Comprehensive Management of Vestibular Schwannoma

Comprehensive Management of Vestibular Schwannoma

Comprehensive Edition by Matthew L Carlson (Editor), Michael J. Link (Editor), Colin L.W. Driscoll (Editor)

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The definitive resource on clinical management of vestibular schwannoma from world renowned experts

Although a histologically benign and relatively uncommon tumor, otolaryngologists and neurosurgeons have maintained a lasting and deep-rooted fascination with vestibular schwannoma, also known as acoustic neuroma. Advancements in microsurgical technique, radiosurgery, and radiotherapy, coupled with an increased understanding of the natural history of the disease, have made modern management of this tumor considerably more complex. Concurrently, new controversies have added to the original debates among pioneering surgeons, with the pendulum swinging between conservatism and definitive cure.

Comprehensive Management of Vestibular Schwannoma, by distinguished Mayo Clinic clinicians and renowned international contributors, is a comprehensive textbook covering all the clinical aspects of vestibular schwannoma management. Eighty-four chapters written by multidisciplinary experts including otolaryngologists, neurosurgeons, radiation oncologists, neurologists, neuroradiologists, and audiologists, ensure a balanced view of all treatment modalities for sporadic and neurofibromatosis type 2-associated vestibular schwannoma.

Key Features

Evaluation, surgical and nonsurgical approaches, rehabilitation, controversies, and long-term clinical outcomes Detailed illustrations by Robert Morreale, senior medical illustrator at the Mayo Clinic, highlight relevant anatomy and surgical approaches Chapter summary tables provide readers with a rapid clinical reference derived from the published world literature The chapter “Anatomy of Vestibular Schwannoma Surgery” by the late internationally renowned neurosurgeon Albert L. Rhoton Jr. reflects his major contributions on this subject With inclusion of fundamental principles to advanced concepts, this is a robust resource for residents, fellows, and early attending physicians, as well as mid- to later-career physicians who care for patients with vestibular schwannoma.

This book includes complimentary access to a digital copy on https://medone.thieme.com.

Retrosigmoid transmeatal approach for vestibular schwannoma videos

Retrosigmoid transmeatal approach for vestibular schwannoma videos

Dorsal displacement of the facial nerve is relatively rare in patients with vestibular schwannoma. Its prediction remains difficult in patients with large tumors, even with the recent advances in preoperative radiologic assessments. Anatomic and functional preservation of the facial nerves combined with maximal tumor removal is particularly challenging in this rare anatomic variant, and surgery may lead to postoperative facial nerve paralysis, inadequate tumor removal, and/or a high retreatment rate.

The 3-dimensional video (Video 1) demonstrates a vestibular schwannoma with dorsally displaced facial nerve, which was surgically treated by the retrosigmoid transmeatal approach under continuous facial nerve monitoring. The video was reproduced after informed consent of the patient. A 46-year-old man presented with transient hearing impairmentNeuroimaging displayed a left vestibular schwannoma extending into the internal acoustic meatus. The retrosigmoid transmeatal approach was performed, and a dorsally displaced facial nerve was predicted by preoperative magnetic resonance images and confirmed during surgery. The facial nerve was accurately dissected under continuous facial nerve monitoring, and gross total resection of the tumor was achieved without postoperative facial dysfunction 1).


A case of a mid-sized vestibular schwannoma (T3b according to the Hannover Grading Scale) that was resected through a Endoscopic assisted retrosigmoid approach in semisitting position

A 52-year-old male with acute loss of functional hearing on the right side. Audiometry confirmed a loss of up to 60 dB and lost speech discrimination, there were no associated symptoms such as tinnitus or vertigo. This 2D video demonstrates positioning, OR set-up, anatomical and surgical nuances of the skull base approach and the operative technique for microdissection of the tumor from the critical neurovascular structures, especially the facial and cochlear nerves. A gross total resection was achieved and the patient discharged home after four days with unaltered function of the facial nerve (HB I). At one year follow up there was no indication of residual or recurrence. In summary, the retrosigmoid transmeatal approach is an important and powerful tool in the armamentarium for the microsurgical management of all kinds of vestibular schwannomas. Provided the necessary anesthesiological precautions and intraoperative procedures the semi-sitting position is safe and effective. If needed, the approach can be complemented by the use of an endoscope for visualization of the distal internal auditory canal. The link to the video can be found at: https://youtu.be/pPKT4_5nIn0 2).


The anterior inferior cerebellar artery (AICA) usually runs loosely within the cerebellopontine cistern; in rare cases, however, it is firmly adherent to the petrous dura mater. Recognizing this variation is particularly important in vestibular schwannoma surgery via the retrosigmoid transmeatal approach to prevent the high morbidity associated with vascular injury. This video demonstrates a surgical technique to effectively mobilize the AICA when firmly adherent to the petrous dura mater.

A 39-year-old man presented with a history of progressive right-sided hearing loss without facial weakness or other associated symptoms. Magnetic resonance imaging (MRI) demonstrated an intracanalicular lesion, suggestive of vestibular schwannoma. During follow-up, audiometryconfirmed a further slight deterioration of hearing and repeated MRI demonstrated tumor growth (T2 according to Hannover Grading Scale). Since the patient opted against radiosurgery, a retrosigmoid transmeatal approach under continuous intraoperative monitoring was performed in supine position. Following drainage of cerebrospinal fluid and exposure of the cerebellopontine cistern, the AICA was found to be firmly adherent to the petrous dura mater. Both structures were elevated conjointly and displaced medially for safe drilling of the inner auditory canal, sufficient exposure, and complete excision of the vestibular schwannoma. The patient had an excellent recovery, hearing and facial function were preserved, and no secondary neurological deficits noted.The patient consented to publication of this anonymized video 3).


Skull Base Neurosurgery – University of Colorado


George Kaptain


Paolo Regolo


Sameer A. Sheth

References

1)

Matsushima K, Kohno M, Nakajima N, Ichimasu N. Dorsally Displaced Facial Nerve in Retrosigmoid Transmeatal Approach for Vestibular Schwannoma: 3-Dimensional Operative Video. World Neurosurg. 2019 Mar;123:300. doi: 10.1016/j.wneu.2018.11.261. Epub 2018 Dec 21. PubMed PMID: 30580063.
2)

Evangelista-Zamora R, Lieber S, Ebner FH, Tatagiba M. Retrosigmoid Transmeatal Endoscope-Assisted Approach in Semi-Sitting Position for Resection of Vestibular Schwannoma: 2-D operative Video. J Neurol Surg B Skull Base. 2018 Dec;79(Suppl 5):S385-S386. doi: 10.1055/s-0038-1669985. Epub 2018 Oct 9. PubMed PMID: 30473983; PubMed Central PMCID: PMC6240135.
3)

Tatagiba MS, Evangelista-Zamora R, Lieber S. Mobilization of the Anterior Inferior Cerebellar Artery When Firmly Adherent to the Petrous Dura Mater-A Technical Nuance in Retromastoid Transmeatal Vestibular Schwannoma Surgery: 3-Dimensional Operative Video. Oper Neurosurg (Hagerstown). 2018 Nov 1;15(5):E58-E59. doi: 10.1093/ons/opy052. PubMed PMID: 29617908.

Intramedullary Schwannoma

Intramedullary Schwannoma

James Watson Kernohan has been recognized as the first neurosurgeon to report an intramedullary schwannoma case in 1952, though Wilder Penfield had already described an intramedullary lesion with schwannomas characteristics in 1932 1).

Epidemiology

Intramedullary (IM) schwannomas are rare entities representing the 0.3-1% of intramedullary tumors and 1.1% of spinal schwannomas. Beside many theories proposed, their rare occurrence might be related to the absence of Schwann cells into the spinal cord.

To date, approximately around 60 cases of intramedullary schwannoma in patients without neurofibromatosis have been reported in the English literature, of which only eight were children 2).

The male:female ratio for intramedullory schwannomas is 3:1 with a mean age of 40 years old. They are usually single lesions affecting the cervical spinal cord (63%), the thoracic spinal cord (26%), and the lumber spinal cord (11%). They have a slow growth pattern and because of this, the average interval between first symptom and diagnosis is 28.2 months (from 6 months through 20 years) 3).

see Thoracic intramedullary schwannoma.

Clinical features

The most described clinical manifestation is the pyramidal syndrome followed by sensitivity complaints and sphincter dysfunction. There are reports of muscular fasciculations as the first symptom 4).

Diagnosis

A tumor located in the dorsolateral spinal cord, causing expansion of the cord, with hypointense areas on T2-weighted and obviously enhancement, should arise suspicion of an intramedullary schwannoma 5).

http://www.asianjns.org/viewimage.asp?img=AsianJNeurosurg_2015_10_1_42_151509_f2.JPG

Outcome

Intramedullary schwannoma may recur after resection 6).

Case series

8 patients with pathologically confirmed intramedullary schwannomas were reviewed.

There were 6 male and 2 female patients (mean age, 49 years). Tumors were located in the cervical cord (2), the thoracic cord (5), and the cervicothoracic cord (1). Most were in the dorsolateral spinal cord and limited to one side. Expansion of the cord was observed. The majority were hypointense on T1-weighted images and hypo-hyperintense on T2-weighted images. Peritumoral edema was easily found. Gadolinium enhancement was obviously. No recurrence was seen during the follow-up period.

A tumor located in the dorsolateral spinal cord, causing expansion of the cord, with hypointense areas on T2-weighted and obviously enhancement, should arise suspicion of an intramedullary schwannoma 7).

Case reports

Dhake and Chatterjee described two cases of thoracic intramedullary schwannomas that recurred after primary excision. A 10 years old boy presented with weakness of both lower limbs. Magnetic resonance imaging showed a D10 to D12 intramedullary lesion, which was excised near totally and confirmed to be a schwannoma on histopathological examination. The tumour recurred twice after that and was re operated both times. Another 57 years old lady presented with weakness of both lower limbs and a history of being operated in the past for D9-D10 intramedullary lesion. She was re-operated with total removal of the lesion confirmed to be schwannoma on histopathological examination. Intramedullary schwannoma may recur after resection. 8).


A 8 year-old female affected by a progressive paraparesis. Neuroradiological investigations showed an oval-shaped mass at the level of T10-T11. The patient underwent surgery, performed under neurophysiological monitoring. The patient was operated on with a complete removal of the lesion. The postoperative course was uneventful.

The clinical, neuroradiological, and intraoperative findings are presented, along with a review of the literature. Despite the number of lesions potentially compressing the spinal cord, IM schwannoma is rare but should be taken into account in the differential diagnosis 9).


A rare case of thoracic intramedullary tumour in a 28 year old male patient who presented with progressive weakness of both the lower limbs and decreased sensation below D2 dermatomal level. Magnetic resonance imaging revealed an intramedullary lesion from D1 toD7. D1 to D7 laminoplasty and near total excision of the mass done. Total removal was difficult because of the infiltrative nature of the tumour 10).

References

1)

Penfield W. Notes on operative technic in neurosurgery. Ann surg. 1946;124:383–5.
2) , 6) , 8)

Dhake RP, Chatterjee S. Recurrent thoracic intramedullary schwannoma: report of two cases with long term follow up. Br J Neurosurg. 2019 Mar 5:1-4. doi: 10.1080/02688697.2019.1566516. [Epub ahead of print] PubMed PMID: 30836024.
3)

Lopez J, Diaz DR, Medina YC, Jeronimo HS, Mendez AZ, Vazquez AG, et al. Schwannoma intramedullary cervical. Arch neurocien. 2004;9:55–8.
4) , 10)

Nayak R, Chaudhuri A, Chattopadhyay A, Ghosh SN. Thoracic intramedullary schwannoma: A case report and review of literature. Asian J Neurosurg. 2015 Apr-Jun;10(2):126-8. doi: 10.4103/1793-5482.145155. PubMed PMID: 25972946; PubMed Central PMCID: PMC4421952.
5) , 7)

Gao L, Sun B, Han F, Jin Y, Zhang J. Magnetic Resonance Imaging Features of Intramedullary Schwannomas. J Comput Assist Tomogr. 2017 Jan;41(1):137-140. doi: 10.1097/RCT.0000000000000493. PubMed PMID: 27680415.
9)

Landi A, Grasso G, Gregori F, Iacopino G, Ruggeri A, Delfini R. Isolated Pediatric Intramedullary Schwannoma. Case report and review of the literature. World Neurosurg. 2018 May 9. pii: S1878-8750(18)30940-9. doi: 10.1016/j.wneu.2018.04.220. [Epub ahead of print] PubMed PMID: 29753078.
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