Retrospective analysis of perioperative factors on outcome of patients undergoing surgery for Moyamoya disease

Introduction

The word Moyamoya in Japanese means “something hazy, like a puff of cigarette smoke drifting in the air.” This rare disease is characterized by worsening stenosis of terminal portions of internal carotid artery, proximal portions of anterior and middle cerebral artery (MCA), sometimes involving the posterior cerebral arteries as well. Net like images on angiograms arise from the proliferated penetrating arteries at the base of the brain that are the main source of collateral flow to the ischemic areas of brain distal to the occlusion.[1]

We retrospectively analyzed the perioperative parameters of 15 patients of Moyamoya disease operated in our institute over last 7 years for their effect on the duration of postoperative hospital stay. The duration of postoperative hospital stay was categorized as short (<5 days) and prolonged (>5 days). The data were compared for the duration of hospital stay.

Materials and Methods

The medical records of all patients who underwent revascularization surgeries for Moyamoya disease from 2007 to January 2014 were analyzed retrospectively. Approval was sought from institutional ethics committee. The following preoperative, intraoperative, and postoperative data were recorded: Age, sex, weight, associated congenital anomalies, clinical features, radiological findings, medications, surgical procedure, first or repeat surgery, type of anesthesia, the induction agent used, the maintenance agent used, intraoperative hemodynamics, value of end-tidal carbon dioxide (EtCO₂), temperature, fluid requirement, blood loss, urine output, emergence, duration of surgery, duration of anesthesia, postoperative recovery, new onset neurological deficit, other complications such as pain, postoperative nausea and vomiting, respiratory complications, sepsis and duration of hospital stay. Primary outcome was the duration of hospital stay that was categorized as either short or prolonged hospital stay. Short stay was defined as <5 days and stay in hospital >5 days was taken as prolonged stay.

Results

Perioperative data were analyzed for 15 patients and 16 procedures. The mean age of the patients was 12.3 (3–45) years with nine male and seven female patients. Mean weight was 28.7 (11–70) kg. Baseline blood investigations were within normal range for all patients. Aspirin, antiepileptics and steroids were continued till the day of surgery. Three patients underwent myo-synangiosis (19%), four underwent encephalo-duro-arterio-myo-synangiosis (EDAMS) (25%), two had MCA bypass (12%) and seven underwent a combination of MCA bypass and EDAMS (44%) under general anesthesia.

Blood loss requiring transfusion was recorded in one patient and all patients had adequate intraoperative urine output. None of the patients had intraoperative hypothermia or hyperthermia. At the end of the procedure, all patients could be extubated, and the mean duration of anesthesia was 2.45 (1.3–4) h. One patient experienced postoperative nausea and vomiting but there was no delay in time to accept oral intake in any patient. Postoperatively, all patients were hemodynamically stable and none experienced severe pain. Among the neurological complications, two patients suffered from aphasia, one had associated new onset right upper limb monoparesis and one patient developed right fronto-temporo-parietal subdural effusion. Among other complications, urinary tract infection was reported in one patient.

Mean duration of hospital stay was 5.13 (3–10) days. Sex of the patient, congenital anomalies, type of induction agent used, type of anesthetic used for maintenance of anesthesia were not found to have any significant effect on the duration of hospital stay (P > 0.05). Clinical features including history of recurrent transient ischemic attack (TIA), seizures and motor weakness had a trend predicting prolonged duration of hospital stay though it was not statistically significant. Average EtCO₂ value < 31 mmHg throughout the surgery showed statistically significant prolongation of hospital stay when compared with patients with mean EtCO₂ value between 31 and 35 mmHg (P < 0.0001). Furthermore, patients with mean EtCO₂ value >35 mmHg had statistically significant prolongation of hospital stay when compared with those with EtCO₂ value between 31 and 35 mmHg throughout the procedure [Table 1]. The hemodynamic variables were maintained and similar in patients who had either short or prolonged hospital stay [Figures 1 and 2].

Table 1 Effect of perioperative factors on duration of postoperative hospital stay

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Figure 1

Systolic blood pressure at different time points of anaesthesia

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Figure 2

Heart rate at different time points of anaesthesia

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Discussion

The outcome of patients undergoing neurosurgery for Moyamoya disease depends on various perioperative factors. Patients presenting with a history of recurrent TIA, seizures and motor deficits are at high risk for postoperative ischemic complications.[2] Furthermore, intraoperative maintenance of cerebral perfusion pressure is crucial for good postoperative neurological recovery.[3] This is influenced by the type of anesthetic used, hemodynamics, fluid resuscitation, blood loss and hematocrit, EtCO₂, temperature regulation, urine output and the type of surgical procedure being done.[4]

In our study, we did not find the effect of preoperative recurrent TIA, motor deficits and seizures on the duration of hospital stay. As the underlying pathophysiology predisposes these patients to ischemic complications, appropriate anesthetic techniques to maintain cerebral blood flow and cerebral perfusion pressure should be followed. There is no consensus or guideline for any specific agent to be used for anesthetic induction or maintenance in these cases as maintenance of cerebral blood flow and cerebral perfusion pressure is the ultimate goal, more so in pediatric patients.[56] In our study, patients induced with propofol had a trend towards short hospital stay (4 days) whereas more proportion of patients who received thiopentone had a prolonged hospital stay (>5 days), though this difference was not statistically significant.

The maintenance of normocarbia is essential to prevent postoperative ischemic complications as both hypocapnia and hypercapnia are detrimental in the presence of already diseased vessels.[7] In our study, patients with normocapnia had shorter hospital stay when compared to those with hypocapnia or hypercapnia intraoperatively and the difference was found to be statistically significant. In a study by Chiu et al., decreased regional cerebral blood flow was observed in all patients when the EtCO₂ decreased <29 mmHg.[8]

We observed that the choice of anesthetic agent used to maintain depth of anesthesia did not have any effect on the duration of hospital stay. Summors et al. reported better preservation of autoregulation during sevoflurane than isoflurane anesthesia.[9] In another study, Sato et al. concluded that regional cortical blood flow (rCoBF) may be decreased with inhalation anesthesia which may in turn provoke intracerebral steal phenomenon when compared to total intravenous anesthesia (TIVA).[10] In contrast, certain studies have not shown any significant difference between TIVA and use of isoflurane. Kikuta et al. reported high rCoBF and low intracranial pressure with the use of propofol when compared with sevoflurane.[11] Perhaps maintaining adequate depth of anesthesia, especially during airway manipulation and at the time of revascularizaton may be more important than the type of anesthetic agent used.

Adequate hydration is the single most important intervention preventing decrease in cerebral blood flow, and it was adequately done for all our patients.[5] We analyzed that despite maintenance of mean arterial blood pressure, adequate depth of anesthesia and adequate fluid resuscitation in our patients, two patients suffered from aphasia, one had associated new onset right upper limb monoparesis and one patient developed right fronto-temporo-parietal subdural effusion. The patient who developed subdural effusion received thiopentone for induction, had lowest EtCO₂ value recorded intraoperatively (27 mmHg) and also, had highest duration of hospital stay (10 days). One patient who developed aphasia had undergone myosynangiosis. This patient had preoperative motor deficit, received thiopentone for induction with EtCO₂ levels were between 34 and 37 mmHg intraoperatively.

The present study concludes that maintaining the intraoperative EtCO₂ between 31 and 35 mmHg may be associated with early hospital discharge when compared to patients who have mean intraoperative EtCO₂ either < 31 or > 35 mmHg.

As this disease is not common in our country, only few patients underwent surgery at our institute in last 7 years. Hence, the data could be obtained on a small patient population. A prospective study in the future with larger sample size may yield more information on this rare but important entity.