- Email: [email protected]
Extensive intramedullary schwannoma of the sub-axial cervical spine – A case report
Interdisciplinary Neurosurgery 19 (2020) 100621
Contents lists available at ScienceDirect
Interdisciplinary Neurosurgery journal homepage: www.elsevier.com/locate/inat
Case Reports & Case Series
Extensive intramedullary schwannoma of the sub-axial cervical spine – A case report
T
⁎
Adrian Kellya, , Patrick Lekgwaraa, Aftab Younusb a b
Department of Neurosurgery, Dr George Mukhari Academic Hospital, Sefako Makgatho Health Sciences University, Pretoria, South Africa Department of Orthopedics, Helen Joseph Hospital, University of the Witwatersrand, Johannesburg, South Africa
A B S T R A C T
Spinal schwannomas originate from Schwann cells and as a group represent 30% of spinal cord tumors. These lesions are commonly intra-dural extramedullary in location and in fact purely intramedullary schwannomas of the spinal cord represent only 1.1% of spinal schwannomas. Almost all of these occur in patients with Neurofibromatosis. Approximately 50 cases of intramedullary schwannomas not related to neurofibromatosis have been described to date. This case report gives an account of a young male patient with no family history nor clinical signs of Neurofibromatosis whom presented to out institution with an extensive schwannoma of his sub-axial cervical spinal cord extending from C4-T2. Neurological examination of his upper limbs on manual muscle testing revealed normal shoulder and elbow power 5/5, weakness of wrist dorsiflexion 3/5 and wasting of his intrinsic hand muscles bilaterally also with power 3/5. His lower limb examination revealed an incomplete T4 sensory level with preserved sensation and on manual muscle testing no motor function 0/5 was present. Under neurophysiological monitoring he was taken to theatre where the intra-operative finding of the schwannoma being subpial and intramedullary was confirmed. A gross total resection was achieved and post operatively his upper limb function showed no deterioration and his lower limb function showed improvement. This case report gives an account of a young male patient whom presented to our department with an extensive intramedullary schwannoma of his cervical spine extending from C4-T2. The surgical management resulted in clinical improvement and prevented ascending motor weakness.
1. Introduction Spinal schwannomas originate from Schwann cells and as a group represent 30% of spinal cord tumors [1]. These lesions are commonly intradural extramedullary in location and in fact purely intramedullary schwannomas of the spinal cord represent only 1.1% of spinal schwannomas [2]. Most of these occur in patients with Neurofibromatosis [2,3]. Approximately 50 cases of intramedullary schwannomas not related to neurofibromatosis have been described to date [4]. This case report gives an account of a young male patient with no family history nor clinical signs of neurofibromatosis whom presented to our institution with a purely intramedullary schwannoma of his cervical spinal cord extending from C4-T2. 2. Case description A 43 year old male presented to the Neurosurgical out-patient department at our institution complaining of progressive lower limb weakness of 18 months duration. He reported being unable to walk for the last 6 months. What had brought him to the hospital was that 3 months ago he had begun to notice that his hands were becoming weak and he was concerned. He reported no bladder nor bowel
symptoms. The patient was tested and found to be HIV negative and had no other medical problems nor any family history of Neurofibromatosis. He denied any history of loss of weight, night sweats nor fever. General examination revealed no signs of Neurofibromatosis. Neurological examination of his upper limbs by means of manual muscle testing revealed normal shoulder and elbow power 5/5 to be present in all muscle groups. His wrists had normal power with regards flexion 5/5 but bilateral weakness of wrist dorsiflexion 3/5 was demonstrated. His intrinsic hand muscles were wasted and bilaterally intrinsic hand muscle power was assessed to be 3/5. His lower limb examination revealed an incomplete T4 sensory level and on manual muscle testing no motor function 0/5 was present. An urgent MRI of his spine was requested which revealed an extensive intramedullary lesion of his cervical spine extending from C4-T2 with associated syringohydromyelia. The lesion was heterogeneous in appearance with a distinct boundary visible between it and the adjacent spinal cord tissue. The lesion was iso/hypo-intense on T1 and vividly hyper-intense on T2 imaging (Figs. 1–4). The lesion did not suppress on the T2 fat suppression MRI. There was no associated bony nor soft tissue abnormalities visible. An MRA excluded anomalies in the course of the vertebral arteries.
⁎ Corresponding author at: Department of Neurosurgery, 3rd floor Sciences Building, Sefako Makgatho Health Sciences University, Garankuwa, Pretoria, South Africa. E-mail address: [email protected] (A. Kelly).
https://doi.org/10.1016/j.inat.2019.100621 Received 25 February 2019; Received in revised form 23 October 2019; Accepted 26 October 2019 2214-7519/ © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/).
Interdisciplinary Neurosurgery 19 (2020) 100621
A. Kelly, et al.
Fig. 1. Pre-operative MRI T1W sagittal: Lesion is iso/hypointense and hardly visible extending from C4 (red arrow) to T2 (blue arrow). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 3. Pre-operative MRI T2W axial: intramedullary hyper-intense lesion with distinct boundaries.
Fig. 2. Pre-operative MRI T2 sagittal: Lesion is vividly hyper-intense extending from C4 (red arrow) to T2 (blue arrow). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 4. Pre-operative MRI T2W axial (additional view): again the intramedullary hyper-intense lesion with distinct boundaries.
presenting surface of the tumoral tissue provided a generous surgical corridor by which to internally decompress the lesion. Once the lesion was internally decompressed the remaining rim of tumoral tissue at the tumoral-neural interface separated easily. There was minimal bleeding from the tumor and the removed specimen had a fatty appearance (Fig. 6). Once resected a duroplasty was performed. No fusion was performed in this adult patient due to the long segment involved however would be re-discussed in the event of the development of post laminectomy kyphosis. The wound was closed in layers and the patient was transferred to ICU. Post operatively the patient reported improvement in lower limb sensation bilaterally however in the early post-operative period the power in his lower limbs on manual muscle testing remained unchanged 0/5. A post-operative MRI showed complete resection of the lesion had been achieved (Fig. 7). The histology result reported palisading cells in a vaguely organoid
Due to the patient being myelopathic with deteriorating neurology he was urgently booked for a resection of this lesion from a posterior approach. Neuro-monitoring was used as is mandatory for an intramedullary tumor resection. The patient was taken to theatre as an urgent case and a midline posterior neck incision was performed. The midline raphe was divided in the avascular plane and a sub periosteal dissection was achieved to expose the cervical laminae from C3-T4. Once exposed wide laminectomies, preserving the facets, were performed from C4-T2 and the dura exposed. A midline durotomy was performed spanning both the cephalad and caudal poles of the tumor. Upon opening the dura the tumor was immediately visible deep to the pia mater at the dorsal surface of the cervical spinal cord (Fig. 5). Upon opening of the pia mater the
2
Interdisciplinary Neurosurgery 19 (2020) 100621
A. Kelly, et al.
Fig. 7. Post-operative MRI T2W sagittal: edematous spinal cord demonstrated with gross total resection of the tumor achieved noted by the complete absence of the vividly hyper-intense lesion as seen on pre-operative imaging.
Fig. 5. Intra-operative photo: generous presentation of the tumor beneath the pia mater at the dorsal surface of the spinal cord.
Fig. 6. Intra-operative photograph: tumor specimen on a sterile drape.
pattern. Verocay bodies were visualized. Parts of the lesion were cystic and the stroma was loosely myxoid in places with fibrous areas in others. Thick walled blood vessels were seen with evidence of previous hemorrhage. S-100 staining was strongly positive and EMA staining was negative. The histology result reported the lesion to be a schwannoma (Figs. 8 and 9). At his 3 month review the patient was carefully examined for any improvement in his lower limb motor function. What was noted on manual muscle testing was that the power in his upper limbs was preserved and that his right ankle had improved dorsiflexion to 2/5 and the flexion in his right big toe was 1/5 (Fig. 10). The patient is for ongoing review in the Neuro-spine out-patient clinic.
Fig. 8. Histology: showing Antoni B area on H&E stain.
intramedullary tumors occurring in the sub-axial cervical spine the most commonly diagnosed is a diffuse fibrillary astrocytoma. Ependymoma’s are less commonly seen at this site and infrequently seen intra-medullary tumors diagnoses are epidermoids; teratomas; hemangioblastomas and lipomas. Rare lesions seen are intramedullary dermoid cysts and intramedullary schwannomas [5]. With regards primary intradural extramedullary lesions of the cervical spine the commonest are nerve sheath tumors namely schwannomas and neurofibromas however rarely meningiomas do occur [6]. In terms of pre-operative diagnoses a study by Takemoto 1988 noted MRI to be able to reliably differentiate schwannomas from meningiomas and hemangioblastomas based on imaging characteristics and location. This study concerned itself with extra-medullary spinal
3. Discussion In terms of affording a comprehensive differential diagnosis of 3
Interdisciplinary Neurosurgery 19 (2020) 100621
A. Kelly, et al.
(63%) of cases, while 26% occur in the thoracic spine [7]. On imaging these lesions are heterogeneous in appearance and are hypo/isointense on T1-weighted sequences and generally hyper intense on T2-weighted sequences. When gadolinium is injected there is a heterogeneous enhancement [10]. Predicting an intramedullary schwannoma purely on radiological grounds is however extremely difficult due to the rarity of these lesions. Misdiagnosis as a classical heterogeneously enhancing astrocytoma would be likely. Pre-operative radiological differentiation of a purely intramedullary schwannoma from the more commonly seen extramedullary schwannoma may be suspected by gross tumor morphology. The classical extramedullary schwannoma typically demonstrates dural and/or intervertebral foraminal constriction as it proliferates along the length of the involved nerve root. Regarding intramedullary schwannomas these barriers to growth and therefore classical dumb-bell appearance is not seen. Histologically schwannomas are comprised of Antoni A cell type area comprising compact cells in a reticular framework, and Antoni B cell type areas comprising large cells in a loose collagenous background [12] Attempting to apply the classification of Antoni to the MRI findings is not possible [8]. The WHO classifies schwannomas into cellular, plexiform and melanotic however does not differentiate these lesions based on location. With regards intramedullary schwannomas although they are often found with discrete edges enabling gross total resection, as was our case, an infiltrative pattern does occasionally occur making gross total resection impossible and there is a role for the use of radiotherapy in these incompletely resected lesions [7]. The controversial question about spinal intramedullary schwannomas emerges from their unknown pathogenesis. Due to the central nervous system containing no Schwann cells their presence at this location has stimulated intense debate regarding their cell of origin. Several theories have been proposed; As early as 1957 Riggs et al. proposed that these lesions could originate from Schwann cell proliferation from naturally occurring Schwann cells associated with the nerve fibers of spinal arteries [13] Ramamurthy et al suggested that ectopic Schwann cells originating from the embryonic neural tube (fourth week of gestation) are the origin of these lesions [14]. McCormick and Wood, in the 1960’s, theorized that intramedullary schwannomas originate from aberrant Schwann cells within intra-medullary medullary nerve fibers, specifically related to the posterior roots [15]. Russell and Rubenstein, in 1971, challenged these earlier theories and proposed the most widely accepted theory that still holds its ground today. They proposed that these tumors are the result of cellular transformation of neuroectodermal pial cells into Schwann cells. This accounts for not only the origin of intra-medullary schwannomas but also explains their neoplastic growth [16]. While dural and/or forminal constriction allows some degrees of pre-operative differentiation between the extramedullary and purely intramedullary schwannoma subtypes, definitive confirmation is often only done intra-operatively where the former is found to be deep to the pia mater which must be opened to gain access to the tumoral tissue. This contrasts the finding in classical extramedullary schwannomas where the pia does not have to be opened and the tumor is immediately accessible upon opening the dura.
Fig. 9. Histology: S-100 staining was strongly positive.
Fig. 10. Post-operative patient photo: Showing preserved shoulder and elbow function on manual muscle testing. Hand function did not improve in the immediate post-operative period.
tumors [8]. With regards differentiating intramedullary spinal tumors based on pre-operative radiographic features one paper noted that the length of involvement, location along the cord and enhancement pattern similarly allows some degree of pre-operative differentiation between the intramedullary tumor types to be made. In this paper astrocytomas for example are noted to occur more commonly in the thoracic spinal cord, to involve 4–7 vertebral bodies in length, and to demonstrate heterogenous enhancement. Intramedullary ependymomas on the other hand are noted to occur more commonly in the cervical spinal cord and to demonstrate solid homogenous enhancement [9]. Intramedullary spinal schwannomas occur most commonly in patients in the 4th decade of life and have a male to female ratio of 3:1. In terms of distribution they occur most commonly in the cervical spine
4. Conclusion This case report gives an account of a young male patient whom presented to our department with an extensive intramedullary schwannoma of his cervical spine extending from C4-T2. The surgical management resulted in clinical improvement and prevented ascending motor weakness that could have occurred with ongoing growth and cord compression by the tumor.
4
Interdisciplinary Neurosurgery 19 (2020) 100621
A. Kelly, et al.
Declaration of Competing Interest
(1984) 546–548. [4] J. Nicácio, J. Rodrigues, M. Galles, I. Faquini, C. Pereira, M. Ganau, Cervical intramedullary schwannoma: a case report and review of the literature, Rare Tumors 1 (2) (2009) e44. [5] B. Steyn, Intramedullary spinal cord tumors, Clin. Neurosurg. 308 (1983) 717–741. [6] K. Arnautovic, A. Arnautovic, Extramedullary intradural spinal tumors: a review of modern diagnostic and treatment options and a report of a series, Bosn. J. Basic Med. Sci. 9 (Suppl 1) (2009 Oct) S40–S45. [7] J. López, D.R. Diaz, Y.C. Medina, H. Jeronimo, A. Mendez, A. Vazquez, et al., Schwanoma intramedular cervical, Arch Neurocien 9 (2004) 55–58. [8] K. Takemoto, Y. Matsumura, H. Hashimoto, et al., MR imaging of intra-spinal tumors- capability in histological differentiation and compartmentalization of extramedullary tumors, Neuroradiology 30 (1988) 303–309. [9] S. Moghaddam, A. Bhatt, Location, length, and enhancement: systematic approach to differentiating intramedullary spinal cord lesions, Insights Imaging 9 (4) (2018) 511–526. [10] H. Demachi, T. Takashima, M. Kadoya, et al., MR imaging of spinal neurinomas with pathological correlation, J. Comput. Assist. Tomogr. 14 (1990) 250–254. [12] R. Carrillo-Esper, G. Solis-Maldonado, V. Trujillo, M. Tellez-Morales, Schwannoma intra-medular cervical, Cir. Ciruj. (2001) 5–7. [13] H. Riggs, W. Clary, A case of intra-medullary sheath cell tumor of the spinal cord; consideration of vascular nerves as a source of origin, J Neuropathol. Exp. Neurol. 16 (1957) 332–336. [14] B. Ramamurthy, V.C. Anguli, C.G. Iyer, A case of intramedullary neurinoma, J. Neurol. Neurosurg. Psychiatry 21 (1958) 92–94. [15] W. McCormick, Intramedullary spinal cord schwannoma. A unique case, Arch. Pathol. 77 (1964) 378–382. [16] D. Russel, L. Rubinstein (Eds.) Pathology of tumors of the nervous system, third ed., Edward Arnold, London, 1971.
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Appendix A. Supplementary data Supplementary data to this article can be found online at https:// doi.org/10.1016/j.inat.2019.100621. References [1] P. Herregodts, M. Vloeberghs, E. Schmedding, et al., Solitary dorsal intramedullary schwannoma. Case report, J. Neurosurg. 74 (1991) 816–820. [2] D.A. Ross, M.S. Edwards, C.B. Wilson, Intra – medullary neurilemomas of the spinal cord: report of two cases and review of the literature, Neurosurgery 19 (1986) 458–464. [3] R. Sharma, S.C. Tandon, S. Mohanty, S. Gupta, Intramedullary neurofibroma of the cervical spinal cord: case report with review of the literature, Neurosurgery 15
5
Contents lists available at ScienceDirect
Interdisciplinary Neurosurgery journal homepage: www.elsevier.com/locate/inat
Case Reports & Case Series
Extensive intramedullary schwannoma of the sub-axial cervical spine – A case report
T
⁎
Adrian Kellya, , Patrick Lekgwaraa, Aftab Younusb a b
Department of Neurosurgery, Dr George Mukhari Academic Hospital, Sefako Makgatho Health Sciences University, Pretoria, South Africa Department of Orthopedics, Helen Joseph Hospital, University of the Witwatersrand, Johannesburg, South Africa
A B S T R A C T
Spinal schwannomas originate from Schwann cells and as a group represent 30% of spinal cord tumors. These lesions are commonly intra-dural extramedullary in location and in fact purely intramedullary schwannomas of the spinal cord represent only 1.1% of spinal schwannomas. Almost all of these occur in patients with Neurofibromatosis. Approximately 50 cases of intramedullary schwannomas not related to neurofibromatosis have been described to date. This case report gives an account of a young male patient with no family history nor clinical signs of Neurofibromatosis whom presented to out institution with an extensive schwannoma of his sub-axial cervical spinal cord extending from C4-T2. Neurological examination of his upper limbs on manual muscle testing revealed normal shoulder and elbow power 5/5, weakness of wrist dorsiflexion 3/5 and wasting of his intrinsic hand muscles bilaterally also with power 3/5. His lower limb examination revealed an incomplete T4 sensory level with preserved sensation and on manual muscle testing no motor function 0/5 was present. Under neurophysiological monitoring he was taken to theatre where the intra-operative finding of the schwannoma being subpial and intramedullary was confirmed. A gross total resection was achieved and post operatively his upper limb function showed no deterioration and his lower limb function showed improvement. This case report gives an account of a young male patient whom presented to our department with an extensive intramedullary schwannoma of his cervical spine extending from C4-T2. The surgical management resulted in clinical improvement and prevented ascending motor weakness.
1. Introduction Spinal schwannomas originate from Schwann cells and as a group represent 30% of spinal cord tumors [1]. These lesions are commonly intradural extramedullary in location and in fact purely intramedullary schwannomas of the spinal cord represent only 1.1% of spinal schwannomas [2]. Most of these occur in patients with Neurofibromatosis [2,3]. Approximately 50 cases of intramedullary schwannomas not related to neurofibromatosis have been described to date [4]. This case report gives an account of a young male patient with no family history nor clinical signs of neurofibromatosis whom presented to our institution with a purely intramedullary schwannoma of his cervical spinal cord extending from C4-T2. 2. Case description A 43 year old male presented to the Neurosurgical out-patient department at our institution complaining of progressive lower limb weakness of 18 months duration. He reported being unable to walk for the last 6 months. What had brought him to the hospital was that 3 months ago he had begun to notice that his hands were becoming weak and he was concerned. He reported no bladder nor bowel
symptoms. The patient was tested and found to be HIV negative and had no other medical problems nor any family history of Neurofibromatosis. He denied any history of loss of weight, night sweats nor fever. General examination revealed no signs of Neurofibromatosis. Neurological examination of his upper limbs by means of manual muscle testing revealed normal shoulder and elbow power 5/5 to be present in all muscle groups. His wrists had normal power with regards flexion 5/5 but bilateral weakness of wrist dorsiflexion 3/5 was demonstrated. His intrinsic hand muscles were wasted and bilaterally intrinsic hand muscle power was assessed to be 3/5. His lower limb examination revealed an incomplete T4 sensory level and on manual muscle testing no motor function 0/5 was present. An urgent MRI of his spine was requested which revealed an extensive intramedullary lesion of his cervical spine extending from C4-T2 with associated syringohydromyelia. The lesion was heterogeneous in appearance with a distinct boundary visible between it and the adjacent spinal cord tissue. The lesion was iso/hypo-intense on T1 and vividly hyper-intense on T2 imaging (Figs. 1–4). The lesion did not suppress on the T2 fat suppression MRI. There was no associated bony nor soft tissue abnormalities visible. An MRA excluded anomalies in the course of the vertebral arteries.
⁎ Corresponding author at: Department of Neurosurgery, 3rd floor Sciences Building, Sefako Makgatho Health Sciences University, Garankuwa, Pretoria, South Africa. E-mail address: [email protected] (A. Kelly).
https://doi.org/10.1016/j.inat.2019.100621 Received 25 February 2019; Received in revised form 23 October 2019; Accepted 26 October 2019 2214-7519/ © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/).
Interdisciplinary Neurosurgery 19 (2020) 100621
A. Kelly, et al.
Fig. 1. Pre-operative MRI T1W sagittal: Lesion is iso/hypointense and hardly visible extending from C4 (red arrow) to T2 (blue arrow). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 3. Pre-operative MRI T2W axial: intramedullary hyper-intense lesion with distinct boundaries.
Fig. 2. Pre-operative MRI T2 sagittal: Lesion is vividly hyper-intense extending from C4 (red arrow) to T2 (blue arrow). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 4. Pre-operative MRI T2W axial (additional view): again the intramedullary hyper-intense lesion with distinct boundaries.
presenting surface of the tumoral tissue provided a generous surgical corridor by which to internally decompress the lesion. Once the lesion was internally decompressed the remaining rim of tumoral tissue at the tumoral-neural interface separated easily. There was minimal bleeding from the tumor and the removed specimen had a fatty appearance (Fig. 6). Once resected a duroplasty was performed. No fusion was performed in this adult patient due to the long segment involved however would be re-discussed in the event of the development of post laminectomy kyphosis. The wound was closed in layers and the patient was transferred to ICU. Post operatively the patient reported improvement in lower limb sensation bilaterally however in the early post-operative period the power in his lower limbs on manual muscle testing remained unchanged 0/5. A post-operative MRI showed complete resection of the lesion had been achieved (Fig. 7). The histology result reported palisading cells in a vaguely organoid
Due to the patient being myelopathic with deteriorating neurology he was urgently booked for a resection of this lesion from a posterior approach. Neuro-monitoring was used as is mandatory for an intramedullary tumor resection. The patient was taken to theatre as an urgent case and a midline posterior neck incision was performed. The midline raphe was divided in the avascular plane and a sub periosteal dissection was achieved to expose the cervical laminae from C3-T4. Once exposed wide laminectomies, preserving the facets, were performed from C4-T2 and the dura exposed. A midline durotomy was performed spanning both the cephalad and caudal poles of the tumor. Upon opening the dura the tumor was immediately visible deep to the pia mater at the dorsal surface of the cervical spinal cord (Fig. 5). Upon opening of the pia mater the
2
Interdisciplinary Neurosurgery 19 (2020) 100621
A. Kelly, et al.
Fig. 7. Post-operative MRI T2W sagittal: edematous spinal cord demonstrated with gross total resection of the tumor achieved noted by the complete absence of the vividly hyper-intense lesion as seen on pre-operative imaging.
Fig. 5. Intra-operative photo: generous presentation of the tumor beneath the pia mater at the dorsal surface of the spinal cord.
Fig. 6. Intra-operative photograph: tumor specimen on a sterile drape.
pattern. Verocay bodies were visualized. Parts of the lesion were cystic and the stroma was loosely myxoid in places with fibrous areas in others. Thick walled blood vessels were seen with evidence of previous hemorrhage. S-100 staining was strongly positive and EMA staining was negative. The histology result reported the lesion to be a schwannoma (Figs. 8 and 9). At his 3 month review the patient was carefully examined for any improvement in his lower limb motor function. What was noted on manual muscle testing was that the power in his upper limbs was preserved and that his right ankle had improved dorsiflexion to 2/5 and the flexion in his right big toe was 1/5 (Fig. 10). The patient is for ongoing review in the Neuro-spine out-patient clinic.
Fig. 8. Histology: showing Antoni B area on H&E stain.
intramedullary tumors occurring in the sub-axial cervical spine the most commonly diagnosed is a diffuse fibrillary astrocytoma. Ependymoma’s are less commonly seen at this site and infrequently seen intra-medullary tumors diagnoses are epidermoids; teratomas; hemangioblastomas and lipomas. Rare lesions seen are intramedullary dermoid cysts and intramedullary schwannomas [5]. With regards primary intradural extramedullary lesions of the cervical spine the commonest are nerve sheath tumors namely schwannomas and neurofibromas however rarely meningiomas do occur [6]. In terms of pre-operative diagnoses a study by Takemoto 1988 noted MRI to be able to reliably differentiate schwannomas from meningiomas and hemangioblastomas based on imaging characteristics and location. This study concerned itself with extra-medullary spinal
3. Discussion In terms of affording a comprehensive differential diagnosis of 3
Interdisciplinary Neurosurgery 19 (2020) 100621
A. Kelly, et al.
(63%) of cases, while 26% occur in the thoracic spine [7]. On imaging these lesions are heterogeneous in appearance and are hypo/isointense on T1-weighted sequences and generally hyper intense on T2-weighted sequences. When gadolinium is injected there is a heterogeneous enhancement [10]. Predicting an intramedullary schwannoma purely on radiological grounds is however extremely difficult due to the rarity of these lesions. Misdiagnosis as a classical heterogeneously enhancing astrocytoma would be likely. Pre-operative radiological differentiation of a purely intramedullary schwannoma from the more commonly seen extramedullary schwannoma may be suspected by gross tumor morphology. The classical extramedullary schwannoma typically demonstrates dural and/or intervertebral foraminal constriction as it proliferates along the length of the involved nerve root. Regarding intramedullary schwannomas these barriers to growth and therefore classical dumb-bell appearance is not seen. Histologically schwannomas are comprised of Antoni A cell type area comprising compact cells in a reticular framework, and Antoni B cell type areas comprising large cells in a loose collagenous background [12] Attempting to apply the classification of Antoni to the MRI findings is not possible [8]. The WHO classifies schwannomas into cellular, plexiform and melanotic however does not differentiate these lesions based on location. With regards intramedullary schwannomas although they are often found with discrete edges enabling gross total resection, as was our case, an infiltrative pattern does occasionally occur making gross total resection impossible and there is a role for the use of radiotherapy in these incompletely resected lesions [7]. The controversial question about spinal intramedullary schwannomas emerges from their unknown pathogenesis. Due to the central nervous system containing no Schwann cells their presence at this location has stimulated intense debate regarding their cell of origin. Several theories have been proposed; As early as 1957 Riggs et al. proposed that these lesions could originate from Schwann cell proliferation from naturally occurring Schwann cells associated with the nerve fibers of spinal arteries [13] Ramamurthy et al suggested that ectopic Schwann cells originating from the embryonic neural tube (fourth week of gestation) are the origin of these lesions [14]. McCormick and Wood, in the 1960’s, theorized that intramedullary schwannomas originate from aberrant Schwann cells within intra-medullary medullary nerve fibers, specifically related to the posterior roots [15]. Russell and Rubenstein, in 1971, challenged these earlier theories and proposed the most widely accepted theory that still holds its ground today. They proposed that these tumors are the result of cellular transformation of neuroectodermal pial cells into Schwann cells. This accounts for not only the origin of intra-medullary schwannomas but also explains their neoplastic growth [16]. While dural and/or forminal constriction allows some degrees of pre-operative differentiation between the extramedullary and purely intramedullary schwannoma subtypes, definitive confirmation is often only done intra-operatively where the former is found to be deep to the pia mater which must be opened to gain access to the tumoral tissue. This contrasts the finding in classical extramedullary schwannomas where the pia does not have to be opened and the tumor is immediately accessible upon opening the dura.
Fig. 9. Histology: S-100 staining was strongly positive.
Fig. 10. Post-operative patient photo: Showing preserved shoulder and elbow function on manual muscle testing. Hand function did not improve in the immediate post-operative period.
tumors [8]. With regards differentiating intramedullary spinal tumors based on pre-operative radiographic features one paper noted that the length of involvement, location along the cord and enhancement pattern similarly allows some degree of pre-operative differentiation between the intramedullary tumor types to be made. In this paper astrocytomas for example are noted to occur more commonly in the thoracic spinal cord, to involve 4–7 vertebral bodies in length, and to demonstrate heterogenous enhancement. Intramedullary ependymomas on the other hand are noted to occur more commonly in the cervical spinal cord and to demonstrate solid homogenous enhancement [9]. Intramedullary spinal schwannomas occur most commonly in patients in the 4th decade of life and have a male to female ratio of 3:1. In terms of distribution they occur most commonly in the cervical spine
4. Conclusion This case report gives an account of a young male patient whom presented to our department with an extensive intramedullary schwannoma of his cervical spine extending from C4-T2. The surgical management resulted in clinical improvement and prevented ascending motor weakness that could have occurred with ongoing growth and cord compression by the tumor.
4
Interdisciplinary Neurosurgery 19 (2020) 100621
A. Kelly, et al.
Declaration of Competing Interest
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