Cerebral Ischemia as an Apparent Complication of Anterior Cervical Discectomy in a Patient with an Incomplete Circle of Willis

Contralateral Middle Cerebral Artery Territory Infarction After Anterior Cervical Diskectomy and Fusion: A Case Report

CASE

A 70-year-old man underwent anterior cervical diskectomy and fusion (ACDF) of the C3/4 and C4/5 levels by a left-sided approach to address canal stenosis causing right arm weakness. Intraoperative neuromonitoring demonstrated an intermittent decrease in left-sided motor signals. Postoperatively, the patient experienced a right middle cerebral artery stroke. At the 1-year follow-up, right arm strength had improved, but there was persistent left-sided weakness due to stroke.

CONCLUSION

Although rare, possible intraoperative stroke should be considered when there are changes in motor or sensory evoked potentials. In addition, considerations should be given to pursue carotid stenosis screening in patients undergoing ACDF with known atherosclerosis or stroke history.

A new classification system for the anatomical variations of the human circle of Willis: A systematic review

The circle of Willis (CoW) is an anastomotic arterial network located on the base of the brain. Studies have shown that it demonstrates considerable anatomical variation in humans. This systematic review aimed to identify and catalogue the described anatomical variations of the CoW in humans to create a new, comprehensive variation classification system. An electronic literature search of five databases identified 5899 studies. A two‐phase screening process was performed, and studies underwent quality assessment. A total of 42 studies were included in the review. Data were extracted and circles were reconstructed digitally using graphics software. The classification system contains 82 CoW variations in five continuous groups. Group one contains 24 circles with one or more hypoplastic segments only. Group two contains 11 circles with one or more absent segments only. Group three contains 6 circles with hypoplastic and absent segments only. Group four contains 26 circles with one or more accessory segments. Group five contains 15 circles with other types of anatomical variation. Within each group, circles were subcategorised according to the number or type of segments affected. An original coding system was created to simplify the description of anatomical variations of the CoW. The new classification system provides a comprehensive ontology of the described anatomical variations of the CoW in humans. When used with the coding system, it allows the description and categorisation of recorded and unrecorded variants identified in past and future studies. It is applicable to current clinical practice and the anatomical community, including human anatomy education and research.

Delayed cerebral infarct following anterior cervical diskectomy and fusion

Background:

Ischemic stroke following anterior cervical diskectomy and fusion (ACDF) is an exceedingly rare complication. There are only three previous cases focusing on this problem in the literature; here, we present the fourth case.

Case Description:

A patient, cared for at an outside institution, developed a delayed ischemic stroke 3 days following an ACDF. This complication was attributed to carotid manipulation precipitating vascular injury in the setting of multiple comorbid vascular and coagulopathic risk factors, including previously undiagnosed carotid atherosclerosis, a prior history of pulmonary embolus requiring Warfarin anticoagulation (held perioperatively), acute dehydration, and atrial fibrillation.

Conclusions:

This case demonstrates the importance of focused history and examination in appropriate patients prior to ACDF, with special consideration given to the significance of age, comorbidities including coagulopathy and arrhythmia, and potential underlying vascular disease as markers for increased risk of perioperative thrombotic stroke associated with carotid manipulation. Patients at higher risk warrant comprehensive preoperative assessment, including medical evaluation, carotid imaging, and consideration for alternative surgical approaches.

Somatosensory evoked potential monitoring detection of carotid compression during ACDF surgery in a patient with a vascularly isolated hemisphere

The authors report herein a case of anterior cervical discectomy and fusion (ACDF) surgery in which findings on somatosensory evoked potential (SSEP) monitoring led to the correction of carotid artery compression in a patient with a vascularly isolated hemisphere (no significant collateral blood vessels to the carotid artery territory). The amplitude of the cortical SSEP component to left ulnar nerve stimulation progressively decreased in multiple runs, but there were no changes in the cervicomedullary SSEP component to the same stimulus. When the lateral (right-sided) retractor was removed, the cortical SSEP component returned to baseline. The retraction was then intermittently relaxed during the rest of the operation, and the patient suffered no neurological morbidity. Magnetic resonance angiography demonstrated a vascularly isolated right hemisphere. During anterior cervical spine surgery, carotid artery compression by the retractor can cause hemispheric ischemia and infarction in patients with inadequate collateral circulation. The primary purpose of SSEP monitoring during ACDF surgery is to detect compromise of the dorsal column somatosensory pathways within the cervical spinal cord, but intraoperative SSEP monitoring can also detect hemispheric ischemia. Concurrent recording of cervicomedullary SSEPs can help differentiate cortical SSEP changes due to hemispheric ischemia from those due to compromise of the dorsal column pathways. If there are adverse changes in the cortical SSEPs but no changes in the cervicomedullary SSEPs, the possibility of hemispheric ischemia due to carotid artery compression by the retractor should be considered.

Pharyngoesophageal perforation 3 years after anterior cervical spine surgery: a rare case report and literature review

Pharyngoesophageal perforation after anterior cervical spine surgery is rare and the delayed cases were more rarely reported but potentially life-threatening. We report a case of pharyngoesophageal perforation 3 years after anterior cervical spine surgery. The patient presented with dysphagia, fever, left cervical mass and developing dyspnea 3 years after cervical spine surgery for trauma. After careful examinations, he underwent an emergency tracheostomy, neck exploration, hardware removal, abscess drainage and infected tissue debridement. 14 days after surgery, CT of the neck with oral contrast demonstrated no contrast extravasation from the esophagus. Upon review of literature, only 14 cases of pharyngoesophageal perforation more than 1 year after anterior cervical spine surgery were found. We discussed possible etiology, diagnosis and management and concluded that in cases of dysphagia, dyspnea, cervical pain, swelling and edema of the cervical area even long time after anterior cervical spine surgery, potential pharyngoesophageal damage should be considered.

Internal carotid artery dissection after anterior cervical disc replacement: first case report and literature review of vascular complications of the approach

We report the case of a 41-year-old woman who underwent cervical total disc replacement at C4C5 and C5C6 levels and fusion at C6C7 level through an anterior right-side approach. After anesthesia recovery, the patient presented left hemiparesia and facial palsy due to large right hemispheric stroke. Diffusion-weighted magnetic resonance imaging was performed as soon as the patient developed neurologic symptoms of stroke and revealed a right internal carotid artery dissection. Digital substraction angiography, endovascular stenting, angioplasty and thrombectomy were performed. Six months after treatment, clinical examination showed mild left-arm spasticity. To the best of our knowledge, only two cases of internal carotid artery stroke without dissection or thrombosis are reported. In conclusion, although vascular complications are rare after anterior cervical spine procedure, internal carotid artery dissection can occur. Suspected risk factors are prolonged retraction of the carotid artery and neck extension.

An anterior cervical retractor utilizing a novel principle

The alarmingly high soft-tissue complication rates after anterior cervical surgery suggests that the design of current retractors is inadequate. A review of retractor design and consideration of new designs is worthwhile. The author reviewed the literature and the 7 described devices (Cloward, Caspar, Thompson-Farley, Tresserras, Ozer, Takayasu, and Oh devices). With the exception of Cloward/Caspar and Thomson-Farley systems, the author's search of the literature failed to disclose any independent review or investigations of the other retractors, suggesting that the use of these devices is limited. The Cloward/Caspar-style retractors depend for stability on small teeth at the ends of the blades that impale and stretch the longus colli muscle. For stability this self-retaining design requires equal tissue counterpressure. These devices are thus ill suited for a wound with substantially greater pressure from the medial structures and are prone to migration. The Thomson-Farley type of systems use arms with mechanical joints fixed to a table-mounted frame. The releasable joints allow adjustability and independent relaxation. Their limitations include bulk causing obstruction to the surgeons and radiographs, increased setup time, and ease with which excessive force can be applied.

The author describes a new anterior cervical retractor that is based on a novel principle. The principle is that bone fixation can be used to provide the retractor blade an axis of rotation inside the wound. This gives improved retractor blade stability with the mechanical advantage of a lever. The stable rotation produced allows adjustable retraction and tissue relaxation without compromise in stability. To the author's knowledge, there are no previously described retractors with this ability.

The system consists of a small 2-piece sliding frame fixed to the spine with the distraction screws. Bone fixation is preferable to sharp teeth and longus colli dissection because it works better and heals without scarring. Surgery is carried out through the frame, which slides during distraction. Independent retractor blades are attached to the sides of the frame, which provides a stable craniocaudal axis inside the wound. The blades rotate to provide retraction or relaxation as required. Intermittent relaxation of tissues under retractors has been shown to be beneficial. Another advantage, compared with systems that maintain wounds with vertical sides, is the ease with which an oblique approach can be used. The mechanical advantage has 3 benefits. First, bulky external mechanisms for retraction are avoided, which improves access. Second, numerous blade lengths are unnecessary, reducing inventory. Third, radiolucent polymers can be used with “snap-fit” properties. The improved stability over conventional systems reduces the need for skilled assistance and avoids surgeon frustration after retraction migration.

Over a 3-year period, 100 anterior cervical operations have been performed. Anecdotally, operations are quicker mainly because the retractors do not slip. Prospective clinical studies with independent evaluation are underway.

Brown-Sequard-type myelopathy due to cervical disc herniation associated with severe carotid stenosis prompting rapid combined corpectomy and carotid endarterectomy under deep anticoagulant therapy

BACKGROUND CONTEXT

The risk of stroke because of carotid retraction during an anterior cervical spine surgery as well as the risk of bleeding complications after an anterior cervical corpectomy under deep anticoagulation and antiplatelet therapy is a surgical issue poorly addressed in the literature.

PURPOSE

To describe the feasibility and safety of a simultaneous carotid endarterectomy and anterior corpectomy and fusion under deep anticoagulation in a patient with a cervical spinal cord compression and a severe carotid artery stenosis.

STUDY DESIGN

Case report.

METHODS

The authors describe the case of a 79-year-old man who had a 1-month history of progressive pain in the neck and left arm, associated with progressive weakness in the left arm and leg. He also presented a history of coronaropathy and bilateral severe carotid stenosis for which he was receiving a regimen of antiplatelet therapy.

RESULTS

The cervical magnetic resonance imaging demonstrated a C4-C5 disc herniation migrating down to C5. His condition worsened rapidly during hospitalization prompting a rapid decompression. Given the necessity of a C5 corpectomy and the risk of stroke during anterior cervical spine surgery, it was therefore decided to undertake the surgical procedure under efficient anticoagulant and antiplatelet therapy. A combined endarterectomy and spinal decompression and fusion were then performed. The postoperative course was uneventful, and the patient recovered neurologically.

CONCLUSIONS

This case suggests that such a combined carotid endarterectomy and cervical corpectomy with fusion under anticoagulant and antiplatelet therapy is feasible. However, even if the unique clinical presentation of our patient led us to undertake such a surgical strategy, therapeutic decision in patients presenting with both severe carotid stenosis and cervical spinal cord compression should rely on a case-by-case analysis.

Anatomical variations of the vertebral artery segment in the lower cervical spine: analysis by three-dimensional computed tomography angiography

STUDY DESIGN

Observational study with retrospective computerized tomography (CT) angiography analysis.

OBJECTIVE

The purpose of this study is to examine the vertebral artery's course in the V2 segment and define the anatomic variations in the adult population using CT angiography.

SUMMARY OF BACKGROUND DATA

The V2 segment of the vertebral artery (VA) usually extends from the transverse processes of C6-C2; however, the presence of abnormal VA course has been reported. These variations may predispose a patient to higher risk of iatrogenic vascular injury during anterior cervical surgery.

METHODS

Retrospectively, 700 vertebral arteries on 350 three-dimensional CT angiographies were analyzed. Measurements were taken describing the relationship between the extraosseous portions of the VA to surgical landmarks. In addition, the diameter of the transverse foramen was measured on axial CT images.

RESULTS

The VA entered the C6 transverse process in 94.9% of the specimens (664 out of 700 VA courses). Abnormal VA entrance was observed in 5.1% of the specimens (36 VA courses), with entrance into the C4, C5, or C7 transverse foramen 1.6%, 3.3%, and 0.3%, respectively.In 2 of 36 cases (5.6%) of abnormal VA entrance, the extraosseous VA formed an unusual medial loop, and the center of VA was positioned medial to the longus colli muscle. Furthermore, transverse foramens filled with VA were significantly larger than unfilled foramens (P < 0.01), but there was no significant difference between the C7 unfilled foraminal area and unfilled foraminal area above C7 (P = 0.768).

CONCLUSION

The present study confirms the presence of anomalous VA routes in the V2 segment. A preoperativethree-dimensional computerized tomography (CT) angiography with axial images may be useful to identify the presence of an anomalous V2 route when suspected on magnetic resonance imaging or CT. Delineation of this anomaly may reduce the risk of intraoperative VA injury.