Cerebrospinal fluid fistula associated with an empty sella. (Imaging Clinic).

Spontaneous nasal cerebrospinal fluid (CSF) fistulae have been described in cases secondary to trauma, cranial surgery, and cranial base tumors. These reported fistulae were located primarily in the anterior cranial fossa in association with a cribriform plate. A fistula associated with an empty sella is less common.(1)

The term empty sella is used to describe an anatomic state in which the arachnoid and CSF extend or herniate into the sella, enlarging it through an incompetent diaphragm. The symptoms of this process are uncommon and nonspecific, despite the facts that (1) the pituitary gland is compromised and (2) there might be a downward traction of the optic chiasma. (2,3) An empty sella is often an incidental finding on computed tomography (CT) and magnetic resonance imaging (MRI). It might be present in only 5% of the population. Occasionally, however, a nasal CSF fistula is associated with an empty sella. (1)

The case illustrated here involved a 53-year-old woman who was known to have an empty sella, which had been discovered as an incidental finding on previous imaging (figure 1). One year later, the patient experienced a sudden onset of CSF rhinorrhea that was associated with severe headaches. CT of the head revealed the presence of pneumocephalus and enlargement of the sella. An additional examination of the paranasal sinuses detected residual pneumocephalus in the suprasellar region and enlargement of the sella turcica. This condition was associated with a bone defect in the posterior ethmoid air cells, which appeared to be the origin of the CSF fistula (figure 2). These findings were subsequently confirmed by glucose analysis and radioisotope examinations. MRI detected an empty sella and fluid collections in the ethmoid sinuses and nasal cavity. Additionally, meningeal enhancement following the administration of contrast was identified, which is an indication of intracranial hypotension without evidence of c erebellar tonsillar herniation. Surgical identification and repair via a subfrontal approach were achieved with immediate good results on short-term follow-up.

References

(1.) Garcia-Uria J, Ley L, Parajon A, Bravo G. Spontaneous cerebrospinal fluid fistulae associated with empty sellae: Surgical treatment and long-term results. Neurosurgery 1999;45:766-73; discussion 773-4.

(2.) Gallardo E. Schachter D. Caceres E, et al. The empty sella: Results of treatment in 76 successive cases and high frequency of endocrine and neurological disturbances. Clin Endocrinol (Oxf) 1992;37:529-33.

(3.) Felsberg GJ, Tien RD. Sellar and parasellar lesions involving the skull base. Neuroimaging Clin N Am 1994;4:543-60.

From the Department of Radiology, Louisiana State University Health Science Center, New Orleans.