Hillary Shurtleff, Molly Warner, Andrew Poliakov, Brian Bournival, Dennis W. Shaw, Gisele Ishak, Tong Yang, Mahesh Karandikar, Russell P. Saneto, Samuel R. Browd and Jeffrey G. Ojemann
The authors describe their experience with functional MR (fMR) imaging in children as young as 5 years of age, or even younger in developmental age equivalent. Functional MR imaging can be useful for identifying eloquent cortex prior to surgical intervention. Most fMR imaging clinical work has been done in adults, and although children as young as 8 years of age have been included in larger clinical series, cases in younger children are rarely reported.
The authors reviewed presurgical fMR images in eight patients who were 8 years of age or younger, six of whom were 5 or 6 years of age. Each patient had undergone neuropsychological testing. Three patients functioned at a below-average level, with adaptive functioning age scores of 3 to 4 years. Self-paced finger tapping (with passive movement in one patient) and silent language tasks were used as activation tasks. The language task was modified for younger children, for whom the same (not novel) stimuli were used for extensive practice ahead of time and in the MR imaging unit. Patient preparation involved techniques such as having experienced staff present to work with patients and providing external management during imaging. Six of eight patients had extensive training and practice prior to the procedure. In the two youngest patients, this training included use of a mock MR unit.
All cases yielded successful imaging. Finger tapping in all seven of the patients who could perform it demonstrated focal motor activation in the frontal-parietal region, with expected activation elsewhere, including in the cerebellum. Three of four patients had the expected verb generation task activations, with left-hemisphere dominance, including a 6-year-old child who functioned at the 3-year, 9-month level. The only child (an 8-year-old) who was not prepared prior to the imaging session for the verb generation task failed this task due to movement artifact.
Despite the challenges of successfully using fMR imaging in very young and clinically involved patients, these studies can be performed successfully in children with a chronological age of 5 or 6 years and a developmental age as young as 3 or 4 years.
Hillary A. Shurtleff, Dwight Barry, Timothy Firman, Molly H. Warner, Rafael L. Aguilar-Estrada, Russell P. Saneto, John D. Kuratani, Richard G. Ellenbogen, Edward J. Novotny and Jeffrey G. Ojemann
Outcomes of focal resection in young children with early-onset epilepsy are varied in the literature due to study differences. In this paper, the authors sought to define the effect of focal resection in a small homogeneous sample of children who were otherwise cognitively intact, but who required early surgical treatment. Preservation of and age-appropriate development of intelligence following focal resection was hypothesized.
Cognitive outcome after focal resection was retrospectively reviewed for 15 cognitively intact children who were operated on at the ages of 2–6 years for lesion-related, early-onset epilepsy. Intelligence was tested prior to and after surgery. Effect sizes and confidence intervals for means and standard deviations were used to infer changes and differences in intelligence between 1) groups (pre vs post), 2) left versus right hemisphere resections, and 3) short versus long duration of seizures prior to resection.
No group changes from baseline occurred in Full Scale, verbal, or nonverbal IQ. No change from baseline intelligence occurred in children who underwent left or right hemisphere surgery, including no group effect on verbal scores following surgery in the dominant hemisphere. Patients with seizure durations of less than 6 months prior to resection showed improvement from their presurgical baseline in contrast to those with seizure duration of greater than 6 months prior to surgery, particularly in Wechsler Full Scale IQ and nonverbal intelligence.
This study suggests that surgical treatment of focal seizures in cognitively intact preschool children is likely to result in seizure remediation, antiepileptic drug discontinuation, and no significant decrement in intelligence. The latter finding is particularly significant in light of the longstanding concern associated with performing resections in the language-dominant hemisphere. Importantly, shorter seizure duration prior to resection can result in improved cognitive outcome, suggesting that surgery for this population should occur sooner to help improve intelligence outcomes.
Anthony C. Wang, George M. Ibrahim, Andrew V. Poliakov, Page I. Wang, Aria Fallah, Gary W. Mathern, Robert T. Buckley, Kelly Collins, Alexander G. Weil, Hillary A. Shurtleff, Molly H. Warner, Francisco A. Perez, Dennis W. Shaw, Jason N. Wright, Russell P. Saneto, Edward J. Novotny, Amy Lee, Samuel R. Browd and Jeffrey G. Ojemann
The potential loss of motor function after cerebral hemispherectomy is a common cause of anguish for patients, their families, and their physicians. The deficits these patients face are individually unique, but as a whole they provide a framework to understand the mechanisms underlying cortical reorganization of motor function. This study investigated whether preoperative functional MRI (fMRI) and diffusion tensor imaging (DTI) could predict the postoperative preservation of hand motor function.
Thirteen independent reviewers analyzed sensorimotor fMRI and colored fractional anisotropy (CoFA)–DTI maps in 25 patients undergoing functional hemispherectomy for treatment of intractable seizures. Pre- and postoperative gross hand motor function were categorized and correlated with fMRI and DTI findings, specifically, abnormally located motor activation on fMRI and corticospinal tract atrophy on DTI.
Normal sensorimotor cortical activation on preoperative fMRI was significantly associated with severe decline in postoperative motor function, demonstrating 92.9% sensitivity (95% CI 0.661–0.998) and 100% specificity (95% CI 0.715–1.00). Bilaterally robust, symmetric corticospinal tracts on CoFA-DTI maps were significantly associated with severe postoperative motor decline, demonstrating 85.7% sensitivity (95% CI 0.572–0.982) and 100% specificity (95% CI 0.715–1.00). Interpreting the fMR images, the reviewers achieved a Fleiss’ kappa coefficient (κ) for interrater agreement of κ = 0.69, indicating good agreement (p < 0.01). When interpreting the CoFA-DTI maps, the reviewers achieved κ = 0.64, again indicating good agreement (p < 0.01).
Functional hemispherectomy offers a high potential for seizure freedom without debilitating functional deficits in certain instances. Patients likely to retain preoperative motor function can be identified prior to hemispherectomy, where fMRI or DTI suggests that cortical reorganization of motor function has occurred prior to the operation.
Fabio Grassia, Andrew V. Poliakov, Sandra L. Poliachik, Kaitlyn Casimo, Seth D. Friedman, Hillary Shurtleff, Carlo Giussani, Edward J. Novotny Jr., Jeffrey G. Ojemann and Jason S. Hauptman
Functional connectivity magnetic resonance imaging (fcMRI) is a form of fMRI that allows for analysis of blood oxygen level–dependent signal changes within a task-free, resting paradigm. This technique has been shown to have efficacy in evaluating network connectivity changes with epilepsy. Presurgical data from patients with unilateral temporal lobe epilepsy were evaluated using the fcMRI technique to define connectivity changes within and between the diseased and healthy temporal lobes using a within-subjects design.
Using presurgical fcMRI data from pediatric patients with unilateral temporal lobe epilepsy, the authors performed seed-based analyses within the diseased and healthy temporal lobes. Connectivity within and between temporal lobe seeds was measured and compared.
In the cohort studied, local ipsilateral temporal lobe connectivity was significantly increased on the diseased side compared to the healthy temporal lobe. Connectivity of the diseased side to the healthy side, on the other hand, was significantly reduced when compared to connectivity of the healthy side to the diseased temporal lobe. A statistically significant regression was observed when comparing the changes in local ipsilateral temporal lobe connectivity to the changes in inter–temporal lobe connectivity. A statistically significant difference was also noted in ipsilateral connectivity changes between patients with and those without mesial temporal sclerosis.
Using fcMRI, significant changes in ipsilateral temporal lobe and inter–temporal lobe connectivity can be appreciated in unilateral temporal lobe epilepsy. Furthermore, fcMRI may have a role in the presurgical evaluation of patients with intractable temporal lobe epilepsy.