From the Guidelines
The cornu ammonis (CA) regions, specifically CA1, and the subiculum in the hippocampus are directly involved in hippocampal sclerosis, characterized by pyramidal cell loss and gliosis, as defined by the National Institute on Aging-Alzheimer's Association guidelines 1. Hippocampal sclerosis is a condition that can be observed in the context of Alzheimer's disease neuropathologic change, frontotemporal lobar degeneration (FTLD), and vascular brain injury (VBI), likely reflecting a heterogeneous etiology. The involvement of CA1 and subiculum in hippocampal sclerosis is supported by the presence of TDP-43 immunoreactive inclusions in the majority of cases of hippocampal sclerosis, as well as in other neurodegenerative diseases 1. Key features of hippocampal sclerosis include:
- Neuronal loss and gliosis primarily affecting the CA1 region of the hippocampus
- Involvement of the subiculum, though typically to a lesser extent than the CA regions
- Characteristic hardening or "sclerosis" of the hippocampal tissue
- Disruption of normal hippocampal circuitry, leading to hyperexcitability and recurrent seizures in temporal lobe epilepsy
- Selective vulnerability of CA1 pyramidal neurons to excitotoxicity and oxidative stress Diagnosis of hippocampal sclerosis typically involves MRI showing hippocampal atrophy and increased signal on T2-weighted images, reflecting the underlying neuronal loss and gliosis in these specific hippocampal subregions, as recommended by the American College of Radiology 1.
From the Research
Hippocampal Sclerosis and Cornu Ammonis and Subiculum Involvement
- The provided studies do not directly address the involvement of cornu ammonis and subiculum in hippocampal sclerosis 2, 3, 4, 5.
- However, one study discusses the volume of hippocampal subfields, including cornu ammonis and subiculum, across the lifespan 6.
- The study found that the volume of combined CA1-2 (part of cornu ammonis) evidenced a negative linear association with age, while the volume of the subiculum was unrelated to age 6.
- Another study mentions that hippocampal sclerosis can occur in association with other brain lesions and that successful surgical treatment usually involves the resection of both the lesion and the involved hippocampus, but does not specifically mention cornu ammonis and subiculum 2.
- The other studies focus on the treatment of mesial temporal lobe epilepsy with hippocampal sclerosis, including the effectiveness of antiepileptic drugs and surgical treatment, but do not provide information on the specific involvement of cornu ammonis and subiculum 3, 4, 5.