June 2026

NEUROSCIENCES

CASE REPORT: ENDOSCOPIC ENDONASAL RESECTION OF AN OLFACTORY GROOVE SCHWANNOMA

2-minute read

Schwannomas arising from the olfactory nerve are exceptionally rare, with fewer than 100 cases reported in the literature. Their presentation often overlaps with common sinonasal conditions, which can delay diagnosis and management.

In this case, successful management required coordinated otolaryngology and neurosurgical expertise to address sinonasal and intracranial components through a unified surgical strategy.

Case Presentation
A female patient in her late 30’s presented with progressive nasal obstruction and loss of smell, symptoms initially consistent with common sinonasal conditions.

Initial evaluation by several non-Northwestern Medicine clinicians led to management that included nasal sprays, saline irrigations and steroid therapy, with consideration given to post-viral anosmia  and other benign etiologies. Despite appropriate treatment, her symptoms persisted.
The patient was referred to Alexander L. Schneider, MD, a Northwestern Medicine otolaryngologist, and underwent CT imaging, which was largely inconclusive but raised concern for atypical findings. Due to lack of response to standard therapy and subtle abnormalities on CT, including bony irregularity, the patient was referred for MRI, which revealed an anterior skull base lesion, prompting biopsy.

Pathology confirmed a schwannoma, an uncommon diagnosis in this location. Given the rarity of olfactory nerve schwannomas, Dr. Schneider reviewed the case with Constantine Karras, MD, neurosurgeon. Surgical intervention was recommended because the tumor was benign and treatable with complete resection, which would relieve the patient’s progressive nasal obstruction.

Surgical Approach
The surgical team aimed to preserve nasal physiology and drainage pathways, minimize skull base disruption and maintain functional outcomes, including olfaction.
  • Dr. Schneider performed the initial endonasal phase, removing the sinonasal component and exposing the skull base.
  • Bone overlying the skull base was removed, and the dura was opened to access the intracranial component.
  • Dr. Karras completed the intracranial tumor resection.
  • The tumor was debulked and carefully mobilized to facilitate complete removal.
  • Reconstruction included placement of an abdominal fat graft, as well as an ipsilateral right nasoseptal flap, to support closure and healing.
  • The surgical team used a unilateral approach to preserve the contralateral nasal cavity and maintain long-term sinonasal function, including the potential for olfactory recovery.
Outcomes
  • Gross total resection was achieved without complications.
  • Improved nasal airflow.
  • Return of olfactory function, with the patient reporting improved smell and taste compared to baseline.
  • Return of some olfaction, anatomically preserved the left side but it was expected that the right side was compromised by the tumor and the surgery.
  • Mild, expected post-op symptoms:
    • Headaches
    • Nasal crusting and drainage

​The patient continues to recover well and will undergo routine surveillance imaging and follow-up. Given the completeness of resection, no adjuvant therapy is required, and the risk of recurrence is considered very low, though ongoing monitoring is planned.

Clinical Considerations
  • Maintain diagnostic vigilance in patients with persistent “routine” sinonasal symptoms that fail standard therapy.
  • Escalate to advanced imaging when CT findings are atypical or clinical response is poor.
  • Olfactory schwannoma, while rare, should remain in the differential diagnosis.
Constantine Karras, MD, Clinical Assistant Professor of Neurological Surgery at Northwestern Medicine
Alexander L. Schneider, MD, otolaryngologist at Northwestern Medicine

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