Endoscopic Endonasal Transclival Approach to a Retroclival Abscess

Introduction: Endoscopic endonasal transclival approach (EETA) is an elegant and relatively minimally invasive corridor to access clival masses and lesions of the ventral brainstem. This approach is classically utilized for clival chordomas, chondrosarcomas and meningiomas. The use of EETA in this population of patients has improved operative time, extent of resection and perioperative morbidity.

EETA is not only reserved for the resection of neoplastic lesions. In rare cases, infections including osteomyelitis can localize to the clival region. In this abstract, we describe a rare case of a retroclival collection accessed via EETA and review the literature regarding similar pathologies.

Case Report: A 26-year-old female with a recent history of intravenous drug use (IVDU) and tooth extraction 6 months prior complicated by infection, developed 5 months of headaches, which progressed to accompany photophobia and vomiting. Aside from neck stiffness, her neurologic exam was unremarkable. A contrasted brain MRI demonstrated a prepontine peripherally-enhancing lesion and along the dorsal clivus, measuring 1.7 × 0.7 cm. Leptomeningeal and ependymal enhancement was noted in the right ventricle and cerebellopontine angle cistern ([Fig. 1]). Corresponding restricted diffusion was seen within the lesions. CT angiogram showed severe stenosis of the basilar artery, redemonstrated in a formal cerebral angiogram ([Fig. 1]). A lumbar puncture was performed and cerebrospinal fluid (CSF) had granulocyte predominant (55%) pleocytosis. No organism was isolated. She was started on empiric broad-spectrum antibiotics.

Collating the findings of rim-enhancing lesions, history of IVDU, basilar stenosis concerning for vasculitis and CSF leukocytosis, infection continued to be highest on the differential diagnosis. In a collaborative approach, a decision was made to pursue a biopsy. She underwent and endoscopic posterior septostomy and transclival access for biopsy and drainage of the collection. A small corridor was drilled through the clivus and the dura and encapsulated collection were opened. Frank pus was expressed. After meticulous exploration, the opening was closed with a vascularized naso-septal flap. She recovered well from the surgery without new neurologic deficits. Intraoperative cultures revealed fungal elements, lactobacillus and coagulase negative staphylococcus. She was started on a prolonged course of antibiotics and antifungal medications. She had a gradual improvement in symptoms as well as near resolution of her diffuse cranial leptomeningeal enhancement and retroclival abscess on MRI 1 year later.

Fig. 1 Gadolinium-enhanced MRI. Axial views depict the ventral pontine collection (A) and ependymal enhancement (B). The collection is redemonstrated in a sagittal view (C). A cerebral angiogram demonstrates severe basilar stenosis (D).

Discussion: We present an interesting case of diffuse cranial infection in a patient with history of IVDU. The retroclival location added a layer of complexity to her diagnosis; however, aspiration and valuable biopsy of this collection was possible via EETA. Non-bony infections in this region are rare. A literature review revealed one case of a clival osteomyelitis and epidural abscess drained via a transoral approach. A retrospective study by Little et al reviewed 55 EETA cases, seven were for infection and one of which was a clival abscess.