title: Combined isolated trigeminal and facial neuropathies from perineural invasion by squamous cell carcinoma: A case series and review of the literature.
abstract: Perineural invasion is a targeted cellular proliferation guided by neurotrophins, rather than a simple diffusion of tumor in a path of least resistance. Invasion of cranial nerves by squamous cell carcinoma can represent an important diagnostic dilemma. It commonly presents as a distinct clinical neurological syndrome of combined isolated trigeminal and facial neuropathies. The focal cancer source may have been overlooked or remain occult. This case series illustrates diverse clinical presentations and neuroimaging challenges in four patients with squamous cell carcinoma of the cranial nerves. Anatomical pathways linking the trigeminal and facial nerves are reviewed, with emphasis on the auriculotemporal and pterygopalatine nerves. A successful neuroimaging strategy requires a targeted multimodality analysis of specific anatomical loci at the base of the skull. Attention must be directed to subtle radiological findings, such as obliteration of fat planes and linear enhancement along nerve branches, rather than bulky tumor tissue or bony invasion. Despite advances in microsurgical dissection and targeted radiotherapy, recovery of established neuropathic deficits is not expected. The prognosis remains poor in cases of advanced disease, emphasizing the importance early diagnosis by clinical acumen and focused neuroimaging.
authors.affiliation: The Ottawa Hospital, Department of Medicine, Division of Neurology, Ontario, Canada; The University of Ottawa, Ontario, Canada; The Ottawa Hospital Research Institute, Ontario, Canada. Electronic address: pbourque@toh.ca.
authors.forename: Pierre R
authors.initials: PR
authors.lastname: Bourque
authors.affiliation: The University of Sherbrooke, Québec, Canada. Electronic address: gabrielle.bourque3@usherbrooke.ca.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Bourque
authors.affiliation: The University of Ottawa, Ontario, Canada; The Ottawa Hospital, Diagnostic Imaging, Ontario, Canada. Electronic address: wmiller@toh.ca.
authors.forename: William
authors.initials: W
authors.lastname: Miller
authors.affiliation: The University of Ottawa, Ontario, Canada; The Ottawa Hospital Research Institute, Ontario, Canada. Electronic address: jwoulfe@toh.ca.
authors.forename: John
authors.initials: J
authors.lastname: Woulfe
authors.affiliation: The Ottawa Hospital, Department of Medicine, Division of Neurology, Ontario, Canada; The University of Ottawa, Ontario, Canada; The Ottawa Hospital Research Institute, Ontario, Canada; The Children's Hospital of Eastern Ontario, Ontario, Canada; The Children's Hospital of Eastern Ontario Research Institute, Ontario, Canada. Electronic address: jwarman@toh.ca.
authors.forename: Jodi
authors.initials: J
authors.lastname: Warman Chardon
mesh_terms: D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000150:complications / Q000000981:diagnostic imaging*; D003390:Cranial Nerve Neoplasms / Q000000981:diagnostic imaging* / Q000209:etiology; D005154:Facial Nerve / Q000000981:diagnostic imaging*; D005155:Facial Nerve Diseases / Q000000981:diagnostic imaging* / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D009361:Neoplasm Invasiveness / Q000000981:diagnostic imaging; D059906:Neuroimaging; D014276:Trigeminal Nerve / Q000000981:diagnostic imaging*
keywords: Facial neuropathy; Perineural invasion; Squamous cell carcinoma; Trigeminal neuropathy