SURGICAL OUTCOME OF CERVICAL CORD TUMORS

Document Type : Original Article

Authors

Neurosurgery Department, Faculty of Medicine, Al-Azhar University

Abstract

Background: Spinal cord tumors represent 10% to 15% of central nervous system (CNS) neoplasms. In adults, two thirds of these tumors are extra medullary and the remaining third are intramedullary.
Objective: To outline the final outcome of cervical cord tumor surgeries.
Patients and Methods: This was a study over a period of two years from January 2018 to January 2020 at Al-AzharUniversityHospital and EldoahHospital of 30 patients with cervical cord tumors with primary or secondary origin subjected to surgery and follow up of patients, the neurological status before surgery and immediate post-operative examination were assessed.
Results: Surgical morbidities were significant more frequent in unimproved patients. There was a significant correlation between the pre-operative state and the final functional outcome.  The better the preoperative state the better was the outcome.
Conclusion: The cervical cord tumors can be treated safely and effectively by surgery. Total resection was the essential aim before surgery. Preoperative neurological state, pathological type, pathological grades, and degree of resection were the most important factors that affect the final outcome.

Keywords

Main Subjects


SURGICAL OUTCOME OF CERVICAL CORD TUMORS

By

Ramadan Abd El-Aziz Ramadan, Abd El-Kafy Sharf El-Deen Ibrahim and Mohammed Hasan Mansour

Neurosurgery Department, Faculty of Medicine, Al-AzharUniversity

Corresponding Author: Ramadan Abd El-Aziz Ramadan

Phone No.: (+2) 01061481034

E-mail: ramadanaboelnasr2020@gmail.com

ABSTRACT

Background: Spinal cord tumors represent 10% to 15% of central nervous system (CNS) neoplasms. In adults, two thirds of these tumors are extra medullary and the remaining third are intramedullary.

Objective: To outline the final outcome of cervical cord tumor surgeries.

Patients and Methods: This was a study over a period of two years from January 2018 to January 2020 at Al-AzharUniversityHospital and EldoahHospital of 30 patients with cervical cord tumors with primary or secondary origin subjected to surgery and follow up of patients, the neurological status before surgery and immediate post-operative examination were assessed.

Results: Surgical morbidities were significant more frequent in unimproved patients. There was a significant correlation between the pre-operative state and the final functional outcome.  The better the preoperative state the better was the outcome.

Conclusion: The cervical cord tumors can be treated safely and effectively by surgery. Total resection was the essential aim before surgery. Preoperative neurological state, pathological type, pathological grades, and degree of resection were the most important factors that affect the final outcome.

Key words: Surgical Outcome, Cervical Cord Tumors.

 

 

INTRODUCTION

     Primary spinal cord tumors are 10 times less common than their cranial counterparts, although they are histopathologically similar. Spine tumors are historically classified as extradural, intradural extramedullary, and intramedullary. Extradural tumors are the most common spinal tumors, are usually of metastatic origin. Gliomas make up 80% of all intramedullary tumors. Metastatic intramedullary tumors are rare but present in 2% of all intramedullary tumors (Ahmed et al., 2014).

     Presenting signs and symptoms vary depening on the spinal levels involved, but typically include pain, sensory changes, motor weakness, ataxia, and autonomic dysfunction. Various scales such as the modified McCormick scale, have been used to grade pre- and postoperative functional status (Treadway, 2014).

     The treatment goal is gross total resection (GTR) where possible while minimizing neurological injury. Low-grade astrocytoma in particular has been reported to have excellent results with gross total resection, although the evidence for surgery in higher-grade tumors remains controversial (Bostrom et al., 2014).

     Many variables influence the prognosis of cord tumor, but the most predictive of these variables is tumor histology. Histology is often predictive of resectability of a tumor which, in turn, impacts the relationship between the extent of surgical resection and the risk of tumor recurrence (Sung et al., 2013).

     The aim of this study was to evaluate surgical outcome of cervical cord tumor.

PATIENTS AND METHODS

     The study had been carried out at Al-AzharUniversityHospital and EldoahHospital, over a period of two years from January 2018 to January 2020 of patients with cervical cord tumors subjected to surgery and follow up of patients.

Inclusion criteria: Patients with cervical cord tumors with primary or secondary origin.

Exclusion criteria: Cases with vertebral bony tumors without cord compression and cases with vascular lesion in cord.

     Patients had been subjected to general clinical and radiological examination.

     All patients included gave written consents to be eligible in the study.

Pre-operative neurologic state: Initial presenting symptoms and extend of tumor resection were reviewed to analyze prognostic factors.

     Initial presenting symptoms were divided into pain, sensory change and motor weakness.

     Extent of tumor removals was classified as total resection (TR) and subtotal resection (STR). The TR was defined as complete removal of tumor by microscopic surgical finding and postoperative MRI finding. All patients had taken magnetic resonance imaging (MRI) pre- and post-operatively. The patients have undergone standard microscopic operations using posterior approach.

     Preoperative assessment was according to Karnofsky performance scale index (KPS) (Péus et al. 2013), and modified Mc Cormick scale (Schneider et al., 2013).

     Post-operative improvement assessment was for Spasticity, hyperreflexia, positive, hoffman’s sign, neck pain, limb weakness, limb paresthesia and gait imbalance.

     Surgical morbidity and mortality was for CSF leak, lower CN deficit, quadriparesis, hemiparesis, paraplegia, hemiplegia.

Administrative considerations: An Official permission was obtained from Al-AzhahrUniversityHospital and EldoahHospital. An official permission was obtained from the Ethical Committee of Faculty of Medicine.

Statistical Analysis: Data entry, processing and statistical analysis was carried out using using SPSS version 20(Statistical Package for the Social Sciences). Data were presented as frequcency and percentage and compared by Chi square test. P less than 0.05 was considered significant.

 

RESULTS

 

 

     The majority of the patients aged 31-40 years and regarding sex, 14 (46.66%) of patients were males, and 16 (53.33%) were females.

 

 

Table (1):   Demographic distribution of the all patients

All patients

Parameters

(n=30)

N

%

Age (years)

0 – 10

0

0

21 – 30

2

6.66

31 – 40

14

46.66

41 – 50

8

26.66

51 – 60

2

6.66

61 – 70

4

13.33

Sex

Male

14

46.66

 

 

     Regarding tumor type, meningioma was the most prevalent type by 73.33%. The majority of the patients 66.66% had total resection and partial resection was done in 33.33% of patients.

 

 

Table (2):   Tumor types and resection grade in all patients

All patients

Parameters

(n=30)

No

%

Tumor type

Astrocytoma

4

13.33

Ependymoma

4

13.33

Meningioma

22

73.33

Other

0

0

Resection grade

Total resection

20

66.66

Partial resection

10

33.33

Biopsy

0

0

 

     Twenty-two patients (73.3%) improved postoperatively.

 

Table (3):   Postoperative improvement status of the studied patients

All patients

parameter

(n=30)

Postoperative

Improvement

Yes

22

73.33

No

8

26.66

 

 

 

 

 

 

 

 

     Preoperative assessment parameters of the studied patients showed that limb weakness was the most parameters to be presented with 73.33% of cases, followed by dysthesia (66.66%), neck pain (60%), hyperreflexia (53.33%), and occipital headache (53.33%). The least presentation was incontinence (6.66%), then spastisity (13.33%).

 

 

Table (4):   Preoperative assessment parameters of the studied patients

All patients

Parameters

(n=30)

N

%

Spasticity

4

13.33

Hyperreflexia

16

53.33

Positive Babinski sign

8

26.66

Positive Hoffman’s sign

8

26.66

Neck pain

18

60

Urinary/stool incontinence

2

6.66

Limb weakness

22

73.33

Dysesthesia

20

66.66

Gait imbalance

8

26.66

Occipital headache

16

53.33

 

 

     There were no complications in 20 (about 66.66%) of cases, while dysthesia and quadriparesis were 6 (20%). The least complication was paraplegia with 4 (13.33%) cases and death in only one case.

 

 

Table (5):   Postoperative complication of the studied patients

All patients

Parameters

(n=30)

N

%

No complications

20

66.66

CSF leak

0

0

Dysthesia

6

20

Quadriparesis

6

20

Paraplegia

4

13.33

Death

1

3.33

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

     There was a statistically significant relation between improvement with age (41-50) with P-value= 0.046, while there was no statistically significant relation between improvement and sex.

 

 

Table (6):   Demographic data of the studied patients according to improvement status

Cases

Parameters

Improved

(n=22)

Not Improved

(n=8)

P-value

Age

(years)

0 – 10 (n=0)

0 (0.0%)

0 (0.0%)

0 (0.0%)

21 – 30 (n=2)

2 (9.1%)

0 (0.0%)

0.377

31 – 40 (n=14)

8 (36.4%)

6 (75%)

0.061

41 – 50 (n=8)

8 (36.4%)

0 (0.0%)

0.046

51 – 60 (n=2)

2 (9.1%)

0 (0.0%)

0.377

61 – 70 (n=4)

2 (9.1%)

2 (25%)

0.257

Sex

Male (n=14)

10 (45.5%)

4 (50%)

0.825

Female (n=16)

12 (54.5%)

4 (50%)

 

 

     There was a statistically significant relation between improvement with tumor type, spasticity, positive Hoffman’s sign, gait imbalance, hyperreflexia, and Limb weakness.

 

 

Table (7):   Clinical data of the studied patients according to improvement status

Cases

Parameters

Improvement

(n=22)

Not Improvement (n=8)

P-value

Tumor Type

Astrocytoma (n=4)

0 (0.0%)

4 (50%)

<0.001

Ependymoma (n=4)

0 (0.0%)

4 (50%)

<0.001

Meningioma (n=22)

22 (100%)

0 (0.0%)

<0.001

Other (n=0)

0 (0.0%)

0 (0.0%)

NA

Resection grade

Total resection (n=20)

15 (68.2%)

5 (62.5%)

0.771

Partial resection (n=10)

7 (31.8%)

3 (37.5%)

Spasticity

0 (0.0%)

4 (50%)

<0.001

Hyperreflexia

8 (36.4%)

8 (100%)

0.002

Positive Hoffman’s sign

2 (9.1%)

6 (75%)

<0.001

Neck pain

14 (63.6%)

4 (50%)

0.500

Limb weakness

14 (63.6%)

8 (100%)

0.046

Dysthesia

14 (63.6%)

6 (75%)

0.559

Gait imbalance

2 (9.1%)

6 (75%)

<0.001

 

 

 

 

 

 

 

 

 

 

 

     There was a statistically significant relation between improvement with paraplegia and quadriparesis.

 

 

Table (8):   Surgical morbidity incidences of the studied patients according to improvement status

Cases

Parameters

Improvement

(n=22)

Not Improvement

(n=8)

P-value

Quadriparesis

2 (9.1%)

4 (50%)

0.013

Paraplegia

0 (0.0%)

4 (50%)

<0.001

 

 

DISCUSSION

     Early clinical manifestations of cervical cord tumors are often untypical nerve root stimulation and compression symptoms, which are easily misdiagnosed as occipital neuralgia, cervical spondylosis, or scapulohumeral periarthritis, among others. However, some patients are not diagnosed until experiencing limb paralysis and bowel dysfunction. Sensory disturbances are the most common symptom during the course of progression, which can be characterized by the numbness of limbs, occipital or facial area, chills, girdle sensation and unstable walking. Furthermore, such tumors can oppress the medulla oblongata structure and cause severe respiratory dysfunction compared with spinal cord tumors at other place, cervical spinal cord tumors make for more serious neurological deficits and surgical challenges. The severe extremity movement and respiration deterioration can threaten life. Operative results improve significantly owing to developments of radiological diagnosis technology and advances of microneurosurgical operations Wang et al. (2018).

     In our study, as regard demographic distribution of the all patients, the majority of the patients aged 41 - 50 years and regarding sex, 47% of patients were males and 53% were females.

     In the study of Babu et al. (2014), to study Surgical outcome of cervical and intra medullary tumors, the mean age of patients was 42.6±8.42 years and male: female ratio was 54%: 46%.

     In the study of Wahdan et al. (2014), prognostic factors of surgery for Cervical Cord Tumors, there were 38 males and 23 females with a percentage of 62.3 and 37.7 respectively.

     In our study, as regarding preoperative assessment parameters of the studied patients, limb weakness was the most parameter to be presented with 73 % of cases, followed by dysthesia (66%), neck pain (60%), hyperreflexia (53%), and occipital headache (53%). The least presentation was incontinence (7%), then spasticity (13%).

     In the study of Fathy et al. (2019), the most common presenting symptom was back pain (87.5%), followed by sensory changes (56.25%) and then motor weakness (n = 6, 37.5%).

     In the study of Bansal et al. (2013) pain was the most frequent sensory symptom (50.7%). Urinary incontinence was the most common autonomic symptom (31%) there was no difference in symptomatology among patients with different tumor types as pain and weakness were most common symptoms in all tumor groups.

     In our study, regarding tumor type, meningioma was the most prevalent type by 73.3%. The majority of the patients (67%) had total resection and partial resection was done in 33% of patients.

     In the study of Wang et al. (2018), the neurilemmoma (also known as schwannoma) was the most common type (45.10%), followed by, meningioma (11.76%), neurofibroma (11.76%), ganglion cell neurofibroma (11.76%), hemangioma (5.88%), ependymoma (WHO grade I) (3.92%), Astrocytoma (WHO grade II) (3.92%), and 2% others. total resection in 52.94% and partial resection in 47.06% patients.

     In the study of Jaiswal and Mittal (2014) the most frequent tumour was ependymoma (41.5%) and followed by astrocytoma (30.1%).

     In the study of Bakhshi et al. (2016), the most common histological diagnosis was ependymoma (60%) and GTR in 30 patients (69.8%).

     In our study, as regarding to improvement and non-improvement of the studied patient’s post-operative, 73.3% improved postoperatively, while 26.7% didn’t improve.

     In the study of Boström et al. (2014), to study outcome in adult intramedullary spinal cord tumors, the proportion of localization in cervical region was 33%. Surgery-related morbidity with worsening postoperative symptoms occurred immediately 18.6%.

     In the study of Lee et al. (2014), the neurological states at last follow-up were improved in 23.2%, unchanged in 47 (68.1%), aggravated in 6 (8.7%). In all patients, the functional outcomes were good in 75.4%, fair in 10 (14.5%) and poor in 7 (10.1%)

     In our study, as regarding surgical morbidity and mortality incidences of the studied patients, there were no complications in about 66% of cases while dysthesia and quadriparesis were 20% cases each. The least complication was paraplegia 13% of cases and death in only one case.

     In the study of Fathy et al. (2019), Common complications were cerebrospinal fluid leak occurred in two cases, in which dural grafts were used, post-operative hematoma in one case, tumor recurrence in two cases at last follow-up, and UTI in one case.

     In the study of Xiao et al. (2015), postoperative Surgical site infection (16%) and syrinx formation (16%) were the most common complications then cerebrospinal fluid leak (11%), deep vein thrombosis (11%) and epidural hematoma (4%).

     In our study, as regarding regression analysis of the improvement status between improvement and non-improvement groups, No significant difference between the groups regarding Demographic data, Clinical data. But surgical morbidities were significant more frequent in unimproved patients.

     In the study of Wahdan et al., (2014), the pathological type of the tumor was strongly correlated with significant value to the outcome and good postoperative state of the patient. Best outcome was with extramedullary tumours specially neurofibroma and meningioma (patients improved 83% for both) followed by Schwannoma with 69%, then intramedullary tumors like ependymoma 36% and astrocytoma 33.4%.

     In the study Zhixu et al. (2017), this study showed that good postoperative outcomes achieved in the majority of patients undergoing intradural spinal tumor excision, with 92% of patients reporting improved neurologic outcomes post-surgery.  Also showed that complete excision of the tumor is associated with improved outcomes.

CONCLUSION

     Surgical management of cervical cord tumors markedly improved, but deterioration and complication rates were still high.

REFERENCES

  1. Ahmed R, Menezes AH and Awe OO (2014): Long-term disease and neurological outcomes in patients with pediatric intramedullary spinal cord tumors. J Neurosurg Pediatric, 13(6):600–612
  2. Babu BK, Narayan PD, Ravindra B, Panigrahi M, Saradhi MV, Mohan PR and Buchineni M (2014): Surgical outcome of cervical and foramen magnum intra dural and intra medullary tumours. Journal of Evolution of Medical and Dental Sciences, 3(74):15469-76.
  3. Bakhshi SK, Waqas M, Shakaib B and Enam SA (2016): Management and outcomes of intramedullary spinal cord tumors: A single center experience from a developing country. Surgical Neurology International, 7: S617-22.
  4. Bansal S., Ailawadhi P., Suri A., Kale S, Chandra S., Singh M., Kumar R., Bhawani S., Mahapatra A., Mehar C., Sarkar C., Bithal P., Gaikwad S. and Mishra A. (2013): Ten years’ experience in the management of spinal intramedullary tumors in a single institution. Journal of Clinical Neuroscience, 20: 292–8.
  5. Boström A, Kanther NC, Grote A and Boström J (2014): Management and outcome in adult intramedullary spinal cord tumours: a 20-year single institution experience. BMC Research notes, 7:908-16.
  6. Fathy M, Keshk M and El Sherif A. (2019): Surgical management and outcome of intramedullary spinal cord tumour. Egyptian Journal of Neurosurgery, 34:2-8.
  7. Jaiswal M. and Mittal R. (2014): Outcome of operative intervention in intramedullaryspinal cord tumours. Romanian Neurosurgery XXI, 3: 283–91.
  8. Lee SM, Cho YE and Kwon YM (2014): Neurological outcome after surgical treatment of intramedullary spinal cord tumors. Korean Journal of Spine, 11(3):121-6.
  9. Péus D, Newcomb N and Hofer S (2013): Appraisal of the Karnofsky Performance Status and proposal of a simple algorithmic system for its evaluation. BMC Medical Informatics and Decision Making, 13(1):1-7.
  10. Schneider C, Hidalgo ET, Schmitt-Mechelke T and Kothbauer KF (2013): Quality of life after surgical treatment of primary intramedullary spinal cord tumors in children. Journal of Neurosurgery: Pediatrics, 13(2):170-7.
  11. Sung WS, Sung MJ and Chan JH (2013): Intramedullary spinal cord metastases: a 20-year institutional experience with a comprehensive literature review. World Neurosurgery, 79(3, 4):576–84.
  12. Treadway TL. (2014): Minimally invasive approaches for the treatment of intramedullary spinal tumors. Neurosurg Clin N Am., 25:327–36.
  13. Wahdan M., El-Noss F., Maaty H., Badawy W. and  Farag A.(2014): Prognostic Factors of Surgery for Cervical Cord Tumors. Egyptian Journal of Neurosurgery, 29 (3): 29-38.
  14. Wang X, Gao J, Wang T, Li Z and Li Y (2018): The Long-term Outcome After Resection of Upper Cervical Spinal Cord Tumors: Report of 51 Consecutive Cases. Scientific Reports, 8(1):1-7.
  15. Xiao R, Jacob A., Kalil G., Lubelski D., Thomas E. and Benzel E. (2016): Quality of Life Outcomes Following Resection of Adult Intramedullary Spinal Cord Tumors. Neurosurgery, 78:821–8.
  16. Zhixu Ng, Sheryl Ng, Vincent Nga, Kejia Teo, Sein Lwin, Chou Ning and Tseng T. (2017): Intradural Spinal Tumors—Review of Postoperative Outcomes Comparing Intramedullary and Extramedullary Tumors from a Single Institution’s Experience. World Neurosurgery, 09:143-7.

 

تقييم العلاج الجراحي لأورام الحبل الشوكى العنقي

رمضان عبدالعزيز رمضان، عبدالكافي شرف الدين إبراهيم، محمد حسن منصور

قسم جراحة المخ والأعصاب، كلية الطب، جامعة الأزهر

هاتف محمول: 01061481034

البريد الإلكتروني:ramadanaboelnasr2020@gmail.com

خلفية البحث: أورام الحبل الشوكى تمثل 10% الي15% من أورام الجهاز العصبي المركزى وثلثي هذة الأورام تكون داخل الأم الجافية خارج نخاع الحبل الشوكي والثلث الأخر في نخاع الحبل الشوكي.

الهدف من البحث: تقييم النتيجة الجراحية لأورام الحبل الشوكي العنقي.

المرضي وطرق البحث: هذه دراسة على مدى عامين من شهر يناير 2018 الي شهر يناير 2020 في مستشفييات جامعة الأزهر ومستشفي الدعاة علي ثلاثين من المرضي اللذين يعانون من أورام الحبل الشوكي العنقي من أورم أولية أو ثانوية وخضعوا لعملية جراحية وتمت متابعة المرضى بعد الجراحة وكان قد تم إستبعاد المرضي اللذين يعانون من أورام الفقرات العنقية أو الوحمات الشريانية.

نتائج البحث: كانت المراضة الجراحية أكثر حدوثا في المرضي اللذين لم يتحسنوا بعد الجراحة و وجدت علاقة قوية بين الحالة الوظيفية للمرضي قبل الجراحة والتقييم النهائي للمرضي بعد الجراحة حيث كان من هو حالته أفضل وظيفيا قبل الجراحة كان هو أفضل تحسنا بعد الجراحة.

الإستنتاج: العلاج الجراحي لأورام الحبل الشوكي أصبح جيدا وأكثر فاعلية كانت أكثر العوامل التى أثرت علي التقييم النهائي للمرضي بعد الجراحة هي حالة المريض الوظيفية العصبية قبل الجراحة ونوع ودرجة التحليل النسيجي للورم ودرجة استئصال الورم اثناء الجراحة.

الكلمات الدالة: التقييم الجراحي، أورام الحبل الشوكي.

  1. REFERENCES

    1. Ahmed R, Menezes AH and Awe OO (2014): Long-term disease and neurological outcomes in patients with pediatric intramedullary spinal cord tumors. J Neurosurg Pediatric, 13(6):600–612
    2. Babu BK, Narayan PD, Ravindra B, Panigrahi M, Saradhi MV, Mohan PR and Buchineni M (2014): Surgical outcome of cervical and foramen magnum intra dural and intra medullary tumours. Journal of Evolution of Medical and Dental Sciences, 3(74):15469-76.
    3. Bakhshi SK, Waqas M, Shakaib B and Enam SA (2016): Management and outcomes of intramedullary spinal cord tumors: A single center experience from a developing country. Surgical Neurology International, 7: S617-22.
    4. Bansal S., Ailawadhi P., Suri A., Kale S, Chandra S., Singh M., Kumar R., Bhawani S., Mahapatra A., Mehar C., Sarkar C., Bithal P., Gaikwad S. and Mishra A. (2013): Ten years’ experience in the management of spinal intramedullary tumors in a single institution. Journal of Clinical Neuroscience, 20: 292–8.
    5. Boström A, Kanther NC, Grote A and Boström J (2014): Management and outcome in adult intramedullary spinal cord tumours: a 20-year single institution experience. BMC Research notes, 7:908-16.
    6. Fathy M, Keshk M and El Sherif A. (2019): Surgical management and outcome of intramedullary spinal cord tumour. Egyptian Journal of Neurosurgery, 34:2-8.
    7. Jaiswal M. and Mittal R. (2014): Outcome of operative intervention in intramedullaryspinal cord tumours. Romanian Neurosurgery XXI, 3: 283–91.
    8. Lee SM, Cho YE and Kwon YM (2014): Neurological outcome after surgical treatment of intramedullary spinal cord tumors. Korean Journal of Spine, 11(3):121-6.
    9. Péus D, Newcomb N and Hofer S (2013): Appraisal of the Karnofsky Performance Status and proposal of a simple algorithmic system for its evaluation. BMC Medical Informatics and Decision Making, 13(1):1-7.
    10. Schneider C, Hidalgo ET, Schmitt-Mechelke T and Kothbauer KF (2013): Quality of life after surgical treatment of primary intramedullary spinal cord tumors in children. Journal of Neurosurgery: Pediatrics, 13(2):170-7.
    11. Sung WS, Sung MJ and Chan JH (2013): Intramedullary spinal cord metastases: a 20-year institutional experience with a comprehensive literature review. World Neurosurgery, 79(3, 4):576–84.
    12. Treadway TL. (2014): Minimally invasive approaches for the treatment of intramedullary spinal tumors. Neurosurg Clin N Am., 25:327–36.
    13. Wahdan M., El-Noss F., Maaty H., Badawy W. and  Farag A.(2014): Prognostic Factors of Surgery for Cervical Cord Tumors. Egyptian Journal of Neurosurgery, 29 (3): 29-38.
    14. Wang X, Gao J, Wang T, Li Z and Li Y (2018): The Long-term Outcome After Resection of Upper Cervical Spinal Cord Tumors: Report of 51 Consecutive Cases. Scientific Reports, 8(1):1-7.
    15. Xiao R, Jacob A., Kalil G., Lubelski D., Thomas E. and Benzel E. (2016): Quality of Life Outcomes Following Resection of Adult Intramedullary Spinal Cord Tumors. Neurosurgery, 78:821–8.
    16. Zhixu Ng, Sheryl Ng, Vincent Nga, Kejia Teo, Sein Lwin, Chou Ning and Tseng T. (2017): Intradural Spinal Tumors—Review of Postoperative Outcomes Comparing Intramedullary and Extramedullary Tumors from a Single Institution’s Experience. World Neurosurgery, 09:143-7.