Perioperative Bioccipital Watershed Strokes in Bilateral Fetal Posterior Cerebral Arteries During Spinal Surgery

Perioperative Care of the Patient with Eye Pathologies Undergoing Nonocular Surgery

The authors reviewed perioperative ocular complications and implications of ocular diseases during nonocular surgeries. Exposure keratopathy, the most common perioperative eye injury, is preventable. Ischemic optic neuropathy, the leading cause of perioperative blindness, has well-defined risk factors. The incidence of ischemic optic neuropathy after spine fusion, but not cardiac surgery, has been decreasing. Central retinal artery occlusion during spine fusion surgery can be prevented by protecting eyes from compression. Perioperative acute angle closure glaucoma is a vision-threatening emergency that can be successfully treated by rapid reduction of elevated intraocular pressure. Differential diagnoses of visual dysfunction in the perioperative period and treatments are detailed. Although glaucoma is increasingly prevalent and often questions arise concerning perioperative anesthetic management, evidence-based recommendations to guide safe anesthesia care in patients with glaucoma are currently lacking. Patients with low vision present challenges to the anesthesia provider that are becoming more common as the population ages.

Risk Factors of Impaired Perfusion in Patients With Symptomatic Internal Carotid Artery Steno-Occlusive Disease

Objective

To quantitatively evaluate the impaired perfusion status of patients with symptomatic internal carotid artery (ICA) steno-occlusive disease and to explore the risk factors of impaired perfusion with computed tomography perfusion (CTP).

Methods

The clinical and imaging data of 187 patients with ICA steno-occlusive disease were retrospectively analyzed. The ICA stenosis rate was divided into Grades I–IV (70–79%; 80–89%; 90–99%; 100%), and the circle of Willis was classified as four types (types I–IV). According to the literature, the value of cerebral blood flow/cerebral blood volume (CBF/CBV) of 7.55/min was used as cut-off to predict symptomatic patients. All patients were categorized into two groups: those with impaired perfusion [n = 99 (52.9%)] and those without impaired perfusion [n = 88 (47.1%)]. Symmetrical bilateral internal watershed areas were selected as the regions of interest (ROIs). Statistical analysis was made on the status of impaired perfusion and the risk factors of impaired perfusion.

Results

Univariate analysis revealed that systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), types of the circle of Willis, and clinical features at admission differed between the two groups (patients with or without impaired perfusion) (p < 0.05). Multiple logistic stepwise regression analysis showed that MAP [odds ratio (OR) = 0.946, 95% confidential interval (CI) = 0.917–0.974, p < 0.001] and type IV (type I vs. IV: OR = 4.987, 95% CI = 1.955–12.723, p = 0.001) at admission were independently associated with impaired perfusion in the internal watershed areas.

Conclusion

MAP and the type of circle of Willis at admission are independent risk factors associated with the impaired perfusion in patients with ICA steno-occlusive disease.

Application of Controlled Hypotension During Surgery for Spinal Metastasis

With advances in tumor treatment, metastasis to bone is increasing, and surgery has become the only choice for most terminal patients. However, spinal surgery has a high risk and is prone to heavy bleeding. Controlled hypotension during surgery has outstanding advantages in reducing intraoperative bleeding and ensuring a clear field of vision, thus avoiding damage to important nerves and vessels. Antihypertensive drugs should be carefully selected after considering the patient's age, different diseases, etc, and a single or combined regimen can be used. Hypotension also inevitably leads to a decrease in perfusion of important organs, so the threshold of hypotension and the maintenance time of hypotension should be strictly limited, and the monitoring of important organs during the operation is particularly important. Information such as blood perfusion, blood oxygen saturation, cardiac output, and neurophysiological conduction potential changes should be obtained in a timely fashion, which will help to reduce the risk of hypotension. In short, when applying controlled hypotension, it is necessary to choose an appropriate threshold and duration, and appropriate monitoring should be conducted during the operation to ensure the safety of the patient.

Cortical Blindness after Cervical Spine Surgery in Supine Position - A Rare Case Report and Review of the Literature

We report the first case of perioperative visual loss due to cortical blindness after supine cervical spine surgery. A 46-year-old female presented with severe right-sided brachialgia of 1½ years' duration. Her magnetic resonance imaging (MRI) (cervical spine) showed severe right foraminal stenosis at C5–6. She underwent C5–6 anterior cervical discectomy and fusion. Nine hours after surgery, during a routine postoperative round, the patient complained of complete bilateral visual loss. The fundus examination and pupillary light reflex were normal. MRI of the brain showed the posterior cerebral artery infarct with hypoplasia of the left vertebral artery. She was transferred to the neurointensive care unit where antiplatelet treatment was started along with heparin. Her vision slowly began to improve, and at the end of 1 year, she had a reasonable visual acuity in both eyes. It is now standard practice in our institution to check patients' vision immediately after surgery.

Unilateral blindness following superior laryngeal nerve block for awake tracheal intubation in a case of posterior cervical spine surgery

Background:

Superior laryngeal nerve block (SUPLANEB) is a popular airway anesthesia technique utilized for successful awake endotracheal intubation in patients with significant cervical spine instability. If not performed by an expert, it carries the risk of general/neurologic complications that are typically minimal/transient. However, permanent blindness and/or upper cranial nerve neuropathies may occur. Here, we describe a case in which a young patient underwent an atlantoaxial fusion for a C2 nonunion (e.g., following a fracture) complicated by unilateral blindness due to a SUPLANEB.

Case Description:

A 25-year-old neurologically intact male underwent a C1-C2 posterior arthrodesis to address a nonunion of a C2 fracture. To perform the awake nasotracheal intubation, a SUPLANEB was performed using a video laryngoscope. Although the operation was uneventful, postoperatively, the patient reported left visual loss accompanied by left-sided facial numbness and hearing loss. On examination of the left eye, the anterior segment and fundus examinations were normal, but the OCT (optical coherence tomography) and retinal angiography demonstrated left-sided postischemic retinal edema with permeability of the intraocular vessels. Although the cranio-orbital computed tomography scan showed only mild pneumocephalus, the CT angiogram scan revealed abnormal air in the left carotid sheath accompanied by diffuse subcutaneous emphysema. Further, brain and orbital magnetic resonance imaging scans were normal. The patient was treated with pure oxygen, systemic steroid therapy, and nimodipine. The pneumocephalus and subcutaneous emphysema resolved on day 3. At 2 months follow-up, the patient remained blind on the left side, but had no further neurological deficits.

Conclusion:

Blindness and upper cranial nerves neuropathies should be considered as potential complications of SUPLANEB. Notably, these deficits were not directly related to the operative positioning or neurosurgical spinal procedure.

Hypoxia induces de novo formation of cerebral collaterals and lessens the severity of ischemic stroke

Pial collaterals provide protection in stroke. Evidence suggests their formation late during gestation (collaterogenesis) is driven by reduced oxygen levels in the cerebral watersheds. The purpose of this study was to determine if collaterogenesis can be re-activated in the adult to induce formation of additional collaterals ("neo-collateral formation", NCF). Mice were gradually acclimated to reduced inspired oxygen (FIO₂) and maintained at 12, 10, 8.5 or 7% for two-to-eight weeks. Hypoxemia induced "dose"-dependent NCF and remodeling of native collaterals, and decreased infarct volume after permanent MCA occlusion. In contrast, no formation occurred of addition collateral-like intra-tree anastomoses, PComs, or branches within the MCA tree. Hypoxic NCF, remodeling and infarct protection were durable, i.e. retained for at least six weeks after return to normoxia. Hypoxia increased expression of Hif2α, Vegfa, Rabep2, Angpt2, Tie2 and Cxcr4. Neo-collateral formation was abolished in mice lacking Rabep2, a novel gene involved in VEGFA→Flk1 signaling and required for formation of collaterals during development, and inhibited by knockdown of Vegfa, Flk1 and Cxcr4. Rabep2-dependent NCF was also induced by permanent MCA occlusion. This is the first report that hypoxia induces new pial collaterals to form. Hypoxia- and occlusion-induced neo-collateral formation provide models to study collaterogenesis in the adult.

[Cerebellar infarct following orchidopexy under spinal anesthesia]

The report describes a case of peri-operative stroke that presented as diplopia and gait difficulty on 2nd post-operative day after routine orchidopexy under spinal anesthesia in an otherwise healthy young boy. Magnetic resonance imaging of the brain revealed acute infarct in bilateral cerebellar hemispheres, left half of medulla and left thalamus. A diagnosis of acute stroke (infarct) was made and patient was started on oral aspirin 75mg.day^-1, following which his vision started improving after 2 weeks. Possible mechanisms of development of stroke in the peri-operative period are discussed, but, even after extensive investigations, the etiology of infarct may be difficult to determine. Acute infarct after elective non-cardiac, non-neurological surgery is rare; it may not be possible to identify the etiology in all cases. Clinicians must have a high index of suspicion to diagnose such unexpected complications even after routine surgical procedures in order to decrease the morbidity and long term sequelae.

[Cerebellar infarct following orchidopexy under spinal anesthesia]

The report describes a case of peri-operative stroke that presented as diplopia and gait difficulty on 2nd post-operative day after routine orchidopexy under spinal anesthesia in an otherwise healthy young boy. Magnetic resonance imaging of the brain revealed acute infarct in bilateral cerebellar hemispheres, left half of medulla and left thalamus. A diagnosis of acute stroke (infarct) was made and patient was started on oral aspirin 75mg.day^-1, following which his vision started improving after 2 weeks. Possible mechanisms of development of stroke in the peri-operative period are discussed, but, even after extensive investigations, the etiology of infarct may be difficult to determine. Acute infarct after elective non-cardiac, non-neurological surgery is rare; it may not be possible to identify the etiology in all cases. Clinicians must have a high index of suspicion to diagnose such unexpected complications even after routine surgical procedures in order to decrease the morbidity and long term sequelae.