The sitting position for posterior fossa surgery has long been regarded as a valuable
tool, primarily favored for its better surgical exposure, gravity-assisted drainage
of blood and cerebrospinal fluid, and a cleaner operative field allowing the surgeon
to operate with greater precision. Despite these advantages, its use has declined
over the decades owing to concerns over serious perioperative complications, especially
venous air embolism (VAE), tension pneumocephalus, quadriparesis, and macroglossia.
However, growing evidence in recent years indicates that the sitting position is a
safe and viable option for neurosurgical procedures, without compromising patient
outcomes.[1]
[2] Early studies in the 1980s and 1990s suggested high rates of VAE and catastrophic
sequelae, leading many centers to abandon the technique.[3]
[4] Considering the benefits and the serious perioperative risks associated, the debate
over its safe use still continues. The question is whether the sitting craniotomy
can continue to claim its rightful position in contemporary practice with advances
in monitoring, anesthetic care, and surgical expertise.
Among the complications associated with sitting position craniotomy, VAE remains the
most significant and feared complication. The elevated operative field above the heart
level predisposes to entrainment of air into venous channels, particularly from diploic
or emissary veins. Reported incidence varies depending on the sensitivity of monitoring,
ranging from <10% with clinical detection to >70% with trans-esophageal echocardiography.[3]
[4] While many episodes are subclinical, clinically significant VAE may manifest with
hypotension, desaturation, or even paradoxical embolism in patients with a patent
foramen ovale.[4] Preventive maneuvers such as adequate hydration, judicious use of positive end-expiratory
pressure, maintenance of venous pressure above atmospheric at the operative site,
and the ready availability of central venous aspiration techniques have substantially
mitigated morbidity.[1]
[4] Other implications of the sitting posture include hemodynamic instability from venous
pooling in the lower limbs, reduced venous return, and, in rare cases, compromised
cerebral perfusion to the brainstem.[5] Cervical spine flexion in vulnerable patients can result in neurological injury,[6]
[7] and macroglossia due to venous congestion may compromise the airway. A rare but
catastrophic complication is tension pneumocephalus, which requires immediate management.[8] Other perioperative issues include prolonged mechanical ventilation following brainstem
handling[1] and cranial nerve dysfunction, particularly involving lower cranial nerves.
Despite these concerns, neurosurgeons continue to value the sitting position for its
evident benefits. Excellent access to the posterior fossa and pineal region, improved
visualization of deep-seated lesions, and reduced intraoperative venous bleeding remain
compelling arguments for its continued use. From a physiological standpoint, the upright
posture improves respiratory mechanics by improving the diaphragmatic excursion.
More recent evidence paints a different picture. In this issue of the journal, Balakrishnan
et al present a retrospective analysis of 188 patients, reporting an overall VAE incidence
of 20.7% but found no correlation with increased mortality, new neurological deficits,
or poor outcomes.[1] In fact, over 88% of patients had good neurological recovery at discharge. Similarly,
Ganslandt et al, in a series of 600 cases, found that while VAE was common, it was
rarely clinically significant, and patient outcomes were favorable in most cases.[2] Comparative studies have also questioned whether the sitting position is inherently
more dangerous than other positions. Black et al observed no difference in outcomes
between patients undergoing posterior fossa craniectomy in sitting and horizontal
positions.[9] More recently, Baro et al found similar complication rates between sitting and prone
positioning in pediatric low-grade posterior fossa tumours.[10]
Pediatric patients are reported to have a higher incidence of VAE than adults, likely
due to anatomical and physiological differences such as smaller venous capacitance
and relatively negative venous pressure at the operative site. There is variability
in the reported incidence of VAE between pediatric and adult populations in the literature.[7]
[11] However, Balakrishnan et al[1] have observed a similar incidence of VAE between adults and pediatric patients,
similar to both Harrison et al and Bithal et al, who reported comparable incidences
of VAE in adults and children, without demonstrable impact on long-term outcomes.[11]
[12]
Although the role of nitrous oxide in the sitting position has long been debated,
the recent study by Balakrishnan et al has found that the intraoperative use of nitrous
oxide was not associated with an increased risk of complications or mortality.[1] Moreover, the rate of perioperative complications, including mortality, was similar
between patients with and without the occurrence of VAE in sitting position craniotomy.[1]
This evolving body of evidence underscores the central debate: whether the sitting
craniotomy should be abandoned because of its potential for catastrophic complications,
or preserved because of its unique surgical advantages. This is emblematic of a broader
principle in perioperative medicine: risk cannot be eliminated, only anticipated and
managed. What is required now are contemporary data–multicenter prospective registries
that quantify complication rates in the current era of advanced monitoring and refined
techniques. Such evidence would allow us to move beyond anecdote and historical apprehension
toward a balanced, evidence-based perspective. Equally important is the training of
future generations. With the declining use of the sitting position craniotomy, there
is a risk that expertise will erode. If the practice is to survive as an option, it
must be taught safely, judiciously, and under the guidance of experienced mentors.
Otherwise, it may fade into disuse, not because it lacks value, but because the collective
skill to perform it safely has been lost.
The sitting position in posterior fossa surgery remains a double-edged sword: associated
with unique perioperative challenges, yet offering unmatched surgical advantages for
selected lesions. To dismiss it entirely would be to deny neurosurgeons a valuable
tool; to employ it indiscriminately would be reckless. The challenge today is to refine
its use—through rigorous selection, vigilant monitoring, and collaborative practice—so
that the balance of risk and benefit consistently favors the patient.
