The medial occipital lobe, composed of the lingual gyrus and cuneus, is necessary for both basic and higher level visual processing. It is also known to facilitate cross-modal, nonvisual functions, ...such as linguistic processing and verbal memory, after the loss of the visual senses. A detailed cortical model elucidating the white matter connectivity associated with this area could improve our understanding of the interacting brain networks that underlie complex human processes and postoperative outcomes related to vision and language.
Generalized q-sampling imaging tractography, validated by gross anatomic dissection for qualitative visual agreement, was performed on 10 healthy adult controls obtained from the Human Connectome Project.
Major white matter connections were identified by tractography and validated by gross dissection, which connected the medial occipital lobe with itself and the adjacent cortices, especially the temporal lobe. The short- and long-range connections identified consisted mainly of U-shaped association fibers, intracuneal fibers, and inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, middle longitudinal fasciculus, and lingual–fusiform connections.
The medial occipital lobe is an extremely interconnected system, supporting its ability to perform coordinated basic visual processing, but also serves as a center for many long-range association fibers, supporting its importance in nonvisual functions, such as language and memory. The presented data represent clinically actionable anatomic information that can be used in multimodal navigation of white matter lesions in the medial occipital lobe to prevent neurologic deficits and improve patients' quality of life after cerebral surgery.
Abstract
BACKGROUND AND IMPORTANCE
Apraxia of speech is a disorder of articulatory coordination and planning in speech sound production. Its diagnosis is based on deficits in articulation, prosody, ...and fluency. It is often described concurrent with aphasia or dysarthria, while pure apraxia of speech is a rare entity.
CLINICAL PRESENTATION
A right-handed man underwent focal surgical resection of a recurrent grade III astrocytoma in the left hemisphere dorsal premotor cortex located in the posterior middle frontal gyrus. After the procedure, he experienced significant long-term speech production difficulties. A battery of standard and custom language and articulatory assessments were administered, revealing intact comprehension and naming abilities, and preserved strength in orofacial articulators, but considerable deficits in articulatory coordination, fluency, and prosody—consistent with diagnosis of pure apraxia of speech. Tractography and resection volumes compared with publicly available imaging data from the Human Connectome Project suggest possible overlap with area 55b, an under-recognized language area in the dorsal premotor cortex and has white matter connectivity with the superior longitudinal fasciculus.
CONCLUSION
The case reported here details a rare clinical entity, pure apraxia of speech resulting from resection of posterior middle frontal gyrus. While not a classical language area, emerging literature supports the role of this area in the production of fluent speech, and has implications for surgical planning and the general neurobiology of language.
The inferior temporal gyrus (ITG) is known to be involved in high-cognitive functions, including visual and language comprehensions and emotion regulation. A detailed understanding of the nature of ...association fibers could significantly improve postoperative morbidity related to declining capacity. Through diffusion spectrum imaging−based fiber tracking, we have characterized these connections on the basis of their relationships to other cortical areas.
Diffusion spectrum images from 10 healthy adults of the Human Connectome Project were randomly selected and used for tractography analysis. We evaluated the ITG as a whole based on connectivity with other regions. All ITG tracts were mapped in both hemispheres, and a lateralization index was calculated with resultant tract volumes.
We identified 5 major connections of the ITG: U-fiber, inferior longitudinal fasciculus, vertical occipital fasciculus, arcuate fasciculus, and uncinate fasciculus. There was no fiber lateralization detected.
This study highlights the principal white-matter pathways of the ITG and demonstrates key underlying connections. We present a summary of the relevant clinical anatomy for this region of the cerebrum as part of a larger effort to understand it in its entirety.
The fusiform gyrus is understood to be involved in the processing of high-order visual information, particularly related to faces, bodies, and stimuli characterized by high spatial frequencies. A ...detailed understanding of the exact location and nature of associated white-tracts could significantly improve post-operative morbidity related to declining capacity. Through generalized q-sampling imaging (GQI) validated by gross dissection as a direct anatomical method of identifying white matter tracts, we have characterized these connections based on relationships to other well-known structures. We created the white matter tracts using GQI and confirmed the tracts using gross dissection. These dissections demonstrated connections to the occipital lobe from the fusiform gyrus along with longer association fibers that course through this gyrus. The fusiform gyrus is an important region implicated in such tasks as the visual processing of human faces and bodies, as well as the perception of stimuli with high spatial frequencies. Post-surgical outcomes related to this region may be better understood in the context of the fiber-bundle anatomy highlighted by this study.
Near-term risk factors for suicidal behavior, referred to as 'warning signs' (WS), distinguish periods of acute heightened risk from periods of lower risk within an individual. No prior published ...study has examined, using a controlled study design, a broad set of hypothesized WS for suicide attempt. This study addressed this gap through examination of hypothesized behavioral/experiential, cognitive, and affective WS among patients recently hospitalized following a suicide attempt.
Participants were recruited during hospitalization from five medical centers across the USA including two civilian hospitals and three Veterans Health Administration facilities (
= 349). A within-person case-crossover study design was used, where each patient served as her/his own control. WS were measured by the Timeline Follow-back for Suicide Attempts Interview and were operationalized as factors that were present (
absent) or that increased in frequency/intensity within an individual during the 6 h preceding the suicide attempt (case period) compared to the corresponding 6 h on the day before (control period).
Select WS were associated with near-term risk for suicide attempt including suicide-related communications, preparing personal affairs, drinking alcohol, experiencing a negative interpersonal event, and increases in key affective (e.g. emptiness) and cognitive (e.g. burdensomeness) responses.
The identification of WS for suicidal behavior can enhance risk recognition efforts by medical providers, patients, their families, and other stakeholders that can serve to inform acute risk management decisions.
This study sought to establish if models involving the specific combinations of identifiable behavioral warning signs (WS; i.e., alcohol use, suicidal communications, preparation of personal affairs, ...experiencing negative interpersonal life events) for a suicide attempt outperformed a simpler count model of WS to distinguish an acute risk period (the six hours prior to a suicide attempt) from a control period (a matched six-hour period the day prior).
Generalized linear mixed models tested all logical combinations of four behavioral WS in addition to a count variable of the number of behavioral warning signs. For the count variable, receiver operating characteristic curve analysis was utilized to determine the optimal cut point for the number of endorsed WS.
Area under the curve (AUC) compared classification across all models, with the count model demonstrating similar classification performance to the best multivariate model (AUCs of 0.72 and 0.73, respectively), with an optimal cut point of endorsing one or more WS.
Although determinations of acute risk should be informed by multiple sources of information, this study suggests a relatively simple count-based approach that considers the presence of one (or more) behavioral WS may be used as a potential indication of increased acute risk for suicide attempt.
Background
Lateralized alterations in hippocampal function in the resting-state have been demonstrated for patients with temporal lobe epilepsy (TLE). However, resting-state fMRI of the hippocampus ...has yet to be substantiated as an adjunct to standard pre-operative assessments of the seizure focus.
Objective
Here we report the results of a systematic review of resting-state fMRI studies investigating laterality of hippocampal network connectivity in TLE patients.
Methods
A search of the PubMed, SCOPUS, Web of Science, and Embase databases for full-length articles written in English was conducted through June 2020 using the following terms: ‘resting state fMRI,’ ‘hippocampus,’ ‘epilepsy,’ and ‘laterality.’
Results
Our literature search yielded a total of 42 papers. After excluding studies that did not include patients with epilepsy, utilize resting-state fMRI, or explore the relationship between functional connectivity and disease lateralization, 20 publications were selected for inclusion. From these studies, a total of 528 patients, 258 with left TLE and 270 with right TLE, and 447 healthy controls were included. Of the 20 studies included, 18 found that patients with TLE demonstrated decreased hippocampal functional connectivity ipsilateral to the epileptogenic focus and 10 additionally reported increased hippocampal functional connectivity contralateral to the epileptogenic focus. Several studies demonstrated that the duration of disease was correlated with these changes in functional connectivity. This implies that a compensatory mechanism may be present in patients with treatment-refractory TLE.
Conclusion
The consistency of this hippocampal connectivity pattern across multiple studies suggests resting-state fMRI may be useful as a non-invasive diagnostic tool for preoperative evaluation of TLE patients.
Deep brain stimulation (DBS) requires a consistent electrical supply from the implantable pulse generator (IPG). Patients may struggle to monitor their IPG, risking severe complications in battery ...failure. This review assesses current literature on DBS IPG battery life management and proposes a protocol for healthcare providers.
A literature search using four databases identified best practices for DBS IPG management. Studies were appraised for IPG management guidelines, categorized as qualitative, quantitative, or both.
Of 408 citations, only seven studies were eligible, none providing clear patient management strategies. Current guidelines lack specificity, relying on clinician suggestions.
Limited guidelines exist for IPG management. Specificity and adaptability to emerging technology are crucial. The findings highlight the need for specificity in patients' needs and adaptability to emerging technology in future studies. To address this need, we developed a protocol for DBS IPG management that we have implemented at our own institution. Further research is needed for effective DBS IPG battery life management, preventing therapy cessation complications.
Background:
There are few treatments with limited efficacy for patients with disorders of consciousness (DoC), such as minimally conscious and persistent vegetative state (MCS and PVS).
Objective:
In ...this meta-analysis of individual patient data (IPD), we examine studies utilizing transcranial magnetic stimulation (TMS) as a treatment in DoC to determine patient and protocol-specific factors associated with improved outcomes.
Methods:
We conducted a systematic review of PubMed, Ovid Medline, and Clinicaltrials.gov through April 2020 using the following terms: “minimally conscious state,” or “persistent vegetative state,” or “unresponsive wakefulness syndrome,” or “disorders of consciousness” and “transcranial magnetic stimulation.” Studies utilizing TMS as an intervention and reporting individual pre- and post-TMS Coma Recovery Scale-Revised (CRS-R) scores and subscores were included. Studies utilizing diagnostic TMS were excluded. We performed a meta-analysis at two time points to generate a pooled estimate for absolute change in CRS-R Index, and performed a second meta-analysis to determine the treatment effect of TMS using data from sham-controlled crossover studies. A linear regression model was also created using significant predictors of absolute CRS-R index change.
Results:
The search yielded 118 papers, of which 10 papers with 90 patients were included. Patients demonstrated a mean pooled absolute change in CRS-R Index of 2.74 (95% CI, 0.62–4.85) after one session of TMS and 5.88 (95% CI, 3.68–8.07) at last post-TMS CRS-R assessment. The standardized mean difference between real rTMS and sham was 2.82 (95% CI, −1.50 to 7.14), favoring rTMS. The linear regression model showed that patients had significantly greater CRS-R index changes if they were in MCS, had an etiology of stroke or intracranial hemorrhage, received 10 or more sessions of TMS, or if TMS was initiated within 3 months from injury.
Conclusions:
TMS may improve outcomes in MCS and PVS. Further evaluation with randomized, clinical trials is necessary to determine its efficacy in this patient population.
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