Diffusion-weighted MR imaging (DWI) in spinal cord ischemia

Diffusion-weighted imaging in noncompressive myelopathies: a 33-patient prospective study

Diffusion-weighted imaging (DWI) is frequently used to differentiate cerebral lesions. The aim of our study was to evaluate the diagnostic value of DWI and the measurement of the apparent diffusion coefficient (ADC) in noncompressive myelopathy explorations. Thirty-three patients presenting a spinal cord syndrome due to a noncompressive myelopathy underwent spinal cord MRI between September 2005 and November 2008. For each patient, the ADC was calculated in the pathological spinal cord. ADC values were also measured in the healthy spinal cord of ten control subjects. Statistical analysis was based on the Student's t test. Twenty-one patients presented an inflammatory myelopathy: Nine patients presented multiple sclerosis, three patients presented a parainfectious myelopathy, two patients acute disseminated encephalomyelitis, one patient neuromyelitis optica, one patient systemic lupus erythematosus, and five patients a myelopathy of unknown aetiology. Six patients presented a spinal cord infarction. ADC values were significantly lower in spinal cord infarct (mean ADC = 0.81 +/- 0.08 x 10(-3) mm(2)/s) than in inflammatory spinal cord lesions (mean ADC = 1.37 +/- 0.23 x 10(-3) mm(2)/s) and in healthy control spinal cord (mean ADC = 0.93 +/- 0.07 x 10(-3) mm(2)/s). These results are important to differentiate ischaemic from inflammatory myelopathies, especially at the acute phase when clinical presentation and extensive work-up are not able to show an aetiologic diagnosis. Although these results are similar to those described in cerebral explorations, ADC measurements remain technically limited for the moment.

Posterior spinal artery infarct due to patent foramen ovale: a case report

STUDY DESIGN

Case report.

OBJECTIVE

To report the first case of posterior spinal artery (PSA) infarct due to patent foramen ovale (PFO).

SUMMARY OF BACKGROUND DATA

Infarct in the territories of PSA are very rare: till now 38 cases are reported in the literature. Moreover only 1 case of spinal cord infarction was attributed to paradoxical embolism through PFO, but in the anterior spinal artery territory.

METHODS

A 60-year-old woman was hospitalized for sudden numbness of the right leg. Neurologic examination revealed right leg mild paresis and loss of proprioception and dysesthesia at T11. Spine-MRI showed T5-T7 posterolateral cord ischemia. Transesophageal echocardiography disclosed a PFO with severe right-left shunt confirmed by transcranial Doppler.

RESULTS

During the hospitalization she was treated with oral-500 mg ticlopidine, because of a mild allergic reaction to acetylsalicylic acid. No steroids were administrated. Physiotherapy was performed daily. Motor and urinary symptoms disappeared in 20 days. At 1-month clinical follow-up only suspended dysesthesia on the right side was present. At 3 months follow-up spine-MRI showed no signal abnormalities within the spinal cord but the patient still complained of dysesthesia. The therapy was changed to oral 75 mg clopidogrel, cause of leucopoenia. At 1-year follow-up dysesthesia was still present, but less complaining and no recurrence and adverse effect due to clopidogrel therapy were reported.

CONCLUSION

This report describe a case of acute nontraumatic myelopathy. At 4 days after onset, PSA infarct was diagnosed on the basis of neurologic findings and MR images. After extensive diagnostic work-up, we were able to identify only PFO, so it was the first case of PSA due to probable paradoxical embolism. The patient was treated with antiplatelet therapy with good recovery and no recurrence at 1-year follow-up.

Central sensory-motor deficit after uneventful single-dose spinal morphine administration in a patient with preexisting migraine headaches

Hemiplegic migraine is a condition associated with vascular alteration of the central nervous system and transient neurologic deficits. Permanent morphine-induced motor dysfunction has been reported after spinal ischemia. We report a persisting central neurological deficit after single-dose spinal administration of 400 microg of morphine in a patient with no previous neurological condition. Hemiplegic migraine was thought to be present when the patient emerged from anesthesia. Weakness in the left quadriceps and saddle anesthesia of the perineum and urinary retention of central origin remained present 3 yr later. Over the 3 postoperative years, the patient was admitted to a neurological unit 5 times because of acute headache associated with complete left-sided hemiplegia. These symptoms resolved within 24 h of onset. Hemiplegic migraine was thought to be the most likely diagnosis of these recurrent attacks. We hypothesize that the patient's persistent deficits were caused by a combination of spinal morphine and spinal cord vascular dysfunction associated with hemiplegic migraine.

Recovery from paraplegia after the treatment of spinal dural arteriovenous fistula: case report and review of the literature

BACKGROUND

Spinal dural arteriovenous fistula (SDAVF) is a rare and enigmatic disease. Functional outcome is particularly uncertain for the small group of patients that are unable to stand at the time of diagnosis (grade 5 gait disturbance on the Aminoff-Logue scale, ALS). The objective of this study is to examine the final functional outcome of patients with SDAVF in grade 5 gait ALS before treatment.

METHODS

We conducted a PubMed search using the keyword "spinal dural arteriovenous fistula." A review of the clinical series and single well-detailed case reports of SDAVF gathered 106 patients with grade 5 gait ALS on the initial examination. Additionally, we report the case of a 56-year-old man presenting acute paraplegia and urinary retention on admission who had complained of sporadic motor and sphincter disturbances for 1 year. Spine T2-weighted MR imaging showed a central hyperintensity within the spinal cord, and the angiography demonstrated a T-11 SDAVF. Interruption of the fistula was performed through an urgent one-level laminectomy.

RESULTS

Grade 5 gait ALS was present in 25% of the patients with SDAVF included in the clinical series. Latest follow-up showed that gait disturbance improved in 73% of patients after treatment, although less than 6% became grade 1 gait ALS. Micturition disturbances improved in 39%. Exploration of our patient showed improvement to grade 1 gait ALS 1 year after the surgical treatment.

CONCLUSION

Interruption of SDAVF in paraplegic patients may improve the final functional gait outcome in some cases. No complete recovery (grade 0 gait ALS) was achieved after treatment. Micturition disturbances had a worse prognosis than motor deficits.

Varicella zoster virus vasculopathies: diverse clinical manifestations, laboratory features, pathogenesis, and treatment

Vasculopathies caused by varicella zoster virus (VZV) are indicative of a productive virus infection in cerebral arteries after either reactivation of VZV (shingles) or primary infection (chickenpox). VZV vasculopathy can cause ischaemic infarction of the brain and spinal cord, as well as aneurysm, subarachnoid and cerebral haemorrhage, carotid dissection, and, rarely, peripheral arterial disease. VZV vasculopathy in immunocompetent or immunocompromised individuals can be unifocal or multifocal with deep-seated and superficial infarctions. Lesions at the grey-white matter junction on brain imaging are a clue to diagnosis. Involvement of both large and small arteries is more common than that of either alone. Most patients have a mononuclear cerebrospinal fluid pleocytosis, often with red blood cells. Cerebrospinal fluid pleocytosis and rash are absent in about a third of cases. Anti-VZV IgG antibody in the cerebrospinal fluid is found more frequently than VZV DNA. In recent years, the number of recognised VZV vasculopathies has grown, and accurate diagnosis is important for the effective treatment of these disorders.

Diffusion-weighted imaging, diffusion-tensor imaging, and fiber tractography of the spinal cord

In the brain, diffusion-weighted imaging (DWI) is an established and reliable method for the characterization of neurologic lesions. Although the diagnostic value of DWI in the early detection of ischemia has not diminished with time, many new clinical applications of DWI have also emerged. Diffusion-tensor imaging and fiber tractography have more recently been developed and optimized, allowing quantification of the magnitude and direction of diffusion along three principal eigenvectors. Diffusion-tensor imaging and fiber tractography are proving to be useful in clinical neuroradiology practice, with application to several categories of disease, and to be a powerful research tool. This article describes some of the applications of DWI and diffusion-tensor imaging in the evaluation of the diseases of the spinal cord.

Studying neonatal bilirubin encephalopathy with conventional MRI, MRS, and DWI

INTRODUCTION

The purpose of this study was to evaluate the diagnostic value of conventional magnetic resonance imaging (MRI), proton magnetic resonance spectroscopy ((1)H-MRS), and diffusion-weighted imaging (DWI) for neonatal bilirubin encephalopathy.

METHODS

We collected conventional MRI in 24 neonates with neonatal bilirubin encephalopathy. We performed (1)H-MRS and DWI sequences to nine of the 24 patients and seven age-matched healthy control subjects. Multiple-voxel (1)H-MRS data were acquired using PRESS pulse sequence with TE = 135 ms and TR = 1500 ms. The spectroscopic regions of interest were the bilateral basal ganglia and thalamus with a 1.0 mL spatial resolution. The data from DWI were collected by using a single shot-spin echo-echo planar imaging sequence with TR/TE: 2900/98, and imaging regions were also focused on the bilateral basal ganglia and thalamus.

RESULTS

Nineteen of the 24 patients had abnormal T(1)-weighted image hyperintensity in the globus pallidus, but these lesions appeared as normal T(2)-weighted image intensity in the same region. Ten of the 24 patients had T(1)-weighted image high signal intensity in the subthalamic nucleus and appeared as normal intensity in the region for the T(2)-weighted images. The peak area ratios of NAA/Cho and NAA/Cr were significantly decreased (t-test, P < 0.05) in the patients compared to the controls in the basal ganglia.

CONCLUSION

Conventional MR imaging and (1)H-MRS are important complementary tools in the diagnosis of neonatal bilirubin encephalopathy. The study provides important information for applying these MR modalities to evaluate neonates with bilirubin encephalopathy.

Diffusion-weighted MR imaging (DWI) in the evaluation of epidural spinal lesions

INTRODUCTION

Epidural spinal cord compression is one of the most critical emergency conditions requiring medical attention and requires prompt and adequate treatment. The aim of our study was to assess the role of diffusion-weighted magnetic resonance (MR) imaging (DWI) in the diagnosis and differentiation of epidural spinal lesions.

METHODS

Three patients with epidural lymphoma, two with sarcoma and three with epidural metastatic disease were imaged on a 1.5T MRI unit. DWI was performed using navigated, interleaved, multi-shot echo planar imaging (IEPI). Three region of interest (ROI)-measurements were obtained on corresponding apparent diffusion coefficient (ADC) maps, and the mean ADC value was used for further analysis. The cellularity of tumors was determined as the N/C ratio (nucleus/cytoplasma ratio) from histological samples. The ADC values and N/C ratios of lesions were compared using a Kruskal-Wallis test.

RESULTS

The mean ADC of the lymphomas was 0.66 x 10(-3) mm2/s, that of the sarcomas was 0.85 x 10(-3) mm2/s and the ADC of the metastatic lesions was 1.05 x 10(-3) mm2/s; however, the differences were not statistically significant. Mean N/C ratios in the lymphoma, sarcomas and metastases were 4:1, 2:1, and 2.6:1, respectively, with a statistically significant difference between the groups (p < 0.025).

CONCLUSION

Although not statistically significant due to the small patient sample, our results clearly show a tendency toward decreased diffusivity in neoplastic lesions with higher cellularity. The data from our study suggest that DWI is a feasible and potentially useful technique for the evaluation of epidural lesions that cause spinal cord compression on a per-patient basis.

Demyelinating and infectious diseases of the spinal cord

Spinal cord diseases generally have distinctive clinical findings that reflect dysfunction of particular sensory or motor tracts. The abnormalities on MR images reflect the pathologic changes that occur in the affected pathways. The complexity and the wide spectrum of diseases affecting the spinal cord require a profound knowledge of neuropathology and exactly tuned imaging strategies. This article describes and illustrates the clinical and imaging characteristics in various demyelinating and infectious conditions of the spinal cord.

Diffusion Tensor Imaging Predicts Hyperacute Spinal Cord Injury Severity

Experimental strategies that focus on ventral white matter (VWM) preservation during the hyperacute phase hold great potential for our improved understanding of functional recovery following traumatic spinal cord injury (SCI). Critical comparisons of human SCI to rapidly accumulating data derived from rodent models are limited by a basic lack of in vivo measures of subclinical pathophysiologic changes and white matter damage in the spinal cord. Spinal cord edema and intraparenchymal hemorrhage demonstrated with routine MR sequences have limited value for predicting functional outcomes in SCI animal models and in human patients. We recently demonstrated that in vivo derived diffusion tensor imaging (DTI) parameters are sensitive and specific biomarkers for spinal cord white matter damage. In this study, non-invasive in vivo DTI was utilized to evaluate the white matter of C57BL/6 mice 3 h after mild (0.3 mm), moderate (0.6 mm), or severe (0.9 mm) contusive SCI. In the hyperacute phase, relative anisotropy maps provided excellent gray-white matter contrast in all degrees of injury. In vivo DTI-derived measurements of axial diffusion differentiated between mild, moderate, and severe contusive SCI with good histological correlation. Cross-sectional regional measurements of white matter injury severity between dorsal columns and VWM varied with increasing cord displacement in a pattern consistent with spinal cord viscoelastic properties.