Tom Meagher

Diffusion-Weighted MRI in 300 Patients Presenting Late With Subacute Transient Ischemic Attack or Minor Stroke

Background and Purpose— Many patients with transient ischemic attack (TIA) or minor stroke present to medical attention after a delay of several days or weeks, at which time it may be more difficult to obtain a clear history and clinical signs may have resolved. Because ischemic lesions on diffusion-weighted MRI (DWI) often persist for several weeks, we hypothesized that adding DWI to a standard protocol with T2-weighted imaging might be useful in the management of patients presenting late. Methods— We studied consecutive patients with TIA or minor stroke presenting ≥3 days after the event. Two independent observers recorded the presence or absence of recent ischemic lesions on 2 different occasions, first with the T2 scan only, and second with T2 and DWI. Each time, with the aid of a written clinical summary, the observers recorded their diagnosis and proposed management. Results— 300 patients (159 men) were scanned at a median of 17 (interquartile range=10 to 23) days after symptom onset. DWI showed a high signal lesion in 114/164 (70%) minor strokes versus 17/136 (13%) TIAs (P<0.0001). The presence of high-signal lesions on DWI decreased nonlinearly with time since symptom onset (P<0.0001) and increased with National Institutes of Health Stroke Score (P=0.038) and with age (P=0.01). In 90/206 (43.7%) patients with 1 or multiple lesions on T2, DWI helped to clarify whether these were related to a recent ischemic event (79 [48%] strokes; 11 [31%] TIAs). Compared with T2 alone, DWI provided additional information in 108 (36%) patients (91 [56%] strokes and 17 [13%] TIAs), such as clarification of clinical diagnosis (18 patients, 6%) or vascular territory (28 patients, 9.3%), which was considered likely to influence management in 42 (14%) patients (32 [19%] strokes; 10 [7.4%] TIAs). Conclusions— The clinically useful information available from DWI provides a further justification for an MRI-based imaging protocol in patients with subacute TIA or minor stroke.

Abnormalities on diffusion weighted magnetic resonance imaging performed several weeks after a minor stroke or transient ischaemic attack

Objectives: Diffusion weighted brain imaging (DWI) is used in acute stroke, and also shows an acute ischaemic lesion in most transient ischamic attack (TIA) patients scanned acutely. However, it may also be useful in identifying subacute ischaemic lesions in patients with minor stroke or TIA who present several weeks after symptom onset. This study investigated the sensitivity and the observer reproducibility of DWI in cerebral TIA and minor ischaemic stroke patients scanned more than two weeks after the last symptomatic event. Methods: Consecutive patients underwent magnetic resonance imaging (T2, DWI, ADC). The presence of clinically appropriate lesions was assessed by two independent observers, and related to the type of presenting event, the NIH score, persistence of symptoms and signs, and the time since the presenting event. Results: 101 patients (53 men) were scanned at a median time of 21 days (IQR=17–28) after symptom onset. Reproducibility of the assessment of DWI abnormalities was high: interobserver agreement =97% (κ=0.94, p<0.0001); intraobserver agreement =94% (κ=0.88, p<0.0001). DWI showed a clinically appropriate ischaemic lesion in 29 of 51 (57%) minor stroke patients, and in 7 of 50 (14%) TIA patients. The independent predictors of a positive DWI scan were presentation with minor stroke versus TIA (p=0.009) and increasing NIH score (p=0.009), but there was no difference between patients presenting 2–4 weeks compared with >4 weeks after symptom onset. In minor stroke patients, the presence of a clinically appropriate lesion was associated with persistent symptoms (63% versus 36%; p=0.12) and signs (64% versus 33%, p=0.06) at the time of scanning. Conclusions: DWI shows a clinically appropriate ischaemic lesion in more than half of minor stroke patients presenting more than two weeks after the symptomatic event, but only in a small proportion of patients with TIA. The persistence of lesions on DWI is closely related to markers of severity of the ischaemic event. These results justify larger studies of the clinical usefulness of DWI in subacute minor stroke.

Audit of a Policy of Magnetic Resonance Imaging with Diffusion-weighted Imaging as First-line Neuroimaging for In-patients with Clinically Suspected Acute Stroke

AIM To audit the feasibility and use of diffusion-weighted (DW) magnetic resonance imaging (MRI) as initial neuroimaging for in-patients with clinically suspected acute stroke. MATERIALS AND METHODS In April 2000, MRI with DW and T2-weighted sequence was locally instituted as initial neuroimaging for patients with clinically suspected acute stroke. This retrospective study reviewed imaging performed for in-patients with suspected acute stroke over a 9-month period. Data were collected on image type, result and need for repeat imaging. RESULTS During the study period, 124 patients had neuroimaging for suspected cerebrovascular accident, and 119 were MRI safe. Eighty-eight (73.9%) patients underwent DW MRI as first-line investigation. Five patients were not MRI safe and 31 had computed tomography (CT) as first-line imaging due to lack of available MRI capacity. Repeat neuroimaging was performed in 16 (12.9%) patients. Study times were comparable for both types of neuroimaging: a mean of 13 min for MRI and 11 min for CT. CONCLUSION The audit standard was achieved in 88 (73.9%) patients. The use of DW MRI as a first-line investigation for patients with a clinical diagnosis of acute stroke is achievable in a district general hospital setting.

Presence of Acute Ischaemic Lesions on Diffusion-Weighted Imaging Is Associated with Clinical Predictors of Early Risk of Stroke after Transient Ischaemic Attack

Background: Early risk of stroke after a transient ischaemic attack (TIA) can be reliably predicted with risk scores based on clinical features of the patient and the event, but it is unclear how these features correlate with findings on brain imaging and few studies have investigated this in the subacute phase. Methods: Two hundred consecutive patients attending a specialist clinic underwent diffusion-weighted brain imaging (DWI) on the day of the clinic (≧3 days after a TIA) and the presence of recent lesions (positive DWI) was related to the presence of clinical features associated with a high stroke risk and to 2 validated risk scores (ABCD and California). Results: Thirty-one patients (16%) had positive DWI. Increasing ABCD and California scores were associated with positive DWI (p = 0.02 for both) independent of the delay from TIA to scan. Conclusion: Presence of recent ischaemic lesions on DWI correlates with validated clinical scores for risk of stroke after TIA in patients scanned subacutely. Future prognostic studies of DWI after TIA should adjust for the risk scores to determine the independent predictive value of DWI and hence the likely role of DWI in refinements of the scores.

Subacute progressive ascending myelopathy following spinal cord injury: MRI appearances and clinical presentation

Study design:Retrospective Case Review.Objectives:To describe the clinical presentation and course of patients with magnetic resonance imaging (MRI) features of subacute progressive ascending myelopathy (SPAM). A rare complication of spinal cord injury.Setting:National Spinal Injuries Centre, Stoke Mandeville Hospital, UK.Materials and methods:A retrospective review of the case notes and MRI studies of 11 cases with typical MRI features of ascending myelopathy presenting to a tertiary Spinal Injuries centre over a 15-year period.Results:Eleven patients were identified with MRI features typical of SPAM, a median of 13 days (mean 24, range 4–86 days) following cord injury. The median number of cord segments involved above the initial insult was 6 (mean 6.2, range 4–11). MRI appearances include extension four or more segments cephalad to the initial cord injured segment, cord expansion and increased intramedullary T2 signal with a rim of cord sparing peripherally. Cord changes and neurological deficits improved over time but did not return to the initial injured level on MRI. One patient died (mortality 9%).Conclusion:SPAM is a rare cause of neurological deterioration following spinal cord injury but may remain subclinical. SPAM most commonly presents as neurological deterioration but may present with shoulder pain, respiratory deterioration or remain subclinical. There are characteristic MRI appearances. It can be fatal.

Differential diagnosis of restricted diffusion confined to the cerebral cortex

Diffusion-weighted MRI (DWI) has become increasingly widely available over recent years and is recognized as a powerful tool in neuroimaging. It is primarily used to identify acute ischaemia in patients presenting with stroke because of the improved sensitivity it offers early in the course of the disease. DWI also contributes useful diagnostic information in a range of other conditions. In this review we describe the magnetic resonance imaging (MRI) features of a number of conditions characterized by cortical diffusion restriction (CDR).

Resolution of SPAM following cordectomy: implications for understanding pathophysiology

Study design:Case report.Objective:To describe the clinical benefit of a spinal cordectomy with the aim of limiting neurological deterioration related to the development of a subacute posttraumatic ascending myelopathy (SPAM) supporting previously described mechanism for SPAM formation.Setting:National Spinal Injuries Centre, Stoke Mandeville Hospital, UK.Method and results:A 38-year old patient presented 6 months after spinal cord injury substantial neurological deterioration expanding from the initial T4-injury level through C4. Magnetic resonance imaging revealed intra-medullary haemorrhage at the site of injury and subsequent-ascending cord oedema. A cordectomy was performed leading to neurological stabilisation and complete resolution of SPAM.Conclusion:Cordectomy can be an effective intervention in case of rapid progressive neurological deterioration.

MRI in acute and subacute post-traumatic spinal cord injury: pictorial review

Study design:Pictorial review.Objectives:To illustrate MRI signs of acute and subacute injury with emphasis on evidence-based links to clinical outcome and implications for treatment.Methods:Description of important aspects of MRI techniques and illustration of critical MRI signs important in the assessment of spinal cord injury following trauma, in the acute and subacute stages.Conclusions:Familiarity with cord MRI appearances has an important impact on planning the management of the acutely spinal cord injured patient and also identifying complications in the subacute phase particularly in the presence of neurological deterioration.

Incidence of pulmonary embolism after the first 3 months of spinal cord injury

Background:Pulmonary embolism (PE) is a significant cause of morbidity and mortality in patients with spinal cord injury (SCI). Prophylactic anticoagulation is associated with a reduction in mortality rates, but there is limited evidence regarding the incidence rate of PE following cessation of anticoagulation after the first 3 months of injury.Study design:Single-centre retrospective study.Objective:To estimate the incidence rate of PE after 90 days of SCI.Setting:The National Spinal Injuries Centre at Stoke Mandeville Hospital, Aylesbury, UK.Methods:The study includes 640 new-onset SCI patients. All computer tomography pulmonary angiograms (CTPAs) or ventilation-perfusion lung scans between 2008 and 2013 were identified. Medical notes and scans were reviewed and clinical outcomes and radiological findings were recorded.Results:A total of 91 patients with a new-onset SCI had a CTPA or a perfusion lung scan. PE was detected in a total of 8 patients. The incidence of PE was 1.25%; 95% confidence interval (0.39–2.11) over a 6-year period. The duration of injury at the time of PE was 7 months.Conclusion:The incidence rate of PE post 3 months of SCI remains significant, though much lower than immediately post injury.

Outcomes of whole-body computed tomography in spinal cord-injured patients with sepsis.

Study design:Retrospective case series.Objectives:To evaluate the efficacy of body computed tomography (CT) in spinal cord injury (SCI) patients with sepsis.Setting:Specialist acute care and rehabilitation SCI centre in United Kingdom.Methods:Patients with SCI and suspected or known sepsis, who had CT of the chest, abdomen and pelvis, over a 4-year period, were identified. Only patients who fulfilled the definition of sepsis or severe sepsis were included. Their medical notes and CT scans were reviewed and clinical outcomes and radiological findings recorded.Results:Twenty-two patients with sepsis were identified including seven categorised as having severe sepsis. A specific radiological diagnosis was found in three patients (14%) and non-specific findings were found in 15 patients (68%).Conclusion:Although in the majority of cases, the findings were non-specific, a small number of patients had significant pathology identified by CT, which influenced their management significantly.