INTRODUCTION

 

Meningiomas are primary and the second most common type of benign tumors of central nervous system derived from arachnoidal (meningothelial) cells. The annual incidence is approximately 2.3 to 6 per 100,000 persons at age between the 5^th and 7^th decade with female predominance. According to World Health Organization (WHO), Meningiomas are classified into three grades: benign (Grade I), atypical (Grade II), and malignant (Grade III) based on the degree of anaplasia, number of mitoses, and presence of necrosis. Grade I, II and III meningiomas account for approximately 80%, 5% to 20%, and 1% to 2% of all meningiomas, respectively. Further classification is possible based on histopathological types; for example, Grade I tumors include meningiothelial, fibrous, transitional (mixed), psammomatous, angiomatous and secretory meningiomas.^1-3

It was stated that a successful spinal meningioma operation represents one of the most gratifying with excellent outcome procedures especially in early diagnosis. The goal of treatment for recurrence avoidance should be complete tumor resection.^4,5

 

Modern neuroimaging and microsurgical techniques markedly improve the surgical prognosis of intraspinal meningiomas but in ventral tumors that exist anteriorly to the spinal cord (especially when calcified), the surgery resection becomes more difficult, hazardous and may cause cord damage. ^6,7

 

Aim of The Work

The aim of current study was designed to evaluate the clinical outcome of posterior approach microsurgical resection of spinal meningiomas.

 

SUBJECTS AND METHODS

 

The current study was designed to analyze the clinical presentation and outcome of operated spinal canal meningiomas during the period from 2005 to 2012 in 32 patients. Foramen magnum meningiomas cases were excluded.

Magnetic resonance imaging (MRI) was the main neuroradiologic diagnostic tool of the tumors before surgery and at follow up. Pre- and post-contrast MRI was performed on a 1.5 T system (Magnetom Vision, Siemens) for all patients according to clinical leveling and suspected localization. T₁-weighted spin-echo images (TR/TE 450-580/15-20ms), and T₂-weighted fast spin-echo images (TR/TE 2500-3500/80-120ms) were obtained. Post-contrast (0.1 mmol/kg gadopentetate dimeglumine) T₁-weighted images were also obtained.

All operations were performed using a microsurgical technique and through a posterior approach. After complete resection of spinal tumor, the involved dura either resected or coagulated as often as possible. In most patients, the dura was closed or the dural defects repaired using lyophilized dura. Standard hematoxylin and eoisin–stained meningioma specimens were reviewed and graded by experienced neuropathologists to type and confirm the diagnosis.

Clinical and radiological outcome was evaluated for all patients after a follow up mean duration period of about 1 year (range from 10 to 14 months) after surgery.

Pain severity was objectively assessed using visual analogue scale (VAS). VAS is usually a horizontal line 10 cm length, anchored by word descriptors at each end. The patient marks on the line the point that he feels represents its perception of its current state. The VAS score is determined by measuring in centimeters from the left head end of the line to the point of that the patient marks. Motor function was evaluated for the flexors and extensors of the hip, flexors and extensors of the knee, and for dorsiflexors and planter flexors of the ankle using medical research council (MRC) grading scale of muscle power that ranged from 0–5 in which grade 0 indicated complete paralysis and grade 5 indicated normal power. 

The average of the 6 muscle groups’ grades was bilaterally calculated. Improvement or deterioration of motor function and pain severity were defined by either increase or decrease of average muscle power grade and inversely VAS by at least 1 point. Superficial sensory dysfunction was assessed by the eliciting pain and touch sensations below the lesion level.

 

Statistical Analysis

The data were collected using a ‘data collection form’, coded and entered into a computer using Statistical Package for Social Sciences (SPSS) version 16.0. The demographic, clinical, and technical data were and entered into a computerized database before statistical analysis. Data were expressed as mean ± standard deviation (SD) for normally distributed data or patient’s number (n) and percentage (%) for non-normally distributions. Chi-square and fisher tests were used to compare Categorical variables. p-value less than 0.05 was considered statistically significant.

 

RESULTS

 

Tumor Locations and Presentations

The most common initial presentation symptoms were pain (87.5%), paraparesis (68.75%) and sphincter dysfunction (40.6%). The mean age 48 (ranged from 22 to 74) years old. Gender distribution was 6 males (18.75%) and 26 females (81.25%).

The locations of spinal canal meningiomas were cervical in 5 patients (15.6%), the cervicothoracic junction in 1 (3.12%), thoracic in 23 (71.8 %), lumbar in 1 (3.1%), and a low thoracolumbar location in 2 (6.25%). Intraoperatively, it was found 2 cases located in the epidural space, 28 cases in the intradural space, and 2 cases in extradural space. Tumor position was laterally in10 cases (31.25%), posterolaterally in 14 cases (43.75%), posteriorly in 5 (15.6%) and anteriorly in 3 (9.3%).

 

Histopathological Characteristics

Microscopically meningiomas show wide tissue variability and mostly had concentric cellular arrangement with whorl appearance. Meningothelial (fibrocellular) was defined in 18(56.25%), Psammomatous (central spherical calcified particle) in 5 (15.6%), transitional in 4 (12.5%), mixed type in 3 (9.3%) and fibrous in 2 (6.2%) patients.

 

Surgical Results

All patients underwent micro­surgical exploration with an attempted gross total resection of the meningiomas using a posterior approach. The extent of the tumor resection at the operation was Simpson grade I in 5, Grade II in 20, and Grade III in 7 patients. The mean duration of the development of symptoms prior to surgery was 7 months. Surgical resection led to overall significant improvement of the most pre-operative symptoms.

Table (1) showed that pain was the prevailing sensory symptom as 28 out of 32 patients (87.5%) suffered from non-specific up to selective pain distribution at presentation with paraparesis was the chief motor symptom as it was noted in 22 patients (68.75%), Bladder and sphincter disturbances were found in 13 patients (40.6%). 10 patients (31.3%) only experienced sensory deficit either radicular or sensory loss with level according to the site of the tumor was the least symptom noted.

At one year follow up better outcome was noted after Simpson grade I surgical resection (gross total resection), followed by grade II then III in respect to radicular pain, paraparesis, sphincter disturbances, and sensory loss  (p=0.008, 0.009, 0.01, and 0.04 respectively).

Surgical results showed improvement in 26 cases (81.25%), no change in 4 cases (12.5%), and deterioration in 2 cases (6.25%) due to iatrogenic cord injury. There was no radiographic evidence of tumor recurrence in patients with an extent of resection of Simpson grade I. II, or III.  The surgical outcomes are summarized in Table (2).

There were two cases of postoperative CSF leakage and two cases of worsened neurological status due to surgery induced spinal cord trauma. No immediate postoperative death occurred in the present series. On the other hand, MRI spine could be detected as encapsulated meningiomas in T₁ or T₂ weighted images in sagittal and axial views (Figure 1 a and b).

 

 

Table 1. Clinical outcome in relation to Simpson grading excision system.

 

*Significant at P<0.05  **Significant at P<0.01

 

Table 2. Final surgical outcome of spinal meningiomas (n= 32).

 

 

              

   

 

Figure 1 (a, b). Pre-postoperative sagital MRI views; (T₁ and T₂ respectively) meningioma opposite to L₂ vertebra.

 

DISCUSSION

 

The annual incidence of primary intraspinal neoplasm is 5/1,000,000 and 3/1,000,000 for females and males consecutively. Spinal intradural extramedullary tumors account for two­-thirds of all intraspinal neoplasm, and include neuromas and meningiomas.^1,8,9

Spinal canal meningioma is a benign lump that commonly occurs in women at middle age, it accounts for approximately 25-46% of spinal tumors (Figure 1 a and b).^10-12

Many investigators have reported a higher proportion of women.¹³ In a recent series, the female - to-male ratio among patients with spinal meningioma ranged from 3.2 to1, and the ages were from 40 to 70 years, In current series, the female-to-male ratio was 4.3 to 1, and women are overrepresented compared with recent series. It has been suggested that spinal meningioma occurs more frequently in fertile women because of the possible dependency of these tumors on sex steroid hormones.^14,15 Although the theory on the effect of hormones on meningioma is controversial, hormonal studies have shown the existence of various receptor types (peptidergic, growth factor, steroid, and aminergic) that may contribute to meningioma formation.^15,16

In the present series, 71.8% of tumors were located in the thoracic region; the incidence of thoracic location was reported to be 75% by Levy and colleagues, 66% by Namer and colleagues, and 79.5% by Rothman and colleagues, Roux and colleagues. They occurred far less frequently in the cervical region (l4-27%), and rarely in the lumbar region (2-14%).^{9,12,14,17,18}

Spinal cord meningiomas, like meningiomas elsewhere, grow from intradural attachments, and then stretch the arachnoid over them, sometimes incorporating the arachnoid, but rarely the pia.^5,7 Extradural meningiomas without an intradural component are exceedingly rare. Spinal canal meningioma arises from cap cells of the arachnoid membrane and originates in proximity to nerve roots.¹⁸

Pain is the most common symptom in the recent series. Paraparesis was the predominant symptom (68.75%) in current series (Table 1). It has usually been confused because the neurological impairment of spinal canal meningiomas is very similar to that seen in degenerative spinal disorder.^3,12,18-20

MRI findings make it possible to distinguish benign from malignant tumors that include parameters such as tumor outline, invasive behavior, and edematous reactions. Spinal meningiomas usually showed strong enhancement with a broad dural base on MRI studies after intravenous injection of gadolinium- DTPA.¹²

In most cases, meningioma growth is slow and well distinguished from the spinal cord that enables easy removal of the tumor.^3,18,20 Total resection of the tumor was achieved in all cases in present study (Table 2).

The rate of total tumor resection was reported to be 82% by Levy and colleagues, 92, 6% by Roux and colleagues, and 97% by Solero and colleagues. Tumors carry a favorable prognosis if completely resected. However, radical surgery may result in higher morbidity, particularly in anteriorly located and en plaque meningiomas in the thoracic spine due to the peculiar configurations of feeding vessels and in the presence of intratumoral calcifications. ^12,18,20,21

There were some technical difficulties of tumor resection, especially because of the ventral location to the cord, although even in those cases, resection of the tumor can be per­formed using a careful microsurgical technique. Recent neuroradiological and neurosurgical technical developments resulted in the improvement of surgical results of spinal tumors.

The postoperative results varied according to preoperative neurological status, the nature and location of the tumor, and the type of surgical resection. No immediate postoperative death occurred in the current series. Although the extent of resection is thought to be the main prognostic factor in the treatment of benign tumors, there has been no convincing data to show any clear relations between recurrence rates, the location of the tumor, and the extent of spinal meningioma resection. Recurrence of spinal meningiomas often has higher morbidity compared to intracranial cases (table 1).^10,19,20

The recurrence rate of intracranial meningioma is approximately 10-20%, depending on the length of follow-up.^13,15 Only a few long-term studies of spinal meningioma including the rate of late recurrence have been reported to date. The late recurrence rate was reported to be 4% by Levy and colleagues and 1.3% by Solero and colleagues.^12,20

Mirimanoff and colleagues, reported  that, after a total resection, the recurrence-free rates at 5, 10, and 15 years, were 93%, 80% ,and 68%, respectively, whereas, a subtotal resection, the progression-free rates were only 63%, 45% and 9%, respectively, during the same periods. Excision of the dural margin, in contrast to simply cauterizing the margins, is associated with a lower recurrence rate (4-8% for dural margin cauterization and 0-5.6% dural margin excision).^2,13,16,18

In the current series, no recurrent cases with Simpson grade I, II, or III (table 1) were recorded because of both their poor tendencies for growth (they are mostly psammomatous calcifying tumors; only 15.6% in the present series) and their prevalence in an aged population in whom the follow-up period is relatively short (Table 2).

Conclusion

Complete surgical removal of spinal canal meningiomas improves clinical symptoms and signs. Early detection and complete resection of spinal canal meningiomas seem to produce a good clinical outcome. Recently, advances in microneurosurgery and neuroimaging techniques reduced the mortality and morbidity rates of spinal meningioma.

It is well-known that the recurrence rate of intracranial meningiomas is correlated with the extent of resection. Gross total resection is quite enough and attempts to control the dural origin after achieving gross total resection should be minimized to avoid complications.

 

[Disclosure: author reports no conflict of interest]

 

REFERENCES

 

1.      Albanese V, Platania N. Spinal intradural extramedullary tumors. Personal experience. J Neurosurg Sci. 2002; 46:18-24.

2.      Baird M, Gallagher PJ. Recurrent intracranial and spinal Meningiomas: Clinical and histological features. Clin Neuropathol. 1989; 8:41-4.

3.      Kleihues P, Louis DN, Scheithauer BW, Rorke LB, Reifenberger G, Burger PC, et al. The WHO classification of tumors of the nervous system. J Neuropathol Exp Neurol. 2002; 61(3):215-25.

4.      Riemenschneider MJ, Perry A, Reifenberger G. Histological classification and molecular genetics of meningiomas. Lancet Neurol. 2006; 5:1045-54

5.      Iacoangeli M, Gladi M, Di Rienzo A, Dobran M, Alvaro L, Nocchi N. Minimally invasive surgery for benign intradural extramedullary spinal meningiomas: experience of a single institution in a cohort of elderly patients and review of the literature. Clin Interv Aging. 2012; 7:557-64.

6.      Frankel HL, Hancock DO, Hyslop G, Melzak J, Michaelis LS, Ungar GH. The value of postural reduction in the initial management of closed injuries of the spine with paraplegia and tetraplegia. Paraplegia. 1969; 7:179-92.

7.      Freidberg SR. Removal of an ossified ventral thoracic meningioma. Case report. J Neurosurg. 1972; 37:728-30.

8.      Gezen F, Kahraman S, Canakci Z, Beduk A. Review of 36 cases of Spinal cord meningioma. Spine. 2000; 25: 727-31.

9.      Gottfried ON, Gluf W, Quinones-Hinojosa A, Kan P, Schmidt MH. Spinal meningiomas: surgical management and outcome. Neurosurg Focus. 2003; 14(6):e2.

10.    Klekamp J, Samii M. Surgical results of spinal meningiomas. Surg Neurpl 1999; 52: 522-62.

11.    Pérez-Magán E, Campos-Martín Y, Mur P, Fiaño C, Ribalta T, García JF, et al. Genetic alterations associated with progression and recurrence in meningiomas. J Neuropathol Exp Neurol. 2012; 71(10):882-93.

12.    Levy WJ Jr, Bay J, Dohn D: Spinal cord meningioma. J Neurosurg. 1982; 57: 804-12.

13.    Mirimanoff RO, Dosrerz DE, Lingood RM, Ojemann RG, Martuza RL. Meningioma: analysis of recurrence and progression following neurosurgical resection. J Neurosurg. 1985; 62:18-24.

14.    Namer IJ, Pamir MN, Benli K, Saglam S, Erbengi A. Spinal meningiomas. Neurochirurgia. 1987; 30: 11-5.

15.    Parisi J, Mena H. Non-glial tumors. In: Nelson J, Parisi J, Schocher S, editors. Principles and Practice of Neuropathology. St. Louis: Mosby; 1993. pp. 203-13.

16.    Philippon J, Bataini JP, Cornu P, Grob R, Kujas M, Poisson M, et al. Les méningiomes récidivantes [Recurrent meningioma]. Neurochirurgie. 1986; 32: 1-84. French.

17.    Weinstein J, Mclain R. Tumors of the spine. In: Rothman R, Simeone F, editors. The Spine. 3^rd ed. Philadelphia: WB Saunders; 1992. p.1299-300.

18.    Roux FX, Nataf F, Pinaudeau M, Borne G, Devaux B, Meder JF. Intraspinal meningiomas: review of 54 cases with discussion of poor prognosis factors and modern therapeutic management. Surg Neurol. 1996; 46: 458-63.

19.    Arie Perry. Meningiomas. In: Bigner D, Mclendon R, Bruner J, editors. Russel and Rubinstein’s Pathology of Tumors of Nervous System. 6^th ed. London: Arnold; 1998. p. 427-474.

20.    Solero CL, Fornari M, Giombini S, Lasio G, Oliver G, Gimino C. Spinal meningiomas: review of 174 operated cases. Neurosurgery. 1989; 25:153-60.

21.    Mariniello G, Briganti F, De Caro ML, Maiuri F. Cervical extradural "en-plaque" meningioma. J Neurol Surg A Cent Eur Neurosurg. 2012; 73(5): 330-3.