Keywords
pneumoventricle - liquoric fistula - cranioencephalic trauma
Introduction
Pneumoventricular and liquoric fistulae are possible complications of traumatic brain injury (TBI), the main cause of trauma-related morbimortality in Brazil.[1] Liquoric fistulae are more common after direct trauma, with fractures of the base of the skull.[1]
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[4] Pneumoventricle is rare and occurs after excessive cerebrospinal fluid (CSF) drainage, in the presence of a poorly compliant ventricular system, resulting in the influx of air into its interior. The pathophysiology of the tension pneumoventricle remains uncertain. However, the traumatic cause is certain, and multiple facial bone fractures and liquoric fistulae may contribute to the process.[1] If it is symptomatic, the tension pneumoventricle can lead to rapid clinical deterioration.[1]
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[7] The authors aim to report a rare case of tension pneumoventricle after TBI.
Discussion
Pneumocephalus is the presence of air in any intracranial compartment through a connection between the central nervous system (CNS) and the environment.[5] It is called a pneumoventricle when the air is in the intraventricular space. Pneumocephalus, despite having a common incidence, have a rare intraventricular presentation and, if symptomatic, may cause rapid clinical deterioration.[1]
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The presence of a liquoric fistula implies the existence of a dural and bone opening that establishes a communication between the subarachnoid space and the contaminated cavities of the upper airways, and its cause can be traumatic or non-traumatic. Among the non-traumatic causes are elective craniotomies.[5] The pneumoventricle is a common postoperative event, especially in posterior fossa or transventricular approaches, particularly in patients operated in the seated position.[5]
[7] The case reported in the present study had a traumatic cause, and this is the most frequently found in the literature.[1]
The majority of the patients with pneumocephalus remains asymptomatic and requires no intervention, with spontaneous resorption. In some cases, however, air collection may cause increased intracranial pressure, with neurological deterioration. The clinical presentation of tension pneumocephalus may include headache, seizures, decreased level of consciousness, nausea, vomiting, dizziness, focal deficits, and even coma, consequent to the intracranial hypertension.[1]
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[9] The time of onset of symptoms is variable. The patient in the present case presented with headache and vomiting, which began ∼ 14 days after the trauma.
The diagnosis can be made by a simple skull radiography, but CT is the gold standard.[1]
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[10] It is a sensitive examination in the detection of air even in small volumes (< 0.5 mL).[2]
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[10] The presence of porencephalic cysts may indicate the fistulation point, since the cyst tends to be located below the fistula. The treatment of pneumocephalus may be conservative, by lumbar shunt, or surgical exploration with intra or extracranial access.[1]
[9] The conservative treatment, often effective, includes oxygen therapy (through the use of 100% oxygen chambers or hyperbaric oxygenation), antibiotic therapy (of controversial use[2]), analgesia, neurological exams and serial CT for the evaluation of the evolution of the patient.
Hyperbaric oxygen therapy was recognized in 1995 by the Federal Council of Medicine (CFM, in the Portuguese acronym) as a therapeutic modality through resolution No. 1457/95, and it was subsequently recognized by the Brazilian Medical Association (AMB, in the Portuguese acronym). Indications for the method are based on clinical studies and indications developed by the International Committee on Hyperbaric Oxygen Therapy, which establishes institutions around the world, such as the Undersea and Hyperbaric Medical Society and the European Committee on Hyperbaric Medicine. In pneumocephalus, oxygen therapy works because oxygen replaces the nitrogen component, which is more rapidly absorbed into the bloodstream (Graham law), and thus stabilizes the condition within 48 hours.[11] In the case of hyperbaric oxygen therapy, there is an acceleration of the pneumocephalus reabsorption process in symptomatic patients or in patients with persistent pneumocephalus after 100% oxygen normobaric therapy.[11]
Unlike pneumocephalus, the occurrence of hypertensive pneumoventricles is rare and occurs, in most reported cases, after procedures for the placement of cerebrospinal fluid shunts in patients with hydrocephalus.[5]
[7] It is a neurosurgical emergency that usually requires an invasive approach.[1]
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[10] Many authors believe that the treatment should be focused on the surgical closure of the airway.[2] In the patient in question, there was no resolution of the liquoric fistula through conservative treatment; on the contrary, the patient developed a worsening of the condition with signs of intracranial hypertension, and surgical treatment was performed by means of bifrontal craniotomy and external ventricular derivation.
The external ventricular derivation in these cases is fundamental, since it provides the output of the hypertensive air. A physiological solution is introduced via a catheter into the ventricular system, occupying the place of the hypertensive air that goes out into the environment.[7] It is important to note that, in this case, there is a somewhat less invasive alternative: the introduction of a physiological solution through a ventricular catheter, concomitant with the attempt to correct the basal fistula by means of an endoscopic procedure at the base of the skull, sparing the patient of bifrontal craniotomy. However, this alternative is only feasible in services where there is experience with the endoscopic technique.
Conclusion
Although rare, the tension pneumoventricle should be considered in patients with post-traumatic liquoric fistula, especially when there is neurological deterioration, since it is a neurosurgical emergency requiring an invasive approach in most cases.
