Radiology of intracranial gas

Pneumocephalus secondary to a spinal surgery: A literature review and a case report

Introduction

We report a case of pneumocephalus, which is identified as the presence of air in the cranial cavity and is a rare complication after spinal surgeries, in addition to a literature review of similarly reported cases.

Case presentation

The patient is a 63-year-old male who developed pneumocephalus after undergoing a minimally invasive left side decompression at L3-L4 with left L4 foraminotomy even though there were no signs of dural tears or Cerebrospinal Fluid (CSF) leaks. After the diagnosis of pneumocephalus using brain Magnetic Resonance Imaging (MRI), the patient was treated conservatively and was discharged after 3 weeks without developing further complications.

Discussion

Pneumocephalus is defined as an abnormal accumulation of air within the cranial cavity. It can occur due to a variety of causes but rarely due to gas forming bacteria. Many theories are suggested concerning the pathophysiology of pneumocephalus, the inverted bottle theory, the ball valve theory, the Nitrous Oxide (N₂O) theory, and as we outweigh in our case, gas forming bacteria theory. Pneumocephalus can be treated surgically, nevertheless, conservative management methods of such cases are usually followed.

Conclusion

The aim of this study is to draw further attention to the management and diagnosis of such surgical complication. A more extended research is needed to provide a full comprehensive approach to deal with this problem if faced in the future. To the best of our knowledge, this study reports the first pneumocephalus case induced by a postoperative bacterial infection in the global English based medical literature.

•

Pneumocephalus caused by gas forming infection in the spine is a rare complication after spinal surgery.

•

Unexplained headache spinal surgeries should raise suspicion toward pneumocephalus.

•

There are many theories regarding the development of pneumocephalus, each one need specific attention.

Gas-forming brain abscess caused by Klebsiella pneumoniae

Gas forming brain abscess is a rare disease caused by Klebsiella pneumoniae occurring in patients with impaired host defense mechanism such as diabetes mellitus or liver cirrhosis. A 59-year-old man with 2-year history of diabetes mellitus and 20-year history of liver cirrhosis presented to the hospital with headache. On the day after admission, severe headache was developed and he deteriorated rapidly. Brain CT showed a non-enhanced mass including multiple air density as well as surrounding edema seen in the right occipital lobe, and isodensity air-fluid level seen in the right lateral ventricle. Despite emergent ventricular drainage and intraventricular and intravenous administration of antibiotics, his condition progressively worsened to sepsis and to death after 5 days. Bacterial culture of blood and ventricular fluids disclosed a Gram (-) rod, Klebsiella pneumoniae. In this report we review the pathogenic mechanism and its management.

Gas-containing otogenic brain abscess

BACKGROUND

Gas-containing brain abscesses are very rare. Two mechanisms may be responsible for the presence of intracavitary gas: bacterial fermentation or penetration through an abnormal communication between the exterior and the intracranium. The need to search for this potential communication is considered an indication for open surgery. We report the case of a surgically treated gas-containing brain abscess originating from an undiagnosed chronic otitis media.

CASE DESCRIPTION

A 54-year-old man developed acute neurologic deterioration, becoming comatose within 24 hours. A contrast-enhanced computed tomography (CT) scan disclosed a gas-containing cystic mass in the right temporal lobe. Urgent surgical decompression revealed the presence of an abscess, which was excised. During the same surgery, we performed a radical mastoidectomy, removing a previously undiagnosed attic cholesteatoma. Neither procedure revealed a discontinuity of the floor of the middle cranial fossa. Cultures grew a mixed flora. Antibiotics were administered for 6 weeks. The patient made a complete neurologic recovery.

CONCLUSION

This report demonstrates that otogenic brain abscesses may contain gas due to fermentation of nonclostridial bacteria.

Posttraumatic gas-containing brain abscess caused by Clostridium perfringens with unique simultaneous fungal suppuration by Myceliophthora thermophila: case report

OBJECTIVE AND IMPORTANCE

Gas-containing brain abscesses are rare, and the vast majority are caused by Clostridium perfringens. Significant simultaneous fungal infection in a bacterial abscess is even rarer. We present such a case and review the literature.

CLINICAL PRESENTATION

A 21-month-old male patient sustained a penetrating head injury in a barnyard, developed a gas-containing left parietal brain abscess, and presented with high fever, galeal swelling, and seizure.

INTERVENTION

The patient initially underwent debridement of his wound and then repeated aspirations. The initial cultures revealed pure growth of Clostridium perfringens. Despite appropriate antibiotic therapy, serial neuroimaging did not demonstrate a decrease in the size of the cavity. An excision had to be undertaken 6 weeks after the injury. The culture from the excised specimen revealed an unexpected growth of a saprophytic and opportunistic fungus, Myceliophthora thermophila. Antifungal treatment consisting of the administration of liposomal amphotericin B and itraconazole was then performed. The child was well and neurologically intact 6 months after the excision.

CONCLUSION

Our review revealed 38 cases of clostridial brain abscess in the literature. Despite the reputation of the organism, the outcome with clostridial brain abscesses was relatively benign. The main characteristics of clostridial brain abscesses are highlighted, with reference to their optimal treatment. Our review also revealed that fungal infection after a penetrating head injury is extremely rare and often fatal. Our case seems to be the first in the medical literature with growth of M. thermophila as a causative agent for intracranial suppuration.

Spontaneous otogenic pneumocephalus

A very rare case of otogenic pneumocephalus in a healthy 24-year-old man with a widely pneumatized right mastoid, precipitated by forceful Valsalva's maneuver, is reported. When a pneumocephalus is suspected, computed tomography scans are mandatory. The pertinent literature is discussed and the potential mechanisms causing spontaneous pneumocephalus are described. To the best of our knowledge, only two other similar cases have been reported up to now.

Spontaneous pneumocephalus in a newborn infant with myelomeningocele and hydromyelia

The authors report a preterm boy, born at 35 weeks gestation with hydrocephalus and an open sacral myelomeningocele. Cranial ultrasound showed ventricular dilatation with posture-dependent intraventricular bright echoes, representing air. Ultrasound of the cervical spine and the craniocervical junction revealed marked hydromyelia of the whole spinal cord, as well as a Chiari II malformation. Air penetrating the enlarged central canal through the neural tube defect and subsequently ascending to the cranial cavity was demonstrated by fluoroscopy. After a review of the literature, the authors conclude that the association of spontaneous pneumocephalus with myelomeningocele could indicate severe hydromyelia. These malformations are readily demonstrated by ultrasound in newborn infants.

Diffuse pneumocephalus due to Clostridium septicum cerebritis in haemolytic uraemic syndrome: CT demonstration

The computed tomography finding of diffuse pneumocephalus due to infection by gas-forming organisms is very unusual. We report such a case due to secondary infection by Clostridium septicum in a child with diarrhoea-associated haemolytic uraemic syndrome.

Symptomatic tension pneumocephalus after evacuation of chronic subdural haematoma: report of seven cases

We present seven cases of tension pneumocephalus developing after burr hole evacuation of chronic subdural haematoma. After a careful review of the literature we discuss the physiopathology, the diagnosis and the treatment of this complication of chronic subdural haematoma surgery.

Pneumocephalus at the cerebellopontine angle secondary to chronic otitis media

Intracranial air is usually asymptomatic but carries a potential risk of increased intracranial pressure or meningitis which require immediate therapy. Although pneumocephalus is quite common following trauma, especially with a fracture involving paranasal sinuses it is a rare manifestation of chronic otitis media. In this report, a case with a tension pneumocephalus at the cerebellopontine angle following a chronic mastoid infection is presented and the possible mechanism, diagnostic measures and the surgical management is discussed.

"Spontaneous" pneumocephalus associated with aerobic bacteremia

Three cases of "spontaneous" pneumocephalus suspected to have resulted from aerobic bacteremia caused by Enterobacter cloacae, Escherichia coli, and Klebsiella aerogenes are reported. In two cases, the E. cloacae and K. aerogenes were isolated from the cerebrospinal fluid. These cases were characterized by a rapid accumulation of air, without niveau, in the subarachnoid space and ventricles.

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.

The potential aggressiveness of sinus osteomas. A report of two cases

The fronto-ethmoidal osteoma is a relatively rare radiological finding and its growth potential, as well as the complications it may lead to, are often underestimated. Osteomas are a frequent cause of mucoceles and sinusitis due to blockage of the nasal ducts but can also present with more dramatic signs such as orbital or intracranial invasion. This knowledge must draw our attention to the need for follow-up of these tumors, whose growth apparently continues after puberty, especially when they are of the spongy type.

Tension pneumocephalus following nasal polypectomy

Subdural tension pneumocephalus in a 80-year-old man following nasal polypectomy, presenting clinically with progressive weakness of both legs, is reported and the pathogenesis is discussed. The diagnosis of tension pneumocephalus and the options of management are considered.

Prognosis, incidence and management of acute traumatic intracranial pneumocephalus. A retrospective analysis of 49 cases

CT scanning was carried out in 508 patients with acute head injuries. Retrospective analysis of the findings revealed intracranial air in 49 cases (9.7%). Air may be situated in the extradural, subdural or subarachnoid spaces or intracerebrally. A pneumocephalus was detected in 40 out of 49 (82%) of head injury patients within 6 hours of the accident. Injuries associated with a pneumatocele or a single intracranial air bubble have a good prognosis, as do frontobasal lesions. Injuries associated with multiple air bubbles have a bad prognosis. Intracranial air was a sign of a frontobasal or laterobasal fracture. In cases with a depressed skull fracture, extracerebral haematoma or pneumocephalus acting as a space occupying lesion, an operation should be performed as soon as possible. If associated with a persistent rhinorrhea the CSF-fistula should be operated according to the generally accepted rules. In other post-traumatic cases intracranial air may be disregarded, although its presence may influence the choice of treatment.

Gas within intracranial abscess cavities: an indication for surgical excision

Five patients were treated in whom gas within an intracranial abscess cavity was identified by plain roentgenogram, computed tomographic scan, or both. Management by aspiration in three patients was unsuccessful. Total excision of the abscess cavity was eventually required in all five patients, and a persistent extracranial communication was identified and closed in each. One patient died secondary to transtentorial herniation and severe brainstem injury; the other four recovered fully. Although certain anaerobic organisms may produce gas in the absence of a communication to the outside of the body, such production is uncommon. Total surgical excision is recommended for gas-containing abscesses because it allows removal of the mass lesion and identification and closure of possible persistent extracorporal communication.

Epidermoid tumor presenting as tension pneumocephalus. Case report

The authors report a patient with an epidermoid tumor that eroded through the frontal sinus, causing an acute neurological deficit secondary to tension pneumocephalus. The historical perspective, radiographic features, and pathophysiological mechanisms are discussed.

Spontaneous infected pneumatocoele secondary to chronic otitis media

A case of spontaneous temporal pneumatocoele secondarily infected by Haemophilus parainfluenzae is reported. Its relation to the lateral ventricle and to a defect in the tegmen tympani was confirmed by computerized tomography (CT). The possible aetiological mechanisms are discussed.

Subdural tension pneumocephalus. Report of two cases

Two patients developed subdural tension pneumocephalus after undergoing posterior fossa surgery performed in the sitting position. The mechanism for entry of air into the intracranial compartment is analogous to the entry of air into an inverted soda-pop bottle. As the fluid pours out, air bubbles to the top of the container. We have thus referred to this as the "inverted pop-bottle syndrome." Computerized tomography provided prompt diagnosis and confirmed brain displacement. Twist-drill aspiration of the air resulted in improvement in both patients, although one patient subsequently died from an intracerebellar hemorrhage. Tension pneumocephalus appears to be another potential complication of posterior fossa surgery in the sitting position. This condition is easily diagnosed and treated, and should be considered whenever a patient fails to recover as expected following posterior fossa surgery.

Intracranial air on computerized tomography

Intracranial gas may be epidural, subdural, subarachnoid, parenchymal, or intraventricular. Intracranial air can be easily diagnosed and its location correctly assessed by computerized tomography. Potentially serious complications of intracranial air, such as tension pneumocephalus, can be rapidly and accurately identified, facilitating appropriate clinical therapy.