Normal Preoperative Magnetic Resonance Imaging Research Articles

Rates and predictors of success and failure in repeat epilepsy surgery: A meta-analysis and systematic review.

Medically refractory epilepsy is a debilitating disorder that is particularly challenging to treat in patients who have already failed a surgical resection. Evidence regarding outcomes of further epilepsy surgery is limited to small case series and reviews. Therefore, our group performed the first quantitative meta-analysis of the literature from the past 30years to assess for rates and predictors of successful reoperations. A PubMed search was conducted for studies reporting outcomes of repeat epilepsy surgery. Studies were excluded if they reported fewer than five eligible patients or had average follow-ups < 1year, and patients were excluded from analysis if they received a nonresective intervention. Outcomes were stratified by each variable of interest, and quantitative meta-analysis was performed to generate odds ratios (ORs) and 95% confidence intervals (CIs). Seven hundred eighty-two patients who received repeat resective epilepsy surgery from 36 studies were included. Engel I outcome was observed in 47% (n=369) of patients. Significant predictors of seizure freedom included congruent over noncongruent electrophysiology data (OR = 3.6, 95% CI = 1.6-8.2), lesional over nonlesional epilepsy (OR = 3.2, 95% CI = 1.9-5.3), and surgical limitations over disease-related factors associated with failure of the first surgery (OR = 2.6, 95% CI = 1.3-5.3). Among patients with at least one of these predictors, seizure freedom was achieved in 58%. Conversely, the use of invasive monitoring was associated with worse outcome (OR = 0.4, 95% CI = 0.2-0.9). Temporal lobe over extratemporal/multilobe resection (OR = 1.5, 95% CI = 0.8-3.0) and abnormal over normal preoperative magnetic resonance imaging (OR = 1.9, 95% CI = 0.6-5.4) showed nonsignificant trends toward seizure freedom. This analysis supports considering further resection in patients with intractable epilepsy who continue to have debilitating seizures after an initial surgery, especially in the context of factors predictive of a favorable outcome.

Is the femoral head dead or alive before surgery of slipped capital femoral epiphysis? Interest of perfusion Magnetic Resonance Imaging.

The most common complication of slipped capital femoral epiphysis (SCFE) is avascular necrosis (AVN) of the femoral head. Surgical treatments including reduction of the femoral head are considered as a risk factor for avascular necrosis. The purpose of this study was to investigate the role of perfusion Magnetic Resonance Imaging (MRI) into the surgical decision-making sequence. Eighteen children with 19 slipped capital femoral epiphysis were retrospectively included. SFCE was unstable in nine cases and stable in ten cases. The slip angle was higher than 60° in 14 cases. Perfusion MRI with dynamic gadolinium-enhanced subtraction sequences were done in all the cases before and after surgical treatment. On nineteen hips, eight were devascularized before surgery. All were unstable. After surgery, six on eight had a complete revascularization, one had a focal necrosis and one remained devascularized. A postoperative devascularization with normal preoperative MRI was noted once. On nineteen hips, a total of three avascular necrosis occurred. Perfusion MRI is useful to assess preoperative and postoperative vascular status in SFCE. Preoperative devascularization could improve or stay equal after surgical treatment. Persistent devascularization could be responsible for avascular necrosis of the femoral head.

Timing of Antiepileptic Drug Withdrawal in Adult Epilepsy Patients After Neocortical Surgical Resection

The ideal efficacy outcome after surgery for medically refractory epilepsy is seizure freedom without need for antiepileptic drug (AED) therapy but the appropriate timing of AED withdrawal and other prognostic factors remain unclear. To critically evaluate current evidence regarding factors that influence the risk of seizure relapse after tapering AEDs in adult postepilepsy surgery patients. The objective was addressed through the development of a structured, critically appraised topic. This included a clinical scenario, structured question, literature search strategy, critical appraisal, results, evidence summary, commentary, and bottom-line conclusions. Participants included consultant and resident neurologists, a medical librarian, clinical epidemiologists, and a content expert in the field of epilepsy. A structured literature search led to selection and appraisal of a retrospective cohort study. Of 147 patients who underwent AED tapering after epilepsy surgery, 61 (41.5%) ended up seizure-free off AEDs, 47 (32%) were seizure-free with AED continuation, and 39 (26.5%) continued to have seizures while on AEDs. Risk factors associated with seizure recurrence included: less time to AED reduction [<9 mo vs. ≥9 mo; P<0.001; hazard ratio (HR)=2.83; 95% confidence interval (CI)=1.62-4.94), seizure recurrence before AED reduction (P=0.002; HR=2.43; 95% CI=1.37-4.31], normal preoperative magnetic resonance imaging (P=0.01; HR=1.96; 95% CI=1.15-3.34), and longer epilepsy duration (>11 y vs. ≤11 y; P=0.02; HR=1.75; 95% CI=1.09-2.81). Cortical location of the epileptic focus was not associated with taper success. In adults who have undergone neocortical resection surgery for medically refractory epilepsy, longer time from surgery to beginning AED taper (eg, greater than 9 months) is associated with a greater proportion of patients maintaining seizure freedom. Other risk factors associated with lower rate of seizure freedom after AED taper include longer duration of epilepsy, normal preoperative magnetic resonance imaging, and occurrence of postoperative seizures before initiation of AED withdrawal, but not cortical location of the epilepsy focus.

Seizure outcome after epilepsy surgery in patients with normal preoperative MRI

Objective: To determine outcome after epilepsy surgery in patients with normal preoperative magnetic resonance imaging (MRI). Methods: 24 adult and paediatric patients with normal preoperative MRIs were studied. They underwent...

Preoperative brain injury in newborns with transposition of the great arteries

Background The objective was to determine the timing and mechanism of brain injury using preoperative and postoperative magnetic resonance imaging (MRI) and three-dimensional MR spectroscopic imaging (MRSI) in newborns with transposition of the great arteries (TGA) repaired with full-flow cardiopulmonary bypass. Methods Ten term newborns with TGA undergoing an arterial switch operation were studied with MRI, MRSI, and neurologic examination preoperatively and postoperatively at a median of 5 days (2 to 9 days) and 19 days (14 to 26 days) of age, respectively. Five term historical controls were studied at a median of 4 days (3 to 9 days). Lactate/choline (marker of cerebral oxidative metabolism) and N-acetylaspartate (NAA)/choline (marker of cerebral metabolism and density) were measured bilaterally from the basal ganglia, thalamus, and corticospinal tracts. Results Four TGA newborns had brain injury on the preoperative MRI. The only new lesion detected on the postoperative study was a focal white matter lesion in one newborn with a normal preoperative MRI. The MRSI of age-adjusted lactate/choline was quantitatively higher in newborns with TGA compared with those without heart disease ( p < 0.0001), even in newborns without MRI evidence of preoperative brain injury. Lactate/choline decreased after surgery but remained elevated compared with controls. In newborns with TGA, those with preoperative brain injury on MRI had lower NAA/choline globally ( p = 0.04) than those with normal preoperative MRI. Five newborns had a decline in NAA/choline from the preoperative to postoperative studies. Conclusions Abnormal brain metabolism and injury was observed preoperatively in newborns with TGA. Brain injury is not solely related to the operative course.

Outcome after surgery in patients with refractory temporal lobe epilepsy and normal MRI

Our purpose is to determine predictors of outcome in patients with refractory temporal lobe epilepsy and normal high resolution magnetic resonance imaging (MRI) who undergo surgical therapy. We identified 23 patients who underwent temporal lobectomy and had normal pre-operative MRI, including surface coil phased array temporal lobe imaging. All were followed at least 2 years after surgery. We graded outcome as seizure-free, >75% reduction in seizures, or <75% reduction in seizures. We examined pre-operative interictal and ictal electroencephalographic (EEG) findings, age of onset, gender, duration of epilepsy, risk factors, family history, physical findings, age at operation, side of operation, and pathology of resected tissue in order to determine if any of these factors were associated with outcome. Overall, 48% (11 /23) of patients were seizure-free, 39% (9 /23) had >75% reduction in seizures, while 13% (3 /23) had <75% reduction in seizures. Only the EEG findings were useful in predicting outcome. When ictal onsets arose from basal-temporal regions, 61% (11 /18) of patients were seizure-free, while none (0 /5) were seizure-free when seizures arose from mid-posterior temporal regions (P= 0.04). Interictally, if all epileptiform patterns were localized exclusively to one basal-temporal region, a finding that invariably correlated with ictal onsets, 78% (7 /9) of patients were seizure-free, while only 29% (4 /14) were seizure-free if discharges were bilateral or multifocal (P= 0.04). We conclude that surgery may be a reasonable treatment for some patients with intractable temporal lobe seizures and normal MRI. The best outcomes occur when seizure onsets and interictal epileptiform patterns are exclusive to one basal-temporal region. Unfavorable outcomes are most likely to occur when ictal origins are from mid-posterior temporal regions and when interictal discharges are bitemporal or multifocal in distribution.

Role of magnetic resonance imaging in assessing factors affecting healing in scaphoid nonunions.

This study evaluates the role of magnetic resonance imaging in assessing the factors affecting the rate and healing time in scaphoid nonunions after surgery. Nineteen patients were assessed before surgery by radiographs, tomography, and magnetic resonance imaging. Fifteen had viable bone marrow and 4 patients had nonviable bone marrow on magnetic resonance imaging. All patients with normal preoperative magnetic resonance imaging healed in an average time of 4.7 months. Of the 4 patients with abnormal magnetic resonance imaging, but normal plain radiographs, 2 went on to heal in 10.5 months. The remaining 2 patients with abnormal magnetic resonance imaging and abnormal plain radiographs did not heal by 24 months. This study suggests 3 groups of scaphoid nonunions. Group 1 has normal trabecular bone radiographically and vascular bone marrow on magnetic resonance imaging and should be expected to heal after surgery. Group 2 has normal trabecular bone radiographically but avascular marrow on magnetic resonance imaging and may be expected to eventually heal after surgery. Group 3 has abnormal radiographs suggestive of fibrous replacement of the scaphoid proximal pole by the presence of cystic changes and the loss of trabecular bone, and avascular bone, as shown on magnetic resonance imaging. This study failed to show healing in this group of patients. Magnetic resonance imaging may be of benefit in predicting the healing potential in patients presenting with scaphoid nonunion.