Mary K. Edwards

MRI in acute disseminated encephalomyelitis

A retrospective analysis of CT and MRI studies in 12 patients with a clinical diagnosis of acute disseminated encephalomyelitis (ADEM) was performed. MRI was the definitive modality for the assessment of the lesions of ADEM: all patients had abnormalities consistent with the clinical diagnosis. Ten had abnormalities in the brain, three spinal cord lesions, and three showed evidence of optic neuritis. CT was normal in 6 of the 7 patients in which it was performed.

Single photon emission computed tomography (SPECT) brain imaging using N,N,N′‐trimethyl‐N′‐(2 hydroxy‐3‐methyl‐5–123Iiodobenzyl)‐1,3‐propanediamine 2 HCl (HIPDM) Intractable complex partial seizures

HIPDM-SPECT brain imaging was performed in four patients with intractable complex partial seizures (CPS). Three patients had an epileptogenic focus in one temporal lobe and underwent anterior temporal lobectomy. Interictal HIPDM-SPECT demonstrated decreased regional cerebral perfusion (rCP) in the epileptogenic area in only one patient, but ictal studies showed increased rCP in the epileptic foci of all three patients. In the fourth patient, interictal HIPDM-SPECT showed increased rCP in the area of epileptogenic focus; when antiepileptic medication was taken, rCP decreased. HIPDM-SPECT brain imaging is useful for localizing epileptogenic foci in CPS.

Multiple sclerosis: magnetic resonance imaging, evoked responses, and spinal fluid electrophoresis.

Magnetic resonance images (MRI), evoked responses (ER), and CSF findings were compared in 39 patients with possible, probable, or definite MS. MRI disclosed multiple lesions (72%) more often than ERs (55%) in the total group of patients. In possible MS, MRI showed multiple lesions in 71%, and ER abnormalities were found in 41%. MRI is the preferred test for patients with suspected MS, but ERs are useful when MRI is normal and in the evaluation of optic nerve or spinal cord lesions.

Gadolinium enhancement in acute disseminated encephalomyelitis

Acute disseminated encephalomyelitis (ADEM) is a widespread CNS inflammation that usually follows an infection or vaccination. We present a case of ADEM, which in addition to the typical MR findings, demonstrates gadolinium enhancement of several of the lesions. Since ADEM is usually a monophasic illness, it has been postulated that all lesions might enhance with paramagnetic contrast medium since they would all be expected to be active. Our case demonstrates enhancement of some of the lesions, without enhancement of others.

MR imaging of central pontine myelinolysis

Central pontine myelinolysis is a demyelinating disorder with characteristic magnetic resonance features. Findings on T1-weighted scans include a symmetric region of low signal involving the basilar pons with sparing of the descending corticospinal tracts as well as the peripheral pontine tissues. The T2-weighted images show an area of high signal corresponding to the abnormal region identified on T1-weighted scans. Associated extrapontine demyelinating lesions are also demonstrated.

Invasive orbital pseudotumor — CT demonstration of extension beyond orbit

SummaryTwo cases of orbital pseudotumor are described with computed tomographic (CT) studies showing extension of the pseudotumor beyond the confines of the bony orbit. In one patient with orbital pseudotumor involving the medial rectus muscle, the pseudotumor extended through the medial wall of the orbit into the ethmoid sinus. A second patient had extension of orbital pseudotumor into the infraorbital fissure causing enlargement of the infraorbital fissure and foramen. Both lesions were confirmed by biopsy.

Magnetic Resonance Evaluation of Pediatric Spinal Dysraphism

Magnetic resonance (MR) scans of 22 children with spinal dysraphism were reviewed. MR scans of the cervicothoracic spine in 12 cases revealed 10 Chiari II malformations, 1 Chiari III malformations, and 4 syringohydromyelias. Twelve MR scans of the lumbosacral region were performed demonstrating 11 tethered cords, 6 myelomeningoceles, 4 lipomyeloschises, 2 diastematomyelias, 2 syringohydromyelias, and 2 dermal sinus tracts. MR is effective in defining the relationship of the cerebellar tonsils and brainstem to the upper cervical spinal canal and in evaluating the extent of syringohydromyelia and the degree of cord expansion. The ability to image the spinal cord and associated paraspinal lesions directly in the sagittal and coronal planes with excellent tissue characterization allows MR to accurately diagnose and define the myriad abnormalities associated with pediatric dysraphism.

Toxoplasmic myelitis in AIDS: gadolinium-enhanced MR.

An acquired immunodeficiency syndrome (AIDS) patient developed acute symptoms suggestive of a lower spinal cord lesion. Magnetic resonance imaging was performed and demonstrated an enhancing lesion of the conus medullaris. Surgical biopsy revealed Toxoplasma gondii. Disease processes involving the spinal cord in AIDS patients are reviewed and differential diagnosis for the lesion in this patient is discussed.

Pitfalls of computed tomography in diagnosis of discitis

SummarySixteen patients with discitis from January 1980 through December 1983 underwent 18CT scans for initial evaluation. In six scans the study produced a false negative result (sensitivity 63%, 11/16). In three of these six the scan was performed at the wrong disc level, and in three the error was interpretive. During the same time period 6 patients had a CT diagnosis of discitis which proved incorrect (positive predictive value 63%), three of which had fractures, two had normal post discectomy changes, and one had a neuropathic arthropathy. These studies were reviewed in a blinded fashion along with 30 CT scans of post operative patients without clinical or laboratory evidence of discitis. The CT findings in the discitis patients were: (a( anterior paravertebral soft tissue swelling with obliteration of paravertebral fat planes, (b) fragmentation or erosions of vertebral end plates, and (c) paravertebral fluid collection (abscess). Both (a) and (b) were seen in 13/15 patients, (a) alone in 1/15, (b) alone in 1/15, and all three (a, b, c) in 2/15. The CT scan is diagnostic of discitis in those with all three findings. In those patients with only (a) or both (a) and (b), the CT can be suggestive of discitis in the proper clinical setting when correlated with plain film findings: however, these CT findings are also observed in other conditions. Involvement of the spinal canal by inflammatory mass was seen in 6/16 patients with discitis. Low attenuation (hypodensity) of the affected disc was not observed.

MRI of Guillain-Barré syndrome.

We describe the results of MRI of the spine in a case of Guillain-Barré syndrome. The main finding was abnormal enhancement of the nerve roots in the region of the conus medullaris and cauda equina.