Posttraumatic tension pneumoventricles have rarely been reported in the scientific literature. [1,8–10]. We were unable to determine exactly how this pathology developed in our patients because none of them underwent successive brain imaging from the acute phase of the trauma (> 72 h). However, we assume that our second patient (Patient 2) developed a simple acute posttraumatic pneumoventricle, which subsequently worsened, given the evolution of his clinical picture. Moreover, cases of secondary worsening of the penumoventricle are the most frequently reported [1,2,7,9]. Monitoring the persistence or reappearance of posttraumatic cerebrospinal rhinorrhea is essential because it is one of the first signs of worsening clinical conditions, as we observed in our patients. In addition, certain skull base abnormalities, such as congenital bony malformations (paranasal sinus pneumoceles, pneumosinus, ethmoidal meningocele), previous skull base surgery, ventricular approaches, and tumors, may increase the risk of posttraumatic tension pneumoventricle [1,2,5,9,11].
The tension pneumoventricle, similar to other types of tension pneumocephalus, can be explained by two pathophysiological mechanisms. The first is the inverted soda bottle mechanism, where air is drawn into the cranial compartment by the negative pressure created by the flow of CSF through an osteodural defect (cerebrospinal rhinorrhea or cerebrospinal otorrhea). The second mechanism is the ball valve mechanism, in which air enters the skull unilaterally through an osteodural defect with high pressure created by the Valsalva maneuver (coughing, sneezing, blowing the nose). The air is then trapped intracranially, increasing the intracranial pressure [1,3,5–7,11]. The accumulation of this air is at the root of the clinical manifestations presented by patients, including persistent headache, vomiting, intracranial hydro-areic noises perceived by patients, seizures, frontal syndrome, deterioration of consciousness, and even a state of coma (requiring emergency surgical decompression) [1,5,8]. The presence of air in the posterior cerebral fossa can lead to signs of brainstem damage and neurovegetative disorders; however, none of our patients showed these signs [3].
Cerebral computed tomography (CT) is the gold standard for diagnosing tension pneumocephalus [3,7,11]. However, the posttraumatic tension pneumoventricle may require precise peroperative localization of the osteodural defect. The latter is generally located at the base of the skull and is revealed by high-resolution CT or T2 cisternography magnetic resonance imaging (MRI) alone or coupled with high-resolution CT [6,7,11]. Unfortunately, in low-income countries, access to these brain imaging methods remains difficult because of the insufficient number or absence of high-field MRI machines and the absence of social security to cover the high cost of these examinations, which cost several times the minimum wage, making diagnosis difficult.
As in the case of our second patient (Patient 2), conservative treatment can be considered a first-line treatment for seven days, with close monitoring when neurological status permits. However, surgery is necessary in the event of signs of encephalic involvement or persistent minimal posttraumatic cerebrospinal rhinorrhea lasting more than ten days. Surgical repair of the osteodural defect is needed to avoid recurrence after conservative treatment or encephalic infection [9,12]. In our department, we routinely include osmotherapy and repeated lumbar puncture (100 to 200 cc/d) as conservative treatments, particularly when cerebrospinal rhinorrhea is not negligible. However, cases of pneumocephalus aggravated by lumbar subtraction of the CSF have been reported [5]. External ventricular drainage with external air aspiration is a simple, less invasive technique for the emergency management of a tension pneumoventricle that is not associated with rhinorrhea [5,7]. Endoscopic osteodural repair involves less morbidity than open surgery; however, few neurosurgical departments in our region have such technical equipment [11]. Notably, regardless of the surgical technique used, pneumocephalus generally progresses well when the diagnosis and management are early and high-quality.
The small size of our study population and the rarity of late posttraumatic pneumoventricle limited our study. Therefore, it would be appropriate to conduct a multicenter study over a long period to identify the main risk factors and propose a codified treatment for low-income countries.