Jacobson nerve schwannomas are rare, benign middle ear tumors that involve the eponymous tympanic branch of the glossopharyngeal nerve. They appear as a mass on the cochlear promontory and enlargement of the inferior tympanic canaliculus 1,2.
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Clinical presentation
Patients may present with hearing loss 1,2, otalgia 2, or pulsatile tinnitus 3. An otoscopic exam reveals a pale, non-pulsatile mass in the middle ear cavity 1.
Pathology
General pathologic features are described separately: schwannoma.
Radiographic features
CT
CT demonstrates the tumor with secondary bony changes 1:
soft tissue mass in the middle ear cavity based on the cochlear promontory
possible erosion of the cochlear promontory
expansion of the inferior tympanic canaliculus
no significant enhancement
MRI
The signal characteristics are typical of schwannomas elsewhere 1:
T1: hypointense
T2: hyperintense
T1 C+: homogeneous moderate enhancement
Differential diagnosis
-
tympanic paraganglioma (most common tumor at the cochlear promontory)
more intensely enhancing
more permeative bone changes
red and pulsatile on otoscopy
-
facial nerve schwannoma (most common middle ear schwannoma)
distinct location along facial nerve canal
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