====== Spinal Schwannoma Classification ======

//[[J.Sales-Llopis]]//

//Neurosurgery Department, [[General University Hospital Alicante]], [[Spain]]//

===== Latest Pubmed articles in real time =====

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[[Preoperative planning]] remains crucial for successful [[Spinal Schwannoma treatment]] and relies to a great extent on proper tumor [[classification]]. The [[literature]] includes multiple classification systems for [[spinal schwannoma]]s, each of which is associated with both positive and negative ramifications for [[preoperative planning]] 
((Chowdhury FH, Haque MR, Sarker MH. High cervical spinal schwannoma;
microneurosurgical management: an experience of 15 cases. Acta Neurol
Taiwan (2013) 22:59–66.))
((Fernandes RL, Lynch JC, Welling L, Gonçalevs M, Tragante R, Temponi V,
et al. Complete removal of the spinal nerve sheath tumors. Surgical techniques and results from a series of 30 patients. Arq Neuropsiquiatr (2014) 72:312–7. doi:10.1590/0004-282X20140008))
((Iwasaki Y, Hida K, Koyanagi I, Yoshimoto T, Abe H. Anterior approach for dumbbell type cervical neurinoma. Neurol Med Chir (1999) 39:835–9. doi:10.2176/nmc.39.835)).
((Kim P, Ebersold MJ, Onofrio BM, Quast LM. Surgery of spinal nerve schwannoma. Risk of neurological deficit after resection of involved root. J Neurosurg (1989) 71:810–4. doi:10.3171/jns.1989.71.6.0810)).

Consequently, there is a lack of consensus concerning the optimal system of classification for schwannomas
((Sun I, Pamir MN. Non-Syndromic Spinal Schwannomas: A Novel Classification.
Front Neurol. 2017 Jul 17;8:318. doi: 10.3389/fneur.2017.00318. eCollection 2017.
PubMed PMID: 28769861; PubMed Central PMCID: PMC5511849.
)).

The [[literature]] includes numerous schwannoma classification systems. 

===== Aydın =====
All tumors were divided into seven types according to the classification method. Type 1 and Type 2 groups were operated on with a posterior midline approach only, Type 3 tumors were operated on with a posterior midline approach and extraforaminal approach, and Type 4 tumors were operated on with only an extraforaminal approach. While the extraforaminal approach was sufficient in type 5 patients, partial facetectomy was required in 2 patients. Combined surgery including hemilaminectomy and extraforaminal approach was performed in the type 6 group. A posterior midline approach with partial sacrectomy/corpectomy was performed in Type 7 group. Conclusion Effective treatment of spinal schwannoma depends on preoperative planning, which includes correctly classifying tumors. In this study, we present a categorization scheme that covers bone erosion and tumor volume for all spinal localizations
((Aydın SO, Etli MU, Sarikaya C, Köylü RC, Varol E, Ramazanoğlu AF, Kayalar AE, Şerifoğlu L, Yaltirik K, Naderi S. Spinal Schwannomas: A Proposal for a New Classification to Aid Surgical Planning. J Neurol Surg A Cent Eur Neurosurg. 2023 Mar 13. doi: 10.1055/a-2053-2901. Epub ahead of print. PMID: 36914156.)).

===== Jinnai and Koyama =====

Jinnai and Koyama 
((Jinnai T, Koyama T. Clinical characteristics of spinal nerve sheath tumors: analysis of 149 cases. Neurosurgery (2005) 56:510–5. doi:10.1227/01. NEU.0000153752.59565.BB))
classified schwannomas into five groups based on the relationship between the tumor and the dura mater and/or intervertebral foramen. This classification system is useful, as it takes into consideration tumor localization relative to the dura, but it does not take into account volume, which is important for preoperative surgical planning.

===== Sridhar classification =====

Sridhar 
((Sridhar K, Ramamurthi R, Vasudevan MC, Ramamurthi B. Giant invasive spinal schwannomas: definition and surgical management. J Neurosurg (2001) 94:210–5.
))
was the first, in [[2001]], to suggest a classification system of benign [[spinal schwannoma]] including giant and invasive spinal schwannomas (type I to V).


Park et al. 
((Park SC, Chung SK, Choe G, Kim HJ. Spinal intraosseous schwannoma : a case
report and review. J Korean Neurosurg Soc. 2009 Oct;46(4):403-8. doi:
10.3340/jkns.2009.46.4.403. Epub 2009 Oct 31. PubMed PMID: 19893734; PubMed
Central PMCID: PMC2773402.
))
reported the use of a new classification system, and Type VI and Type VII were added. But the classification system as defined by Park et al. were inadequate because both the figures and the tumors were not clearly described in their manuscript. 

A case could not be classified based on Sridhar's spinal schwannoma classification system. Thus, as shown in a case, of Kotil 
type VIII must be added to the modified Sridhar classification (Kotil classification) system of benign spinal schwannomas
((Kotil K. An extremely giant lumbar schwannoma: new classification (kotil) and 
mini-open microsurgical resection. Asian Spine J. 2014 Aug;8(4):506-11. doi:
10.4184/asj.2014.8.4.506. Epub 2014 Aug 19. PubMed PMID: 25187870; PubMed Central
PMCID: PMC4149996.
)).

Sun and Pamir however, think classification of seven distinct types of schwannomas using Sridhar et al.’s system is not practical because the characteristics of seven tumors types are difficult to remember. Another drawback of their system is that tumor volume is only considered for dumbbell-shaped tumors, and craniocaudal dimension is not a consideration, which limit the diagnostic value and consistency of the classification system
((Sun I, Pamir MN. Non-Syndromic Spinal Schwannomas: A Novel Classification.
Front Neurol. 2017 Jul 17;8:318. doi: 10.3389/fneur.2017.00318. eCollection 2017.
PubMed PMID: 28769861; PubMed Central PMCID: PMC5511849.)).



===== Asazuma Classification =====

[[Asazuma Classification]].

===== Toyama classification =====
[[Toyama classification]].

===== Sun and Pamir Classification =====
It is based on consideration of [[tumor volume]] and localization relative to the [[dura]] and [[spinal canal]]. For approximate calculation of tumor volume, spinal schwannomas were considered ellipsoid bodies, and tumor volume was calculated using the following formula:

Tumor volume = 4 / 3 π × (craniocaudal length / 2) × (transverse diameter / 2)2 .

Tumors were then assigned to 1–3 volume groups (group A, B, and C) and designated as 1 of 4 types (type I, II, III, and IV) accord- ing to localization (i.e., group B type II tumor). Tumor volume <2 cm3 was considered group A, 2–4 cm3 group B, and >4 cm3 group C. Tumor typing was as follows: localized exclusively intra- durally: type I; intradural localization with extradural extension to the nerve root foramina, but restricted to the spinal canal: type II; intradural dumbbell-shaped tumor in the spinal canal extending to the extraforaminal region: type III; and localized completely outside the root foramina: type IV 

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Sridhar et al.’s 
((Sridhar K, Ramamurthi R, Vasudevan MC, Ramamurthi B. Giant invasive spinal schwannomas: definition and surgical management. J Neurosurg (2001) 94:210–5.
))
classification system is arguably the most similar of the previously reported systems to the novel classification system described by Sun and Pamir however, they think classification of seven distinct types of schwannomas using Sridhar et al.’s system is not practical because the characteristics of seven tumors types are difficult to remember. Another drawback of their system is that tumor volume is only considered for dumbbell-shaped tumors, and craniocaudal dimension is not a consideration, which limit the diagnostic value and consistency of the classification system
((Sun I, Pamir MN. Non-Syndromic Spinal Schwannomas: A Novel Classification.
Front Neurol. 2017 Jul 17;8:318. doi: 10.3389/fneur.2017.00318. eCollection 2017.
PubMed PMID: 28769861; PubMed Central PMCID: PMC5511849.)).
----
{{::sunandpamirclassification.jpg?600|}}

Based on the findings, Sun and Pamir think that all schwannomas should be classified according to localization and volume, so as to achieve the desired benefit of classification—ease and reliability of preoperative decision making and preparation. In addition, this classification system makes tumor localization easier to understand, as compared to other systems, and is suitable for all schwannoma types.

It is a simple and effective tool that shows extremely helpful for avoiding unnecessary surgical approaches and complications. Due to the system’s simplicity of having only three tumor groups and its reliability—indicated by the associated low postoperative side effect rate, use of this novel classification system should be considered by any surgical department that seeks a standardized schwannoma surgery protocol.
((Sun I, Pamir MN. Non-Syndromic Spinal Schwannomas: A Novel Classification.
Front Neurol. 2017 Jul 17;8:318. doi: 10.3389/fneur.2017.00318. eCollection 2017.
PubMed PMID: 28769861; PubMed Central PMCID: PMC5511849.)).

===== Eden's classification =====

Eden's classification for [[dumbbell tumor]]s of the spine, long considered a "gold standard," 

{{::edensclassification.jpg|}}

no longer is sufficient to determine surgical strategy in view of recent advances in computed tomography and magnetic resonance imaging.

===== Dumbbell spinal schwannoma =====

see [[Dumbbell spinal schwannoma]].

===== Giant spinal schwannoma =====

see [[Giant spinal schwannoma]].

===== Cervical spinal schwannoma =====

[[Cervical spinal schwannoma]].

===== Thoracic spinal schwannoma =====

[[Thoracic spinal schwannoma]].

===== Lumbar spinal schwannoma =====

[[Lumbar spinal schwannoma]].

===== Sacral spinal schwannoma =====

[[Sacral spinal schwannoma]].

===== Intramedullary schwannoma =====
[[Intramedullary schwannoma]]
===== References =====