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Case Report:
A 57 year-old woman was referred to our tertiary care rhinology practice for evaluation of persistent pneumocephalus two months following head trauma. The patient initially presented with multiple skull base fractures and a comminuted, depressed frontal sinus fracture following a motor vehicle collision. At that time, she was taken emergently to the operating room for elevation of her depressed frontal sinus fracture and closure of several dural lacerations. Cranialization of the frontal sinus was not performed. The patient also required a period of lumbar drainage for a persistent post-surgical CSF leak.
Follow-up CT scan in the hospital showed improved pneumocephalus, as compared to imaging at the time of injury. After discharge, however, the patient experienced recurrent CSF leak and follow-up CT scan demonstrated progression of pheumocephalus adjacent to the frontal lobes bilaterally. The patient was then referred to our care. High resolution sinus CT scan and CT cisternogram revealed comminuted fracture of the right frontal sinus posterior table with a skull base defect near the frontal recess. Additionally, there was a separate fracture in the sphenoid sinus roof near the optic nerve and possible extravasation of contrast into the right sphenoid sinus.
Endoscopic exploration of the right frontal sinus and bilateral sphenoid sinuses was performed following placement of a lumbar drain and instillation of intrathecal fluorescein. The right frontal sinus posterior table defect was identified (Figure 1) and repaired endscopically with an underlay graft of synthetic dural substitute. However, no CSF leak was identified at this site. A defect in the sphenoid roof was also identified (Figure 2). This defect contained a small meningocele and CSF leak, confirmed with visualization of fluorescein, and it was repaired endoscopically with an overlay graft of synthetic dural substitute. The patient had no complications and was discharged home following lumbar drain removal on postoperative day 2.
Discussion:
Trauma represents the most common etiology of pneumocephalus, with approximately 74% of pneumocephalus cases resulting from trauma.1 The incidence of pneumocephalus following head injury is approximately 0.5-3.6%,1,2 and its presence carries a 16% mortality and a 25% risk of meningitis.3 Fractures of the skull base, paranasal sinuses, and sella turcica are the most commonly injured sites that result in pneumocephalus.2 For pneumocephalus to occur, a pressure gradient must exist between the intracranial and extracranial spaces. This pressure gradient is often caused by a persistent CSF leak, which creates intracranial negative pressure.4,5
Symptoms and signs of pneumocephalus include headache, confusion, agitation, disorientation, hiccups, anisocoria, seizures, and other neurologic signs.2 In our experience, the presence of CSF rhinorrhea or otorrhea is variable, depending upon whether the skull base defect extends through the dura or simply communicates with the epidural space. Patients are occasionally asyptomatic. Although precise localization of pneumocephalus is not always possible, air typically follows the same pattern of localization as intracranial blood collections. Endoscopic repair of CSF leaks and skull base defects is well-established in the rhinology community. However, this case highlights some important points related to traumatic skull base injuries. Fractures of the skull base are often multiple, and precise localization of sites of bony defect, dural tear and CSF leak is important.
Figure 1. Endoscopic picture and triplanar CT reconstructions of skull base defect alongposterior wall of right frontal sinus. On sagittal view, an air space exists between the posterior wall of the frontal sinus and the pericranial flap. No CSF leak was identified in this location.
Figure 2. Endoscopic picture and triplanar CT reconstructions of sphenoid roof skull base defect. A small meningocele (tip of pointer) and CSF leak were identified in this location.
References
- Markham J. Pneumocephalus. In: Vinken P, Bruyn G, eds. Handbook of Clinical Neurology, Injuries of the Brain and Skull. New York: American Elsevier Publishing, 1976.
- Keskil S, Baykaner K, Ceviker N, Isik S, Cengel M, Orbay T. Clinical significance of acute traumatic intracranial pneumocephalus. Neurosurgical review 1998;21:10-13.
- Noth J. On the importance of intracranial air. British Journal of Surgery 1971;58:826-829.
- Lunsford L, Maroon J, Sheptak P. Subdural tension pneumocephalus: report of two cases. Journal of Neurosurgery 1979;50:525-527.
- Walker F, Vern B. The mechanism of pneumocephalus formation with CSF fistulas. Journal of Neurology, Neurosurgery, and Psychiatry 1986;49:203-205.
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