Successful anesthetic management for microsurgical excision of ruptured cerebellar arteriovenous malformation with trapped endovascular microcatheter.

Microsurgical excision and good anesthetic management of arteriovenous malformation (AVM) that ruptures during endovascular embolization can ensure good outcome despite per-procedural catastrophe. This case report illustrates the successful anesthetic management of microsurgical excision of ruptured AVM with entrapped microcatheter and highlights the role of the anesthesiologist in careful monitoring of the patient's hemodynamic status and communicating any changes to the radiology team to facilitate check angiography to diagnose the intracranial complication. This case highlights the need for anticipating and defining a catastrophe plan in advance of each interventional neuroradiology procedure as complications are rapid and require good multidisciplinary communication to ensure safe and successful outcomes.

Introduction

Cerebral AVMs are uncommon lesions with prevalence in general population of 0.5 to 1%.[12] Unlike their supratentorial counterparts, infratentorial AVM are likely to present with hemorrhage rather than with seizures.[3456] Progressive neurological deficit is the next most common presentation seen in up to 28% of the patients.[7] Endovascular procedures in AVM may cause intracranial hemorrhage due to gluing of the liquid embolic material to the microcatheter within the cerebral vasculature. We report an unusual complication of retained microcatheter that got glued during onyx embolization and the anesthetic management of its successful retrieval micro surgically along with resection of AVM.

Case Report

A 27-year-old lady, previously hospitalized elsewhere following an episode of headache and altered sensorium with a Glasgow Coma Score (GCS) of E1V1M3 who improved neurologically following the ventilation and external ventricular drainage (EVD), was referred to our hospital for further management. Magnetic resonance imaging (MRI) showed cerebellar AVM with intracranial hemorrhage. Biochemical and hematological investigations were normal. Computed tomography (CT) brain showed blood in the ventricles with mild pan ventriculomegaly.

Elective embolization of the AVM was planned under general anesthesia. The patient was induced with fentanyl 100 μg and propofol 80 mg and intubation with 7.5 mm internal diameter endotracheal tube was facilitated with rocuronium 40 mg. Standard anesthesia monitoring was used. Anesthesia was maintained using oxygen: Nitrous-oxide: Isoflurane and rocuronium intermittent boluses.

Diagnostic angiogram demonstrated an AVM in the left cerebellum measuring 32 × 18 × 22 mm, with feeders from left posterior inferior cerebellar artery (PICA)[Figure 1a]. An ultraflow microcatheter was guided over a 0.08 micro mirage guidewire and maneuvered into the distal PICA. Onyx was used for embolization.

Figure 1

Preopertive diagnostic subtraction angiogram (DSA) showing AVM in the left cerebellum (a), intraoperative leakage of contrast outside the vasculature (b) and postoperative DSA (c) that shows no residual AVM

Halfway through the procedure, there was sudden hypertension (blood pressure (BP) increased from 110/70 to 150/90 mmHg) with bradycardia (heart rate decreased from 120/min to 50/min). The intervention radiologist was immediately informed, who immediately felt resistance to Onyx injection followed by sudden give away feeling. A check angiogram showed leakage of contrast outside the vasculature [Figure 1b]. Immediately N-butyl cyanoacrylate glue was injected into the rent to seal the leak. Subsequently microcatheter retrieval became difficult; hence it was left in situ.

Once it was confirmed that the microcatheter was stuck, heparin was reversed with protamine, 200 ml of 20% mannitol was administered with mild hyperventilation. N2O and isoflurane were discontinued and anesthesia was maintained with air-O2 mixture and propofol infusion. A right frontal EVD was placed by the neurosurgeon. Intravenous labetalol 5 mg was administered to maintain low normal BP. CT showed significant subarachnoid hemorrhage (SAH) and blood in the fourth ventricle [Figure 2a]. Neuromuscular blockade was reversed to assess the neurological condition. Pupils were dilated, unreactive, with GCS 5. The patient was immediately shifted for an emergency left paramedian suboccipital craniectomy, hematoma evacuation, AVM excision and microcatheter tip removal. The distal portion of the microcatheter was removed from the femoral sheath.

Figure 2

Preoperative CT (a) demonstrating the blood in the fourth ventricle and postoperative CT (b) showing no hematoma or hydrocephalus

During surgery, the patient had one episode of bradycardia (36/min) which improved to 55/min with intravenous atropine 0.6 mg. Norepinephrine infusion was started for hypotension (80/50 mmHg). The blood loss was 900 ml which was replaced. Postoperative GCS was E3VTM6 with bilateral equal and reactive pupils and was shifted to ICU and mechanically ventilated. Post-operative CT head showed no hematoma or hydrocephalus with EVD tip in situ [Figure 2b]. Check angiogram revealed no residual AVM [Figure 1c]. The patient was extubated on second and discharged on tenth postoperative day with no neurological deficits.

Discussion

This case report describes the successful multimodal management of cerebellar AVM that bled during the endovascular embolization associated with entrapment of microcatheter during glue injection to close off the rent in the feeding vessel. Careful monitoring, early identification of complication, prompt and aggressive resuscitation, immediate rescue surgery with complete excision of the AVM and evacuation of the hematoma along with retrieval of the stuck microcatheter were the corner stone for successful management and good outcome in this patient.

Posterior fossa AVM with bleed carries considerable greater morbidity and mortality. There is very little published data on AVM surgery in the acute setting but it might be essential in specific settings such as bleeding from the AVM during endovascular embolization. In a series of 283 AVMs treated with embolization, SAH and intracerebral hemorrhage occurred in 3.1% and 2.1% of the patients, respectively.[8] Early surgery can reduce the mass effect and spare the adjacent healthy neuronal tissue.[9]

In the event of intracranial catastrophe, aggressive resuscitative measures need to be performed which include manipulating systemic or regional blood flow, anticoagulation management, rapid recovery from the anesthesia and sedation during or immediately after the procedure to facilitate neurologic examination and intensive monitoring.[10]

In our case, once the rent in the vessel was identified by extravasation of contrast, heparin was reversed with protamine,[11] Intracranial pressure (ICP) was reduced with mannitol, mild hyperventilation and switching from inhalational anesthesia to intravenous anesthesia. A right frontal EVD was placed to reduce ICP and drain the ventricular blood. AVM was excised surgically and entrapped microcatheter removed.

Young et al. suggest that heparinization should be performed routinely during any superselective catheterization. The rapidity with which heparin is reversed is directly proportional to the good outcome from the bleed.[11]

Massoud et al. concluded in their study that the induction of systemic hypotension during and after AVM embolization appeared theoretically to be of potential use in preventing iatrogenic nidus hemorrhage.[12]

However, one of the limitations of our management was the lack of ICP monitoring which could have been done with EVD in situ to help us have ICP guided management in the perioperative period as compared to only clinical based management. Though the provision of Air: O2 was available, N2O was used during the early period of neuroradiology intervention as it was at the discretion of the attending neuroanesthesiologist. But once the periprocedural catastrophe was anticipated, immediately N2O was stopped and intravenous anesthesia with Air: O2 with all other measures to decrease the ICP were taken.

Conclusion

Vascular injury due to microcatheter in the cerebral vasculature by glue/onyx can be managed bysurgical excision/interventional sealing the rent to prevent further intracranial bleeding.

As an anesthesiologist, having thorough knowledge of INR procedures, management of complications, techniques of deliberate hypotension and hypertension, ensuring adequate brain relaxation, controlled systemic and cerebral hemodynamics, maintenance of isotonicity and euglycemia, and mild hypothermia can ensure good outcome.