Spine - Myelopathy

Dr Sidra AfzalNew RadiologyDept.

Services Hospital Lahore.

In this presentation we will focus on spinal cord diseases that are characterised by high signal within the cord on T2WI.

The most common causes are inflammatory and demyelinating disorders.

Differential diagnosis

If we exclude myelopathy due to cord compression as seen in trauma, degeneration and metastatic disease, which is usually not a diagnostic dilemma, then the most common diseases of the spinal cord are Demyelinating diseases.

AND

Multiple Sclerosis is by far the most common demyelinating disease.

Whenever there is an abnormality in the spinal cord, we need a systematic approach to analyse the findings

Transverse involvement

MULTIPLE SCLEROSIS:

MS is an immune-mediated inflammatory demyelinating disease of the brain and the spinal cord.

Multiple lesions disseminated over time and space.

Pathologic studies have shown that 95% of MS patients have spinal cord lesions, whether they have spinal symptoms or not.

Brain lesions are typically in periventricular, subcortical and cerebellar white matter and also in brainstem and corpus callosum.

CSF: monoclonal bands.

MS: short segment focal wedge-shaped involvement of the posterior column of the spinal cord with typical periventricular WM-lesions.

On transverse images MS lesions typically have a round or triangular shape and are located posteriorly or laterally

So can we exclude MS if a lesion is located anteriorly?Unfortunately not.MS is the great mimicker and can also be located anteriorly like in this patient who has a lesion in the typical location (blue arrow) but also a lesion ventrally in the cord (red arrow). This is uncommon, but we can not exclude MS.

When MS lesions are active, they can enhance, but enhancement is not as common as in the brain. The enhancement patterns are non-specific. We can see ring enhancement, intense and less-intense enhancement. The less intense enhancement is the most common pattern.

Diffuse abnormalities that can look like transverse myelitis or extensive astrocytoma are sometimes seen.

This pattern is more common in primary progressive and secondary progressive MS.

Atrophy in longstanding MS

Neuromyelitis Optica (NMO)

is an autoimmune demyelinating disease induced by a specific auto-antibody, the NMO-IgG, which is a specific biomarker for NMO

NMO preferentially affects the optic nerve and spinal cord.

Brain lesions do occur and often are distinct from those seen in MS.

Demyelination of the spinal cord looks like transverse myelitis, i.e. often extensive over 4 -7 vertebral segments and the full transverse diameter.

Female:male = 9:1

Also called Devic disease

NMO presenting with neuritis optica (arrows). The brain is normal

One month later this child presented with acute transverse myelopathy, i.e. bilateral symptoms. The images show abnormal signal in the spinal cord with swelling and some enhancement. An astrocytoma could very well present with these images, but given the history of an optic neuritis and the acute myelopathy, we do not think of a tumor. This proved to be NMO and the Ig-test for NMO was positive.

Previously it was thought that in NMO the brain was spared, but now we know, that brain lesions do occur.

They are often distinct from those seen in MS.

The location of the brain lesions in NMO is only around the ventricles.

It is also possible to have large lesions in the corpus callosum of patients with NMO as was described by Nakamura. So in any CNS disease with optic nerve and spinal cord involvement it is good to do the test for NMO-IgG.

ADEM

Acute disseminated encephalomyelitis (ADEM) is an inflammatory demyelinating disease of the CNS after viral infection or vaccination.

In 75% of patients there is a clear infectious event or vaccination (1-4 weeks) Mostly seen in young children.

In 50% of ADEM patients the anti-MOG IgG test is positive and supports the diagnosis. This is antibody-reactivity against Myelin Oligodendrocyte Glycoprotein (MOG).

Usually the brain is also involved. 30% of cases has spinal involvement.

These are images of a teenage child with a typical history of respiratory tract infection There is swelling and cord involvement and no enhancement The imaging findings and clinical history is typical of ADEM

What is typical for ADEM and uncommon for MS is: • Massive involvement of the pons. • Involvement of the basal ganglia.

The follow up MR shows that the cord has returned to normal again

Another case of ADEM.Notice the typical involvement of the pons and basal ganglia.

On follow up scan almost complete normalisation.

Transverse Myelitis (TM)

Focal inflammatory disorder of the spinal cord resulting in motor, sensory and autonomic dysfunction.

Imaging findings:• More than 2/3 of the cross sectional area is involved. • Focal enlargement. • T2WI hyperintensity • Enhancement + / -.

Two forms of TM: Acute partial transverse myelitis - APTMLesions extending less than two Segments. These patients are at risk of developing MS.

Acute complete transverse myelitis - ACTM Lesions extending more than two Segments

The sagittal image shows a large segment of hyperintensity on T2WI. The transverse image shows that most of the cord is involved.

These images are of a 31 year old male The images show a long segment myelopathy with full transverse involvement.There is no swelling and no enhancement.It does not look like MS or tumor, so we should think of ATM - acute transverse myelitis.

Transverse myelitis may occur in isolation or in the setting of another illness.

When it occurs without apparent underlying cause, it is referred to as idiopathic.

Idiopathic transverse myelitis is assumed to be the result of abnormal activation of the immune system against the spinal cord.

Patients with an acute short segment TM (or APTM) are at risk of developing MS if there is one of the following: • partial TM, i.e. short segment TM. • Family history of MS. Brain lesions on MR. • Oligoclonoal bands in CSF.

Here images of a typical case of TM.There is multisegment high signal on STIR and T2WI with some swelling.There is no enhancement, which is usually the case in TM. When there is enhancement, it can be difficult to differentiate TM from an astrocytoma.

Spinal cord tumor

Astrocytoma

The major differential of the spinal cord diseases that we have discussed so far is an astrocytoma.

Astrocytoma is a diffusely infiltrating tumor, that is not mass-like.

Usually there is some patchy enhancement.

This ia a case of astrocytoma.T2 hyperintense expansion of the thoracic cord is demonstrated. Postcontrast images demonstrate patchy irregular peripheral enhancement of this lesion, and central low intensity

The other two common spinal cord tumors are ependymoma and hemangioblastoma and they just look like a tumor.

They present as enhancing masses and will not cause a differential problem.

The images are of a patient with neurofibromatosis who has multiple ependymomas. They present as multiple enhancing masses.

Vascular

Arterial infarction

Spinal cord ischemia is typically seen as a complication of aortic aneurysm surgery or stenting

Aortic aneurysm stenting is the most common cause of spinal chord infarction

The images are of a patient who developed a paraparesis after stenting of an aortic aneurysm.Notice the high signal ventrally in the chord, which is typical for arterial infarction.On transverse images a typical snake-eye appearance can be seen.

The diffusion images show restricted diffusion in spinl cord ischemia.

Vasculitis

Vasculitis can be idiopathic, but is also seen in SLE, Sjogren and Behcet.

Normally we think of vasculitis as a disease of the vessels in the brain, but all vasculitis can be seen in the spine as well.

It produces MS-like images

The images are of a child . The images are non-specific with multiple focal lesions and probably the first choise would be MS. The differential diagnosis would include inflammation, infection and metastases.In such cases always perform a transverse image of the spine to look for the exact location and perform a MRI of the brain.

The lesions are located dorsally and one of the lesions is enhancing.Now if this was infection or metastases it would be strange that not all lesions enhance.MS is still on our list.We continue with brain images in next slide

On the CE-T1WI only one lesion shows enhancement.The location of the lesions and the enhancement could very well fit to the diagnosis of MS, but this proved to be vasculitis.

Thank you