The Midline Biorbitofrontal Craniotomy Approach to Meningiomas of the Olfactory Groove and Planum Sphenoidale

Objective: The evolution of endoscopic endonasal approaches to sellar, suprasellar, and clival lesions has permanently changed management of these lesions. However, the role of the endoscopic endonasal approach to anterior skull base meningiomas remains controversial. We reviewed our operative management of meningiomas of the olfactory groove and planum sphenoidale. Attention was paid to rate of CSF leak, use of post-operative lumbar drains, and need for reoperation. Our approach to anterior skull base meningiomas was the midline biorbitofrontal craniotomy.

Methods: We reviewed our experience treating olfactory groove and planum sphenoidale meningiomas. Meningiomas of the tuberculum sella, clinoid, and orbital roof were excluded. All cases were attended by a neurosurgeon (CBH) alone or with a second neurosurgeon or otolaryngologist. Technical aspects of the approach, microsurgical technique, radiographic and clinical perioperative, and follow-up data were reviewed.

Results: From 1994–2011, 27 patients were identified, 5 with planum sphenoidale and 22 with olfactory groove meningiomas. All patients underwent two-piece bifrontal craniotomy with biorbital-bar osteotomy (23/27) or one-piece biorbitofrontal craniotomy (4/27) with cranialization of the frontal sinus, and anterior fossa floor reconstruction where necessary. Complete resection was performed on 25/27 patients. Residual tumor was left in two cases where tumor encased the callosomarginal arteries. Excellent end cosmetic results were achieved in all cases. There were no new permanent neurologic deficits except for anosmia in some patients with functional smell preoperatively. CSF rhinorrhea was seen in 2/27 patients (7.4%); one was managed with a lumbar drain, and the second required endoscopic endonasal repair after failure of a lumbar drain. Two patients had lumbar drains placed for subgaleal effusions without CSF leak. There was one instance of meningitis (3.7%), no surgical site infections, no need for nasal irrigation, no need for repeated follow-up with the otolaryngologist, and no nasal complaints. There were no delayed CSF leaks. In 103 patient-years follow-up, one patient had tumor recurrence (3.7%), requiring reoperation on two occasions.

Conclusions: The midline biorbitofrontal craniotomy allows low rates of CSF leak, infection, and neurologic deficit. This approach affords excellent cosmetic outcomes when used to approach meningiomas of the olfactory groove and planum sphenoidale. Superior degrees of tumor resection and low recurrence rates are attainable.