Lumbar punctures are safe in patients with ALS and have a risk profile similar to that in the non-ALS population

INTRODUCTION/AIMS

Analysis of biofluids, especially cerebrospinal fluid (CSF), is critically important for amyotrophic lateral sclerosis (ALS) research. Collection of CSF is typically performed by lumbar puncture (LP). Previous studies have demonstrated the safety of LPs in patients with other neurodegenerative diseases, such as Alzheimer's disease, although there are no published studies of the safety of LPs in patients with ALS. We performed a retrospective analysis of complications resulting from LPs.

METHODS

This is a retrospective study of LPs performed between 2015 and 2021 on a total of 233 participants (healthy controls [n = 63], ALS [n = 154], and disease controls [n = 16]) as part of clinical research studies at the Washington University ALS Center. We used bivariate logistical analyses looking for associations between participant characteristics and adverse events (AEs), and likelihood ratio tests were used for significance testing.

RESULTS

We found an overall AE rate of 21.03%. AEs included headache, back pain, vasovagal syncope, and severe headache requiring epidural blood patch. Participants with ALS were not more likely to experience post-LP AEs compared to controls (odds ratio [OR] 0.61 [0.32-1.18]). Post-LP headaches were significantly less likely in participants with ALS (OR 0.36 [0.15-0.83]).

DISCUSSION

Our findings demonstrate that LP is a safe procedure for participants with ALS, with a similar or lower rate of AEs than in participants without ALS.

Protective Effects of Lovastatin in a Population-Based ALS Study and Mouse Model

OBJECTIVE

The objective of this study was to use a novel combined pharmacoepidemiologic and amyotrophic lateral sclerosis (ALS) mouse model approach to identify potential motor neuron protective medications.

METHODS

We constructed a large, population-based case-control study to investigate motor neuron disease (MND) among US Medicare beneficiaries aged 66 to 90 in 2009. We included 1,128 incident MND cases and 56,400 age, sex, race, and ethnicity matched controls. We calculated MND relative risk for >1,000 active ingredients represented in Part D (pharmacy) claims in 2006 to 2007 (>1 year before diagnosis/reference). We then applied a comprehensive screening approach to select medications for testing in SOD1^G93A mice: sulfasalazine, telmisartan, and lovastatin. We treated mice with the human dose equivalent of the medication or vehicle via subcutaneous osmotic pump before onset of weakness. We then assessed weight, gait, and survival. In additional mice, we conducted histological studies.

RESULTS

We observed previously established medical associations for MND and an inverse dose-response association between lovastatin and MND, with 28% reduced risk at 40 mg/day. In SOD1^G93A mouse studies, sulfasalazine and telmisartan conferred no benefit, whereas lovastatin treatment delayed onset and prolonged survival. Lovastatin treated mice also had less microgliosis, misfolded SOD1, and spinal motor neuron loss in the ventral horn.

INTERPRETATION

Lovastatin reduced the risk of ALS in humans, which was confirmed in an ALS mouse model by delayed symptom onset, prolonged survival, and preservation of motor neurons. Although further studies to understand the mechanism are required, lovastatin may represent a potential neuroprotective therapy for patients with ALS. These data demonstrate the utility of a combined pharmacoepidemiologic and mouse model approach. ANN NEUROL 2023.

Antisense Oligonucleotides for the Study and Treatment of ALS

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by motor neuron loss. ALS is now associated with mutations in numerous genes, many of which cause disease in part through toxic gain-of-function mechanisms. Antisense oligonucleotides (ASOs) are small sequences of DNA that can reduce expression of a target gene at the post-transcriptional level, making them attractive for neutralizing mutant or toxic gene products. Advancements in the medicinal chemistries of ASOs have improved their pharmacodynamic profile to allow safe and effective delivery to the central nervous system. ASO therapies for ALS have rapidly developed over the last two decades, and ASOs that target SOD1, C9orf72, FUS, and ATXN2 are now in clinical trials for familial or sporadic forms of ALS. This review discusses the current state of ASO therapies for ALS, outlining their successes from preclinical development to early clinical trials.

Adult-Onset Subacute Sclerosing Panencephalitis With a 30-Year Latent Period

Subacute sclerosing panencephalitis (SSPE) is a rare progressive neuroinfectious disease due to a late complication of the measles virus. The hallmark clinical features of this disease include behavioral changes, myoclonus, dementia, visual disturbances, and pyramidal and extrapyramidal signs. The presence of characteristic high-amplitude periodic complexes on electroencephalography and raised antibody titers against measles in the cerebrospinal fluid help solidify the diagnosis. We present a case of a 40-year-old patient with SSPE who initially developed ophthalmologic manifestations 30 years after the primary measles infection. This case highlights both typical and atypical features of SSPE and provides a diagnostic framework for evaluating cases that fall outside of the standard scope of this disease.

The amygdala differentially regulates defensive behaviors evoked by CO2

CO₂ inhalation can provoke panic attacks in humans, and the likelihood is increased in patients with panic disorder. Identifying brain sites involved could provide important mechanistic insight into the illness. In mice, the amygdala has been suggested to promote CO₂ responses; however, recent studies in humans with amygdala damage indicate the amygdala is not required for CO₂-induced fear and panic and might actually oppose these responses. To clarify the role of the amygdala, we produced lesions in mice paralleling the human lesions, and characterized behavioral responses to CO₂. Compared to sham controls, we found that amygdala-lesioned mice froze less to 10% CO₂, and unlike shams they also began to jump frenetically. At 20% CO₂, controls also exhibited jumping, suggesting it is a normal response to more extreme CO₂ concentrations. The effect of amygdala lesions was specific to CO₂ as amygdala-lesioned mice did not jump in response to a predator odor or to an auditory conditioned stimulus. In amygdala-lesioned mice, jumping evoked by 10% CO₂ was eliminated by co-lesioning the dorsal periaqueductal gray, a structure implicated in panic and escape-related behaviors. Together, these observations suggest a dual role for the amygdala in the CO₂ response: promoting CO₂-induced freezing, and opposing CO₂-induced jumping, which may help explain the exaggerated CO₂ responses in humans with amygdala lesions.

ASIC1A in neurons is critical for fear-related behaviors

Acid-sensing ion channels (ASICs) have been implicated in fear-, addiction- and depression-related behaviors in mice. While these effects have been attributed to ASIC1A in neurons, it has been reported that ASICs may also function in nonneuronal cells. To determine if ASIC1A in neurons is indeed required, we generated neuron-specific knockout (KO) mice with floxed Asic1a alleles disrupted by Cre recombinase driven by the neuron-specific synapsin I promoter (SynAsic1a KO mice). We confirmed that Cre expression occurred in neurons, but not all neurons, and not in nonneuronal cells including astrocytes. Consequent loss of ASIC1A in some but not all neurons was verified by western blotting, immunohistochemistry and electrophysiology. We found ASIC1A was disrupted in fear circuit neurons, and SynAsic1a KO mice exhibited prominent deficits in multiple fear-related behaviors including Pavlovian fear conditioning to cue and context, predator odor-evoked freezing and freezing responses to carbon dioxide inhalation. In contrast, in the nucleus accumbens ASIC1A expression was relatively normal in SynAsic1a KO mice, and consistent with this observation, cocaine conditioned place preference (CPP) was normal. Interestingly, depression-related behavior in the forced swim test, which has been previously linked to ASIC1A in the amygdala, was also normal. Together, these data suggest neurons are an important site of ASIC1A action in fear-related behaviors, whereas other behaviors likely depend on ASIC1A in other neurons or cell types not targeted in SynAsic1a KO mice. These findings highlight the need for further work to discern the roles of ASICs in specific cell types and brain sites.

Drug abuse and the simplest neurotransmitter

Neurotransmitter vesicles are known to concentrate hydrogen ions (or protons), the simplest ion, and to release them during neurotransmission. Furthermore, receptors highly sensitive to protons, acid-sensing ion channels (ASICs), were previously localized on the opposite side of the synaptic cleft on dendritic spines. Now, recent experiments provide some of the strongest support to date that protons function as a neurotransmitter in mice, crossing synapses onto medium spiny neurons of the nucleus accumbens (NAc), activating ASICs, and ultimately suppressing drug abuse-related behaviors.