Abstract
Background: Pneumoceles of the paranasal sinuses are a very rare condition; characterized by a distended air-filled paranasal sinus extending beyond the margins of the paranasal bone, with bony defects and extension of air into the surrounding soft tissues. Also, spontaneous pneumo-cephalus is a rare condition which represented only 0.6% in the largest reported series of pneumocephalus. Although pneumocephalus caused by sinogenic origins, such as osteoma, has been reported, spontaneous pneumocephalus has not been reported as a complication associated with pneumocele of the frontal sinus.
Methods: We report a case of spontaneous pneumocephalus associated with a pneumocele involving the frontal sinus which presented as acute severe headache.
Results: To the best of our knowledge, this is the first case report in literature reporting spontaneous pneumocephalus in association with pneumocele of the frontal sinus.
Conclusions: Although pneumocele of the frontal sinus is a very rare condition, it can develop into spontaneous pneumocephalus, and thus it needs to be included in the differential diagnosis of acute severe headache.
Pneumoceles of the paranasal sinuses are a very rare condition. The condition is characterized by a distended air-filled paranasal sinus extending beyond the margins of the paranasal bone, with bony defects and extension of air into the surrounding soft tissues (1). Pneumoceles most commonly affect the frontal sinus, followed in frequency by the sphenoid, ethmoid and maxillary sinuses (2). Although pneumoceles are commonly asymptomatic, the most frequent complaints are of slowly changing facial contours and dull pain in the affected area, diplopia or other local pressure symptoms (1,3). Patients may also complain of headaches (4). In this article, we report a case of spontaneous pneumocephalus associated with a pneumocele involving the frontal sinus which presented as acute severe headache. To the best of our knowledge, this is the first case report in literature reporting spontaneous pneumocephalus in association with pneumocele of the frontal sinus.
Case Report
A 35-year-old right-handed man in previously excellent general condition presented with a chief complaint of a sudden, acute, severe frontal headache after forceful nose blowing. The headache was not aggravated by body position. There was no history of habitual nose blowing, Valsalva maneuver or coughing. Nor was there any history of head trauma, surgery or ear infections. On admission neurological examination found no abnormalities, and no evidence of fever, cerebrospinal fluid (CSF) rhinorrhea or CSF otorrhea. The nose and ear were examined and seen to be normal. Vital signs were normal. Routine laboratory parameters including white blood cell count and C-reactive protein were normal.
Computed tomography (CT) scans showed a large, epidural air collection seemingly in continuity with the left frontal sinus. Extensive hyperpneumatization with protrusion of the left frontal sinus and multiple small defects of the posterior wall of the frontal sinus were also present (Figure 1). However, the sinus showed no signs of acute or chronic inflammatory changes. No pathological enhancement indicative of an underlying tumor was present.
CT scans showed a large epidural air collection seemingly in continuity with the left frontal sinus. Extensive hyperpneumatization and protrusion of the left frontal sinus and multiple small defects (white arrow) of the posterior wall of the frontal sinus were also present.
We decided to refrain from surgical intervention and advised the patient to receive conservative treatment. Follow-up MRI four days later showed complete resolution of the pneumocephalus (Figure 2). His headache spontaneously regressed without complications. With instructions to avoid nose blowing, he has done well during a follow-up period of 12 months with no signs of recurrence.
MRI shows complete resolution of multifocal pneumocephalus.
Discussion
Spontaneous pneumocephalus is a rare condition which represented only 0.6% of cases in the largest reported series of pneumocephalus (5). Most often in otorhinolaryngology, it develops on the basis of a congenital abnormally pneumatized bone surrounding the middle ear that is in communication with the intracranial compartment (5). Although pneumocephalus caused by sinogenic origins, such as osteoma (6,7), has been reported, spontaneous pneumocephalus has not been reported as a complication associated with pneumocele of the frontal sinus.
The etiology and exact pathophysiologic mechanism of the development of pneumoceles in the frontal sinus are not clearly understood (1). It is believed to be caused by a one-way valve mechanism at the level of the frontal sinus ostium, allowing entry but not exit of air, which progressively increases the pressure within the sinus resulting in its expansion. The one-way valve mechanism may be related to developmental, inflammatory, neoplastic, or posttraumatic causes (1). Another potential mechanism is that a pneumocele may be related to spontaneous evacuation of a mucocele (7).
Two pathogenic factors have been suggested to be important for the development of a spontaneous pneumocephalus. First, a defect in the temporal bone, most commonly the tegmen tympani, must be presumed, allowing a communication of air from the mastoid cells to the intracranial compartment. Second, a pressure difference is needed between the temporal bone and the intracranial space to allow the air to enter the cranium. A “ball valve” mechanism might explain the intracranial air accumulation: increased air pressure caused by the Valsalva maneuver or ambient pressure changes force air through the fistula into the intracranial cavity (8). As with our case, there is no report as to whether there is any link between the two separate diseases. Although the association between spontaneous pneumocephalus and pneumocele of the frontal sinus remains unknown, we think a possible common pathophysiology for both separate diseases is the “one-way valve” mechanism.
A pneumocephalus can be symptomatic or asymptomatic. The most frequently reported symptom of a spontaneous pneumocephalus is headache. Additional symptoms are otalgia, tinnitus, aural fullness, loss of balance and scotoma (9,10). Obviously, the onset and severity of symptoms are related to the volume of entrapped air and the pressure exerted on the brain, as well as the time frame of the disease (11). Our patient visited our hospital complaining of acute, severe headache. Although this might have resulted from the pneumocele, we believe that the spontaneous pneumocephalus was the major factor for his symptoms.
Although clinical symptoms and signs suggest the diagnosis, a CT is absolutely necessary for the diagnosis and preoperative plan of both diseases (11,12).
There are no standard methods for the treatment of pneumocele due to the rarity of cases, but endoscopic frontal sinusotomy and various methods to correct cosmetic defects have been reported to be effective (13,14).
Most patients with spontaneous pneumocephalus have been treated surgically. Presumed risk of meningitis has been an argument in favor of closing bony or dural defects (9). However, a surgical approach may not be necessary for all patients with spontaneous pneumocephalus. If the patient's history makes a “ball valve” effect plausible or the patient has a small pneumocephalus with no evidence of infection, conservative management is the therapeutic method of choice (15). Surgery was not performed in our patient because there was spontaneous relief of his symptoms and he later showed complete resolution.
Conclusion
Although pneumocele of the frontal sinus is a very rare condition, it can develop into spontaneous pneumocephalus, and thus needs to be included in the differential diagnosis of acute severe headache.