Facial Schwannoma
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Introduction[edit | edit source]
Facial Schwannoma is a very rare tumour which grows on the 7th Cranial Nerve, the Facial Nerve.
It is also known as a Facial Neuroma.
Clinically Relevant Anatomy[edit | edit source]
For details of the path of the Cranial Nerve 7, please see the Facial Nerve page.
Location of Tumour[edit | edit source]
The majority of tumours are found on the segment of the nerve within the internal auditory canal, with one UK study[1] of a cohort of 28 Facial Schwannoma patients reporting 68% incidence in this section of the nerve.
The same study also found multi-segmental lesions in 46% of the patients.
Facial weakness was most commonly associated with involvement of the labyrinthine segment (89%).
Mechanism of Injury / Pathological Process[edit | edit source]
Schwannomas are extremely slow growing tumours, the majority of which are benign[2].
They originate from the Schwann cell sheath of the facial nerve.
Clinical Presentation[edit | edit source]
The presentation frequently comprises hearing loss and facial weakness or paralysis[3]:
Facial Palsy/Paralysis[edit | edit source]
In Facial Schwannoma, the patient often reports a very slow onset unilateral facial palsy, ie. paralysis or weakness of the facial muscles. It is a lower motor neuron palsy.
There are more details on the Facial Palsy page.
Hearing Loss[edit | edit source]
The Auditory or Acoustic Nerve, 8th Cranial Nerve, travels next to the facial nerve in the Internal Auditory Canal. A growing tumour on the portion of the Facial Nerve within the Internal Auditory Canal can therefore cause compression on the Acoustic Nerve, which results in hearing loss.
Other symptoms[edit | edit source]
These can include pain, balance difficulties, vertigo and tinnitus.
Incidence of Symptoms[edit | edit source]
A 2006 study[4] examined 24 patients with Facial Schwannoma and reported the following incidence of symptoms:
Peripheral facial nerve neuropathy in 10 cases, ie. 42% of patients. This encompassed weakness, focal twitch, and/or full hemifacial spasm.
Sensorineural hearing loss occurred in 7 cases (29%),
Conductive hearing loss in 4 cases (17%)
Clinical presentation with a middle ear mass in 3 cases (13%)
Vestibular symptoms in 3 cases (13%)
Diagnostic Procedures[edit | edit source]
In the majority of centres, a brain MRI is used as part of the evaluation of facial paralysis[5][4][6]; however, this often misses a Facial Schwannoma because of the very small diameter of the facial nerve - approx 1 mm - and the thickness of the image slices - 5 mm.
The optimal imaging technique is an MRI of the internal auditory canals, with and without the contrast agent gadolinium. This imaging technique allows thinner slices through the temporal bone, it is much more likely to show the tumour[7].
Outcome Measures[edit | edit source]
- Sunnybrook Facial Grading System
- House-Brackmann facial nerve grading scale
- Linear Measurement Index
- Facial Disability Index
Management / Interventions[edit | edit source]
Surgical Intervention[edit | edit source]
Facial Schwannomas are frequently resected surgically, although if the tumour is not causing any problems it will generally just be monitored and no surgical intervention undertaken[8].
Radiosurgery/Gamma Knife[edit | edit source]
In recent years, a number of studies have evaluated Gamma Knife radiosurgery, and other forms of stereotactic radiosurgery, for management of Facial Schwannomas. The results have been promising with one study[9] concluding " GKS is a safe alternative to resection"; another[10] concludes: "study demonstrates that radiosurgery allows treatment of these patients while preserving normal motor facial function. Such an advantage should lead to the consideration of radiosurgery as a first treatment option for small- to medium-size facial nerve schwannomas."
Oculoplastic Surgery[edit | edit source]
Patients at high risk of a corneal ulcer may be offered oculoplastic surgery to protect the eye.
For patients with dense facial palsy and no nerve function, a number of surgical interventions may be used. These fall into the following categories:
- Facial reanimation surgeries which involve nerve graft or anastomosis
- Facial reanimation surgeries which involve muscle transposition
- Static surgeries, ie. plastic surgery to improve symmetry at rest but no improvement in movement
Differential Diagnosis[edit | edit source]
Acoustic Neuroma - due to the difficulties in imaging this region, and also as a number of patients with Facial Schwannoma present with no facial neuropathy at all, but do present with hearing loss, the lesion may easily be mis-diagnosed as an Acoustic Neuroma/Schwannoma, and only on performing surgery does it become apparent that the tumour is not on the Acoustic Nerve but on the Facial Nerve. One study[4] found that out of 24 patients with Facial Schwannoma 5 cases were misdiagnosed preoperatively as an acoustic schwannoma, ie. 24% of the group.
Parotid Adenoma[2]
Physiotherapy Management[edit | edit source]
Resources[edit | edit source]
add appropriate resources here
References[edit | edit source]
- ↑ Doshi J, Heyes R, Freeman SR, Potter G, Ward C, Rutherford S, King A, Ramsden R, Lloyd SK. Clinical and Radiological Guidance in Managing Facial Nerve Schwannomas Otology & Neurotology. 36(5):892–895, JUNE 2015
- ↑ 2.0 2.1 Jayashankar N, Sankhla S. Facial schwannomas: Diagnosis and surgical perspectives. Neurol India [serial online] 2018 [cited 2019 Nov 28];66:144-6. Available from: http://www.neurologyindia.com/text.asp?2018/66/1/144/222821
- ↑ Lahlou G; Nguyen Y; Russo FY; Ferrary E; Sterkers O; Bernardeschi D Intratemporal facial nerve schwannoma: clinical presentation and management. Eur Arch Otorhinolaryngol. 2016; 273(11):3497-3504 (ISSN: 1434-4726)
- ↑ 4.0 4.1 4.2 R.H. Wiggins, H.R. Harnsberger, K.L. Salzman, C. Shelton, T.R. Kertesz and C.M. Glastonbury The Many Faces of Facial Nerve Schwannoma American Journal of Neuroradiology March 2006, 27 (3) 694-699;
- ↑ Chung SY, Kim DI, Lee BH, Yoon PH, Jeon P, Chung TS. Facial nerve schwannomas: CT and MR findings. Yonsei Med J. 1998 Apr;39(2):148-53.
- ↑ Sherman JD, Dagnew E, Pensak ML, van Loveren HR, Tew JM Jr. Facial nerve neuromas: report of 10 cases and review of the literature. Neurosurgery. 2002 Mar;50(3):450-6.
- ↑ Djalilian, Hamid R. MD Symptoms: Hearing Loss and Facial Paralysis The Hearing Journal: May 2014 - Volume 67 - Issue 5 - p 11,14
- ↑ Marzo SJ1, Zender CA, Leonetti JP. Facial nerve schwannoma. Curr Opin Otolaryngol Head Neck Surg. 2009 Oct;17(5):346-50. doi: 10.1097/MOO.0b013e32832ea999.
- ↑ Hasegawa T, Kato T, Kida Y, Hayashi M, et al. Gamma Knife surgery for patients with facial nerve schwannomas: a multi-institutional retrospective study in Japan. J Neurosurg. 2016 Feb;124(2):403-10. doi: 10.3171/2015.3.JNS142677. Epub 2015 Sep 11.
- ↑ Litre CF, Gourg GP, Tamura M, Mdarhri D, Touzani A, Roche PH, Régis J. Gamma knife surgery for facial nerve schwannomas. Neurosurgery. 2007 May;60(5):853-9; discussion 853-9.
