Posterior approach to ventrally located spinal meningiomas

Abstract

For the resection of anteriorly located meningiomas, various approaches have been used. Posterior approach is less invasive and demanding; however, it has been associated with increased risk of spinal cord injury. We evaluated ten consecutive patients that underwent surgery for spinal meningiomas. All patients were preoperative assessed by neurological examination, computed tomography and magnetic resonance imaging. All tumors were ventrally located and removed via a posterior approach. Transcranial motor-evoked potentials (TcMEPs), somatosensory-evoked potential (SSEP) and free running electromyography (EMG) were monitored intraoperative. Postoperative all patients had regular follow-up examinations. There were four males and six females. The mean age was 68.2 years (range 39-82 years). In nine out of ten cases, the tumor was located in the thoracic spine. A case of a lumbar meningioma was recorded. The most common presenting symptom was motor and sensory deficits and unsteady gait, whereas no patient presented with paraplegia. All meningiomas were operated using a microsurgical technique via a posterior approach. During the operation, free running EMG monitoring prompted a surgical alert in case of irritation, whereas TcMEP and SSEP amplitudes remained unchanged. Histopathology revealed the presence of typical (World Health Organisation grade I) meningiomas. The mean Ki-67/MIB-1 index was 2.75% (range 0.5-7). None of our patients sustained a transient or permanent motor deficit. After a mean follow-up period of 26 months (range 56-16 months), no tumor recurrence and no instability were found. Posterior approach for anteriorly located meningiomas is a safe procedure with the use of intraoperative monitoring, less invasive and well-tolerated especially in older patients. Complete tumor excision can be performed with satisfactory results.

Fig. 1

Illustrative case of patient no. 3, a 56-year-old female with an anterior located thoracic meningioma at T7–T8 level. The tumor displayed intermediate signal intensity on sagittal T2-weighted MRI (a), marked enhancement after intravenous contrast administration (b). c Gadolinium-enhanced T1-weighted MRI 1 year later without evidence of tumor recurrence

Fig. 2

Axial gadolinium-enhanced T1-weighted MRI revealing the thoracic meningioma and the dorso-lateral displacement of the spinal cord

Fig. 3

Patient no. 3: Compared TcMEP values before (green wave) and after removal of a thoracic meningioma, revealing no significant amplitude change