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Infection, Inflammatory, Demyelination, and Vascular Disorders


INTRODUCTION

Background

Reproduced from Mayo Foundation for Medical Education and Research.

  • Infectious, inflammatory, and demyelinating disorders of the spinal cord are commonly encountered in children. Children typically present with acute neurologic signs and symptoms, including sensory and motor deficits, hyporeflexia or hyperreflexia, and bowel or bladder incontinence.

  • Lumbar puncture is often performed to confirm an infectious, inflammatory, or demyelinating process via demonstration of CSF pleocytosis or the presence of oligoclonal bands.

  • Similar to adults, spinal vascular disorders including spinal cord infarcts and vascular malformations are rare in children. While spinal cord infarcts in adults are often attributable to atherosclerosis or aortic surgery, these are uncommon etiologies in children. Conversely, children are more likely to develop spinal cord infarcts from disc embolism compared to adults.

Imaging

From McDougall CG, Deshmukh VR, Fiorella DJ, Albuquerque FC, Spetzler RF. Endovascular techniques for vascular malformations of the Spinal Axis. Neurosurg Clin N Am. 2005;16(2):395–410.

  • MRI is the primary modality for evaluating infectious, inflammatory, demyelinating, and vascular disorders of the spine because these disorders primarily affect the spinal cord and nerve roots.

  • MRI is typically not able to provide a specific cause of spinal cord inflammation or demyelination due to the imaging overlap but can suggest greater likelihood of a specific process when additional findings from brain MRI and CSF are combined with clinical history.

  • Spinal DWI has improved over time. Modern techniques such as RESOLVE or ZOOM sequences allow for reliable diffusion imaging of the spine. Usage of a spinal DWI sequence can add value to patient care when a spinal cord infarct, epidural abscess or phlegmon is encountered.

  • This section will illustrate the common infectious, inflammatory, demyelinating, and vascular disorders affecting the spine in children.

TRANSVERSE MYELITIS

< Fig. 18.1 A to D>

Fig. 18.1, Transverse Myelitis. (A) Sagittal T2W and (B) sagittal T1W+C images demonstrate a longitudinally extensive minimally expansile T2 hyperintense spinal cord abnormality with minimal mild patchy areas of enhancement. Different patient with (C) Sagittal STIR and (D) sagittal T1W+C fat saturation images demonstrating a longitudinally extensive minimally expansile STIR hyperintense spinal cord abnormality with incomplete enhancement. Imaging patterns of both patients demonstrate typical appearance of transverse myelitis with T2W hyperintensity extending more than 2 vertebral body lengths, mild expansion and variable enhancement.

< Fig. 18.2 A to D>

Fig. 18.2, Transverse Myelitis. A 10-year-old with lower extremity weakness, urinary retention, and T6 level decreased light touch and pinprick sensation but intact position and vibratory sensation. CSF demonstrated elevated white blood cell (WBC) count (124 cells/mm 3 ), normal glucose, and elevated total protein (171 mg/dL). (A to C) Sagittal and axial T2W and (D) sagittal T1W+C images demonstrate a longitudinally extensive minimally expansile T2W hyperintense spinal cord abnormality involving majority of the cross section of the spinal cord with mild patchy areas of enhancement.

Key Points

Background

  • Inflammatory process resulting in acute onset of motor, sensory, and autonomic dysfunction with maximum symptoms ∼24 hours (range 4 hours–21 days) after the onset of symptoms

  • Criteria from the Transverse Myelitis Consortium Working Group: (1) Appropriate clinical picture; (2) evolution of symptoms to maximum severity between 4 hours and 21 days; and (3) CSF demonstrating cellular infiltrate and/or elevated protein or spinal cord enhancement on MRI

  • Transverse myelitis can be divided into disease-associated and idiopathic transverse myelitis. Disease-associated causes include para-infectious, post-infectious, NMO, ant-MOG, autoimmune disorders, and multiple sclerosis (uncommon). Para-infectious transverse myelitis accounts for ~ 40% of cases and can be diagnosed when there is a history of an infectious prodrome within 4 weeks of clinical presentation and culture, serologic or PCR evidence of infection is present.

  • Immune-mediated mechanisms include molecular mimicry which is damage to neuronal structures due to similarity between microbial antigens and neuronal components, microbial superantigen mediated infection in which microbial peptides bind to T-cell receptors causing polyclonal activation, and humoral derangement in which there is polyclonal B-cell activation or deposition of immunocomplexes in the spinal cord Approximately 30% of children with transverse myelitis have a recent history of vaccination

  • Prognosis: One-third good/complete recovery, one-third fair recovery, and one-third poor outcome

  • Poor outcome associated with cord signal abnormality involving >10 spinal levels

  • Treated with high-dose steroids. Most often has a monophasic course.

Imaging

  • Typically longitudinally extensive (more than two vertebral body lengths)

  • T2W hyperintense, central cord involvement or more than two-thirds cross-sectional area

  • Nonenhancing or partially enhancing , minimal/mild expansion

  • Facilitated diffusion on DWI

  • Improvements in spinal cord DWI and DTI may improve diagnosis and allow better determination of prognosis of transverse myelitis. Small studies have shown that a spinal cord DTI fractional anisotropy could detect additional lesions not seen on T2W images, and greater reduction of fractional anisotropy within the lesion and normal appearing spinal cord distal to the lesion correlated with worse outcomes

REFERENCES

  • 1. Rossi A. Pediatric Neuroradiology . 1st ed. Berlin/Heidelberg: Springer-Verlag.
  • 2. Goh C., Phal P.M., Desmond P.M.: Neuroimaging in acute transverse myelitis. Neuroimag Clin N Am 2011; 21: pp. 951-973.

NEUROMYELITIS OPTICA

< Fig 18.3 A to D>

Fig. 18.3, Neuromyelitis Optica. (A and C) Sagittal and axial T2W and (B) sagittal T1W+C images demonstrate a longitudinally extensive nonexpansile T2W hyperintense spinal cord abnormality with incomplete enhancement. (D) Coronal T1W+C image of the orbits demonstrates abnormal homogeneous enhancement of the right optic nerve.

Key Points

Background

  • An autoimmune disease targeting the aquaporin-4 protein on astrocytes.

  • Aquaporin-4 IgG is positive in 60% to 80% of patients.

  • Number of attacks and disability level at 2 years from diagnosis may be greater than with MS.

Imaging

  • Longitudinally extensive myelitis: T2W hyperintensity involving two or more spinal segments typically with central gray predominance; enhancement is variable but present to some degree in 78% of patients; the entire cross-section of the cord may be involved.

  • Intracranially involves optic nerves , hypothalamus, medial thalami, and dorsal brainstem. Minimal to no involvement of the cerebral white matter is present.

REFERENCE

  • 1. Chitnis T., Ness J., Waubant E., et. al.: Clinical features of neuromyelitis optica in children: US Network of Pediatric MS Centers report. Neurology 2016; 86: pp. 245-252.

ANTI-MOG DEMYELINATION

< Fig. 18.4 A to D>

Fig. 18.4, Anti-MOG Myelitis. A 15-year-old with numbness in the toes and hands progressing to upper and lower extremity weakness. (A to C) Sagittal and axial T2W images demonstrate multiple short and a longitudinally extensive minimally expansile T2W hyperintense spinal cord lesions involving gray and white matter without enhancement.

Key Points

Background

  • Inflammatory disorder associated with antibodies to myelin oligodendrocyte glycoprotein (MOG). Associated with a variety of demyelinating disorders including optic neuritis, ADEM, myelitis, and non-ADEM encephalitis

  • Monophasic or relapsing-remitting course

Imaging

  • Longitudinally extensive transverse myelitis : two or more vertebral body lengths with minimal expansion and patchy or no enhancement.

  • Clinical and imaging criteria can result in a diagnosis of acute flaccid myelitis in 21%.

  • No reliable imaging differentiators from ADEM and NMO. Involvement of the lower spinal cord and conus is more common in anti-MOG (11%–41%) than other CNS demyelinating diseases; one-third of cases have multifocal cord lesions; typically gray matter predominant.

  • Differential Diagnosis:

  • MS—less severe, short craniocaudal cord involvement, and eccentric location.

  • NMO—worse outcome than anti-MOG, central cord involvement more often cervical and thoracic spinal cord, and more often enhancing (78% compared to 26% with anti-MOG).

REFERENCE

  • 1. Parrotta E., Kister I.: The expanding clinical spectrum of myelin oligodendrocyte glycoprotein (MOG) antibody associated disease in children and adults. Front Neurol 2020; 11: pp. 960.

ACUTE FLACCID MYELITIS

< Fig. 18.5 A to E>

Fig. 18.5, Acute Flaccid Myelitis. (A to C) A 17-year-old with acute-onset flaccid lower extremity weakness. (A and B) Sagittal and axial T2W images demonstrate longitudinally extensive nonexpansile linear T2W hyperintense spinal cord abnormality in the central gray matter of the thoracic spinal cord without enhancement (not shown). (C) Axial FLAIR image demonstrates FLAIR hyperintense signal in the dorsal pons. (D and E) Acute onset of upper extremity weakness in a child. Sagittal and axial T2W images demonstrate short segment T2W hyperintensity limited to the anterior horns of the central gray matter.

Key Points

Background

  • Etiology presumed to be secondary to a viral infection or postinfectious immune response. Enterovirus D68 implicated.

Imaging

  • Longitudinally extensive T2W hyperintense signal predominantly involving the central gray matter or limited to the anterior horns of the central gray matter. Minimal to no enhancement.

  • Brain findings can include T2W hyperintensity in the medulla, and dorsal pons. Less commonly the thalami may be involved.

  • Cauda equina can enhance in the subacute phase.

REFERENCE

  • 1. Messacar K., Schreiner T.L., Van Haren K., et. al.: Acute flaccid myelitis: a clinical review of US cases 2012–2015. Ann Neurol 2016 Sept; 80: pp. 326-338.

MULTIPLE SCLEROSIS

< Fig 18.6 A to C>

Fig. 18.6, Multiple Sclerosis. (A and B) Sagittal and axial T2W images demonstrate short segment nonexpansile T2W hyperintense right lateral spinal cord abnormality. (C) Axial FLAIR image demonstrates ovoid FLAIR hyperintensities in the juxtacortical white matter.

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