Brain Shift during Staged Deep Brain Stimulation for Movement Disorders.

INTRODUCTION: Deep brain stimulation (DBS) is a routine neurosurgical procedure utilized to treat various movement disorders including Parkinson's disease (PD), essential tremor (ET), and dystonia. Treatment efficacy is dependent on stereotactic accuracy of lead placement into the deep brain target of interest. However, brain shift attributed to pneumocephalus can introduce unpredictable inaccuracies during DBS lead placement. This study aimed to determine whether intracranial air is associated with brain shift in patients undergoing staged DBS surgery. METHODS: We retrospectively evaluated 46 patients who underwent staged DBS surgery for PD, ET, and dystonia. Due to the staged nature of DBS surgery at our institution, the first electrode placement is used as a concrete fiducial marker for movement in the target location. Postoperative computed tomography (CT) images after the first electrode implantation, as well as preoperative, and postoperative CT images after the second electrode implantation were collected. Images were analyzed in stereotactic targeting software (BrainLab); intracranial air was manually segmented, and electrode shift was measured in the x, y, and z plane, as well as a Euclidian distance on each set of merged CT scans. A Pearson correlation analysis was used to determine the relationship between intracranial air and brain shift, and student's t test was used to compare means between patients with and without radiographic evidence of intracranial air. RESULTS: Thirty-six patients had pneumocephalus after the first electrode implantation, while 35 had pneumocephalus after the second electrode implantation. Accumulation of intracranial air following the first electrode implantation (4.49 ± 6.05 cm3) was significantly correlated with brain shift along the y axis (0.04 ± 0.35 mm; r (34) = 0.36; p = 0.03), as well as the Euclidean distance of deviation (0.57 ± 0.33 mm; r (34) = 0.33; p = 0.05) indicating statistically significant shift on the ipsilateral side. However, there was no significant correlation between intracranial air and brain shift following the second electrode implantation, suggesting contralateral shift is minimal. Furthermore, there was no significant difference in brain shift between patients with and without radiographic evidence of intracranial air following both electrode implantation surgeries. CONCLUSION: Despite observing volumes as high as 22.0 cm3 in patients with radiographic evidence of pneumocephalus, there was no significant difference in brain shift when compared to patients without pneumocephalus. Furthermore, the mean magnitude of brain shift was <1.0 mm regardless of whether pneumocephalus was presenting, suggesting that intracranial air accumulation may not produce clinical significant brain shift in our patients.

Use of oxygen therapy for pneumocephalus: a systematic review.

Pneumocephalus is the pathologic collection of air in the intracranial cavity. In sufficient volumes, it can contribute to symptoms ranging from headaches to death. For conservative treatment, oxygen use is commonplace. Although this is an accepted tenet of clinical practice, it is not necessarily founded on robust trials. An electronic search of databases EMBASE and MEDLINE and the Cochrane Library was undertaken as per the 2020 Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) statement. Three articles were included. Although the modes of oxygen delivery were heterogenous (non-rebreather versus endotracheal versus hyperbaric chamber), all studies concluded favorably on the use of oxygen therapy for increased reabsorption of pneumocephalus.

Fatal postoperative tension pneumocephalus after acute subdural hematoma evacuation: a case report.

PURPOSE: Tension pneumocephalus (TP) represents a rare pathology characterized by constant accumulation of air in the intracranial space, being associated with increased risk of herniation, neurologic deterioration and death. Regarding neurosurgical trauma cases, TP is majorly encountered after chronic subdural hematoma evacuation. In this case report, we present a rare case of fatal postoperative TP encountered after craniotomy for evacuation of acute subdural hematoma (aSDH). CASE PRESENTATION: An 83-year old gentleman was presented to the emergency department of our hospital with impaired level of consciousness. Initial examination revealed Glascow Coma Scale (GCS) 3/15, with pupils of 3 mm bilaterally and impaired pupillary light reflex. CT scan demonstrated a large left aSDH, with significant pressure phenomena and midline shift. Patient was subjected to an uneventful evacuation of hematoma via craniotomy and a closed subgaleal drain to gravity was placed. The following day and immediately after his transfer to the CT scanner, he presented with rapid neurologic deterioration with acute onset anisocoria and finally mydriasis with fixed and dilated pupils. Postoperative CT scan showed massive TP, and the patient was transferred to the operating room for urgent left decompressive craniectomy, with no intraoperative signs of entrapped air intracranially. Finally, he remained in severe clinical status, passing away on the eighth postoperative day. CONCLUSION: TP represents a rare but severe neurosurgical emergency that may be also encountered after craniotomy in the acute trauma setting. Involved practitioners should be aware of this potentially fatal complication, so that early detection and proper management are conducted.

60-year-old male with rapidly progressive pneumocephalus caused by Clostridium septicum in the setting of an occult colonic adenocarcinoma.

BACKGROUND: Disseminated Clostridium septicum infection is an uncommon complication associated with malignancies, particular colonic adenocarcinoma. The organism appears to preferentially colonize large masses in rare individuals and subsequently seed the blood via mucosal ulceration. This has rarely been reported to lead to central nervous system infection and, in several cases, rapidly progressive pneumocephalus. In the few cases reported, this was a universally fatal condition. The current case adds to the reports of this extremely rare complication and provides a unique and complete clinicopathologic characterization with autopsy examination, microscopy, and molecular testing. CASE PRESENTATION: A 60-year-old man with no known past medical history was discovered having seizure-like activity and stroke-like symptoms. Blood cultures turned positive after six hours. Imaging revealed a large, irregular cecal mass as well as 1.4 cm collection of air in the left parietal lobe that progressed to over 7 cm within 8 h. By the following morning, the patient had lost all neurologic reflexes and died. Post-mortem examination revealed brain tissue with multiple grossly evident cystic spaces and intraparenchymal hemorrhage, while microscopic exam showed diffuse hypoxic-ischemic injury and gram-positive rods. Clostridium septicum was identified on blood cultures and was confirmed in paraffin embedded tissue from the brain by 16 S ribosomal sequencing and from the colon by C. septicum specific PCR. CONCLUSIONS: C. septicum is an anaerobic, gram-positive rod that can become invasive and is strongly associated with gastrointestinal pathology including colonic adenocarcinomas. Central nervous system infection with rapidly progressive pneumocephalus is a rarely reported and universally fatal complication of disseminated C. septicum infection.

Post-dural puncture headache combined with pneumocephalus secondary to vaginal delivery following epidural anesthesia: a case report.

BACKGROUND: Pneumocephalus is rare in vaginal deliveries. Pneumocephalus may be asymptomatic or present with signs of increased intracranial pressure. However, parturients who received epidural anesthesia with air in their brains may experience low intracranial pressure headaches after giving birth, causing the diagnosis of pneumocephalus to be delayed. We report a case of a parturient who developed post-dural puncture headache combined with pneumocephalus secondary to vaginal delivery following epidural anesthesia. CASE PRESENTATION: A 24-year-old G1P0 Chinese woman at 38 weeks gestation was in labor and received epidural anesthesia using the loss of resistance to air technique and had a negative prior medical history. She presented with postural headache, neck stiffness and auditory changes 2 h after vaginal delivery. The head non-contrast computed tomography revealed distributed gas density shadows in the brain, indicating pneumocephalus. Her headache was relieved by bed rest, rehydration, analgesia, and oxygen therapy and completely disappeared after 2 weeks of postpartum bed rest. CONCLUSIONS: This is the first report that positional headaches after epidural anesthesia may not indicate low intracranial pressure alone; it may combine with pneumocephalus, particularly when using the loss of resistance to air technique. At this moment, head computed tomography is essential to discover other conditions like pneumocephalus.

Tension pneumocephalus in a patient with NF1 following ventriculoperitoneal shunt-deciphering the cause and proposed management strategy.

INTRODUCTION: Spontaneous pneumocephalus following ventriculoperitoneal shunting is a very unique complication, seen in a handful of patients. Small bony defects form as a result of chronically raised intracranial pressure, which can later lead to pneumocephalus once intracranial pressure decreases following ventriculoperitoneal shunting. CASE REPORT: Here, we present a case of a 15-year-old girl with NF1 who presented to us with pneumocephalus 10 months following shunting and our management strategy along with a literature review of this condition. CONCLUSION: NF1 & hydrocephalus can lead to skull base erosion, which needs to be looked up before proceeding with VP shunting to avoid delayed onset pneumocephalus. SOKHA with the opening of LT is a minimally invasive approach suitable to tackle both problems simultaneously.

Different Approaches in Skull Base Surgery Carry Risks for Different Types of Complications.

Complications are not uncommon in the complex field of skull base surgery. The intrinsic relationship of lesions in this region to important neurovascular structures, dura mater, and bone may lead to significant morbidity and mortality. The evolution of endoscopic endonasal surgery has had a significant impact on this field as a less invasive option for treatment of selected lesions, but major morbidity may still occur; moreover, endoscopic approaches have been associated with higher rates of some specific complications, such as cerebrospinal fluid leaks. Based on a presented case report, the authors discuss the management of various complications associated with different approaches for resection of skull base malignancies, including epidural and intradural pneumocephalus, subdural hematoma, and subdural empyema. Important lessons learned by the senior author throughout more than 30 years of his skull base surgery practice are highlighted. The inherent risk of complications in skull base surgery emphasizes the importance of their avoidance, prevention, and learning from one's unfavorable experience so as not to repeat them.

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.

Modified Puerto Rico Recurrence Scale for chronic subdural hematomas: augmenting the grading scale with postoperative pneumocephalus volume.

BACKGROUND: Chronic subdural hematomas (CSDHs) are common in the elderly, with a relatively high rate of recurrence after initial surgical intervention. Our research team previously created a predictive grading system, the Puerto Rico Recurrence Scale (PRRS), to identify patients at high risk of CSDH recurrence. In this study, we introduce a modification of the (mPRRS) that includes pneumocephalus volume, which has been independently associated with recurrence. METHODS: A single-center Puerto Rican population-based retrospective study was performed to analyze data for patients treated for CSDH at 1 institution between July 1, 2017, and December 31, 2019. Univariate and multivariate analyses were used to create a grading scale predictive of recurrence. Retrospective validation was conducted for the cohort. RESULTS: Of 108 patients included in the study, 42 had recurrence, and 66 had nonrecurrence. Postoperative subdural space, postoperative midline shift, and pneumocephalus volume were all higher with recurrence (P = 0.002, P = 0.009, and P < 0.001, respectively). Multivariate analysis was used to create a 6-point grading scale comprising 3 variables (pneumocephalus volume [< 10, 10-20, 21-30, and > 30 cm3], postoperative midline shift [< 0.4, 0.41-1.0, and > 1.0 cm], and laterality [unilateral and bilateral]). Recurrence rates progressively increased in low-risk to high-risk groups (2/18 [11%] vs 21/34 [62%]; P < 0.003). CONCLUSION: The mPRRS incorporating pneumocephalus measurement improves CSDH recurrence prediction. The mPRRS indicated that patients with higher scores have a greater risk of recurrence and emphasized the importance of measuring postoperative variables for prediction. The mPRRS grading scale for CSDHs may be applicable not only to the Puerto Rican population but also to the general population.

Spontaneous Pneumocephalus: A Case Report with a Literature Review.

BACKGROUND: Pneumocephalus is defined as gas in the intracranial space. Common causes include head trauma, surgery, and diagnostic/therapeutic procedures resulting from the direct disruption of the dura. Spontaneous or nontraumatic pneumocephalus is an uncommon condition, often caused by infection, either due to insidious disruption of the dura or gas-forming pathogens. CASE REPORT: Herein, we report a rare case of spontaneous pneumocephalus associated with meningitis in a patient who received conservative treatment without surgical intervention. Blood culture revealed group A streptococcus. The pneumocephalus subsided gradually with antibiotic treatment, and no neurological deficits remained. A follow-up brain computed tomography scan showed the absence of pneumocephalus, but it showed progressive hydrocephalus. The patient was discharged on the 21st day of hospitalization. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Spontaneous pneumocephalus associated with meningitis is rare. It should always raise the suspicion of meningitis and prompt suitable treatment. Emergency physicians should always be vigilant for this particular possibility on brain computed tomography.

Tension pneumocephalus following bariatric surgery: case report.

Bariatric surgery is an effective treatment for patients with idiopathic intracranial hypertension (IIH), a condition that is associated with skull base defects. A 55-year-old woman presented with symptoms of intractable nausea and vomiting, followed by headache and confusion two weeks after an elective laparoscopic vertical sleeve gastrectomy procedure. She had a presumed diagnosis of IIH and a remote history of CSF oto/rhinorrhea treated with a lumbar peritoneal (LP) shunt. Computed tomography (CT) scan of the head revealed tension pneumocephalus with midline shift and dehiscence of the tegmen. The patient underwent emergent craniotomy for decompression of the air-filled temporal lobe, clamping of the LP shunt, and repair of the skull base defect. Caution should be exercised in obese patients with a history of CSF leak secondary to a middle fossa skull base defect when being evaluated for bariatric surgery.

The Effect of Surgical Positioning on Pneumocephalus in Subthalamic Nucleus Deep Brain Stimulation Surgery for Parkinson Disease.

OBJECTIVES: This research analyzed the effect of surgical positioning on postoperative pneumocephalus and assessed additional potential risk factors of pneumocephalus in subthalamic nucleus (STN) deep brain stimulation (DBS) for Parkinson disease (PD). MATERIALS AND METHODS: In this study, 255 consecutive patients with PD who received bilateral STN DBS under general anesthesia were retrospectively included. Of these, 180 patients underwent surgery with their heads in an elevated position, and 75 patients underwent surgery in a supine position. The postoperative pneumocephalus volume was compared between the two groups. Other potential risk factors for pneumocephalus also were analyzed. RESULTS: The mean pneumocephalus volume for the group with elevated-head positioning (16.76 ± 15.23 cm3) was greater than for the supine group (3.25 ± 8.78 cm3) (p < 0.001). Multivariable analysis indicated that the pneumocephalus volume was related to surgical positioning, lateral trajectory angle, intraoperative mean arterial pressure (MAP), microelectrode recording (MER) passage number, brain atrophy degree, and the anterior trajectory angle. No correlation was found between pneumocephalus and age, sex, duration of PD, surgery length, or intracranial volume. In the subgroup analysis, the pneumocephalus volume exhibited a negative correlation with intraoperative MAP (r = -0.210, p = 0.005) and positive correlations with degree of brain atrophy (r = 0.242, p = 0.001) and MER passage number (r = 0.184, p = 0.014) in the elevated-head group. Specifically, an MER passage number > 3 was a significant risk factor for pneumocephalus in the elevated-head group. A positive correlation was observed between the pneumocephalus volume and the lateral trajectory angle in both groups (elevated-head positioning, r = 0.153, p = 0.041; supine positioning, r = 0.546, p < 0.001). CONCLUSIONS: In patients with PD who were anesthetized and receiving STN DBS, supine positioning reduced pneumocephalus volume compared with patients with PD receiving STN DBS with their heads elevated. The pneumocephalus volume was negatively correlated with intraoperative MAP and positively correlated with the degree of brain atrophy, the lateral trajectory angle, and the MER passage number.

Postoperative pneumocephalus and recurrence and outcome of chronic subdural hematoma: a systematic review and meta-analysis.

We conducted a meta-analysis to analyze the effects of pneumocephalus after chronic subdural hematoma (CSDH) surgery on hematoma recurrence, mortality, and functional outcomes. In this meta-analysis, following PRISMA guidelines, PubMed, Embase, Cochrane Library, and Web of Science online databases were queried using the keywords "pneumocephalus," "pneumoencephalos," "intracranial pneumatocele," "pneumo encephalon," "subdural air," and "chronic subdural hematoma." The results were limited to English-language articles. Through the online database, we identified a total of 276 articles and finally included 14 articles for meta-analysis. The results showed that the recurrence rate in the pneumocephalus group was higher than that in the control group, with a pooled OR of 3.35 (CI: 2.51-4.46, P < 0.001). There was no difference in recurrence rate between the no/few and moderate pneumocephalus groups (OR: 1.27, CI: 0.68-2.37, P = 0.46), but the recurrence rate of the large pneumocephalus group was significantly higher than that of the moderate group, with a pooled OR of 3.29 (CI: 1.71-6.32, P < 0.001). This study failed to show higher mortality and worse outcomes in the pneumocephalus group than in the control. Pneumocephalus after surgical evacuation of CSDH was associated with the recurrence rate of hematoma. Pneumocephalus affecting recurrence was correlated with gas volume, and moderate pneumocephalus may have less impact, while patients with large pneumocephalus are more likely to recur than those with moderate pneumocephalus. More prospective cohort studies are needed for further investigation and verification. This meta-analysis was registered (PROSPERO CRD42022321800).

Tension Pneumocephalus Associated with Negative Pressure Wound Therapy with Instillation and Dwell Time for Methicillin-resistant Staphylococcus aureus Infection After Spinal Deformity Surgery.

PURPOSE: Surgical site infection (SSI) is a serious complication after spine surgery. Recently, it has become possible to perform negative pressure wound therapy with instillation and dwell time (NPWTi-d) for postoperative infected wounds. We report the first rare case of symptomatic pneumoencephalopathy following NPWTi-d for methicillin-resistant Staphylococcus aureus (MRSA) infection after spinal deformity surgery. METHODS: Retrospective review of a patient's medical record and imaging. RESULTS: A 77-year-old female patient underwent posterior corrective fixation with no intraoperative complications. On the 10th postoperative day, SSI was diagnosed, and debridement was performed. Since MRSA was detected in the wound culture, and a prolonged inflammatory reaction was observed, NPWTi-d was started to preserve the instrumentation. Gradually, good granulation was observed, and the extensive soft tissue defect decreased. On the 29th day after the start of NPWTi-d, the patient experienced sudden headache and neck pain while standing, and head computed tomography led to the diagnosis of symptomatic pneumoencephalopathy. NPWTi-d was discontinued, and when surgery was performed to close the wound, dural injury was found, which was not present at the time of the initial surgery, and dural repair was performed. After 2 weeks of bed rest, the patient's pneumoencephalopathy improved. Three years have passed since the surgery, and no recurrence of cerebrospinal fluid leakage or infection has been observed. CONCLUSIONS: Although NPWTi-d is a useful treatment for SSI, it is always necessary to pay attention to the development of pneumoencephalopathy and promptly diagnose and treat it because of the risk of life-threatening complications.

Air travel with pneumocephalus: a systematic review.

INTRODUCTION: Concerns arise when patients with pneumocephalus engage in air travel. How hypobaric cabin pressure affects intracranial air is largely unclear. A widespread concern is that the intracranial volume could relevantly expand during flight and lead to elevated intracranial pressure. The aim of this systematic review was to identify and summarise models and case reports with confirmed pre-flight pneumocephalus. METHODS: The terms (pneumocephalus OR intracranial air) AND (flying OR fly OR travel OR air transport OR aircraft) were used to search the database PubMed on 30 November 2021. This search returned 144 results. To be included, a paper needed to fulfil each of the following criteria: (i) peer-reviewed publication of case reports, surveys, simulations or laboratory experiments that focussed on air travel with pre-existing pneumocephalus; (ii) available in full text. RESULTS: Thirteen studies met the inclusion criteria after title or abstract screening. We additionally identified five more articles when reviewing the references. A notion that repeatedly surfaced is that any air contained within the neurocranium increases in volume at higher altitude, much like any extracranial gas, potentially resulting in tension pneumocephalus or increased intracranial pressure. DISCUSSION: Relatively conservative thresholds for patients flying with pneumocephalus are suggested based on models where the intracranial air equilibrates with cabin pressure, although intracranial air in a confined space would be surrounded by the intracranial pressure. There is a discrepancy between the models and case presentations in that we found no reports of permanent or transient decompensation secondary to a pre-existing pneumocephalus during air travel. Nevertheless, the quality of examination varies and clinicians might tend to refrain from reporting adverse events. We identified a persistent extracranial to intracranial fistulous process in multiple cases with newly diagnosed pneumocephalus after flight. Finally, we summarised management principles to avoid complications from pneumocephalus during air travel and argue that a patient-specific understanding of the pathophysiology and time course of the pneumocephalus are potentially more important than its volume.

Pneumocephalus and headache following craniotomy during the immediate postoperative period.

BACKGROUND: Pneumocephalus may be responsible for post-craniotomy headache but is easily overlooked in the clinical situation. In the present study, the relationship between the amount of intracranial air and post-craniotomy headache was investigated. METHODS: A retrospective observational study was performed on 79 patients who underwent minimal invasive craniotomy for unruptured cerebral aneurysms. Those who had undergone previous neurosurgery, neurological deficit before and after surgery were excluded The amount of air in the cranial cavity was measured using brain computed tomography (CT) taken within 6 h after surgery. To measure the degree of pain due to intracranial air, daily and total analgesic administration amount were used as a pain index. Correlation between intracranial air volume and total consumption of analgesic during hospitalization was tested using Spearman rank correlation coefficients. Receiver operating characteristics (ROC) analysis was used to determine the amount of air associated with increased analgesic consumption over 72 h postoperatively. RESULTS: The mean amount of intracranial air was 15.6 ± 9.1 mL. Total administration of parenteral and oral analgesics frequency were 6.5 ± 4.5, 13.2 ± 7.9 respectively. A statically significant correlation was observed between daily and total parenteral analgesic consumption after surgery and the amount of intracranial air at followed-up brain CT postoperatively within 24 h (r = 0.69, p < 0.001), within 48 h (r = 0.68, p < 0.001), and total duration after surgery (r = 0.84, p < 0.001). The optimal cut-off value of 12.14 mL of intracranial air predicts the use of parenteral analgesics over 72 h after surgery. CONCLUSIONS: Pneumocephalus may be a causative factor for post-craniotomy pain and headache with surgical injuries.

An unusual case of spontaneous nontraumatic pneumocephalus in the setting of remote craniofacial surgery.

BACKGROUND: Pneumocephalus is an uncommon pathology that typically follows head trauma, neurosurgery, or skull base tumors. Rarely, cases of spontaneous pneumocephalus can occur, most often in the setting of barotrauma. CASE DESCRIPTION: We describe a rare case of spontaneous pneumocephalus in the absence of barotrauma in a 31-year-old male who presented with a headache and a normal neurologic exam. Imaging revealed subarachnoid and subdural pneumocephalus. The patient underwent surgical exploration, revealing an ethmoid bone defect caused by encroachment of material from a remote reconstructive surgery of the left orbit, which was subsequently repaired. CONCLUSION: Although rare, spontaneous pneumocephalus should be considered even in the absence of clinical neurologic findings or barotrauma, in patients with previous cranial surgery and unexplained headaches.

Tension pneumocephalus and bilateral orbital compartment syndrome relieved by lateral canthotomies.

Traumatic tension pneumocephalus and orbital compartment syndrome are rare, tend to be associated with severe craniofacial injuries, and can occur following both blunt and penetrating injury. Early recognition and high index of clinical suspicion are important in both cases. Emergency decompression results in improvement in vast majority of cases.

Pneumocephalus in subthalamic deep brain stimulation for Parkinson's disease: a comparison of two different surgical techniques considering factors conditioning brain shift and target precision.

BACKGROUND: Precise placement of electrodes in deep brain stimulation (DBS) may be influenced by brain shift caused by cerebrospinal fluid leaking or air inflow. We compared accuracy and treatment outcomes between a standard technique and one aiming at reducing brain shift. METHODS: We retrospectively reviewed 46 patients (92 targets) treated with bilateral subthalamic-DBS for Parkinson's disease. The patients were divided into two groups: group A surgery was performed in supine position with standard burr hole, dural opening, fibrin glue and gelfoam plugging. Group B patients were operated in a semi-sitting position with direct dural puncture to reduce CSF loss. We analysed target deviation on head CT performed immediately after surgery and at 1 month merged with preoperative MRI planning. We recorded pneumocephalus volume, brain atrophy and target correction by intraoperative neurophysiology (ION). RESULTS: In group A, the mean pneumocephalus volume was 10.55 cm3, mean brain volume 1116 cm3, mean target deviation 1.09 mm and ION corrected 70% of targets. In group B, mean pneumocephalus was 7.60 cm3 (p = 0.3048), mean brain volume 1132 cm3 (p = 0.6526), mean target deviation 0.64 mm (p = 0.0074) and ION corrected 50% of targets (p = 0.4886). Most leads' deviations realigned to the planned target after pneumocephalus reabsorbtion suggesting a deviation caused by displacement of anatomical structures due to brain shift. Definitive lead position was always decided with ION. CONCLUSIONS: The modified DBS technique significantly reduced errors of electrode placement, though such difference was clinically irrelevant. ION corrected a high amount of trajectories in both groups (70% vs 50%). The choice of either strategy is acceptable.

The importance of imaging in diagnosis of infected otogenic pneumatoceles.

OBJECTIVE: Spontaneous otogenic pneumatocele is a rare entity resulting from a pressure gradient between a dehiscent temporal bone and the intracranial space. Secondary infection can ensue in patients with concurrent otomastoiditis. The current study discusses the clinical presentation and imaging characteristics of two cases of secondarily infected otogenic pneumatoceles. STUDY DESIGN: Case series. RESULTS: Two patients were diagnosed with a temporal lobe abscess in the setting of otogenic pneumatocele. Diagnosis was aided by both CT and MRI demonstrating a diffusion restricting lesion within brain parenchyma in association with free air in close proximity to an underlying tegmen defect. CONCLUSION: Prompt diagnosis of a secondarily infected otogenic pneumatocele with CT and MRI allows for surgical drainage with closure of the tegmen defect to prevent further complications and recurrence.