Characterizing Diaschisis-Related Thalamic Perfusion and Diffusion After Middle Cerebral Artery Infarction

Brain growth until adolescence after a neonatal focal injury: sex related differences beyond lesion effect

Introduction

Early focal brain injuries lead to long-term disabilities with frequent cognitive impairments, suggesting global dysfunction beyond the lesion. While plasticity of the immature brain promotes better learning, outcome variability across individuals is multifactorial. Males are more vulnerable to early injuries and neurodevelopmental disorders than females, but long-term sex differences in brain growth after an early focal lesion have not been described yet. With this MRI longitudinal morphometry study of brain development after a Neonatal Arterial Ischemic Stroke (NAIS), we searched for differences between males and females in the trajectories of ipsi- and contralesional gray matter growth in childhood and adolescence, while accounting for lesion characteristics.

Methods

We relied on a longitudinal cohort (AVCnn) of patients with unilateral NAIS who underwent clinical and MRI assessments at ages 7 and 16 were compared to age-matched controls. Non-lesioned volumes of gray matter (hemispheres, lobes, regions, deep structures, cerebellum) were extracted from segmented T1 MRI images at 7 (Patients: 23 M, 16 F; Controls: 17 M, 18 F) and 16 (Patients: 18 M, 11 F; Controls: 16 M, 15 F). These volumes were analyzed using a Linear Mixed Model accounting for age, sex, and lesion characteristics.

Results

Whole hemisphere volumes were reduced at both ages in patients compared to controls (gray matter volume: -16% in males, -10% in females). In ipsilesional hemisphere, cortical gray matter and thalamic volume losses (average -13%) mostly depended on lesion severity, suggesting diaschisis, with minimal effect of patient sex. In the contralesional hemisphere however, we consistently found sex differences in gray matter volumes, as only male volumes were smaller than in male controls (average -7.5%), mostly in territories mirroring the contralateral lesion. Females did not significantly deviate from the typical trajectories of female controls. Similar sex differences were found in both cerebellar hemispheres.

Discussion

These results suggest sex-dependent growth trajectories after an early brain lesion with a contralesional growth deficit in males only. The similarity of patterns at ages 7 and 16 suggests that puberty has little effect on these trajectories, and that most of the deviation in males occurs in early childhood, in line with the well-described perinatal vulnerability of the male brain, and with no compensation thereafter.

Exploring the Thalamus as a Target for Neuropathic Pain Management: An Integrative Review

Neuropathic pain (NP), resulting from damage to the somatosensory system, is characterized by either spontaneous or evoked pain. In the context of NP, wherein aberrant signaling pathways contribute to the perception of pain, the thalamus emerges as a key player. This structure is integral to the pain network that includes connections to the dorsal horn of the spinal cord, highlighting its role in the affective-motivational aspects of pain perception. Given its significant involvement, the thalamus is targeted in advanced treatments such as thalamotomy and deep brain stimulation (DBS) when traditional therapies fail, emphasizing the need to understand its function in NP to improve management strategies. This review aimed to provide an overview of the role of the thalamus in the transmission of nociceptive information in NP by discussing the existing evidence, including the effectiveness and safety of current techniques in the management and treatment of NP. This is an integrative review involving the qualitative analysis of scientific articles published in PubMed/MEDLINE, Embase, Scopus, and Web of Science. A total of 687 articles were identified, and after selection, 15 articles were included in this study. All studies reviewed demonstrated varying degrees of effectiveness of DBS and thalamotomy in alleviating painful symptoms, although the relief was often temporary. Many studies noted a reduction in pain perception at the conclusion of treatment compared to pre-treatment levels, with this decrease maintained throughout patient follow-ups. However, adverse events associated with these treatments were also reported. In conclusion, there are some benefits, albeit temporary, to using thalamotomy and DBS to alleviate the painful symptoms of NP. Both procedures are considered advanced forms of surgical intervention that aim to modulate pain pathways in the brain, providing significant relief for patients suffering from chronic pain resistant to conventional treatment. Despite limitations, these surgical interventions offer renewed hope for patients facing disabling chronic pain and can provide a significant improvement in quality of life.

Neuronal Alterations in Secondary Thalamic Degeneration Due to Cerebral Infarction: A 11 C-Flumazenil Positron Emission Tomography Study

Studies using animal experiments have shown secondary neuronal degeneration in the thalamus after cerebral infarction. Neuroimaging studies in humans have revealed changes in imaging parameters in the thalamus, remote to the infarction. However, few studies have directly demonstrated neuronal changes in the thalamus in vivo. The purpose of this study was to determine whether secondary thalamic neuronal damage may manifest as a decrease in central benzodiazepine receptors in patients with cerebral infarction and internal carotid artery or middle cerebral artery disease.