Spinal meningioma

Meningiomas arising from the coverings of the spinal cord represent a minority of all meningiomas (approximately 12%⁵) but are the second most common intradural extramedullary spinal tumour representing 25% of all such tumours². Despite usually being small, due to the confines of the spinal canal they can result in significant neurologic dysfunction.

This article specifically relates to spinal meningiomas. For a discussion intracranial meningiomas and for a general discussion of the pathology refer to the main article: meningioma. 

Epidemiology

Spinal meningiomas have a peak incidence is in the fifth and sixth decades.

Interestingly, and unlike intracranial meningiomas, in the adult population, females are approximately ten times more commonly affected than males. In children, there does not appear to be a sex predilection.

There is an increased incidence of spinal meningiomas in patients with neurofibromatosis type 2, and in fact in the paediatric population, meningiomas uncommonly occur outside of the setting of NF2.

Clinical presentation

The majority of patients present with motor deficits as a result of compression of the spinal cord. Less common presentations include sensory deficits, pain and sphincter dysfunction.

Pathology

Most spinal meningiomas are benign, with greater than 95% being classified as WHO grade I lesions⁶. They are believed to originate from the denticulate ligaments. 

For a discussion of the pathology of meningiomas pathology refer to the general meningioma article. 

Radiographic features

The vast majority (90%) of spinal meningiomas are extramedullary/intradural in location. Occasionally (5%) purely extradural tumours are found and the remainder (5%) have both intradural and extradural components taking on a dumbbell appearance². 

Interestingly spinal meningiomas are also not distributed evenly along the canal:

• cervical spine - 15%
• thoracic spine - 80%
• lumbosacral spine: uncommon²

Meningiomas are often located posterolaterally in the thoracic region and anteriorly in the cervical region⁶. 

Most meningiomas are solitary lesions (98%). Multiple meningiomas are most often associated with NF2⁶.

Plain film

• usually normal
• rarely bone erosion or calcification

CT (non-contrast)

• Isodense or moderately hyperdense mass
• hyperostosis may be seen but is not as common as in the intracranial forms
• calcification may be present

MRI

• well-circumscribed
• broad-based dural attachment
• dural tail sign

They share similar signal characteristics to intracranial meningiomas:

• T1
  • isointense to slightly hypointense
  • may have a heterogenous texture
• T2 - isointense to slightly hyperintense
• T1 C+ (Gd) - moderate homogeneous enhancement

Occasionally, densely calcified meningiomas are hypointense on T1 and T2, and show only minimal contrast enhancement.

Treatment and prognosis

Spinal meningiomas are typically slow growing. Surgery is the treatment of choice and complete tumour removal is achieved in the vast majority of patients. Less than 10% experience recurrence².

Differential diagnosis

The main differential are neurogenic tumours (spinal schwannoma & spinal neurofibroma):

• typically located anteriorly (compared to meningiomas which are usually located posterolaterally)
• tendency for multiplicity
• may have low intensity central regions on post-contrast T1 and T2 weighted images
• not associated with a broad dural base
• neural exit foraminal widening is more commonly seen with nerve sheath tumours