Hemispherectomy for dominant hemisphere Rasmussen's Encephalitis - how late is too late?

It is unclear whether a dominant hemispherectomy/hemispherotomy in someone with Rasmussen's Encephalitis (RE) may produce a satisfactory outcome when performed over the age of 40 years. Important questions include whether RE may continue to evolve three decades after onset, and whether a hemispherectomy may adequately shift language function when performed in older ages. Two cases illustrate seizure, language, motor and functional outcomes after dominant hemispherotomies. The cases were selected from an epilepsy surgery database of procedures performed at a private hospital in Cape Town, South Africa, spanning the period 1998-2023. A man in his 40s with epilepsy since childhood and dominant hemisphere RE partially regained impaired comprehension and ambulation, while expressive language function did not recover post-hemispherotomy. By contrast, a young teenage patient with dominant hemisphere RE demonstrated considerable recovery of expressive and receptive language and ambulation post-surgery. Both remain seizure-free. These two cases demonstrate that a dominant hemispherotomy, when performed on a quadragenarian, may produce a satisfactory, albeit inferior, functional outcome in comparison to when performed in childhood. RE may cause progressive neurological dysfunction in the late thirties and older and should be considered in patients presenting with functional decline decades after disease onset.

Cell type-specific gene expression dynamics during human brain maturation.

The human brain undergoes protracted post-natal maturation, guided by dynamic changes in gene expression. To date, studies exploring these processes have used bulk tissue analyses, which mask cell type-specific gene expression dynamics. Here, using single nucleus (sn)RNA-Sseq on temporal lobe tissue, including samples of African ancestry, we build a joint paediatric and adult atlas of 54 cell subtypes, which we verify with spatial transcriptomics. We explore the differences in cell states between paediatric and adult cell types, revealing the genes and pathways that change during brain maturation. Our results highlight excitatory neuron subtypes, including the LTK and FREM subtypes, that show elevated expression of genes associated with cognition and synaptic plasticity in paediatric tissue. The new resources we present here improve our understanding of the brain during a critical period of its development and contribute to global efforts to build an inclusive cell map of the brain.

Stereotactic proton beam therapy for intracranial arteriovenous malformations.

PURPOSE: To investigate hypofractionated stereotactic proton therapy of predominantly large intracranial arteriovenous malformations (AVMs) by analyzing retrospectively the results from a cohort of patients. METHODS AND MATERIALS: Since 1993, a total of 85 patients with vascular lesions have been treated. Of those, 64 patients fulfilled the criteria of having an arteriovenous malformation and sufficient follow-up. The AVMs were grouped by volume: <14 cc (26 patients) and > or =14 cc (38 patients). Treatment was delivered with a fixed horizontal 200 MeV proton beam under stereotactic conditions, using a stereophotogrammetric positioning system. The majority of patients were hypofractionated (2 or 3 fractions), and the proton doses are presented as single-fraction equivalent cobalt Gray equivalent doses (SFEcGyE). The overall mean minimum target volume dose was 17.37 SFEcGyE, ranging from 10.38-22.05 SFEcGyE. RESULTS: Analysis by volume group showed obliteration in 67% for volumes <14 cc and 43% for volumes > or =14 cc. Grade IV acute complications were observed in 3% of patients. Transient delayed effects were seen in 15 patients (23%), becoming permanent in 3 patients. One patient also developed a cyst 8 years after therapy. CONCLUSIONS: Stereotactic proton beam therapy applied in a hypofractionated schedule allows for the safe treatment of large AVMs, with acceptable results. It is an alternative to other treatment strategies for large AVMs. AVMs are likely not static entities, but probably undergo vascular remodeling. Factors influencing angiogenesis could play a new role in a form of adjuvant therapy to improve on the radiosurgical results.

A quick and universal method for stereotactic visualization of the subthalamic nucleus before and after implantation of deep brain stimulation electrodes.

For deep brain stimulation (DBS) of the subthalamic nucleus (STN), it would be an advantage if the STN could be visualized with fast acquisition of MR images, allowing direct and individual targeting. We present a protocol for T2-weighted, nonvolumetric fast-acquisition MRI, implemented at 8 centers in 6 countries. Acquisition time varied between 3 min 5 s and 7 min 48 s according to the center, and imaging often provided visualization of the STN on axial and coronal scans. Postoperatively, the same imaging protocol permitted visualization of the target area and DBS electrodes with minimum artifacts. This imaging technique may contribute to a decrease in the number of electrode passes at surgery.