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Division of Endocrinology, Metabolism and Nutrition, Internal Medicine (A.M.S., J.P.A., W.F.Y., T.B.N.), Division of Hypertension and Internal Medicine (W.F.Y.), Department of Neurosurgery (P.Y., M.J.E.), Mayo Clinic, Mayo Foundation, Rochester, Minnesota 55902
Address correspondence and requests for reprints to: William F. Young, Jr., MD, Division of Endocrinology, Metabolism, Nutrition and Internal Medicine, Mayo Clinic, 200 First Street Southwest, Rochester, Minnesota 55905.
Abstract
We describe four cases of symptomatic pneumocranium, a rare, potentially life-threatening complication of transsphenoidal pituitary surgery. Symptomatic pneumocranium manifested as impaired mental status, headaches, and grand mal seizures, early in the postoperative course after transsphenoidal pituitary surgery. Furthermore, a Cushing response, including systemic hypertension and bradycardia (secondary to intracranial hypertension) was seen, which has not been previously described in association with symptomatic pneumocranium. We describe a previously unreported risk factor for tension pneumocranium, untreated obstructive sleep apnea. Other factors predisposing to tension pneumocranium in our patients included: cerebrospinal fluid leaks, postoperative positive-pressure mask ventilation, large pituitary tumors, and intraoperative lumbar drainage catheters. Surgical drainage of the pneumocranium and repair of any coexistent cerebrospinal fluid leak markedly improved neurologic status.
Symptomatic pneumocranium occurring early in the postoperative course after transsphenoidal pituitary surgery is rare, but prompt recognition and treatment of this condition can be life-saving.
PNEUMOCRANIUM (pneumocephalus) has been associated with various conditions such as: basilar skull fracture, facial trauma, neurosurgery, paranasal sinus surgery, mask or nasal continuous positive-airway pressure, and even lumbar puncture (1, 2, 3, 4, 5). Pneumocranium usually resolves, as air is gradually absorbed, without neurologic sequelae or need for treatment (6).
Symptomatic pneumocranium after transsphenoidal pituitary surgery is rare (1, 4, 5, 6, 7, 8). Potential complications include tension pneumocranium (neurologic dysfunction with increased intracranial pressure) and meningitis, both of which can be fatal (4, 5). Tension pneumocranium may be manifested clinically by decreased level of consciousness, headache, seizures, decreased visual acuity, visual field defects, or papilledema (1, 5, 6, 7, 8). Treatments of pneumocranium include observation, prophylactic therapy with systemically administered antibiotics, insertion of intracranial drains, and repair or packing of the floor of the sella (1, 5, 6, 7, 8). Symptoms of tension pneumocranium may resolve rapidly after venting and draining the air pocket, repair of the sella, or both (1, 5, 6). We describe four cases of symptomatic pneumocranium after transsphenoidal surgery, and possible associations.
Subjects and Methods
We reviewed the medical records of patients encountered at Mayo Clinic Rochester from 1976 to 1998. Cases eligible for analysis were identified by computer-based cross-index codes for pneumocephalus or pneumocranium. Four cases were identified of tension pneumocranium after transsphenoidal surgery.
Results
This condition is extremely rare. Over 2500 transsphenoidal surgeries were performed at the Mayo Clinic from 1976 to1998, 4 of which were complicated by tension pneumocranium. All 4 patients presented with sudden onset of decreased level of consciousness in the days after transsphenoidal surgery. Headaches, seizures, and cranial nerve palsies were present to various degrees. A Cushing response, consisting of systemic hypertension with or without bradycardia (secondary to intracranial hypertension) was also seen, which has not previously been reported in association with pneumocranium. CSF leakage was present in 2 cases, both of which required formal repair. We describe obstructive sleep apnea (OSA) as a possible risk factor for symptomatic pneumocranium after transsphenoidal surgery (seen in 2 cases), which has not been previously published. Furthermore, positive-pressure bag-valve mask ventilation postoperatively was associated with tension pneumocranium in 1 case. Prompt drainage of intracranial air (and subsequent repair of CSF leak, if present) resulted in rapid improvement of neurologic status.
Case Reports
Case 1
A 74-yr-old man presented with clinical acromegaly, confirmed with a basal GH level of 74 µg/L (which failed to suppress on oral glucose tolerance testing), and insulin-like growth factor-1 level of 468 ng/mL (normal, <100). He also had untreated OSA (confirmed by consultation in a sleep disorders center).
The patient underwent transsphenoidal excision of a 1-cm macroadenoma
with an unremarkable intraoperative course. On postoperative day 1, the
patient became hypertensive and extremely lethargic. A computed
tomographic (CT) scan revealed a large subdural air collection,
consistent with the diagnosis of tension pneumocranium (Fig. 1A
). A right frontal
subdural drain was placed via a right frontal burr hole, immediately
releasing a small gush of air. The drain was in place for 6 days, and
the patient recovered completely without neurologic sequelae. Blood
pressure normalized, and subdural air gradually resorbed (Fig. 1B).
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A 56-yr-old woman presented with ACTH-dependent Cushing syndrome. Head magnetic resonance scan showed shift of the pituitary stalk to the left. OSA was newly diagnosed from symptoms and abnormal findings on overnight oximetry.
Transsphenoidal dissection was performed without difficulty; however, no discrete pituitary adenoma was identified, and a hypophysectomy was performed. Biochemical cure of the Cushing syndrome was confirmed postoperatively.
Starting on postoperative day 1, the patient complained of severe
occipital headaches, and nasal drip of CSF was noted. Lethargy,
hypertension (up to 180/60 mm Hg), and a generalized tonic-clonic
seizure were noted on postoperative day 3; iv phenytoin and empiric
antibiotics were given. Head CT showed bifrontal pneumocranium (Fig. 2A). A right frontal subdural drain was placed, and pneumocranium
gradually resolved (Fig. 2B). Blood pressure normalized. The CSF leak
was surgically repaired on postoperative day 8; and thereafter, mental
status markedly improved, and no long-term neurologic deficits were
noted.
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A 20-yr-old man presented with headaches, lethargy, and hypogonadotropic hypogonadism. A CT scan of the head showed a large suprasellar calcified mass that extended superiorly and displaced the brain stem posteriorly.
Transsphenoidal exploration of the sella was performed, and the large intrasellar component of a craniopharyngioma was removed. A lumbar spinal catheter was placed intraoperatively. The patient returned to the operating room on postoperative day 7 for a right frontal craniotomy and gross total removal of his craniopharyngioma. Another intraoperative lumbar spinal drain was inserted. The patient had no new neurologic deficits postoperatively.
Three days after his craniotomy (10 days after transsphenoidal surgery), the patient developed a left lower lobe nosocomial pneumonia. He was treated with broad-spectrum antibiotics and aggressive chest physiotherapy, including intermittent positive-pressure ventilation via bag-valve mask. Nasal-tracheal suctioning was strictly avoided.
On day 5 after his craniotomy, the patient became unresponsive, with dilated pupils. A CT scan of the brain showed a large tension pneumocranium displacing the brainstem posteriorly. A right ventricular needle was used to release air under pressure and resulted in mild improvement in level of consciousness. A cerebrospinal fluid (CSF) leak was then repaired transsphenoidally. Neurologic status markedly improved. No long-term neurologic deficits were attributed to tension pneumocranium.
Case 4
A 56-yr-old male was transferred to the Mayo Clinic with a huge nonfunctioning pituitary tumor. He had been in a state of coma for 16 days, and a ventriculoatrial shunt had been placed for obstructive hydrocephalus in the weeks preceding transfer. A CT scan of the head showed a large enhancing mass filling the sella and suprasellar region into the anterior third ventricle, which obstructed the foramen of Munro, producing obstructive hydrocephalus. Laboratory investigations were significant for hypogonadotropic hypogonadism.
The patient was given high-dose dexamethasone and underwent urgent transsphenoidal exploration of the sella. A lumbar spinal needle was inserted intraoperatively. Massive amounts of a nonfunctioning pituitary adenoma (5–6 cm in diameter) were removed. A small CSF leak occurred intraoperatively. Postoperatively, the patient awakened and had no gross motor deficits. Bilateral temporal hemianopsia was present.
On postoperative day 10, the patient became extremely lethargic. A CT scan of the head showed large air collections in the extracerebral spaces, with collapse of the brain. Drilling bilateral frontal burr holes and venting of subdural air with bilateral Jackson-Pratt drains were done emergently. Level of consciousness improved dramatically. The patient was dismissed home within a few weeks.
The patient subsequently underwent external beam radiation therapy. However, 6 months after the original transsphenoidal surgery, symptomatic recurrence of the pituitary tumor with obstruction of the third ventricle was noted. Repeat transsphenoidal exploration with intraoperative insertion of a lumbar CSF drain was performed.
Clinical course was unremarkable until postoperative day 4, when the patient suddenly became lethargic, hypertensive (184/110 mm Hg), and bradycardic (pulse 52 bpm). An emergent CT scan of the head showed a large amount of air in the third and fourth ventricles. Because the patient’s level of consciousness seemed to be improving, transsphenoidal reexploration and drainage of intracranial air were deferred. After a month in hospital, the patient was dismissed home and completed further radiation therapy as an outpatient.
Discussion
Tension pneumocranium occurs when air enters the cranium but cannot exit, likely secondary to a one-way valve mechanism. The result is increased intracranial pressure. After transsphenoidal surgery, the intracranial contents are in direct continuity with the nasopharynx, providing a potential route for such a one-way valve.
We have noted an association of OSA with symptomatic pneumocranium following transsphenoidal surgery. OSA is common in obesity and acromegaly (9, 10, 11). Recurrent upper airway narrowing or closure during sleep and frequent recurrent elevations in CSF pressure characterize OSA (12, 13). Such dynamic pressure changes could result in pneumocranium following transsphenoidal surgery. Similarly, positive-pressure mask ventilation could insufflate air into the cranium.
The insertion of lumbar CSF drains has rarely been reported as a cause of pneumocranium (8, 14). Perioperative CSF drainage, either from a shunt, a leak, or a spinal drainage catheter could predispose to air entering the diaphragm sella opening from the transsphenoidal surgery. Resection of a huge sellar mass may also result in decreased CSF pressure, predisposing to air accumulation.
In terms of clinical signs of tension pneumocranium, systemic hypertension and bradycardia have not previously been described in association with intracranial air. Both of these signs are part of the Cushing response to increased intracranial pressure (15). The most sensitive sign of tension pneumocranium in our case series was change in mental status. Headache was an inconsistent finding, as were seizures and cranial nerve deficits.
Conclusions
Symptomatic pneumocranium is a rare but life-threatening complication of transsphenoidal pituitary surgery. We have described several risk factors including OSA, positive-pressure mask ventilation, resection of large sellar masses, postoperative CSF leak, and possibly insertion of a lumbar subarachnoid drain intraoperatively. Clinical symptoms and signs of this condition include: altered mental status, headaches, seizures, cranial nerve palsies, hypertension, and bradycardia (as part of the Cushing response). In this age of short hospital stays, patients and their families should be alerted to call for medical assistance if such symptoms occur in the days following transsphenoidal surgery. Long-term outcome is generally favorable if this condition is recognized and treated promptly.
Received July 21, 1999.
Revised August 17, 1999.
Accepted August 24, 1999.
References
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