Magnetic resonance imaging in posterior circulation infarction: impact on diagnosis and management

A comparison of benign positional vertigo and stroke patients presenting to the emergency department with vertigo or dizziness

PURPOSE

To compare imaging utilization between patients presenting to the emergency department (ED) with vertigo and dizziness (VDS) who are diagnosed with stroke and benign paroxysmal positional vertigo (BPPV).

METHODS

All patients presenting to the ED with VDS (January 2014-June 2018) were identified. Those with a discharge diagnosis of stroke and BPPV were analyzed.

RESULTS

17,884 patients presented to with VDS. 452 were diagnosed with BPPV and 174 with acute stroke. 55.7% of stroke patients had at least one neurologic symptom beyond VDS, 63.8% had a positive neurologic exam, and 80.5% had either; 90.2% had at least one stroke risk factor (RF). 42.0% of BPPV patients received imaging, of which 24.7% had neurologic symptoms beyond VDS, 16.3% had neurologic exam findings, and 34.2% had either (P < 0.001, as compared to stroke). 43 patients (22.6%) lacked neurologic symptoms, exam findings, and stroke RFs; 40 had an adequate HINTS (head impulse, nystagmus, skew) exam. The most common imaging modality received by BPPV patients was plain CT Head (54.2%), followed by CT/CTA (43.7%), and MRI brain (26.3%). CT head was the initial imaging of choice in 44.7% and CT/CTA in 42.6%.

CONCLUSIONS

Imaging utilization in BPPV patients presenting with VDS is high. The profile of patients with BPPV that received imaging was substantially more benign than that of stroke patients (a quarter had no neurologic symptoms, exam findings, or stroke RFs). The HINTS exam was underutilized, and computed tomography was heavily utilized despite well-established limitations in diagnosing posterior circulation strokes. This study highlights the need for increased training in the HINTS exam, narrowing of the scope for computed tomography, and a higher threshold for imaging patients with isolated VDS.

Added Value of MRI over CT of the Brain in Intensive Care Unit Patients

BACKGROUND

Intensive care unit (ICU) patients with neurological impairments often require neuroimaging. However, the relative sensitivity of various imaging modalities of the brain has not yet been explored in this population.

METHODS

In this study, we compare the findings of CT and MRI scans in ICU patients to (1) identify the number and rate of clinically relevant lesion detected by MRI while missed by CT and vice versa and (2) determine specific lesion types for which CT versus MRI discrepancies exist. A review of medical records included CT and MRI reports of patients who underwent these procedures while they were patients in our ICUs between July 2004 and July 2009. MRI and CT were compared regarding their ability to detect clinically relevant abnormalities. Odds ratios with 95% confidence limits were calculated to compare diagnostic categories regarding the rate of discrepant MRI versus CT findings, followed by power analyses to estimate sample sizes necessary to allow for further testing in a larger trial.

RESULTS

MRI revealed clinically relevant additional abnormalities over CT in 129 of 136 patients (95%) that included the detection of additional finding for 15/27 hemorrhagic lesions (55.6%), 33/36 (92%) ischemic strokes, 19/27 (70%) traumatic lesions, 8/14 (57%) infections, 15/24 (62.5%) metabolic abnormalities, and all seven neoplasms. Odds ratio analysis revealed the added sensitivity of MRI to be greater for ischemic and neoplastic lesions than for trauma, metabolic-related abnormalities, infection, or hemorrhage.

CONCLUSIONS

MRI is more sensitive than CT in identifying clinically meaningful lesions in at least a subset of ICU patients, regardless of pathology.

Comparative sensitivity of computed tomography vs. magnetic resonance imaging for detecting acute posterior fossa infarct

BACKGROUND

Posterior fossa strokes, particularly those related to basilar occlusion, pose a high risk for progression and poor neurological outcomes. The clinical history and examination are often not adequately sensitive or specific for detection.

STUDY OBJECTIVES

Because this population stands to benefit from acute interventions such as intravenous and intra-arterial tissue plasminogen activator, mechanical thrombectomy, and intensive monitoring for neurologic deterioration, this study examined the sensitivity of non-contrast head computed tomography (NCCT) for diagnosing posterior fossa strokes in the emergency department.

METHODS

This study analyzed a prospectively collected database of acute ischemic stroke patients who underwent head NCCT within 30 h of symptom onset and who were subsequently found to have a posterior fossa infarct on brain magnetic resonance imaging (MRI) performed within 6 h of the NCCT.

RESULTS

There were 67 patients identified who had restricted diffusion on MRI in the posterior fossa. The National Institutes of Health Stroke Scale (NIHSS) scores ranged from 0 to 36, median 3. Only 28 patients had evidence of infarction on the initial NCCT scan. The timing of NCCT scans ranged from 1.2 to 28.9 h after symptom onset. The sensitivity of NCCT was 41.8% (95% confidence interval 30.1-54.4). The longest period of time between symptom onset and a negative NCCT with a subsequent positive diffusion-weighted imaging MRI was 26.7 h.

CONCLUSIONS

Head NCCT imaging is frequently insensitive for detecting posterior fossa infarction. Temporal evolution of strokes in this distribution, coupled with beam-hardening artifact, may contribute to this limitation. When a posterior fossa stroke is suspected and the NCCT is non-diagnostic, MRI is the preferred imaging modality to exclude posterior fossa infarction.

Cost-effective investigation of patients with suspected transient ischaemic attacks

Images

Investigation of acute stroke: what is the most effective strategy?

Techniques of investigation of acute stroke syndromes have progressed rapidly in recent years, outpacing developments in effective stroke treatment. The clinician is thus faced with a variety of tests, each with different cost implications and each altering management to a greater or lesser extent. This review will concentrate on the basic tests which should be performed for all strokes (full blood count, ESR, biochemical screen, blood glucose, cholesterol, syphilis serology, chest X-ray and electrocardiogram). Additional tests may be required in selected cases: CT scan to diagnose 'non-stroke' lesions, to exclude cerebral haemorrhage if anti-haemostatic therapy is planned, and to detect strokes which may require emergency intervention (such as cerebellar stroke with hydrocephalus); echocardiography to detect cardiac sources of emboli; and in a few cases lumbar puncture and specialized haematological tests. Other tests, which are currently research tools, may be suitable for widespread use in the future including NMR, SPECT and PET scanning.