Pictorial reviewMagnetic resonance imaging of acute intramedullary myelopathy: radiological differential diagnosis for the on-call radiologist
Introduction
Spinal cord compression is perhaps the most common indication for out-of-hours MRI. In this situation, relatively inexperienced radiologists are often required to supervise the imaging and give a first opinion of the findings. Occasionally, these MRI studies performed on patients with an acute myelopathy will demonstrate intramedullary pathology rather than showing a compressive lesion (Figure 1, Figure 2). In this situation detailed knowledge of the anatomy of the cord and predilection of various diseases for different patterns of cord, brain, and extra-central nervous system (CNS) involvement, is of paramount importance.
The clinical information provided is also vital for MRI image interpretation in acute myelopathy. This is especially in regard to elucidating the likely pathological process from a list of what can be very similar imaging features. Of particular importance is the onset of symptoms differentiating vascular from inflammatory causes, which can be difficult on imaging alone. The patient's age and sex also help to narrow the differential. Accurate clinical examination will determine the likely anatomical location of lesions within the cord and provide clues to the nature of the underlying pathology. Knowledge of this enables better-targeted imaging and interpretation of incidental findings in the wrong location (Table 1).
The main causes of acute non-compressive myelopathy can be broadly classified into the following: inflammatory and autoimmune; infections; vascular; and others, including metabolic, radiation, and metastatic.
Although syringomyelia and primary cord tumours can result in similar imaging findings they do not often present acutely, so are not specifically covered in this review.
Section snippets
Inflammatory and autoimmune
Inflammatory and demyelinating myelopathy can be thought of as clinicopathological sequelae of a spectrum of disorders with a similar endpoint. These typically include viral and post-viral infections [enteroviruses, human immunodeficiency virus (HIV), human T-lymphotrophic virus -1 (HTLV-1), Epstein–Barr virus (EBV), cytomegalovirus (CMV), varicella zoster virus (VZV), acute disseminated encephalomyelitis (ADEM)], vasculitic/multisystem (systemic lupus erythematous, Bechet's sydrome, Sjogren's
Infection
On the whole, infectious myelopathy due to viral myelitis is equivalent in imaging terms to idiopathic transverse transverse myelitis. The diagnosis is reached by laboratory testing of the cerebrospinal fluid, serum serology, or by exclusion of other causes. Occasionally, however, the imaging is specific for other infectious causes. Being aware of and differentiating these is important as early treatment is vital.
Arterial infarction (Fig. 10)
Spinal cord infarcts most commonly affect the territory of the anterior spinal artery, involving the corticospinal and spinothalamic tracts.15 Although classically spared, impairment of proprioception may occur due to involvement of the inner part of the dorsal columns, which is also supplied by the anterior spinal artery, and may represent more extensive infarction.
Causes of cord ischaemia and infarction include aortic aneurysms, dissection, or surgery, vertebral artery dissection and
B12 deficiency (Fig. 13)
Subacute combined degeneration of the cord results from a deficit of vitamin B12 most often due to pernicious anaemia. A lack of B12 results in a paucity of both central and peripheral neuronal myelination. One small study showed MRI to be normal in 50% of cases pre-treatment. When abnormal, longitudinally orientated areas of high T2 signal are seen within the dorsal columns, occasionally resembling an inverted “V”. These typically will not enhance following gadolinium23 and will resolve
Summary
There is a myriad of disease conditions that result in very similar imaging features consisting of poorly defined areas of high T2 and low T1 signal with slight enhancement and expansion of the cord. This description could represent anything from MS, through cord infarction, transverse myelitis to an astrocytoma. It is often not possible to give a definitive answer as to the cause, and the diagnosis is usually achieved from a combination of history, laboratory tests, and imaging. Imaging can
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Localization of macroscopically undetectable intramedullary hematoma by intraoperative epidural motor evoked potential
2022, Clinical Neurophysiology PracticeCitation Excerpt :Intramedullary hematomas remain a diagnostic challenge, but they need to be considered as an uncommon cause of myelopathy (Leep Hunderfund and Wijdicks, 2009). The preferred imaging modality should be MRI (Sheerin et al., 2009). Early diagnosis is crucial and the treatment of choice should be surgical (Kreppel et al., 2003; Groen, 2004).
Spinal vascular lesions: anatomy, imaging techniques and treatment
2021, European Journal of Radiology OpenCitation Excerpt :Detection of SDAVFs is tricky, due to nonspecific symptoms; diagnostic delays are common and significantly influence prognosis and good patients’ outcome. Classical MR imaging findings include, on T2 WI, centro-medullary spinal cord hyperintensity, as a result of intramedullary oedema affecting a long segment (LETM), and multiple flow voids from dilated veins on the cord surface [55], better recognized on heavily T2-weighted sequences as fast imaging employing steady-state acquisition (FIESTA) or 3D-TSE. Contrast administration may be useful in enhancing dilated and tortuous perimedullary veins, detecting small shunt [54], showing cord enhancement as consequence of the breakdown of the blood-spinal cord barrier due to venous hypertension (Fig. 8).
Enterovirus D68 infection in a cluster of children with acute flaccid myelitis, Buenos Aires, Argentina, 2016
2017, European Journal of Paediatric NeurologyCitation Excerpt :Similar images may be observed in post-infectious or vascular disorders. Nevertheless, the clinical manifestations in our patients were not compatible with these conditions.1,10 Moreover, in the context of a cluster of patients with clinically similar features, a viral infection, including HEV-D68, should be considered.
Abnormal Spinal Cord Magnetic Resonance Signal: Approach to the Differential Diagnosis
2016, Seminars in Ultrasound, CT and MRICitation Excerpt :In the absence of trauma, hemorrhagic changes in the cord should prompt the exclusion of an underlying tumor or vascular malformation (eg, cavernomas or dural arteriovenous fistulas) (Fig. 17). Overall, although the patterns of signal abnormalities can overlap with different processes, careful evaluation of the anatomical involvement can help with the differential diagnosis in most cases.29-33 Detailed description of inflammatory, infectious, demyelinating, vascular, metabolic, or malignant involvement of the spinal cord and imaging correlations are provided in the reviews dedicated to specific cord diseases of the current Seminars issue.
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