While the primary and secondary progressive forms of multiple sclerosis (PPMS and SPMS) have different pathological characteristics, scientists do not know if they share common neurodegenerative mechanisms.
The authors of a recent paper in the Journal of Neurology measured cerebrospinal fluid levels of some proteins called neurofilaments in patients at the Cemcat Centre in Barcelona, from 1994 to 2008.
The cerebrospinal fluid surrounds and protects the brain and spinal cord. It can be collected by lumbar puncture and analysed to reveal aspects of the disease related to inflammation.
Neurofilaments are normally present within nerve fibres. There are two different types of neurofilament – heavy and light. When these fibres are destroyed, as happens in MS, the level of neurofilaments in the cerebrospinal fluid increases.
Several studies have shown a correlation between the level of neurofilaments and disability in MS. Neurofilament levels were identified as possible markers of nerve fibre damage in MS patients.
The researchers measured neurofilament levels in the cerebrospinal fluid of 21 people with PPMS, 10 people with SPMS, and 15 controls.
They aimed to investigate whether PPMS patients had different levels of nerve fibre damage to SPMS patients. They also assessed the role of neurofilaments in predicting long-term disease progression.
Their findings suggest that PPMS and SPMS may share similar mechanisms of nerve fibre damage.
Moreover, neurofilament heavy can be a biomarker of ongoing nerve fibre damage, while neurofilament light can be used as to predict accumulating disability, suggesting they are a good way to monitor treatments in progressive MS.