Endonasal Management of a Pediatric Occult Retroclival Abscess

Background: The retroclival space houses the brainstem and associated cranial nerves, and pathology in this area can present with an array of cranial neuropathies and brainstem dysfunction. Occult abscesses not readily visualized on imaging are a diagnostic challenge.

Clinical Case: A 12-year-old previously healthy boy was referred for a 2-week history of diffuse headaches associated with intermittent fevers, nausea, and vomiting. During this time, he developed left ptosis and diplopia. Examination demonstrated near complete left ophthalmoplegia. He had normal right eye movement and normal vision in both eyes. Computed tomography (CT) angiography (CTA) showed an aneurysm of the cavernous left internal carotid artery (LICA). This was presumed a mycotic aneurysm. Broad spectrum antibiotics and dexamethasone were initiated. Blood culture grew streptococcus milleri. The eye symptoms progressed to a left fixed pupil.

Repeat CTA 1 week later showed enlargement of the LICA aneurysm. CTA appearance was a complex, fusiform, bilobed aneurysm (lobe size 1.3 cm and 1.1 cm) with narrowing of LICA at proximal and distal ends. Cerebral angiography, left carotid artery balloon test occlusion (BTO) with electroencephalography (EEG) monitoring, and coil occlusion of the LICA proximal to the aneurysm were performed. After recovery, the child was stable and discharged home on a 4-week course of ceftriaxone, a dexamethasone taper, and aspirin.

One week after completion of ceftriaxone, the child presented with 5 days of intermittent fevers to 101 degrees, neck stiffness, thoracic back pain, and progressive lethargy. Examination showed a new right-sided cranial nerve (CN) VI palsy and continued left ophthalmoplegia. Magnetic resonance (MR) imaging of the brain showed enhancement and dural thickening of the cavernous sinus dura bilaterally and enhancement of the clival recess bone. No overt abscess was visualized. Treatment with IV vancomycin and ceftriaxone was started. Lumbar puncture and blood cultures showed no growth. Pituitary dysfunction arose with fluctuating diabetes insipidus (DI) versus syndrome of inappropriate antidiuretic hormone secretion (SIADH) and low thyroid hormone.

The patient was taken to the operating room for endonasal sphenoidectomy to look for a source of the presumed infection. The pathology showed mucosal inflammation and normal bone. Cultures did not show a causative organism. The patient was taken to the operating room 1 week later for endonasal biopsy of the clival bone, sellar dura, and cavernous sinus dura. This second surgery was done with a four-hand technique as described by Kassam et al (Kassam 2005). The clival recess bone was drilled, and purulent fluid was evacuated from the epidural space. Culture of the fluid grew alpha hemolytic streptococcus mitis and oralis. Antibiotic coverage was broadened.

The patient had dramatic improvement in his headaches. One week after surgery, he was converted to a 6-week course of oral antibiotics. Two months postoperatively he continues to be afebrile and is headache free. He is showing improvement in his ophthalmoplegia.

Conclusion: This case demonstrates the challenges in diagnosis and management of an occult retroclival abscess. The usefulness of endonasal surgery for draining the abscess is demonstrated.