Basilar Artery Occlusion Successfully Treated with Delayed Intravascular Intervention and Mild Hypothermia
Acute basilar artery occlusion (BAO) is a severe and often catastrophic form of stroke, accounting for approximately 1% of all strokes. Despite its rarity, BAO is associated with high morbidity and mortality rates. Even with treatment, the rate of death or disability remains as high as 80%. Early recanalization, whether through thrombolysis or intravascular thrombectomy, has been shown to significantly improve outcomes for patients with BAO. Animal stroke models have demonstrated that post-ischemic induction of hypothermia can significantly reduce the final infarct volume. Moderate hypothermia suppresses the post-ischemic generation of oxygen free radicals and inflammatory responses, which are known to contribute to reperfusion injury. Therapeutic hypothermia is considered one of the most potent neuroprotective strategies, activating numerous pathways through several mechanisms during the ischemic and reperfusion window. Based on robust laboratory data, clinical studies on therapeutic hypothermia for patients with acute ischemic stroke have been designed, and recent studies have shown that therapeutic hypothermia is safe and achievable in these patients. Definitive efficacy trials of therapeutic hypothermia combined with artery recanalization in acute ischemic stroke are ongoing.
This case report describes a 49-year-old Chinese male patient who was successfully treated for BAO using intravascular intervention and therapeutic hypothermia. The patient was transferred to the Emergency Department (ED) of Nanfang Hospital, Southern Medical University, in a deep coma. He had experienced sudden onset of dizziness, vertigo, numbness in both arms and legs, and slight weakness in his upper and lower extremities 16 hours prior to admission. He was initially admitted to a local hospital where cranial computed tomography (CT) revealed no abnormalities. Acute stroke of the posterior circulation was suspected, and anti-platelet therapy was initiated. However, the patient’s neurological status deteriorated, and he was transferred to our institute.
Upon arrival at the ED, the patient was comatose with a Glasgow Coma Scale (GCS) score of 4 (E1V1M2). His vital signs were stable, with a temperature of 37°C, blood pressure of 130/75 mmHg, heart rate of 86 beats/min, and respiratory rate of 18 breaths/min. A prompt cranial CT revealed hypointensity in the right cerebellum, leading to a high suspicion of BAO. With informed consent from the patient’s family, the patient was orally intubated and transferred for urgent vascular evaluation. Initial angiography via the left vertebral artery revealed upper and middle occlusions of the basilar artery, along with occlusions of the bilateral superior cerebellar arteries and the right posterior cerebral artery. The left posterior cerebral artery was visible via the opening of the left posterior communicating artery. Urgent thrombectomy was initiated using a Solitaire-FR 6mm x 30mm stent, which was deployed from the right P2 segment to the mid-basilar trunk and slowly withdrawn while simultaneously guiding catheter aspiration. Two passes were made, resulting in the removal of a 3mm x 10mm thrombus. Recanalization was achieved 20 hours after the onset of symptoms, with a thrombolysis in cerebral infarction (TICI) grade of 3. During the procedure, 5 mg of tirofiban was administered to prevent thrombosis.
Following recanalization, the patient was transferred to the neuro-intensive care unit. He remained in a coma with a GCS score of 4 (E1VTM2) and was mechanically ventilated. To avoid reperfusion injury to the brainstem, the patient was treated with intravascular mild hypothermia, targeting a temperature of 33°C using the COOLGARD3000 system. Intravascular hypothermia is based on the technology of intravascular heat exchange cooling, which involves inserting a temperature control catheter into deep human veins to directly cool and rewarm the blood. The target temperature of 33°C was achieved within 2 hours and maintained for 12 hours. The patient was then gradually rewarmed to 36.5°C at a rate of 1°C per 12 hours. Midazolam was used for sedation, and vecuronium was used for neuromuscular blockade.
On day 4 after recanalization, the patient developed a fever with a peak temperature of 38.6°C. A chest X-ray confirmed the diagnosis of pneumonia involving the bilateral lower lobes, and sputum culture revealed Klebsiella pneumoniae infection. Antibiotics were administered based on susceptibility results. The patient was extubated on day 11 post-recanalization, and his neurological status gradually improved. On day 4 post-procedure, the patient’s NIH Stroke Scale (NIHSS) score was 26. A post-procedure CT confirmed hypointensity in the pons and right cerebellum. Further evaluations of the patient’s risk factors revealed heavy smoking but no hypertension, diabetes, hyperlipidemia, atrial fibrillation, cardiac source of embolism, vasculitis, or thrombophilia.
Two weeks post-procedure, magnetic resonance imaging (MRI) of the brain confirmed the presence of infarcts in the bilateral midbrain, pons, and right cerebellum. Magnetic resonance angiography (MRA) confirmed the presence of the basilar artery. The patient was transferred to a local hospital for rehabilitation with an NIHSS score of 13 and a modified Rankin Scale (mRS) score of 5. The patient was advised to regularly take anti-platelet medications and quit smoking. During follow-up, the patient gradually improved, with an mRS score of 3 at the third month and an mRS score of 2 at the sixth month. MRI evaluation revealed old infarcts in the bilateral midbrain, pons, and right cerebellum.
BAO is a rare but devastating condition, with an estimated annual incidence of approximately one patient per 100,000. Patients are usually elderly, although younger individuals and even children can also be affected. The clinical presentation of BAO varies from mild transient symptoms to severe stroke. Common prodromal symptoms include vertigo and headaches, followed by hallmark signs such as decreased consciousness, quadriparesis, pupillary and oculomotor abnormalities, dysarthria, and dysphagia. Clinicians should recognize these prodromal symptoms and closely monitor patients. If available, multimodal CT or MRI should be promptly performed to confirm the diagnosis of BAO and initiate appropriate treatment without delay.
Early recanalization of BAO has been shown to improve outcomes, and this can be achieved using intravenous or intra-arterial thrombolytic agents, thromboaspiration, and/or thrombectomy. However, the best treatment approach remains unknown. A recent systematic review and meta-analysis revealed that stent retriever thrombectomy achieved a high rate of recanalization (TICI 2b-3, 80.0%) and functional independence (mRS ≤ 2, 42.8%) while being relatively safe for patients with BAO. The optimal time window for thrombectomy in BAO remains unknown, but recanalization beyond the standard treatment window has been reported. For selected patients with favorable prognostic factors such as young age, small core infarct, and collateral circulation, recanalization beyond the treatment window may be beneficial.
Experimental stroke models have proven the efficacy of hypothermia, and therapeutic hypothermia coupled with reperfusion strategies may yield synergistic benefits for patients with stroke. In a recent study involving patients with anterior circulation stroke treated with successful recanalization, the hypothermia group had less cerebral edema, hemorrhagic transformation, and better outcomes compared to the normothermia group. Mortality, hemicraniectomy rate, and medical complications were not statistically different. After adjusting for potential confounders, therapeutic hypothermia was an independent predictor for favorable outcome.
This case report describes a 49-year-old Chinese male patient with BAO who benefited from delayed thrombectomy and mild hypothermia. Therapeutic mild hypothermia combined with successful recanalization may improve the prognosis of patients. However, since this is a case report, the conclusions should be interpreted carefully, and more research is warranted. Large randomized clinical trials are required to elucidate the efficacy of thrombectomy and mild hypothermia for treating BAO.
doi.org/10.1097/CM9.0000000000000131
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