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Show ORIGINAL CONTRIBUTION Progressive Visual Loss Because of a Suprasellar Pneumatocele After Trans- sphenoidal Resection of a Pituitary Adenoma Andrew G Lee, MD, John C. Van Gilder, MD, and Matthew L. White, MD Abstract: A 63- year- old man who underwent uneventful trans- sphenoidal resection of a pituitary adenoma with fat packing complained postoperatively of progressive binocular visual acuity loss. Neuroimaging showed a suprasellar pneumatocele compressing the optic chiasm and a communication between the sphenoid sinus and the sella. After a second trans- sphenoidal procedure to remove the air and fully pack the sphenoid sinus, visual acuity recovered dramatically. A rare complication of trans- sphenoidal surgery for pituitary adenoma, suprasellar pneumatocele probably forms through a ball- valve mechanism that results from incomplete packing of the sellar floor. This case highlights the need for effective sphenoid sinus packing and for ophthalmic monitoring after trans- sphenoidal surgery. ( JNeuro- Ophthalmol 2003; 23: 142- 144) Pneumocephalus, or intracranial air, is a well- recognized complication after trauma or following craniotomy, but it is an uncommon presentation after trans- sphenoidal surgery ( 1- 5). We report a patient who developed progressive visual acuity loss after uneventful trans- sphenoidal surgery for a pituitary adenoma who developed progressive binocular visual acuity loss several months after the procedure. Imaging showed marked elevation of the optic chiasm by a tension pneumocephalus trapped within the sellar cavity. A second trans- sphenoidal procedure to remove the air and repack the sellar floor and sphenoid sinus restored baseline visual acuity. CASE REPORT A 63- year- old man developed painless, progressive visual loss OU. He had had impotence for the past several Departments of Ophthalmology ( AGL), Neurology ( AGL), Neurosurgery ( AGL, JCVG), and Radiology ( MLW), the University of Iowa Hospitals and Clinics, Iowa City, Iowa. Address correspondence to Andrew G. Lee, MD, Department of Ophthalmology, 200 Hawkins Drive, PFP, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA; E- mail: andrew- lee@ uiowa. edu Supported in part by an unrestricted grant from Research to Prevent Blindness, New York, New York. years and was found to have a low serum testosterone level. Magnetic resonance imaging ( MRI) showed an intrasellar mass with suprasellar extension ( Fig. 1). The preoperative visual acuity was 20/ 60 OD and 20/ 20 OS, and an automated visual field test ( Humphrey 30- 2) showed an almost complete bitemporal hemianopia ( Fig. 2). The patient underwent uncomplicated transsphenoidal surgery. During the procedure, the mucosa of the sphenoid sinus was stripped entirely, the dura was incised, and the tumor was resected in a piecemeal fashion. After adequate decompression and tumor resection, abdominal wall fascia and fat were packed into the sella. Postoperatively, the patient reported subjectively improved vision, but no formal ocular examination or visual field testing was performed. Four weeks after surgery, he complained of painless, progressive worsening of vision in both eyes. If m\ I I * tT 1 FIG. 1. Preoperative enhanced T1- weighted coronal magnetic resonance imaging scan shows an intrasellar mass with suprasellar extension and elevation and flattening of Copyright © Lippincott Williams & Wilkins. Unauthothreiz oepdti c rcehpiarsomd u( acrrtoiown). of this article is prohibited. 142 J Neuro- Ophthalmol, Vol. 23, No. 2, 2003 SUPRASELLAR PNEUMATOCELE JNeuro- Ophthalmol, Vol. 23, No. 2, 2003 FIG. 2. Preoperative automated visual field testing shows a bitemporal hemianopia with drift across the vertical meridian inferiorly. Neuro- ophthalmic examination 2 months after the surgery showed a visual acuity of 20/ 400 OU, and Gold-mann visual field testing revealed a bitemporal hemianopsia denser superiorly in the OD and more complete temporal hemianopic loss in the OS. ( A Goldmann visual field test was performed rather than a repeat automated [ Humphrey 30- 2] field test because of the loss of central visual acuity OU and the desire to document the extent of peripheral field loss outside of 30 degrees.) There was mild optic disc pallor OU. A plain skull radiograph ( Fig. 3), computed tomographic scan ( Fig. 4), and MRI scan ( Fig. 5) showed a large collection of air in the suprasellar space compressing the optic chiasm from below. The MRI showed that the packing did not completely bridge the gap between the sphenoid sinus and the sella. The patient underwent a second trans- sphenoidal surgery in which the air was removed and a fat pack completely placed in the sphenoid sinus. Postoperatively, the FIG. 3. Postoperative plain skull radiograph shows a suprasellar air bubble, or pneumatocele. FIG. 4. Postoperative wide- window computed tomography scan shows the pneumatocele in the suprasellar cistern ( arrow). patient's visual function improved to 20/ 40 OD and 20/ 20 OS. The bitemporal hemianopia persisted ( Fig. 6). A postoperative sagittal MRI scan showed restoration of chiasmal anatomy, absence of suprasellar air, and complete fat packing of the sphenoid sinus ( Fig. 7). DISCUSSION We describe a patient who suffered progressive visual acuity loss attributed to compression of the optic chiasm by intracranial air under pressure ( tension pneumocephalus, or pneumatocele). This is an extremely rare phenomenon. One of us ( JVG) has performed more than 2000 transsphenoidal surgeries, and this is the only case of postoperative suprasellar pneumatocele encountered. Haran and FIG. 5. Postoperative sagittal T1- weighted magnetic resonance imaging scan shows the suprasellar pneumatocele. There is communication between the sphenoid sinus, the sella, and the pneumatocele ( curved arrow). Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. 143 JNeuro- Ophthalmol, Vol. 23, No. 2, 2003 Lee et al. FIG. 6. Automated visual field testing after the second trans- sphenoidal surgery to remove the pneumatocele and pack the sphenoid sinus shows a persistent bitemporal hemianopia. ( The patient's visual acuity improved considerably.) Chandry ( 4) reported only three cases of pneumocephalus among 300 trans- sphenoidal surgeries for pituitary mac-roadenoma or craniopharyngioma during a 12- year span ( 4). The authors postulated that air could enter the intracranial cavity through a cerebrospinal fluid ( CSF) fistula at the skull base, a tendency that was exacerbated by decreased intracranial CSF pressure produced by a lumbar drain or ventriculoperitoneal shunt. In another case, the authors postulated that postoperative radiation therapy produced tumor shrinkage and an " uncorking effect," leading to a secondary CSF leak and admission of air. The authors reported that re- exploration, repair of the sella, and re- packing of the sphenoid sinus with fat had to be performed in all three cases. They recommended reducing intracranial pressure FIG. 7. Enhanced sagittal T1 - weighted magnetic resonance imaging scan obtained after the second trans-sphenoid surgery shows fat packing in the sphenoid sinus { thin arrow), disappearance of the pneumatocele, and restoration of normal diencephalic anatomy { thick arrow). Copyright © Lippincott Williams & Wilkins. Un 144 " by tapping ventricular air and draining the CSF, but only after repair of the CSF fistula. Air under pressure can act as a mass lesion and produce compression on the optic pathway. Shehu and Ismail ( 1) presented a case of traumatic tension pneumocephalus associated with light perception vision in the OS, presumably from an acute compressive optic neuropathy. Although the reported ophthalmologic details of this case are insufficient to exclude a concomitant traumatic optic neuropathy, the patient " regained full vision" after surgical release of the tension pneumocephalus. Hayman et al ( 5) reported a case of headache, bitemporal hemianopsia, and a tension pneumocephalus following endoscopic surgery of the ethmoid and sphenoid sinuses. The authors initially postulated that the chiasmatic visual loss may have been due to the pneumocephalus and ventricular dilation from trapping of air due to a ball- valve mechanism. The post- decompression MRI scan, however, showed chiasmal " hyperintense" signal, and the visual field did not recover ( 5). To our knowledge, ours is the only case of suprasellar pneumatocele following trans- sphenoidal surgery causing reversible visual acuity loss. We presume that incomplete packing created an opening between the sphenoid sinus and the sella that acted as a ball- valve mechanism to allow increasing amounts of air to enter the suprasellar space, accounting for the slowly progressive nature of the visual acuity loss after initially successful surgery. The tension was created by trapping of the air within the confined space between the sellar floor, its lateral walls, and the umbrella of tumor capsule. The second surgery replaced the initial fat packing with new and more complete fat packing of the sinus and resolved the chiasmal compression. This improved the visual acuity dramatically, but the patient was left with residual bitemporal field loss. Our case highlights the importance of the proper amount of fat packing of the sphenoid sinus after trans- sphenoidal surgery- enough to prevent a pneumatocele but not too much to compress the optic chiasm. It also emphasizes the need for careful ophthalmic monitoring of vision in patients who have undergone trans- sphenoidal surgery. REFERENCES 1. Shehu BB, Ismail NJ. Traumatic tension pneumocephalus presenting with blindness. Br JNeurosurg 2002; 16: 77. 2. Wein FB, Gans MS. The perils of a sneeze. J Neuro- ophthalmol 1999; 19: 128- 130. 3. Yu L, Farnsworth TA. Late tension pneumocephalus following frontal craniotomy. IntJClin Pract 1997; 51: 406- 407. 4. Haran RP, Chandy MJ. Symptomatic pneumocephalus after transsphenoidal surgery. Surg Neurol 1997; 48: 575- 578. 5. Hayman LA, Carter K, Schiffman JS, Tang RA. A sellar misadventure: imaging considerations. Surv Ophthalmol 1996; 41: 252- 254. reproduction of this article is prohibited. © 2003 Lippincott Williams & Wilkins |
