Pneumocephalus and tension pneumocephalus after posterior fossa surgery in the sitting position: a prospective study

Semisitting position for cerebello-pontine angle surgery: Analysis of complications and how to avoid it

OBJECTIVE

To analyze the primary complications related to semisitting position in patients undergoing cerebelo-pontine angle surgery.

METHODS

Retrospective data analysis from patients undergoing elective tumoral cerebelo-pontine angle surgery in a semisitting position. The incidence, severity, occurrence moment, treatment, duration, and outcomes of venous air embolism (VAE), pneumocephalus, postural hypotension, and other complications were recorded. Neurointensive care unit (NICU), length of stay (LOS), hospital LOS, and modified Rankin scale scores were calculated six months after surgery.

RESULTS

Fifty patients were operated on. Eleven (22%) presented VAE (mean duration 8±4.5min): five (10%) during tumor resection, and four (8%) during dural opening. Ten (20%) were resolved by covering the surgical bed, air bubbles aspiration, jugular compression, and one (2%) tilted to a steep Trendelenburg position. One (2%) had intraoperative hemodynamic instability. The only variable associated with VAE was meningioma at histopathology OR=4.58, p=0.001. NICU was higher in patients with VAE (5.5±1.06 vs. 1.9±0.20 days, p=0.01). There were no differences in the Rankin scale. All patients presented postoperative pneumocephalus with a good level of consciousness, except one (2%) who required evacuation. Seven patients (14%) showed postural hypotension, three (6%) after positioning, and one (2%) after developing a VAE; all were reversed with usual vasoactive drugs. No other position-related complications or mortality were registered in this series.

CONCLUSIONS

The semisitting position is a safe option with the knowledge, prevention, detection, and early solution of all the possible complications. The development of VAE rarely implies hemodynamic instability or greater disability after surgery. Postoperative pneumocephalus is very common and rarely requires evacuation. Excellent cooperation between anesthesia, nursing, neurophysiology, and neurosurgery teams is essential to manage complications.

The semi-sitting position in patients with indwelling CSF shunts: perioperative management and avoidance of complications

OBJECTIVE

Posterior fossa or midline tumors are often associated with hydrocephalus and primary tumor removal with or without perioperative placement of an external ventricular drain (EVD) is commonly accepted as first-line treatment. Shunting prior to posterior fossa surgery (PFS) is mostly reserved for symptomatic cases or special circumstances. There are limited data regarding the anticipated risk for symptomatic pneumocephalus and the perioperative management using the semi-sitting position (SSP) in such a scenario. Here, we therefore assessed the safety of performing PFS in a consecutive series of patients over a period of 15 years to allow the elaboration of recommendations for perioperative management.

METHODS

According to specific inclusion and exclusion criteria a total of 13 patients who underwent 17 operations was identified. Supratentorial pneumocephalus was evaluated with semiautomatic-volumetric segmentation. The volume of pneumocephalus was evaluated according to age and ventricular size.

RESULTS

Ten of the 13 patients had a programmable valve (preoperative valve setting range 6-14 cmH20; mean 7.5 cmH20) while 3 patients had non programmable valves. A variable amount of supratentorial air collection was evident in all patients postoperatively (range 3.2-331 ml; mean 122.32 ml). Positive predictors for the volume of postoperative pneumocephalus were higher age and a preoperative Evans ratio > 0.3. In our series, we encountered no cases of tension pneumocephalus necessitating an air replacement procedure as well as no obstruction, disconnection, infection or hardware malfunction of the shunt system.

CONCLUSIONS

Our findings indicate that a CSF shunt in situ is not a contraindication for performing PFS in the semi-sitting position and it does not increase the pre-existing risk for postoperative tension pneumocephalus. In cases of primary shunting for hydrocephalus associated with posterior fossa tumors a programmable valve set at a medium opening pressure with a gravitational device is a valid option when PFS in the semi-sitting position is opted. In patients with an indwelling shunt diversion system special caution is indicated in order to prevent and detect overdrainage especially in not adjustable valves or shunts without antisiphon devices.

The semisitting position in pediatric neurosurgery: pearls and pitfalls of a 10-year experience

OBJECTIVE

The authors sought to investigate the pearls and pitfalls of using the semisitting position in pediatric neurosurgery, with special focus on related morbidity and surgical practicability.

METHODS

All pediatric cases at a single institution were evaluated retrospectively. Those patients who underwent procedures in the semisitting position between December 2010 and December 2020 were included in the final analysis. Results were compared with all children who underwent surgery in the prone position for posterior fossa lesions within the same time frame.

RESULTS

A total of 42 posterior fossa surgeries were performed in 38 children in the semisitting position between December 2010 and December 2020. The mean patient age at the time of surgery was 8.9 years (range 13 months-18 years). The data of 24 surgeries performed in the prone position in 22 children during the same time frame were analyzed in comparison. Three children (7.9%) were diagnosed with a persistent foramen ovale preoperatively. The surgery was completed in all cases. The incidence of venous air embolism (VAE) was 11.9%. There was no VAE-related hemodynamic instability, infarction, or death. Endoscopic techniques were applied safely in 14 cases (33.3%). Postoperative pneumocephalus occurred significantly more frequently in patients who had undergone procedures in the semisitting position (p < 0.05), but without the need for intervention. During 1 surgery (2.4%), the patient experienced a postoperative skull fracture and epidural bleeding due to the skull clamp application. Clinical status of the patients immediately after surgery was improved or stable in 33 of the 42 surgeries (78.6%) performed in the semisitting position.

CONCLUSIONS

With attentive performance and an experienced surgical team, the semisitting position is a safe option for posterior fossa surgery in the pediatric population. With a comparable complication profile, the semisitting position offers excellent anatomical exposure, which is ideal for the application of endoscopic visualization. Careful skull clamp application and appropriate monitoring are highly recommended.

European position paper on the management of patients with patent foramen ovale. Part II - Decompression sickness, migraine, arterial deoxygenation syndromes and select high-risk clinical conditions

Patent foramen ovale (PFO) is implicated in the pathogenesis of a number of medical conditions but to date only one official position paper related to left circulation thromboembolism has been published. This interdisciplinary paper, prepared with the involvement of eight European scientific societies, reviews the available evidence and proposes a rationale for decision making for other PFO-related clinical conditions. In order to guarantee a strict evidence-based process, we used a modified grading of recommendations, assessment, development, and evaluation (GRADE) methodology. A critical qualitative and quantitative evaluation of diagnostic and therapeutic procedures was performed, including assessment of the risk/benefit ratio. The level of evidence and the strength of the position statements were weighed and graded according to predefined scales. Despite being based on limited and observational or low-certainty randomised data, a number of position statements were made to frame PFO management in different clinical settings, along with suggestions for new research avenues. This interdisciplinary position paper, recognising the low or very low certainty of existing evidence, provides the first approach to several PFO-related clinical scenarios beyond left circulation thromboembolism and strongly stresses the need for fresh high-quality evidence on these topics.

Occurrence and management of postoperative pneumocephalus using the semi-sitting position in vestibular schwannoma surgery

Background

The semi-sitting position in neurosurgical procedures is still under debate due to possible complications such as venous air embolism (VAE) or postoperative pneumocephalus (PP). Studies reporting a high frequency of the latter raise the question about the clinical relevance (i.e., the incidence of tension pneumocephalus) and the efficacy of a treatment by an air replacement procedure.

Methods

This retrospective study enrolled 540 patients harboring vestibular schwannomas who underwent posterior fossa surgery in a supine (n = 111) or semi-sitting (n = 429) position. The extent of the PP was evaluated by voxel-based volumetry (VBV) and related to clinical predictive factors (i.e., age, gender, position, duration of surgery, and tumor size).

Results

PP with a mean volume of 32 ± 33 ml (range: 0–179.1 ml) was detected in 517/540 (96%) patients. The semi-sitting position was associated with a significantly higher PP volume than the supine position (40.3 ± 33.0 ml [0–179.1] and 0.8 ± 1.4 [0–10.2], p < 0.001). Tension pneumocephalus was observed in only 14/429 (3.3%) of the semi-sitting cases, while no tension pneumocephalus occurred in the supine position. Positive predictors for PP were higher age, male gender, and longer surgery duration, while large (T4) tumor size was established as a negative predictor. Air exchange via a twist-drill was only necessary in 14 cases with an intracranial air volume > 60 ml. Air replacement procedures did not add any complications or prolong the ICU stay.

Conclusion

Although pneumocephalus is frequently observed following posterior fossa surgery in semi-sitting position, relevant clinical symptoms (i.e., a tension pneumocephalus) occur in only very few cases. These cases are well-treated by an air evacuation procedure. This study indicates that the risk of postoperative pneumocephalus is not a contraindication for semi-sitting positioning.

Pneumocephalus and Catatonia in a Patient With Persistent Drain Dysfunctions and Infections After a Hydrocephalus due to an Aquaduct Stenosis: A Case Report

The combination of catatonia and pneumocephalus is very rare and literature is very scarce on this topic. Here, we report a patient with pneumocephalus and catatonia after persistent drain dysfunctions and infections after a hydrocephalus due to an aquaduct stenosis. The combination of a catatonic syndrome and pneumocephalus in neurosurgical and intensive care practice is a rare phenomenon. One should consider it in patients after complicated neurosurgery with pneumocephalus.

Prone versus sitting position in pediatric low-grade posterior fossa tumors

PURPOSE

The choice between sitting and prone position to access the infratentorial space in a suboccipital craniotomy is still a matter of debate. The comparisons in terms of complications and outcome of both positions are scarce, and the pediatric population is indeed more infrequent in these in scientific reviews. In this paper, we assess intraoperative and postoperative complications and neurological outcome in pediatric patients undergoing posterior cranial fossa surgery for pilocytic astrocytoma in sitting and prone position respectively.

METHODS

We retrospectively analyzed 30 consecutive patients undergoing surgery for cerebellar pilocytic astrocytoma at the two neurosurgical units referring to the University of Padova Medical School from 1999 to 2017. Preoperative, intraoperative, and postoperative data were retrieved from our medical archives.

RESULTS

The statistical analysis did not show any differences between the two groups in terms of preoperative, intraoperative, and postoperative data. The neurological status at last follow-up was similar in both groups of patients.

CONCLUSIONS

Our results suggest that both sitting and prone position can be considered safe in suboccipital craniotomies. Further studies are needed to show if there are possible differences between these positions for other frequent pediatric tumors such as medulloblastomas and ependymomas.

Quality of life following surgical treatment of lesions within the pineal region

OBJECTIVEPineal region tumors are a rare and heterogeneous group of lesions. The optimal therapeutic approach is currently a topic of controversy, particularly in light of the potential operative risks and complications. The potential beneficial effects of surgery have already been described, but information about neurological outcome and, in particular, health-related quality of life (HRQOL) is still lacking in the literature. The aim of this study was to assess the therapeutic effect of resection of pineal region lesions, emphasizing grade of tumor resection, neurological outcome, quality of life, and the necessity of additional shunt procedures.METHODSThe authors performed a prospective study of HRQOL in 32 patients who had undergone surgical treatment of lesions in the pineal region (20 tumors and 12 cysts) between 2008 and 2014. All patients had at least 6 months of follow-up, with reexamination including standardized neurological assessment, an evaluation of dependency using the modified Rankin Scale, and an evaluation of HRQOL. The authors retrospectively examined patient charts and collected information regarding imaging studies, neurological status prior to surgery, surgical strategies used, any complications, and histological diagnoses.RESULTSIn this study, there was no surgery-associated mortality or major morbidity. Permanent minor morbidity was reported for 4 patients (13%). Comparing pre- and postoperative neurological symptoms, 75% of tumor patients had either complete resolution or improvement of preoperative symptoms; symptoms were unchanged in 10% of tumor patients and deteriorated in 15%. In patients with pineal cysts, long-term follow-up showed that 42% of patients were free of any symptoms and 58% experienced improvement of their preoperative symptoms. These outcomes were also reflected in the modified Rankin Scale scores, which demonstrated significant improvement following resection of pineal region lesions. Furthermore, significant improvements in HRQOL scores occurred in global health status, in all functional scales, and in pain, nausea and vomiting, fatigue, and insomnia (p < 0.0001). Moreover, a significant reduction in the necessity for permanent shunt procedures was observed after gross-total tumor resection compared with subtotal resection (p = 0.035) of pineal cysts.CONCLUSIONSDespite potential risks, (radical) surgery is a highly effective and safe treatment option for pineal region lesions and should be considered for the majority of patients.

Comparison of Anesthetic Management and Outcomes in Patients Having Either Transnasal or Transoral Endoscopic Odontoid Process Surgery

BACKGROUND

Endoscopic neurosurgical procedures involving the upper cervical vertebrae are challenging due to a narrow operating field and close proximity to vital anatomical structures. Historically, transoropharyngeal (transoral) endoscopy has been the preferred approach. More recently, however, an endoscopic transnasal approach was developed as an alternative method in hopes to reduce postoperative dysphagia, a common complication following transoral neurosurgery.

METHODS

Twenty-two endoscopic neurosurgical cases involving the odontoid or C1 vertebra were reviewed between January 1, 2005 and December 31, 2015 (17 and 5 through transoral and transnasal approaches, respectively). Patient demographics, anesthetic technique, intraoperative course, and postoperative outcomes such as were recorded.

RESULTS

Patients who underwent transnasal odontoidectomy had a shorter length of stay and lower rates of tracheostomy compared with those having similar surgery via the transoral route. In those having transoral surgery, no patient presented to the operating room with a preexisting tracheostomy. In 16 of 17 patients within the transoral group, a tracheostomy was performed. In those having transnasal surgery, 2 of 5 patients had a preexisting tracheostomy. In the remaining 3 of 5 patients, orotracheal intubation was performed and patients were extubated after the procedure.

CONCLUSIONS

The transnasal odontoid resection technique may become a more popular surgical approach without increasing rates of complications compared with those having transoral surgery. Ultimately, a larger, study is needed to further clarify these relationships.

Predictors of ventricular tension pneumocephalus after posterior fossa surgery in the sitting position

BACKGROUND

Ventricular pneumocephalus is a rare but potentially life-threatening complication of cranial surgery in the sitting position.

OBJECTIVE

The objective of the study is to assess the incidence and risk factors of postoperative ventricular pneumocephalus.

METHODS

We performed a retrospective chart review of 307 consecutive patients (147 men, 160 women) treated at our institution by intracranial surgery in the sitting position from January 2010 to October 2014. Ventricular air entrapment with lack of arousal or neurologic deterioration requiring external ventriculostomy (EVD) was defined as ventricular tension pneumocephalus (VTP). Demographic variables were recorded along with radiological and clinical data. The occurrence of pneumocephalus was correlated with patient-related and surgical variables.

RESULTS

VTP was observed in 12 cases (3.9%). These patients had higher intraventricular air volumes (48.5 cm³ (CI 95% [29.06-67.86])) compared to asymptomatic patients (7.4 cm³ (CI 95% [5.43-9.48])). Opening of the fourth ventricle was the most potent predictor of VTP (OR = 34.7, CI 95% [4.4-273.5], p = 0.001). In patients undergoing no additional treatment for pneumocephalus, ventricular air volume declined to an average of 41.7% of the initial postoperative volume on postoperative day 3.

CONCLUSIONS

Entrapment of intracranial and particularly ventricular air requiring emergent EVD occurred in 3.9% cases of intracranial surgery in the sitting position. Especially the opening of the fourth ventricle was associated with the development of VTP, which should warrant particularly diligent postoperative observation of these patients. In cases without neurological symptoms, the rate of spontaneous air resorption is sufficiently high to warrant expectant management.

Spontaneous Epidural Pneumocephalus

Spontaneous epidural pneumocephalus is a rare condition. The authors reported a 35-year-old male patient with tinnutus, dull headache, and swelling on his head. Patient had a history of head trauma and skull fracture from when he was 5 years old. Cranial computed tomography revealed increase in pneumatization of right mastoid air cells and large epidural air in temporoparietal region. Inner table of right temporal bone got thinner, causing communication of mastoid air cells with epidural space. Epidural air had septations and exerted mass effect on the right parietal lobe with minimal midline shift. Thinning of also right parietal bone caused extension of epidural air into the right parietal subcutaneous tissue and hence subcutaneous swelling. There was no obvious fracture line. Spontaneous epidural pneumocephalus is extremely rare condition that may cause severe complications. There are several etiologic factors. Head trauma can be the eliciting factor in the authors' patient. It is important to be familiar with its presentation and imaging findings to make early diagnosis and treatment.

[Mount Fuji sign in postoperative period after surgery for ependymoma of the third ventricle (V3): case report and review of the literature]

Le signe de « Mont Fuji » appelé autrement une pneumocéphalie compressive constitue une complication post-operatoire redoutable en neurochirurgie. Nous rapportons le cas clinique d'un patient de 10 mois, hospitalisé en réanimation pour prise en charge post-operatoire d'une chirurgie pour épendymome du troisième ventricule, dont l'evolution a été marquait par la survenue d'une pneumocéphalie compressive post-operatoire précoce, responsable d'une aggravation neurologique et hemodynamique. A travers cette observation, on met en évidence la possibilité de survenue d'un tel événement indésirable, Ainsi que des moyens thérapeutiques et surtout préventifs de cette complication.

Contemporary analysis of the intraoperative and perioperative complications of neurosurgical procedures performed in the sitting position

OBJECTIVE Historically, performing neurosurgery with the patient in the sitting position offered advantages such as improved visualization and gravity-assisted retraction. However, this position fell out of favor at many centers due to the perceived risk of venous air embolism (VAE) and other position-related complications. Some neurosurgical centers continue to perform sitting-position cases in select patients, often using modern monitoring techniques that may improve procedural safety. Therefore, this paper reports the risks associated with neurosurgical procedures performed in the sitting position in a modern series. METHODS The authors reviewed the anesthesia records for instances of clinically significant VAE and other complications for all neurosurgical procedures performed in the sitting position between January 1, 2000, and October 8, 2013. In addition, a prospectively maintained morbidity and mortality log of these procedures was reviewed for instances of subdural or intracerebral hemorrhage, tension pneumocephalus, and quadriplegia. Both overall and specific complication rates were calculated in relation to the specific type of procedure. RESULTS In a series of 1792 procedures, the overall complication rate related to the sitting position was 1.45%, which included clinically significant VAE, tension pneumocephalus, and subdural hemorrhage. The rate of any detected VAE was 4.7%, but the rate of VAE requiring clinical intervention was 1.06%. The risk of clinically significant VAE was highest in patients undergoing suboccipital craniotomy/craniectomy with a rate of 2.7% and an odds ratio (OR) of 2.8 relative to deep brain stimulator cases (95% confidence interval [CI] 1.2-70, p = 0.04). Sitting cervical spine cases had a comparatively lower complication rate of 0.7% and an OR of 0.28 as compared with all cranial procedures (95% CI 0.12-0.67, p < 0.01). Sitting cervical cases were further subdivided into extradural and intradural procedures. The rate of complications in intradural cases was significantly higher (OR 7.3, 95% CI 1.4-39, p = 0.02) than for extradural cases. The risk of VAE in intradural spine procedures did not differ significantly from sitting suboccipital craniotomy/craniectomy cases (OR 0.69, 95% CI 0.09-5.4, p = 0.7). Two cases (0.1%) had to be aborted intraoperatively due to complications. There were no instances of intraoperative deaths, although there was a single death within 30 days of surgery. CONCLUSIONS In this large, modern series of cases performed in the sitting position, the complication rate was low. Suboccipital craniotomy/craniectomy was associated with the highest risk of complications. When appropriately used with modern anesthesia techniques, the sitting position provides a safe means of surgical access.

Post-traumatic epidural tension pneumocephalus: a case report

Introduction

Pneumocephalus is usually a self-limiting condition commonly associated with neurosurgical interventions, head and facial trauma. In contrast, tension pneumocephalus is extremely rare, and considered a neurosurgical emergency.

Case presentation

We present a rare case of post-traumatic epidural tension pneumocephalus in a 30-year-old white man who deteriorated rapidly after a blunt head trauma. Imaging revealed a large, right temporoparietal epidural pneumocephalus with mass effect, most likely arising from a small defect in the mastoid sinus. A pre-existing mucocele was also suspected. Emergency burr hole evacuation was performed and he experienced full recovery, but more invasive treatment was eventually needed to resolve the condition.

Conclusions

Epidural tension pneumocephalus is a rare and potentially life-threatening condition, but treatable with the right management. To the best of our knowledge, a post-traumatic tension pneumocephalus caused by a pre-existing mucocele has not been reported in the literature.

Normobaric hyperoxia for treatment of pneumocephalus after posterior fossa surgery in the semisitting position: a prospective randomized controlled trial

Background

Supratentorial pneumocephalus after posterior fossa surgery in the semisitting position may lead to decreased alertness and other symptoms. We here aimed to prove the efficacy of normobaric hyperoxia on the absorption of postoperative pneumocephalus according to a standardized treatment protocol.

Methods and Findings

We enrolled 44 patients with postoperative supratentorial pneumocephalus (> 30 ml) after posterior fossa surgery in a semisitting position. After randomisation procedure, patients received either normobaric hyperoxia at FiO₂ 100% over an endotracheal tube for 3 hours (treatment arm) or room air (control arm). Routine cranial CT scans were performed immediately (CT1) and 24 hours (CT2) after completion of surgery and were rated without knowledge of the therapy arm. Two co-primary endpoints were assessed: (i) mean change of pneumocephalus volume, and (ii) air resorption rate in 24 hours. Secondary endpoints were subjective alertness (Stanford Sleepiness Scale) postoperatively and attention (Stroop test), which were evaluated preoperatively and 24 hours after surgery. The mean change in pneumocephalus volume was higher in patients in the treatment arm as compared to patients in the control arm (p = 0.001). The air resorption rate was higher in patients in the treatment arm as compared to patients in the control arm (p = 0.0015). Differences were more pronounced in patients aged 52 years and older. No difference between patients in treatment arm and control arm was observed for the Stroop test. The distribution of scores in the Stanford Sleepiness Scale differed in the treatment arm as compared to the control arm, and there was a difference in mean values (p = 0.015).

Conclusions

Administration of normobaric hyperoxia at FiO₂ 100% via an endotracheal tube for 3 hours is safe and efficacious in the treatment of pneumocephalus after posterior fossa surgery in the semisitting position. Largest benefit was found in elderly patients and particularly in older men.

Trial Registration

German Clinical Trials Register DRKS00006273

Postoperative tension pneumocephalus following cerebral aneurysm surgery in supine position without prior lumbar drainage

The occurrence of tension pneumocephalus in neurosurgeries done in the supine position is scarcely reported. We present a case of 57-year-old man who developed tension pneumocephalus postoperatively, following cerebral aneurysm surgery, in supine position, where lumbar drainage before clipping surgery was not done. The patient's neurological status deteriorated rapidly, characterized by convulsion and unresponsiveness to external stimuli, 1 h following the uneventful surgery. Immediate computed tomography scan revealed bi-frontal tension pneumocephalus. Long duration of surgery and cerebrospinal fluid loss were assumed to be the causative factors. The patient was treated immediately with frontal drill hole evacuation for intracranial air, which saved the patient from a life threatening complication.

Pneumocephalus: case illustrations and review

BACKGROUND

Pneumocephalus is commonly encountered after neurosurgical procedures but can also be caused by craniofacial trauma and tumors of the skull base and rarely, can occur spontaneously. Contributing factors for the development of pneumocephalus include head position, duration of surgery, nitrous oxide (N(2)O) anesthesia, hydrocephalus, intraoperative osmotherapy, hyperventilation, spinal anesthesia, barotauma, continuous CSF drainage via lumbar drain, epidural anesthesia, infections, and neoplasms. Clinical presentation includes headaches, nausea and vomiting, seizures, dizziness, and depressed neurological status. In this article, we review the incidence, mechanisms, precipitating factors, diagnosis, and management of pneumocephalus. Search of Medline, databases, and manual review of article bibliographies. Considering four case illustrations that typify pneumocephalus in clinical practice, we discuss the common etiologies, and confirm the diagnosis with neuroimaging and management strategies. Avoidance of contributing factors, high index of suspicion, and confirmation with neuroimaging are important in attenuating mortality and morbidity. A significant amount of pneumocephalus can simulate a space-occupying lesion. Supplemental oxygen increases the rate of absorption of pneumocephalus.

A standardized protocol for the prevention of clinically relevant venous air embolism during neurosurgical interventions in the semisitting position

OBJECTIVE

We report the results and complications associated with standardized intraoperative management designed for the prevention of hemodynamically relevant venous air embolism during surgery performed in the semisitting position.

METHODS

A protocol for preoperative evaluation and intraoperative monitoring was developed and applied in 187 consecutive patients who underwent surgery in the semisitting position between 1999 and 2004. The protocol included preoperative transesophageal echocardiography examination (TEE), intraoperative TEE monitoring, catheterization of the right atrium and a combination of fluid input, positive end expiratory pressure, and standardized positioning aiming at a positive pressure in the transverse and sigmoid sinuses. Data were collected retrospectively from the charts and intraoperative anesthesiological protocols of the patients for the incidence of clinically relevant air embolism (i.e., TEE-diagnosed air embolism plus a decrease in end tidal CO2 or hemodynamic changes) and other complications related to the semisitting position.

RESULTS

Three cases (1.6%) of relevant venous air embolism occurred in 187 patients. Only 1 case (0.5%) was hemodynamically relevant, with temporary arterial blood pressure decrease and heart rate increase. Pneumatocephalus leading to lethargy was a frequent postoperative finding, which resolved spontaneously in all except 1 patient with epileptic seizure and oculomotor nerve palsy attributable to space-occupying subdurally trapped air, which had to be treated surgically. There was no permanent morbidity or mortality related to the semisitting position.

CONCLUSION

Fear of massive venous air embolism is one reason for dramatic decline in the use of the semisitting position in neurosurgical practice. We found that strict adherence to a standardized protocol using TEE monitoring before and during surgery; exclusion of patients with patent foramen ovale; and a combination of positive end expiratory pressure, fluid input, and a standardized position aiming a positive pressure in the transverse and sigmoid sinuses helped to greatly minimize this complication to a rate of 0.5% for hemodynamically relevant events.

Stereotactic biopsy complicated by pneumocephalus and acute pulmonary edema

BACKGROUND

The aim of this study was to describe pneumocephalus as a rare complication of stereotactic biopsy and as a possible cause of acute neurogenic pulmonary edema.

CASE DESCRIPTION

A case of frameless stereotactic biopsy complicated by pneumocephalus presenting with acute lung injury 48 hours after the procedure. A frameless stereotactic procedure was performed in the standard fashion. Immediate postoperative CT showed no intracranial air except for a gas inclusion at the biopsy site within the lesion. The skin staple placed at the end of surgery on the skin incision was removed 36 hours later. A CT scan performed 48 hours postoperatively showed new pneumocephalus. The patient exhibited acute respiratory distress but no new neurologic symptoms. There was no detectable systemic cause for the pulmonary edema. The patient received supportive respiratory treatment and fully recovered.

CONCLUSION

Pneumocephalus is apparently a rare complication of stereotactic brain biopsy and one that may result from early removal of the skin staple or suture. The occurrence of acute neurogenic pulmonary edema may be attributed to the pneumocephalus.

Delayed lateral rectus palsy following resection of a pineal cyst in sitting position: direct or indirect compressive phenomenon?

A rare case of delayed lateral rectus palsy in a patient following resection of a pineal lesion in the sitting position is presented. Postoperative pneumocephalus is common following craniospinal surgical intervention in the sitting position. The sixth cranial nerve is frequently injured because of its prolonged intracranial course. A 13-year-old girl was evaluated for unremitting headaches. No focal deficits were demonstrated on neurological examination. Magnetic resonance imaging revealed a cystlike pineal region mass with peripheral enhancement following intravenous contrast administration. A supracerebellar infratentorial craniotomy was performed in the sitting position, and complete resection of the lesion was achieved. Her postoperative course was complicated by sixth nerve palsy on the third postoperative day. Her symptoms improved with conservative management. The occurrence of sixth cranial nerve palsy secondary to pneumocephalus is a rare entity. Even rarer is the report of this anomaly following craniotomy in the sitting position. This patient's symptoms manifested in a delayed fashion. Although uncommon, this complication should be considered in patients undergoing cranial or spinal surgical interventions in this position.

Risks and benefits of patient positioning during neurosurgical care

Positioning of the surgical patient is an important part of anesthesia care and attention to the physical and physiologic consequences of positioning can help prevent serious adverse events and complications. The general principles of patient positioning of the anesthetized and awake neurosurgical patient are discussed in this article.

Postoperative brain stem tension pneumocephalus causing transient locked-in syndrome

The incidence of pneumocephalus after supratentorial craniotomy has been reported to be as high as 100%. However, transformation of postoperative pneumocephalus into tension pneumocephalus (symptomatic intracranial air) is a rather rare phenomenon. Tension pneumocephalus after posterior fossa surgery is reported mainly when the surgery is performed in a sitting position. We hereby report on a patient who developed brain-stem tension pneumocephalus in the early postoperative period after posterior fossa craniotomy for an exophytic brainstem astrocytoma, operated in the prone position. A complete locked-in syndrome resolved following surgical relief of the trapped air.

Alleviation of intracranial air using carbon dioxide gas during intraventricular tumor resection

OBJECTIVES/PURPOSES

Postoperative vomiting occurs more frequently in patients after intraventricular surgery than after other intracranial surgeries. This has been attributed to intracranial air. Carbon dioxide gas (CO2) has properties beneficial to the treatment of some medical disorders, displaying a higher specific gravity and more rapid absorption into surrounding tissues than air. We therefore, attempted to replace air with CO2 during intra- and paraventricular tumor resections. The aim of the present study was to elucidate whether intracranial air after intraventricular surgery could be alleviated safely using CO2, and investigate its clinical usefulness.

PATIENTS AND METHODS

CO2 was introduced into the subdural space at 2l/min through a silicon tube from time of dural incision to closure. Subjects comprised 40 patients alternately assigned to one of two groups: the trial group (n=20) receiving CO2 treatment; and controls (n=20) without CO2 treatment.

RESULTS

Intra- and postoperatively, no patients showed complications caused by CO2 treatment. Postoperatively, intraventricular gas shown on CT scans disappeared significantly sooner in the trial group than in controls. Frequency of postoperative vomiting was significantly lower in the trial group than in controls.

CONCLUSION

Intracranial air after intraventricular surgery can be safety alleviated using CO2.

[Tension pneumocephalus after intracranial surgery in the supine position]

Tension pneumocephalus is a rare and severe complication appearing after posterior fossa procedures in the sitting position. This complication may endanger the patient's life and require immediate treatment. However, tension pneumocephalus after neurosurgical procedure in the supine position have been scarcely reported. We report such a complication occurring in a 14-year-old girl submitted to a frontotemporal craniotomy for removal of an astrocytome performed with the patient supine. We discuss ethiopathogenesis and management of this complication.

Surgical approaches to posterior third ventricular tumors

A variety of surgical approaches to the posterior third ventricle and pineal region exist. The choice of approach is influenced by the exact location of the lesion, its expected pathologic findings, and the comfort level of the operating surgeon with the approach that is being considered. For most pineal region masses that are situated in the midline below the deep venous system, we favor the supracerebellar-infratentorial approach in the sitting position. For pineal region lesions that displace the deep venous system inferiorly or have significant lateral extension, we prefer the occipital-transtentorial approach in the three-quarter prone or sitting position. For lesions that are truly in the posterior third ventricle without extension posterior to the splenium, we prefer the interhemispheric-transcallosal approach in the lateral position.

Meningiomas of the velum interpositum: surgical considerations

Meningiomas of the third ventricle are a rare subtype of pineal region tumor that arise from the posterior portion of the velum interpositum, the double layer of pia mater that forms the roof of the third ventricle. The authors review the literature concerning these meningiomas and present a case in which the lesion was resected via the supracerebellar-infratentorial approach. The relationship of the tumor to the deep venous system and the splenium of the corpus callosum guides the selection of the most advantageous surgical approach. Posterior displacement of the internal cerebral veins demonstrated on preoperative imaging provides a strong rationale for use of the supracerebellar-infratentorial approach.

Anesthetic technique and development of pneumocephalus after posterior fossa surgery in the sitting position

OBJECTIVE

Pneumocephalus is a well-known complication of surgical procedures performed with the patients placed in the sitting position. Its incidence and intensity were prospectively studied in 90 consecutive patients undergoing a posterior fossa procedure in this position. Various anesthetic agents, with different effects on cerebral hemodynamics, were used.

MATERIAL AND METHODS

Patients were randomly assigned to one of three groups. In group 1 (n=30), anesthesia was induced and maintained with propofol. In group 2 (n=30), anesthesia was induced with thiopental and maintained with isoflurane. In group 3 (n=30), anesthesia was induced with thiopental and maintained with nitrous oxide and low-dose isoflurane. All patients received a load dose and an infusion of fentanyl. A cerebral computed tomography scan was performed to all patients 8 hours after surgery for detecting the presence and location of intracranial air. The size of pneumocephalus was ascertained using the formula for calculating the volume of a spheroid: v = PI / 6. x. y. z. Preoperative diagnosis, existence of shunted or non-shunted hydrocephalus, type and duration of the surgical procedure, detection of intraoperative venous air embolism, and appearance of new neurological symptoms in the postoperative period, were recorded.

RESULTS

All patients included in the study developed postoperative pneumocephalus. There were no significant differences (P = 0.133) in the estimated volume of intracranial air between the groups (group 1, volume = 38.3 -/+ 35.4 ml; group 2, volume = 48.9 -/+ 36.3 ml; group 3, volume = 31.5 -/+ 28.4 ml). Only two patients in the group 2 manifested symptoms of neurological involvement due to the pressure exerted by the intracranial air.

CONCLUSIONS

Despite the hypothetical diverse effects of the three anesthetic techniques used in this series on cerebral hemodynamics, our results suggest that none of them has a substantial effect on the amount of intracranial air detected after posterior fossa procedures performed in seated individuals. To the best of our knowledge this is the first report that addresses in a prospective manner the effects of several habitual anesthetic techniques on the development of pneumocephalus in patients submitted to posterior fossa procedures performed in the sitting position.

Tension pneumocyst after transsphenoidal surgery for Rathke's cleft cyst: case report

OBJECTIVE AND IMPORTANCE

Tension pneumocephalus is a rare but well-described complication of transsphenoidal surgery. It is usually associated with postoperative cerebrospinal fluid fistulae causing lower intracranial pressure, with air located in the subdural, subarachnoid, or intraventricular space. We report a case of suprasellar tension pneumocyst that caused visual deterioration to develop after an operation for a Rathke's cleft cyst. Only one similar case has been reported previously.

CLINICAL PRESENTATION

A 54-year-old woman with a cystic sellar-suprasellar mass compressing the chiasm was operated on via a standard transsphenoidal approach. The intraoperative diagnosis was Rathke's cleft cyst, and the floor of sella was left open to avoid recurrence. The sphenoid sinus was filled with a fat graft, and the rostrum of the sphenoid was reconstructed with a bone fragment. The patient's postoperative course was uneventful, and her vision improved. Ten days after discharge, the patient was readmitted to the emergency service with headache and visual impairment. Emergent computed tomography confirmed a suprasellar tension pneumocyst.

INTERVENTION

The patient underwent immediate reoperation via an endonasal endoscopic approach. After the trapped air was evacuated, the sella was closed with fascia lata and muscle using fibrin glue. The patient's vision improved postoperatively.

CONCLUSION

Suprasellar tension pneumocyst is an extremely rare complication of transsphenoidal surgery. To avoid this complication, the sellar floor should be repaired in a watertight fashion, and patients should be instructed to avoid blowing the nose, sneezing, straining, and coughing postoperatively.

An unusual fatal complication of low basilar trunk aneurysm surgery: isolated prepontine tension pneumocephalus

OBJECTIVE

A case of postoperative tension pneumocephalus after low basilar trunk aneurysm clipping is presented. To our knowledge, this is the first case of isolated prepontine tension pneumocephalus.

BACKGROUND

A 63-year-old woman was admitted for repair of a basilar aneurysm that had caused a subarachnoid hemorrhage. She was cooperative and partially oriented. According to Hunt & Hess classification, she was considered Grade III.

METHOD

The aneurysm was clipped, using a right lateral suboccipital craniectomy with the patient in the sitting position. In the early postoperative period, she had no new neurological deficit. However, 2 hours later the patient became lethargic and unresponsive to verbal commands. Emergency CT scan revealed an isolated prepontine tension pneumocephalus with prominent posterior displacement of the pons. She was immediately taken back to surgery. Upon incision of the dura mater, air could be heard escaping under pressure from the posterior fossa cavity. The clip was in its proper position and all arteries were patent. Spontaneous respiration and pupil reflexes returned soon after surgery, but she remained unconscious and died 3 days later.

CONCLUSION

We believe that this death was directly attributable to the tension pneumocephalus and the distortion of the pons. Postoperative prepontine tension pneumocephalus, although this is an extremely rare condition, should be considered if a patient deteriorates after basilar aneurysm surgery in the sitting position.

Suprasellar tension pneumocyst after transsphenoidal surgery. Case report

Tension pneumocephalus is an uncommon occurrence after transsphenoidal surgery. The author presents an unusual case of postoperative visual deterioration related to expanding air within a suprasellar tumor cavity.

Surgical treatment of posterior fossa tumors in infancy and childhood: techniques and results

In a collective of 72 children with tumors of the posterior fossa, the preoperative diagnosis, operation planning and performance, and use of additional procedures, like the preliminary ventricular drainage and interventriculostomy are described. The extent of intra- and postoperative complications is given. Postoperative lethality was 0% in the group operated on between 1979 and 1991. The responsible factors are discussed. The findings support the opinion of ALBRIGHT (1989) that the prognosis for such patients is most promising in the hands of a specialist in pediatric neurosurgery.

Postoperative fourth ventricle tension pneumocephalus

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Tension pneumocephalus following evacuation of chronic subdural haematoma

Five cases of a rare complication of tension pneumocephalus following evacuation of chronic subdural haematoma are described. This occurred in 8% of all cases of chronic subdural haematoma treated following installation of a CT scanner. The chronically compressed brain contributes to the ingress of this intracranial air. The increase in the brain bulk and gradual re-expansion of the brain, in the early postoperative period, competes with the trapped subdural air resulting in a rise in intracranial pressure leading to neurological deterioration. Twist drill craniostomy and aspiration, using a brain cannula with a three-way connector, has produced excellent results.

Tension pneumocephalus after CSF shunting procedures

We report a case of tension pneumocephalus following the insertion of a ventriculoperitoneal shunt for hydrocephalus secondary to aqueduct stenosis and discuss the possible genesis of the complication, diagnosis and treatment.