A 35-year-old man presented with progressive headaches, visual disturbances, gait instability, and generalized weakness. Brain imaging revealed a 1.3 × 1.6 × 1.8 cm hemorrhagic pineal mass causing obstructive hydrocephalus. His medical history was notable for asthma and gastroesophageal reflux disease. Routine laboratory studies were normal. Preoperative echocardiography demonstrated normal cardiac function without evidence of a patent foramen ovale which was confirmed with a bubble study.

Because of the deep midline location and hemorrhagic nature of the lesion, the surgical team elected to perform tumor resection in the sitting position to optimize surgical exposure and facilitate venous drainage.

General anesthesia was induced uneventfully. In addition to standard monitoring, an arterial catheter, central venous catheter, and transesophageal echocardiography (TEE) were used. Following positioning, transient hypotension responded to fluid administration and vasopressor support.

Approximately four hours into the operation, a sudden decrease in blood pressure from 120/70 mmHg to 60/40 mmHg occurred, accompanied by an abrupt decline in end-tidal CO₂. TEE demonstrated air within the right atrium and ventricle.

What Would You Do?

The abrupt hypotension, decrease in end-tidal CO₂, and intracardiac air on TEE were diagnostic of hemodynamically significant venous air embolism (VAE), one of the most feared complications of sitting-position neurosurgery.

The surgical team was immediately notified and surgical manipulation was paused. The operative field was flooded with saline, and the suspected air entry site was identified and occluded. FiO₂ was increased to 1.0, vasoactive support was initiated, and air was aspirated through the multi-orifice central venous catheter. The patient’s hemodynamics and end-tidal CO₂ subsequently returned to baseline, and TEE demonstrated resolution of the intracardiac air. After multidisciplinary reassessment, surgery proceeded without further incident.

The procedure lasted approximately eight hours. At the completion of surgery, the patient remained intubated because of significant facial and tongue swelling. Severe macroglossia was noted, raising concern for airway compromise following extubation. The patient was transferred intubated to the neurocritical care unit.

The Next Challenge

Over the subsequent two days, the patient’s tongue edema gradually improved. On postoperative day 1, the patient was awake and able to follow commands when sedation was lightened. However, on postoperative day 2, despite further reduction in sedation, the patient became progressively somnolent and increasingly difficult to arouse.

The differential diagnosis included intracranial hemorrhage, ischemic stroke, hydrocephalus, metabolic derangement, residual sedative effects, cerebral arterial air embolism, and tension pneumocephalus.

An urgent CT scan of the head was obtained.

What Was the Diagnosis?

CT shows massive air pooling in the deep midline (basal cisterns and third ventricle) with brainstem compression, consistent with tension pneumocephalus.

Although postoperative pneumocephalus is common after craniotomy, tension pneumocephalus is rare and potentially life-threatening. Air trapped within the cranial vault accumulates under pressure and compresses surrounding brain tissue, resulting in progressive neurological deterioration.

Potential contributing factors included the prolonged sitting-position, intraoperative cerebrospinal fluid loss, and the postoperative intracranial cavity. Continued positive pressure ventilation may also have promoted air accumulation if a persistent communication with the operative field was present.

The patient was treated with 100% oxygen, and an external ventricular drain (EVD) was placed to allows the pocketed intraventricular air and obstructed CSF to be vented seamlessly. His neurological status subsequently improved. Final pathology revealed a pineal germinoma.

Discussion

The sitting position continues to offer important advantages for selected pineal region and posterior fossa procedures, including improved surgical exposure, gravity assisted drainage of blood and cerebrospinal fluid from the operative field, and decreased blood loss. However, it also introduces unique anesthetic risks¹.

Venous air embolism remains the most recognized complication. Even small amounts of entrained air can be detected by TEE, which remains the most sensitive monitoring modality. Prompt recognition and coordinated communication between anesthesia and surgical teams are essential for successful management².

Macroglossia is a less common but potentially devastating complication. Prolonged operative duration, excessive neck flexion, impaired venous and lymphatic drainage, and compression from oral or pharyngeal devices-including a prolonged indwelling TEE probe- may contribute to tongue edema. Significant swelling should prompt caution regarding extubation, as airway obstruction and difficult reintubation can occur³.

Tension pneumocephalus is an uncommon but important cause of delayed neurological deterioration following cranial surgery. Symptoms may develop hours to days postoperatively and can mimic stroke, hemorrhage, or residual sedation. Early neuroimaging is critical whenever an unexpected decline in neurological status occurs⁴.

This case highlights how multiple complications associated with sitting position cranial surgery may occur sequentially in a single patient. Successful outcomes depend on anticipation, vigilance, and timely multidisciplinary intervention.

Clinical Pearls

• Sitting craniotomy provides excellent surgical exposure but carries unique anesthetic risks.
• Sudden hypotension accompanied by a decrease in end-tidal CO₂ should prompt immediate evaluation for venous air embolism.
• TEE remains the most sensitive monitor for detecting intracardiac air.
• Prolonged sitting-position procedures increase the risk of postoperative macroglossia and airway compromise.
• Significant tongue edema warrants delayed extubation and continued airway protection.
• Delayed neurological deterioration after craniotomy should raise suspicion for tension pneumocephalus.
• Early diagnosis and intervention are critical for preventing permanent neurological injury.

References:

1. Rozet, I. and Vavilala, M. Risks and Benefits of Patient Positioning During Neurosurgical Care. Anesthesiol Clin. 2007 Sep; 25(3): 631–x. doi: 10.1016/j.anclin.2007.05.009
2. D’Souza, R.S., Abcejo, A.S., Sexton, M.A. Intraoperative Management of Large Resuscitation-Associated Venous Air Embolism (VAE) for Emergent Neurological Surgery. Case Reports in Anesthesiology. 2020. Doi:10.1155/2020/8868037.
3. Ababneh, O. et al. Acute Macroglossia Post Craniotomy in Sitting Position: A Case Report and Proposed Management Guideline. Int Med Case Rep J. 2020; 13: 391–397. Published online 2020 Aug 31. doi: 10.2147/IMCRJ.S265206
4. Wankhade, BS et al. What should an intensivist know about pneumocephalus and tension pneumocephalus? Acute and Critical Care 2023;38(2):244-248. DOI: https://doi.org/10.4266/acc.2021.01102 Published online: April 13, 2022