Bicknell, L. | Search bioRxiv

bioRxiv2025

Elevated Thalamic Blood Flow in Self-Limited Epilepsy with Centrotemporal Spikes

Children with self-limited epilepsy syndrome with centrotemporal spikes (SeLECTS) exhibit altered thalamocortical connectivity, but whether thalamic function itself is abnormal remains unclear. We investigated whether thalamic blood flow, a marker of metabolism, differs between children with SeLECTS and controls, and examined the effects of spike distribution and antiseizure medications (ASMs) on thalamic perfusion. In this retrospective cohort study, we identified consecutive children with SeLECTS who underwent magnetic resonance imaging (MRI) for epilepsy evaluation (n = 44) and age- and sex-matched children who underwent MRI for non-epilepsy indications (n = 35). We quantified thalamic blood flow via manual segmentation of cerebral blood flow (CBF) sequences obtained from arterial spin labeling MRI. Clinical variables including sedation use during MRI, daily ASM use, and spike distribution (unilateral or bilateral) were extracted from medical records. Children with SeLECTS demonstrated elevated thalamic blood flow compared to controls, with the most pronounced differences in specific subgroups. Children with unilateral spikes showed the highest CBF, particularly in the thalamus contralateral to spike activity. ASM use significantly modulated thalamic blood flow: children taking oxcarbazepine showed the highest CBF, while those on levetiracetam had CBF similar to controls. Unmedicated children showed intermediate elevations. These findings demonstrate that elevated thalamic blood flow may be intrinsic to SeLECTS pathophysiology, with different ASMs producing distinct neurobiological effects. The differential medication effects may relate to their clinical efficacy and provide neurobiological rationale for treatment selection in this common childhood epilepsy syndrome.

neuroscience↗

bioRxiv2025

Unilateral loss of recql4 function in Xenopus laevis tadpoles leads to ipsilateral ablation of the forelimb, hypoplastic Meckel's cartilage and vascular defects.

RECQL4 encodes a RecQ helicase, one of a family of DNA unwinding enzymes with roles in DNA replication, double strand break repair and genomic stability. Pathogenic variants in RECQL4 are clinically associated with three rare autosomal recessive conditions: Rothmund-Thomson Syndrome type II, Baller-Gerold Syndrome and RAPADILINO syndrome. These three syndromes show overlapping growth retardation, low bone density and skeletal defects affecting the arms and hands. Here, we take advantage of the ability to generate one-sided CRISPR knockdowns of recql4 in Xenopus laevis tadpoles. Tadpoles develop normally until feeding starts, after which growth slows on the edited side leading to a curved posture, smaller eyes (micropthalmia) and reduced head size (microcephaly). Forelimb buds fail to develop, leading to complete absense of the forelimb on the edited side. Additionally, Meckels cartilage (lower jaw) ossification is absent or reduced and the hyoid cartilage is smaller, but this is not due to deficiencies in cranial neural crest migration on the edited side. Knockdown of recql4 also results in hypoplastic vasculature, with reduced branching from the aorta on the edited side. Taken together, our results clearly show the utility of unilateral CRISPR editing in Xenopus for understanding the specific phenotypic developmental effects of mutations affecting cell proliferation.

developmental biology↗