2019 AGM: What is HSP? - Rebecca Schüle

The first talk at the AGM was from Rebecca Schüle, from the University of Tübingen
 in Germany. We had asked Rebecca to attend the 2018 AGM, but there were various problems with flights which meant that she wasn't able to attend.

Rebecca began by giving a general description of HSP, reminding us that it is a group of diseases, all of which give rise to a spastic gait. HSP is an upper motor neuron disease - i.e. it affects the part of the nerve from the brain down into the spinal column. Upper motor neuron diseases are characterised by loss of voluntary muscle control, weakness, spasticity and clonus. There tends to be an increased stretch reflex. Where conditions affect the lower nerves the characteristics tend to be muscle atrophy, weakness, twitching and a decreased stretch reflex. HSP affects the longest motor neurons the most, so those affecting walking. After the discovery of HSP back in the 1800's, key work was undertaken by Anita Harding in the 1970's to 1990's. Anita identified that the types of HSP fell into two groups, one group with cognitive effects and one without.

Medication

Rebecca covered antispastic medication, and highlighted the need to get the right dose balance. It is difficult to get the right dose. The medication has both positive and negative effects. Positive effects include reduction in spasticity, pain, clonus and spastic jerks. Negative effects include muscle weakness, slowing down movements and reduced fine motor control and tiredness. There is a need to balance the positive benefits against the negative outcomes. 

Medical cannabis can have some benefits on muscles, but cal also make any depression worse.

Exercise

Most people do too little exercise, and you cannot do too much exercise. In judging how much effort to put into exercise, if you take 2-3 hours to recover from the exercise that is good, but if you take 2-3 days to recover that is not good! Gait training can be good to help with instability. It is important to find exercises which you like doing, everything gets boring after a while.

For those thinking about surgery as a treatment, it is important to remember that HSP is progressive, and this needs to be taken into account in any decisions. What is right today may not be right in 15 years time.

Bladder

Two thirds of people report bladder problems with HSP, which is sever in 5% of people and mild/moderate in about a third. There are good treatment options for bladder issues, which arise from the imbalance between the large bladder muscle against the small sphincter muscle.

Pain

Half of people with HSP report pain. Pain can arise from spasticity, arthritis, herniated discs or be neuropathic. Pain tends to increase as the gait changes and the loads on the muscles/joints changes.

Sensory Deficit

Half of people with HSP suffer from some kind of sensory deficit. This is often balance and co-ordination issues arising from changes in the sense of proprioception. Some (less than 10% get numbness or tingling. Some (30%) get ataxia which can affect coordination of upper limbs, speech and swallowing.  Less than 10% get cognitive effects which are more than just memory problems, and can affect the ability to solve problems, but this aspect has not been studies thoroughly to date.  

The Overall Effects of HSP

Some 10% of people start showing effects of HSP before they are 5 years old. The most frequent age for starting to show effects is 35-45. People who show HSP early tend to have a slower rate of progression than those who start to show symptoms later in life.

Half of people with HSP are still walking independently after 22 years of having HSP. After 37 years with HSP about one quarter of people use a wheelchair on a daily basis.

Those with a dominant type of HSP have a 50% chance of passing it on to the next generation, who would be affected. Those with a recessive gene have a 25% chance of an affected child if both parents carry the gene. Sometimes HSP is caused by a new mutation and neither parent has HSP.

If you know the type of HSP which you have then you are able to take these overall effects into account and know the chance of passing it on to the next generation. Overall it is expected that there are some 150-200 genes for HSP, and not all of these have been discovered yet. Many recently discovered HSP genes do not have a number. Some genes can be either dominant or recessive. The future may hold gene therapy for HSP.

European Reference Networks
HSP is covered be a European Reference Network (ERN). This network looks at how to manage HSP and has prepared management guidelines. Two main areas for treatment are drug re-purposing - i.e. finding an existing drug which can repair or compensate for a defect, and modifying the gene directly to repair the defect. No gene treatments are approved for HSP at the moment, but some are for similar conditions.

In terms of trials for all kinds of treatments there is a need to have a cohort of people with HSP who are willing to take part in the study. There is a need for national history studies to understand the population and help plan for trials.

With all treatments there is a need to be able to measure the benefit of the treatment. This could be done using a scale like the SPRS (Spastic Paraplegia Rating Scale) but could also consider a specific  scale for the area being tested.