Comparative Evaluation of Total Intravenous and Inhalational Anesthesia in Posterior Fossa Surgery

Posterior fossa surgery represents one of the most demanding areas in neuroanesthesia due to the confined anatomical space, close proximity to the brainstem and lower cranial nerves, and limited capacity to accommodate increases in intracranial volume. Even minimal increases in intracranial pressure (ICP) can significantly compromise surgical exposure and neurological outcome [1]. Anesthetic management in these cases must ensure stable hemodynamics, optimal brain relaxation, controlled ICP, and smooth emergence to allow early neurological evaluation. Anesthetic techniques influence cerebral blood flow (CBF), cerebral metabolic rate (CMRO₂), and ICP. Propofol-based total intravenous anesthesia (TIVA) produces dose-dependent reductions in CMRO₂ and CBF, thereby lowering ICP and improving brain relaxation [2,3]. Dexmedetomidine, frequently used as an adjunct to TIVA, provides sympatholysis, attenuates stress responses, and facilitates smoother emergence without significant respiratory depression [4]. Inhalational anesthetic agents such as sevoflurane are widely used in neurosurgery due to ease of administration and rapid recovery. However, volatile agents cause cerebral vasodilation in a dose-dependent manner, which may increase ICP, particularly in posterior fossa surgery where intracranial compliance is limited [5]. Furthermore, inhalational anesthesia is associated with a higher incidence of postoperative nausea and vomiting (PONV), which may adversely affect postoperative recovery [6].  Despite extensive literature comparing TIVA and inhalational anesthesia in supratentorial craniotomies, data specifically addressing posterior fossa surgery—particularly with direct ICP monitoring—remain scarce. This study was therefore designed to compare TIVA and sevoflurane-based inhalational anesthesia in posterior fossa surgery with respect to ICP control, brain relaxation, surgeon satisfaction, and perioperative outcomes.

MATERIALS AND METHODS

Study Design and Ethical Approval

This prospective, randomized, comparative study was conducted between October 2024 and September 2025 after obtaining approval from the Institutional Ethics Committee of the Pacific Institute of Medical Sciences (PIMS), Udaipur. Written informed consent was obtained from all participants. The study was conducted in accordance with the Declaration of Helsinki.

Study Population

Sixty adult patients aged 18–65 years, of either sex, belonging to ASA physical status I or II, scheduled for elective posterior fossa surgery were included.

Inclusion Criteria

• Adult patients aged 18–65 years
• ASA physical status I or II
• Patients scheduled for elective posterior fossa surgery
• Surgery performed in park bench position
• Patients in whom direct ICP monitoring was planned
• Written informed consent obtained

Exclusion Criteria

• ASA physical status III or IV
• Emergency posterior fossa surgeries
• Pre-existing raised ICP requiring emergency decompression
• Anticipated difficult airway
• Severe cardiac, hepatic, or renal dysfunction
• Known hypersensitivity to study drugs

Randomization

Patients were randomized into two equal groups (n = 30 each) using a computer-generated randomization sequence with sealed opaque envelopes.

Anesthetic Technique

Standard ASA monitoring was applied, including electrocardiography, pulse oximetry, capnography, temperature monitoring, invasive arterial blood pressure, and bispectral index (BIS). Direct intracranial pressure monitoring was established using an intraparenchymal ICP monitor placed by the neurosurgical team after dural exposure.

Group T (TIVA)

Anesthesia was maintained using propofol infusion titrated to maintain BIS values between 40 and 50. Dexmedetomidine was administered as a continuous infusion (0.2–0.5 μg/kg/h) without a loading dose. Fentanyl was administered in intermittent boluses for analgesia. Neuromuscular blockade was maintained using atracurium.

Group I (Inhalational)

Anesthesia was maintained using sevoflurane in an oxygen–air mixture, titrated to maintain BIS values between 40 and 50. Analgesia and neuromuscular blockade were managed similarly to Group T.

Mechanical ventilation was adjusted to maintain end-tidal carbon dioxide between 30 and 35 mmHg in both groups.

Positioning and Surgical Management

All patients were positioned in the park bench position, with meticulous attention to padding and head fixation. Standard neurosurgical measures for brain relaxation, including mannitol administration and mild hyperventilation, were uniformly applied.

Outcome Measures

Primary Outcomes

• Heart rate (HR)
• Mean arterial pressure (MAP)
• Direct intracranial pressure (ICP) trends
• Brain relaxation score (4-point scale)
• Surgeon satisfaction score (4-point scale)

Surgeon Satisfaction Scale

1. Poor
2. Satisfactory
3. Satisfied
4. Very satisfied

Secondary Outcomes

• Emergence time (discontinuation of anesthetic agents to extubation)
• Incidence of coughing or bucking during extubation
• Incidence of PONV within 24 hours
• Duration of postoperative ICU ventilation

Statistical Analysis

Continuous variables were analyzed using Student’s t-test, while categorical variables were analyzed using Chi-square or Fisher’s exact test as appropriate. A p-value < 0.05 was considered statistically significant.

RESULTS

Demographic and Surgical Data

Table 1. Demographic and Surgical Characteristics

Table 1 demonstrates that both study groups were comparable with respect to age distribution, sex ratio, ASA physical status, and duration of surgery. The absence of statistically significant differences confirms adequate randomization and baseline homogeneity between the two groups.

Hemodynamics and ICP Trends

Table 2. Hemodynamic and ICP Comparison

Table 2 illustrates intraoperative trends in mean arterial pressure (MAP) and intracranial pressure (ICP) at predefined surgical time points. Although MAP values remained within clinically acceptable limits in both groups, ICP values were consistently lower in the TIVA group, indicating better intracranial pressure control with propofol-dexmedetomidine anesthesia.

Figure 1. Comparison of intracranial pressure at dural opening demonstrating superior ICP control with total intravenous anesthesia.

This chart compares the mean intracranial pressure values recorded at the time of dural opening in both study groups. The TIVA group consistently demonstrated lower ICP values relative to the sevoflurane group, indicating superior intracranial pressure control. Improved ICP management contributes to better brain relaxation, enhanced surgical field visibility, and increased surgeon satisfaction, thereby reinforcing the physiological benefits of total intravenous anesthesia in posterior fossa surgery.

Figure 2. Trend of mean arterial pressure at predefined intraoperative time points demonstrating comparable hemodynamic stability between TIVA and sevoflurane groups

This line chart illustrates intraoperative mean arterial pressure trends at baseline, after positioning, dural opening, and end of surgery. Both anesthetic techniques-maintained MAP within clinically acceptable ranges, indicating effective depth of anesthesia and cardiovascular stability throughout the procedure.

Figure 3. Intraoperative intracranial pressure trends demonstrating lower ICP values with total intravenous anesthesia

This chart depicts intracranial pressure measurements recorded at key intraoperative stages. The TIVA group consistently demonstrated lower ICP values compared to the inhalational group, reflecting superior intracranial pressure control and improved neurosurgical operating conditions.

Brain Relaxation and Surgeon Satisfaction

Table 3. Brain Relaxation Scores

Table 3 reflects neurosurgeon-assessed brain relaxation at the time of dural opening. A higher proportion of patients in the TIVA group achieved “adequate” or “perfect” relaxation, suggesting improved surgical field conditions with intravenous anesthesia.

Table 4. Surgeon Satisfaction Scores

Table 4 presents overall surgeon satisfaction with intraoperative conditions. The greater number of “very satisfied” responses in the TIVA group indicates superior operative conditions, likely attributable to improved brain relaxation and stable intraoperative hemodynamics.

Emergence and Postoperative Outcomes

Table 5. Recovery Characteristics

Table 5 summarizes postoperative recovery parameters. Although emergence time was marginally longer in the TIVA group, the incidence of coughing, postoperative nausea and vomiting (PONV), and airway-related complications was lower, indicating smoother recovery characteristics without prolonging ICU ventilation duration.

Figure 4. Comparison of emergence time between TIVA and sevoflurane groups demonstrating marginally prolonged but clinically acceptable recovery in the TIVA group

This chart illustrates the mean emergence time in minutes for both study groups. Although the TIVA group demonstrated a marginally longer emergence duration compared to the sevoflurane group, the difference remained within clinically acceptable limits and did not delay postoperative neurological assessment. The findings suggest that the use of propofol-dexmedetomidine–based anesthesia provides smoother emergence characteristics without causing clinically significant recovery delay.

Figure 5. Incidence of postoperative nausea and vomiting showing significantly reduced PONV in the TIVA group