Schwannoma of the Jugular Foramen
Schwannoma in the jugular foramen may arise from CN IX through XII. The specific nerve of origin is difficult, if not impossible, to identify in many cases. Clinically they are often confused with glomus jugulare tumor (jugulotympanic paraganglioma) because of their growth pattern, anatomic location, and symptoms (1). On MRI, glomus jugulare tumors characteristically show intense contrast enhancement and multiple small voids ("salt and pepper" appearance), whereas schwannomas typically do not show internal flow voids, with the exception of highly vascular vestibular schwannomas which can show them peripherally (2). Intracranial nerve sheath tumors represent only 4-8% of intracranial neoplasms. Most intracranial schwannomas are associated with neurofibromatosis type 2. Jugular foramen schwannomas represent 3-4% of these tumors. Grossly the tumors tend to be dumbbell-shaped or round and are well-circumscribed. The cell of origin is the Schwann cell. Grossly, some tumors may display a cystic component with moderate vascularity. The cellular component classically contains architectural regions designated as Antoni type A and Antoni type B. Antoni A regions are densely packed with spindled cells. Antoni B areas are sparsely populated with loosely organized stellate cells. Verocay bodies, palisades of spindled nuclei alternating with anuclear processes, may also be present.
The symptoms of jugular foramen schwannomas include problems with speaking and swallowing and are related to vessel and nerve compression,. These slow-growing tumors often fill a significant amount of space prior to causing symptoms. Once a tumor has reached a critical size, which varies by precise location, signs and symptoms of nerve root compression and brain stem compression can evolve quickly to the syndrome of upper brain stem compression (3). Patients may present with headache, vomiting and neck stiffness, with global impairment of all mental functions, progressing from lethargy to drowsiness and confusion and then to a semi-comatose state. In medullary compression, death can occur in minutes with sudden respiratory arrest and acute hypotension. Treatment for jugular foramen schwannoma has included radiosurgery (4) and excision (5,6).
Contributed by Rebecca J. Asch-Kendrick MD, Elizabeth Burton, MD, Liam Chen, MD, PhD, David Nauen, MD, PhD