Intrasellar abscess following transspehnoidal surgery

ELSEVIER

INTRASELLAR ABSCESS FOLLOWING TRANSSPHENOIDAL SURGERY Martin M. Henegar,* M.D., Myles B. Koby,** D.D.S., M.D., Daniel L. Silbergeld, Keith M. Rich, M.D.,* and Christopher J. Moran, M.D.**

M.D.,*

*Department of Neurological Surgery and **MalIinkrodt Institute of Radiology, Division of Neuroradiology, Washington University, St. Louis, Missouri

Henegar MM, Koby MB, Silbergeld DL, Rich KM, Moran CJ. Intrasellar abscess following transsphenoidal surgery. Surg Neurol 1996;45:183-8. BACKGROUND

Intrasellar abscess following transsphenoidal surgery has been described only twice in the English language medical literature. Overall mortality associated with intrasellar abscesses is 51%, while mortality in reported cases not treated surgically is 100%. METHODS

Two cases of intrasellar abscess following uncomplicated transsphenoidal surgery for pituitary pathology are reported. The incidence, radiographic features, clinical presentations, and treatment of intrasellar abscesses are discussed. RESULTS

Both patients described underwent uncomplicated transsphenoidal procedures for treatment of a primary pituitary lesion. Neither developed postoperative CSF rhinorrhea, and initial recovery was uneventful. The first patient presented with new symptoms several weeks after transsphenoidal surgery; the second patient almost two years postoperatively. The first displayed signs of an expanding sellar mass, requiring transsphenoidal drainage and postoperative antibiotics. The second presented with recurrent meningitis without discernible CSF leak, and was treated with transnasal endoscopic drainage in conjunction with antibiotic therapy.

T

ranssphenoidal surgery for treatment of sellar lesions was described by and suprasellar Schloffer in 1907 [l&20]. The transsphenoidal approach was associated with a mortality of approximately 6% in early series by Cushing, Dott and others, but subsequent medical and technological advances have reduced mortality significantly [5,7, 16,18,20]. In recent series, accurate diagnosis and treatment of endocrinopathies, the use of antibiotics, and utilization of the operating microscope and intraoperative fluoroscopy, have reduced mortality rates to 0.5%-2% [4,16,18]. Hypothalamic injury, vascular damage and postoperative meningitis are the most common causes of significant morbidity and mortality [4,7,14,16,18,20]. lntrasellar abscess following transsphenoidal surgery has been described twice in the English language medical literature [ 19,201. Overall mortality associated with intrasellar abscesses is 51% [2]. Mortality in reported cases not treated with surgical drainage is 100% [ 10,191. We report two cases of intrasellar abscess following transsphenoidal surgery. The clinical signs and symptoms, radiographic diagnosis and surgical treatment are discussed.

CONCLUSIONS

The high mortality associated with intrasellar abscess mandates its inclusion in the differential diagnosis of patients presenting with symptoms of meningitis or an expanding sellar mass after transsphenoidal intervention. Although antibiotic therapy is an important adjunct, surgical drainage is required for definitive treatment. KEY WORDS

Abscess, intrasellar abscess, pituitary surgery, transsphenoida1 surgery.

Address reprint requests to: Daniel L. Silbergeld, M.D., Washington University Epilepsy Program, Department of Neurological Surgery, Campus Box 8057, 660 South Euclid Avenue, St. Louis, MO 63110-1093. Received July 22, 1994; accepted August 22, 1995. 0 1996 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010

CASEREPORTS CASE 1 This 47-year-old female presented with a threemonth history of frequent headaches and episodic blurred vision. Magnetic resonance (MR) imaging (Figure 1) revealed a 12 mm mass within the sella extending to and displacing the diaphragma sella superiorly to the optic chiasm. Endocrine function and visual field examinations were normal. Transsphenoidal resection of the cyst contents and biopsy of the cyst wall were performed without complication. The sella was packed loosely with a small 0090-3019/96/515.00 SSDI 00903019(95)00404-l

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Preoperative examination of Case 1. T, sagittal MR following gadolinium administration. The peripherally enhancing, low signal sellar mass elevates the diaphragma sella near the optic chiasm.

of fat obtained from the abdomen. A small bone strut was placed using bone from the transnasal opening. No intraoperative CSF leak was appreciated. Histopathologic examination of the cyst wall and cyst contents revealed an acellular colloidal coagulum and fragments of columnar epithelium, consistent with an intrasellar colloid cyst. The patient’s postoperative course was unremarkable. One week after discharge, the patient began experiencing intermittent headaches. MR imaging five weeks after surgery demonstrated a new 5 mm sellar mass. Headaches persisted, and by eight the patient developed weeks postoperatively, blurred vision with occasional nausea and vomiting. She also noted intermittent polydypsia, polyuria, perception of an unpleasant odor, and decreased energy. Repeat MR imaging at eight weeks showed that the residual sellar mass was unchanged in size but had developed a cystic central component. Symptoms persisted and MR imaging fifteen weeks postoperatively demonstrated enlargement and ring enhancement of the cystic mass (Figure 2). Pituitary function was slightly depressed by laboratory evaluation. Formal visual field testing revealed a new bitemporal superior quadrantanopsia. The patient underwent sellar exploration via a transsphenoidal approach. The fat graft placed during the previous procedure was noted to be vascularized and fibrotic. Removal of the underlying bone strut revealed a yellow-white exudate under pressure. Specimens were obtained for culture and the

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Sagittal T, MR following gadolinium administration. Study performed five months after surgery when the patient had visual changes, nausea, polydypsia and polyuria. A low intensity mass with rim enhancement fills the sella turcica. It extends into the suprasellar cistern and compresses the optic chiasm. There is marked enhancement of the sphenoid sinus.

fragment

remaining material was removed with aspiration and irrigation. Inspection of the sella revealed normal appearing pituitary tissue and sellar walls. Cultures grew staphylococcus aureus. The patient was initially treated with vancomycin, ceftazidime, and metronidazole and was discharged on a six week course of dicloxacillin and rifampin. Postoperatively, she required desmopressin acetate for mild diabetes insipidus. Pituitary function otherwise returned to normal and preoperative symptoms, including visual field deficits, were completely resolved. One month postoperatively, the sella turcica appeared normal by MR imaging. CASE

2

This 45-year-old male presented to another institution with complaints of left frontal headache, blurred vision in the left eye, diplopia and fever. Physical findings included left third and fourth cranial nerve palsies and signs of acromegaly. White blood cell count was 13,200. A computed tomography (CT) scan demonstrated a sellar mass with minimal suprasellar extension, with extension inferiorly into the sphenoid sinus, and lateral displacement of left internal carotid artery. Because the lesion involved both the sella and the sphenoid sinus, it may have arisen from either of these. Transsphenoidal surgery showed that the posterior wall of the sphenoid sinus had been replaced by

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fibrous tissue with signs of recent hemorrhage. No CSF was encountered intraoperatively. On histopathological evaluation of the resected specimen, no tumor cells were identified. Postoperatively, the patient displayed a left abducens palsy in addition to the occulomotor and trochlear palsies present preoperatively. He suffered transiently from mild diabetes insipidus. The additional postoperative deficits were felt to be surgical morbidity. It is likely that the persistent deficits were due to inadequate surgical decompression. One month after surgery, MR demonstrated a residual sphenoid mass, but normal configuration of the sella turcica (Figure 3). Despite the abscence of neoplasia on histology, the referring institution made the decision to radiate the patient because of persistent extrasellar mass (as seen at surgery and documented postoperatively on MR) and acromegaly. The patient underwent this radiotherapy six months after resection. Twenty two months postoperatively, he returned with fever, headache, and neck stiffness. Cerebrospinal fluid (CSF) was normal. He was treated empirically with Ampicillin. His symptoms improved and he was discharged. Four months later he presented with meningitis manifested by high fever, nuchal rigidity, headache, confusion and loss of short term memory, polyuria, and polydypsia. CSF, obtained by lumbar puncture, showed marked pleocytosis with 3570 nucleated of 3800 total cells. Diplococci were seen on gram stain and cultures grew Streptococcus pneumoniue. The patient was treated with antibiotics and transferred to our institution. On arrival he was disoriented with a depressed level of consciousness. His pupils were sluggishly reactive and he had bilateral papilledema. With continuation of antibiotic therapy he displayed mild improvement in his mental status. MR scan (Figure 4) demonstrated a ring enhancing lesion involving the sella turcica and the sphenoid sinus, as well as profound leptomeningeal and gyral enhancement of the temporal and frontal lobes. The sphenoid sinus was explored endoscopically and a lumbar drain was placed postoperatively for CSF leakage visualized intraoperatively as the patient refused further surgical intervention. Penetration of fibrous tissue released a purulent gray exudate and cerebrospinal fluid. Specimens were sent for culture. The purulence remaining in the sinus and sella was evacuated by irrigation and aspiration. Oxicillin resistant Staphylococcus epiderrnitis grew from the aspirate. Treatment with penicillin G benzathine was continued postoperatively and vancomycin was added to the regimen. His neurologic status improved postoperatively except for residual short term memory difficulties. MR

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T, gadolinium enhanced MRI, in sagittal (A) and q coronal (B) planes. Four months after surgery the optic chiasm and infundibulum have a normal appearance. There is enhancing soft tissue in the sphenoid sinus.

imaging, one month after surgery, revealed a normal appearing sella with resolving gyral enhancement. The patient required exogenous hormone administration (including thyroid, testosterone and prednisone) for hypopituitarism.

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1 Gadolinium enhanced T, MR in sagittal (A) and 0 coronal (J3) planes. This study was performed thirty-eight months after the initial operation when the patient had mental status changes, fever and meningismus. A hypointense, rim-enhancing mass fills the sella turcica and sphenoid sinus. The cortex of the medial and inferior temporal lobes and the left gyrus rectus enhance intensely.

DISCUSSION Sellar abscesses are uncommon lesions [2,10, 17,191. Although cases of tubercular [ 131, mycotic [ 151, and parasitic [8,23] pituitary abscesses have

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been reported, less than 70 cases of presumed bacterial pituitary abscess have been described in the English literature [2,10,17,24]. A number of these were discovered postmortem in patients succumbing to sepsis in the pre-antibiotic era [l,lO]. Although the etiology of pituitary abscesses is not always apparent [3], extension from sphenoid sinusitis or cavernous sinus thrombophlebitis has been described [1,2,10]. Approximately 40% of pituitary abscesses are associated with concurrent meningitis [lo]. In this setting, differentiation between primary and secondary pathology is difficult [ 10,171. Primary pituitary lesions are a risk factor for pituitary abscess (possibly secondarily to local impairment in immune function) [ 1,2,21]. Thirty percent of pituitary abscesses occur in association with pituitary adenoma [2,10,24]. Greater than 90% of pituitary abscesses present with symptoms suggestive of a pituitary mass, meningitis or both [2,10,24]. Diagnosis is often made at autopsy after unsuccessful treatment of multiple episodes of meningitis [ 1,101 or intraoperatively during planned adenomectomy [ 1,6,10,24]. Preoperative diagnosis of pituitary abscess was made in only two of re ported cases [ 10,19,24]. Rate of survival in patients undergoing surgical drainage is 71% but no cases of survival without surgical drainage have been described [10,19,24]. Sixty percent of patients dying with pituitary abscess had been treated unsuccessfully for meningitis [lo]. Although meningitis occurs as a complication of transsphenoidal surgery in only 0.4%-9% of cases, it is associated with a high incidence of mortality [4,14,18,20]. In a retrospective analysis of 185 patients undergoing transsphenoidal intervention, meningitis occurred with an incidence of 1.6% and mortality was 2%, but 50% of deaths were secondary to meningitis unresponsive to antibiotic therapy [16]. In two other series (98 patients and 200 patients), the one postoperative fatality in each series was attributed to meningitis [ 18,201. Intrasellar abscess as a complication of transsphenoidal surgery has been reported twice in the literature [10,19,24]. In only one of these cases was the correct diagnosis made prior to reoperation [19]. Surgical drainage of intrasellar abscesses is the only effective treatment described in the literature and reduces the rate of mortality to 28% [lo]. Drainage by the subfrontal approach has been associated with postoperative cerebral abscess formation, leading most authors to recommend transsphenoida1 evacuation [ 10,241. The cases presented illustrate a number of points. Each patient underwent an uncomplicated transsphenoidal procedure, without CSF leak, for

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treatment of a primary pituitary lesion. Neither developed postoperative CSF rhinorrhea, and initial recovery was uneventful with the exception of a postoperative abducens palsy in Case 2. Each patient presented with new symptoms weeks to months after transsphenoidal surgery. Case 2 was not definitively diagnosed with sellar abscess for 26 months. The first patient displayed signs of an expanding sellar mass, requiring transsphenoidal drainage and postoperative antibiotics. The patient in Case 2 presented with recurrent meningitis without discernible CSF leak, and was treated with transnasal endoscopic drainage in conjunction with antibiotic therapy. As the anatomic extent of pathology in Case 2 prevents definitive determination of the initial site of abscess formation, it is possible that the abscess arose in the sphenoid sinus and extended to involve the sellar and then suprasellar regions. This may explain the differences in time and nature of presentation. Case 2 illustrates an additional complication of intrasellar abscess. The gyral enhancement seen with MR indicates cerebritis involving the frontal and temporal lobes. The epicenter of enhancing cortex overlies the sella turcica, suggesting contiguous spread of bacteria rather than CSF seeding. Meningitis may cause diffuse leptomeningeal enhancement, but the severe cortical involvement and the slow resolution of these changes characterize cerebritis. The diagnosis of pituitary abscess was suspected preoperatively in each case because of the MR findings. Utilization of MR imaging in the diagnosis of pituitary abscess has been described twice in the international literature [6,9]. On MR imaging, a sellar abscess appears as an expanding sellar mass (with possible suprasellar or intrasphenoid extension) which displays low signal intensity on T,weighted images and high signal on T,-weighted images. Administration of contrast agent produces rim enhancement with intense enhancement of sphenoid mucosa. This profound mucosal enhancement most readily distinguishes an abscess from a necrotic adenoma [6,9,21]. Intrasellar abscess is an uncommon lesion which occurs rarely as a complication of transsphenoidal surgery. Differentiation from meningitis or recurrent pituitary adenoma on the basis of clinical examination is difficult. Diagnosis can be made on the basis of MR appearance if studies are reviewed with a high index of suspicion, in the appropriate clinical setting. The high mortality associated with this clinical entity mandates its inclusion in the differential diagnosis of patients presenting with symptoms of meningitis or an expanding sellar mass after transsphenoidal intervention. Although antibiotic ther-

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apy is an important adjunct, surgical required for definitive treatment.

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coccidioidomycosis simulating a pituitary adenoma. Neurosurgery 1991; 28:748-51. 24. Zorub DS, Martinez J, Nelson PB, Lam M. Invasive

pituitary adenoma with abscess formation: case report. Neurosurgery 1979;5:718-22. COMMENTARY

Henegar et al describe two cases of sellar abscess that occurred following transsphenoidal surgery. In each case, the clinical course of the abscess was very indolent, particularly in Case 2. In both patients, imaging studies were eventually suggestive of abscess. It is interesting that both patients developed diabetes insipidus with their symptoms of abscess. Sometimes following transsphenoidal surgery, imaging studies in the early postoperative period are difficult to interpret. However, new signs of endocrine deficiency, specifically the delayed appearance of diabetes insipidus occurring in association with a sellar mass, should raise suspicions of a suppurative process. I suspect neurosurgeons will be using more endoscopy for transsphenoidal procedures in the near future. In Case 2, it was obviously a slick way of draining the abscess. Fortunately, in Case 2, an open communication between the sphenoid sinus and subarachnoid

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space via the abscess cavity healed with spinal drainage alone, the patient having refused another procedure to mechanically occlude the fistula. As in this case, CSF diversion is sometimes very helpful in healing a delayed CSF leak following transsphenoida1 surgery. However, the neurosurgeon must be cautious about the rare occurrence of a tension pneumocephalus, which I have observed in this situation. Julius M. Goodman, M.D. Indianapolis, Indiana The authors of this paper document two cases of symptomatic abscesses following transsphenoidal surgery for sella turcica and sphenoid sinus pathology. As documented by the authors, the symptoms may be protean in nature, may occur weeks or months after the surgical procedure, and require surgical drainage in addition to antibiotics. We have not encountered this rare complication in an excess of 1400 cases at the University of Iowa, but the diagnosis must be entertained in the differential with the onset of new symptomatology following uneventful transsphenoidal surgery. John C. VanGilder, M.D. Iowa City, Iowa