• Effect of Maxillary Features on Tongue Anteriority in Glossectomy and Control Speakers

      Hwang, Jun Hyuk; Stone, Maureen L. (2015)
      This study examines the behavior of glossectomy (N = 15) and normal tongue (N =20) movement using combination of high-resolution and cine- MRI. The speech task "a souk" was used to measure anterior tongue displacement, termed "anteriority", from /uh/ to /s/. Effects on anteriority due to palate height, /s/ type, arch perimeter, canine width, and orthodontic extraction of teeth were measured on controls and patients. Results showed that all factors except canine width had no significant difference in anteriority of tongue. Canine width was significantly related to anteriority in an inverse relationship. The fact that arch perimeter is less important than canine width on anteriority is consistent with our understanding of the criticality of the location of the tongue tip, rather than the tongue body, in producing /s/. Data also suggests that less than average arch perimeter improves speech intelligibility in patients with T2 tumor of the tongue.
    • The Effects of Glossectomy and Palatal Dimension on Activity of the Tongue Muscles: A Quantitative MRI Analysis

      Lim, Ji Youn; Stone, Maureen L. (2016)
      Purpose: The purpose of this study was to compare the tongue muscle activity of glossectomy patients and normal controls and to determine which of the following factors - palate height, palate width, and tumor size (T1 vs. T2) - might influence muscle activity after glossectomy. Methods: Muscle shortening within the hemi-tongue of 12 controls and 9 glossectomy patients was measured during the elevation and retraction of the tongue from /s/ into the /uk/ of the word "a souk" using cine-MRI and tagged-MRI. The muscle length measurements were performed on the following five tongue muscle segments: 1) genioglossus posterior (GGp), 2) geniohyoid (GH), 3) transverse anterior (Ta), 4) transverse middle (Tm), and 5) transverse posterior (Tp). Results: The controls demonstrated significant asymmetric Ta and Tp muscle shortening with the larger side shortening more than the smaller side. The patients showed relatively symmetric muscle shortening on the native and the resected sides. High palate subjects showed greater GH shortening, while wide palate subjects showed greater GH and Ta shortening. No significant interaction was found between the effects of palate dimension and glossectomy on muscle shortening. A significant positive correlation between shortening was found in five pairs of muscles in controls' both sides and in one pair (Ta and Tm) in patients' native side. The T2 patients showed less shortening than T1 patients on both the native and the resected sides for Ta and Tm. Conclusion: There were no statistically significant differences in muscle shortening between the controls and the patients, suggesting that patients were unable to adapt to an easier, asymmetric muscle activity as in controls during multiple repetitions of speech task. The effects of palate height and width were independent of the surgical effects. In controls, the muscles functioned synergistically in order to elevate the tongue by decreasing its length and width. In patients, the Ta and Tm worked in concert to decrease tongue width and create a compensatory behavior during tongue elevation. The lesser muscle shortening in T2 than T1 patients suggested greater impairment and limited muscle activity in T2 patients.
    • An Investigation of the Default Mode Interference Hypothesis in Mild Traumatic Brain Injury

      Sours, Chandler; Gullapalli, Rao P. (2014)
      Traumatic brain injury (TBI) is a leading cause of death and lifelong disability throughout developed nations, resulting in an emotional burden on the patients and a vast financial burden on the nation. While the majority of these cases are mild in nature, current clinical imaging often fails to perceive the extent of this subtle injury, making it difficult to predict which of these individuals will go on to suffer from persistent post concussive symptoms. Through the use of resting state functional MRI (fMRI), resting state cerebral perfusion, and task based fMRI, we test the hypothesis that the diffuse neuronal damage associated with mild TBI (mTBI) interrupts large-scale network function resulting in cognitive and neuropsychological symptoms. The Default Mode Interference Hypothesis suggests that the interactions within and between the Default Mode Network (DMN), Task Positive Network (TPN), and Salience Network (SN) are associated with cognitive performance. Therefore, we focused our investigation upon these three networks. Using resting state fMRI on prospectively collected data, our results demonstrate reduced resting state functional connectivity (rs-FC) within the DMN and TPN, but increased rs-FC between the three networks across the acute, sub-acute, and chronic stages of injury. Furthermore, the alterations noted in rs-FC are exacerbated in mTBI patients with persistent symptoms and are associated with reduced cognitive performance. Through the use of resting state cerebral perfusion, our findings demonstrate an altered balance in network perfusion of the DMN and TPN that is more prominent in mTBI patients with greater symptom severity. Finally, through the use of task based fMRI during the N-back working memory paradigm, we note that mTBI patients reveal reduced deactivation of regions of the DMN, over recruitment of regions of the TPN, as well as regions of novel recruitment. Further, mTBI patients demonstrate reduced segregation between the DMN and TPN during the most cognitively demanding task. These findings provide strong evidence for the Default Mode Interference Hypothesis in mTBI. Through lending support that altered communication within these large-scale neural networks contributes to the persistence of post concussive symptoms, we provide a potential avenue for therapeutic intervention to mitigate post concussive symptoms.
    • Neuroimaging in Headache Patients: The Sensitivity of Computerized Tomography (CT) in Missed Stroke Diagnoses

      Heetderks, Elizabeth; Johantgen, Mary E. (2018)
      Background: Stroke is the leading cause of disability in the US, costing $34 billion a year and affecting 800,000 patients. Early detection and treatment is the best way to improve outcomes. Yet, 12.5% of strokes are discharged from the ED within the prior 30 days, with headache the most common diagnosis. Neuroimaging, ideally, would catch an impending stroke, but head CT has variable sensitivity based on onset of symptoms and there are both Federal and provider-led (including Choosing Wisely and the American College of Radiology Appropriateness Criteria (ACR-AC) initiatives to reduce overuse of imaging. Purpose: This study examined variation in ED treatment for patients presenting with a headache, particularly focusing on use of neuroimaging. Potential missed strokes were identified to determine if CT or MRI could have captured stroke. Methods: Using HCUP 2013 Maryland State Emergency Department Dataset, and State Inpatient Data, patients who were seen in the ED within 30 days of a stroke with a complaint of headache were identified. Generalized linear mixed modeling determined if neuroimaging predicted stroke bounce back while controlling for patient and hospital variables. Results: Of the 63,942 headache visits in Maryland EDs, 337 patients presented with a stroke within 30 days of ED discharge. Half (54%) were seen in the ED the day of their stroke and 72% were seen within 7 days. A large majority of the stroke patients (82%) underwent CT for their ED headache visit. Patients who underwent CT for their headache were 2.5 times more likely to return with ischemic stroke, and 7.7 times more likely to return with hemorrhagic. Patients who underwent MRI were 1.7 times more likely to return with any stroke, and 2.8 times more likely to return with ischemic stroke. Conclusions: Providers were concerned about pathology, given the large percentage of patients imaged; however, imaging did not catch active ischemia or bleeding. The negative predictive value of imaging for headache may need to be reconsidered. Patients with high suspicion of pathology should be placed in observation and have appropriate follow up testing. The ACR-AC should be incorporated into diagnostic pathways to optimize use.
    • Neuroimaging Insights Into Neuromodulation for Addiction: Effects of Transcranial Direct Current Stimulation on Cognitive Circuits Implicated in the Nicotine Withdrawal Syndrome

      Aronson Fischell, Sarah; Stein, Elliot; Keller, Asaf (2020)
      Cigarette smoking is the leading cause of preventable death in the United States. The nicotine withdrawal syndrome (NWS) remains a barrier to successful smoking cessation; however, current pharmacological treatments minimally impact sustained abstinence. An emerging class of non-invasive neuromodulation devices, such as transcranial direct current stimulation (tDCS), have been proposed as novel therapeutics for smoking cessation. tDCS has the potential to modulate brain circuits by application of weak currents through the scalp; its use builds upon recent advances in mapping the large-scale network organization of the brain. Functional magnetic resonance imaging (fMRI) functional connectivity (FC) studies have identified three networks as particularly vulnerable to disruption in psychopathology: the Executive Control Network (ECN), Salience Network (SN), and Default Mode Network (DMN). The NWS has been hypothesized to be mediated by reduced FC within the ECN, and between ECN–SN; and increased FC within the DMN, and between DMN–SN. It is hypothesized that tDCS, applied to cortical nodes of the ECN (e.g. dorsolateral prefrontal cortex) and DMN (e.g. ventromedial prefrontal cortex), may remediate NWS network dysregulation. Network effects of tDCS were assessed by simultaneous task-based fMRI. 15 smokers (in sated and withdrawal states) and 28 matched nonsmokers participated in a double-blind, randomized crossover design of three tDCS conditions: anodal left-dlPFC/cathodal right-vmPFC (“An-dlPFC”), polarity reversed (“An-vmPFC”), and Sham. Although single-session (25min, 2mA) tDCS did not evoke task behavior changes, An-dlPFC tDCS robustly suppressed DMN nodes during a working memory task, and enhanced anterior cingulate activity (SN node) during a conflict monitoring task. DMN suppression within smokers was more pronounced during the sated (vs. withdrawn) state. Given that DMN and SN are hypothesized to be dysregulated in nicotine and other addictions, these data quantitatively support the hypothesis that tDCS may modify large-scale circuits implicated in addictive disease. Additionally, the observation of state-dependent tDCS effects in smokers suggests that tDCS may be most efficacious when combined with standard smoking cessation therapies. This work contributes a translational approach to assessment of tDCS, an emerging intervention at the crossroads of basic neuroscience research and clinical therapeutics in addiction and psychiatric disease.
    • Tongue Muscle Shortening Differences in Glossectomy Versus Non-Glossectomy Patients

      Dao, Anh; Stone, Maureen L. (2021)
      In cancers that affect the tongue, the most common treatment is glossectomy, a procedure that can have substantial effects on a patient’s intelligibility. We are seeking to identify the effect of this resection on the use of four muscles – genioglossus, transversus, verticalis, and superior longitudinal, which comprise the bulk of the tongue. MRI data was used to study differences in tongue muscle shortening patterns during the speech task “a thing” between patients who have undergone glossectomies and controls who have not. Speech data was collected from 2D tagged-MRI movies and reconstructed into 3D volumes at 26 timeframes. Velocity fields and tissue points were extracted and shortening was calculated to study how the muscles were used by glossectomies vs. controls to protract and retract the tongue during /θ/. The results reveal differences in function between the two groups, and potential compensation strategies for glossectomy patients.