up: illustrative case.

BACKGROUND: Intermediate nerve neuralgia (INN) is a rare condition believed to be caused by vascular compression, with external auditory canal pain as the chief symptom. The authors reported a rare case of a 78-year-old woman who developed INN during follow-up for hemifacial spasm (HFS). OBSERVATIONS: The patient had been receiving Botox treatment for right HFS for 20 years when she developed paroxysmal electric shock pain in the right external auditory canal and tinnitus induced by opening her mouth. A three-dimensional magnetic resonance fusion image showed the cisternal portion of the facial-vestibulocochlear nerve complex to be compressed by the meatal loop of the anterior inferior cerebellar artery (AICA), which was pressed against by the posterior inferior cerebellar artery. The authors diagnosed INN, and microvascular decompression (MVD) was performed. Surgical findings were consistent with preoperative neuroimaging. In addition, the proximal portion of the meatal loop of the AICA had passed between the facial and vestibulocochlear nerves, compressing both. The AICA was moved and the nerve completely decompressed. All symptoms improved immediately following surgery. LESSONS: When INN occurs during HFS follow-up, aggressive MVD should be considered based on detailed neuroimaging. This treatment is a very effective single-stage cure for INN, HFS, and vestibulocochlear symptoms.

A complete thrombotic large aneurysm at the nonbranching segment of the distal anterior cerebral artery mimicking a cavernous malformation: illustrative case.

BACKGROUND: Thrombotic aneurysms at the nonbranching segment of the distal anterior cerebral artery (ACA) are extremely rare and difficult to differentiate from cavernous malformations by radiographic features alone. OBSERVATIONS: Computed tomography and magnetic resonance imaging of a 30-year-old female patient with a chronic headache complaint revealed a 22-mm frontal lobe mass. The mass showed heterogeneous mixed intensity and hemosiderin deposits on magnetic resonance images. It was not visualized by conventional angiography, indicating that the mass and ACA/other vessels were not connected. The patient was preoperatively diagnosed with a cavernous malformation. However, during resection, the mass surface was white and smooth, different from a cavernous malformation. Although the mass was adherent to the pericallosal artery branch, no luminal continuity was observed. After detachment, the mass was completely resected. Pathological and immunohistochemical findings indicated a vessel wall and interior thrombus. The patient was rediagnosed with a thrombotic aneurysm at the distal ACA nonbranching segment and discharged 10 days postsurgery without neurological deficits. LESSONS: Because radiographic findings of thrombotic aneurysm and cavernous malformation are similar, mass lesions in contact with major arteries should be differentiated as thrombotic aneurysms, even when the artery lumen appears disconnected from the mass.

Unilateral C1 Posterior Arch Screw-C2 Laminar Screw Posterior Fixation for Vertebral Artery Preservation in Bow Hunter's Syndrome.

Pedicle or lateral mass screws, which are usually used to fix atlantoaxial instability, increase the risk of vertebral artery (VA) injury in patients with bone or arterial anomalies or osteoporotic bone. Here, we report the use of a unilateral C1 posterior arch screw-C2 laminar screw posterior fixation with a contralateral C1 lateral mass screw for VA preservation in a patient with bow hunter's syndrome (BHS). A 65-year-old male presented with recurrent loss of consciousness in the right rotational and backward-bending head positions for 1 year. Cerebral angiography in the same head position showed that the left VA was disrupted at C1/2 and the right VA was hypoplastic. The patient was diagnosed with BHS. C1-2 posterior fixation and iliac bone grafting were performed. The left VA was on the dominant side, and the VA was in a high position; thus, a C1 posterior arch screw was selected for the left side, a C1 lateral mass screw was selected for the right side, and a C2 laminar screw with O-arm navigation and a C-arm was used to prevent arterial injury. Intraoperative findings revealed no VA injury, and postoperative computed tomography showed the screw at the planned site. In a patient with BHS, posterior fixation with a unilateral C1 posterior arch screw-C2 laminar screw prevented VA injury because the screw could be inserted while avoiding the VA.