April 2026 Research Update

This month, small human studies reported that surgery or implanted stimulation aimed at the spinal cord was followed by lower muscle tightness (spasticity) and better walking measures in some people with hereditary spastic paraplegia (HSP). [1] [2] The results point in the same direction across adults and children, but both reports are early and do not prove how well these approaches work compared with other options. [1] [2]

In 18 people with HSP who received epidural spinal cord stimulation (an implanted system that sends electrical signals near the spinal cord), scores for spasticity, walking tests, and quality of life were better at 6 months than before implantation. [2] Because the study compared people to their own baseline rather than to a separate control group, the improvement is encouraging but still needs confirmation in other research settings. [2]

In a small group of 6 children with HSP who underwent selective dorsal rhizotomy (a surgery that cuts selected sensory nerve fibers to reduce spasticity), spasticity scores dropped sharply and several movement and daily-life measures improved during follow-up. [1] The report also described reduced reliance on braces and improvements in pain and fatigue for many children, with no major surgical complications noted in this series. [1]

For patients and caregivers, these studies add to the picture that procedures targeting nerve and spinal cord signaling may reduce spasticity and may translate into easier walking and better day-to-day functioning for some people with HSP. The evidence this month comes from small, single-center experiences without a comparison group, so it mainly helps set expectations for what researchers are testing and what outcomes they are measuring. What remains uncertain is who benefits most, how long improvements last, and how these options compare with other approaches in larger studies. [1] [2]

This month, genetic testing research reinforced that SPG4 (caused by changes in the SPAST gene) is a common genetic form of HSP, and that its clinical features -- including severity and age of onset -- can vary within families. [3] The study also expanded the list of known SPAST changes by reporting new variants and larger missing pieces of the gene in a group of families from Central China. [3]

Among 63 unrelated HSP families, SPAST variants were identified in 21 index patients (33.3%), and the researchers reported 7 variants that had not been described before. [3] They also detected exon deletions (a type of genetic change where part of the gene is missing), which matters because these can be missed if testing only looks for small spelling changes in DNA. [3]

The clinical descriptions highlighted that SPG4 can look different from person to person, even within the same family, including differences in severity and the age when symptoms begin. [3] The report also noted a complicated presentation in a small number of people, including reduced sense of smell (hyposmia) in one patient, reminding readers that SPG4 is not always limited to leg stiffness and walking issues. [3]

For families going through genetic testing, this study strengthens the message that SPAST is a frequent finding in HSP and that testing may need to look for more than one kind of genetic change, including missing gene segments. It also adds to what is known about how variable SPG4 can be, which can help explain why relatives may have different symptom patterns or ages of onset. What remains uncertain from this single regional cohort is how often these specific variants and features appear in other populations, and how strongly any one genetic change predicts the course of symptoms. [3]

This month, laboratory studies in mice and human stem-cell-based brain models described a possible chain of events linking SPG11 gene loss to early brain development changes. [4] The work suggests SPG11-related problems in lysosomes (the cell's recycling system) may reduce the growth of early nerve cells, and it identifies specific signaling steps that could be studied as drug targets. [4]

The researchers reported that SPG11 loss led to calcium building up inside lysosomes and lower activity in mTOR signaling (a major pathway that supports cell growth and metabolism), alongside reduced proliferation of neural progenitor cells in these models. [4] They also reported that changing the activity of a lysosome channel called TRPML1 with a drug-like tool improved the developmental changes seen in human cortical organoids. [4]

For patients and caregivers, this is early-stage research that does not predict near-term treatment results, but it helps clarify what scientists think may be going wrong inside cells in SPG11. The practical value right now is mainly in building a clearer map of biological steps that can be measured and tested in future studies, including potential pathways related to lysosomes and mTOR signaling. What remains uncertain is whether changing TRPML1 or related pathways would be safe or helpful in people, since the reported work was in animal and laboratory models rather than clinical trials. [4]