Fallopian canal arachnoid cyst with acute facial nerve paralysis in children: a report of two cases and literature review

Abstract

Introduction: Symptoms induced by arachnoid cysts in the fallopian canal are uncommon, and facial nerve paralysis without cerebrospinal fluid otorrhea is comparatively rarer.

Methods: Herein, we present two cases of arachnoid cysts in the fallopian canal with acute severe facial nerve paralysis and review the relevant literature.

Results: The symptoms and imaging findings of these two cases resembled those of facial nerve schwannomas. Cerebrospinal fluid otorrhea occurred upon removal of the arachnoid cyst, and the facial nerve was observed to be separated into multiple filaments or compressed and atrophied. Facial-hypoglossal nerve anastomosis and decompression were conducted after packing the dehiscence of cerebrospinal fluid otorrhea for the two cases.

Conclusion: Arachnoid cysts of the fallopian canal rarely cause facial nerve paralysis. Enhanced magnetic resonance imaging is vital for differentiating schwannomas. Different treatment strategies should be adopted for patients with different degrees of facial nerve paralysis; however, concurrent repair of cerebrospinal fluid otorrhea and facial nerves during surgery can occasionally be challenging.

Keywords: arachnoid cyst; cerebrospinal fluid otorrhea; facial nerve paralysis; fallopian canal; meningitis.

Figure 1

Imaging of case one. (A–C) Cystic lesion in the tympanic cavity on axial computed tomographic (CT) imaging; (B) enlarged fallopian canal at labyrinthine segment; (D) normal fallopian canal and tympanic cavity on the contralateral left side; (E) hypointensity of the lesion on T1-weighted imaging (T1WI), with mixed signals of exudate in the mastoid cavity; (F) hyperintensity of the perigeniculate lesion on T2-weighted imaging (T2WI); (G) hypointensity of the lesion on coronal T2 fluid-attenuated inversion recovery imaging (T2 FLAIR); (H) part of the lesion was enhanced on T1-weighted contrast-enhanced imaging; (I) exploration revealed a cyst-like lesion was located in the tympanic cavity, along the length of the facial nerve; (J) massive cerebrospinal fluid (CSF) leaked was observed upon piercing the cyst; (K) CSF was released from the defective fundus of the internal auditory meatus.

Figure 2

Imaging of case two. (A) Axial computed tomographic (CT) image displaying enlarged fallopian canal at the labyrinthine segment, a cystic lesion at geniculate ganglion, and defective adjacent middle cranial fossa floor; (B) mixed hypointensity and hyperintensity at the tympanic segment of the facial nerve on T1-weighted imaging (T1WI); (C) hyperintensity of the perigeniculate lesion on T2-weighted imaging (T2WI); (D) mixed hypointensity and isointensity at the tympanic segment on T2 fluid-attenuated inversion recovery imaging (T2 FLAIR).