Trochlear nerve neuroma manifested with intractable atypical facial pain: Case report

OBJECTIVE AND IMPORTANCE: Trochlear nerve neuromas are extremely rare. Seventeen surgical cases of this pathological condition have been reported in the English literature. The presented case is distinct from previous reports. CLINICAL PRESENTATION: A 26-year-old woman presented with atypical facial pain. The neurological examination results were normal. Magnetic resonance imaging revealed a left parasellar mass. INTERVENTION: A left pterional craniotomy was performed, providing access to the left parasellar area. After incision of the tentorial edge, the tumor was observed to originate from the short segment of the trochlear nerve that runs between the tentorial leaves. The neuroma was totally removed. CONCLUSION: The facial pain resolved immediately after surgery. Although facial dysesthesias have been noted among patients with trochlear nerve neuromas, here the atypical facial pain was the only clinical manifestation. In all previously reported cases, neuromas originated from the cisternal segment of the trochlear nerve (always before the site of nerve entrance into the tentorial leaves) and expanded mainly into the prepontine and interpeduncular cisterns. Subtemporal and suboccipital approaches were used. In this case, the tumor arose from the short segment of the nerve running between the tentorial leaves. The tumor did not extend either into the ambient cistern or into the cavernous sinus but did involve the parasellar area. A pterional approach was appropriate for tumor removal. A trochlear nerve neuroma should be considered as a potential cause of atypical facial pain.