Hereditary spastic paraplegia
A range of rare genetic disorders in which there is stiffness ( spasticity) or paralysis of the lower limbs, or both, are grouped together and referred to as hereditary spastic paraplegia (HSP). There are several other terms used for these disorders, including familial spastic paraparesis (FSP) and Strumpell-Lorrain syndrome.
People with hereditary spastic paraplegia have a type of motor neurone disorder. Motor neurones are nerve cells that enable muscles to move - upper motor neurones in the brain and spinal cord trigger lower motor neurones to activate muscles. Due to genetic abnormalities in people with HSP, the upper motor neurones degenerate, eventually losing their ability to send signals to the lower motor neurones. The axons (long thread-like fibres) within the neurones that connect with the lower limbs are the longest, so these are the ones mostly affected.
What are the symptoms of HSP?
The effects of hereditary spastic paraplegia are gradual, starting with stiffness and weakness in the legs. A person may stub their toes more often or stumble a lot. It may be years later before the condition progresses to a scissor-like stiff gait when walking. It takes much more effort for someone with HSP to walk than other people and they often experience fatigue.
Foot problems such as high arches, shortened Achilles tendons, foot drop, hammer toes, bunions and cold feet or swelling are common in people with HSP. They can also develop bladder problems, and in some cases the arms, speech or swallowing muscles can be affected.
Although symptoms can start at any age, they generally first appear in people between 10 and 40 years old. The severity of the symptoms varies from one person to another, even within the same family. There have been occasions where symptoms appear in children before they occur in a parent. Some people who develop the symptoms of HSP early on will be able to walk without aids for life, but others will need to use a wheelchair within years of diagnosis.
What causes HSP?
Most commonly HSP is an inherited condition, which means that one or both parents have passed down an abnormal (mutated) gene to their child. However, sometimes an abnormal gene develops spontaneously and is not passed down from a parent. More than 30 genes have been linked to HSP. Having a mutated gene does not necessarily mean a child will develop the symptoms - there are families in which some children have the condition but not others - but the gene could be passed down to the next generation.
How is HSP managed?
A diagnosis can be made through a careful examination that will include ruling out various other conditions and noting the person's family history.
There is no cure for HSP but treatments are available to help manage the condition based on the severity of the symptoms. Walking aids such as walking sticks, lower leg braces and walkers may be necessary. Treatment is based around:
Exercise and physiotherapy. Doing exercises on a regular basis can help keep muscles stretched, which reduces stiffness and pain. A neuro-physiotherapist can develop an exercise regime that ensures the neurological problems of the condition are considered too. Occupational therapy to provide help with everyday activities may also be provided to help the person remain independent.
Prescribed medications. Medications are available to help reduce stiffness and pain. Muscle relaxants such as baclofentizandine and botulinum (Botox) injections can reduce stiffness, and drugs are sometimes recommended to weaken opposing muscles (muscles work in pairs), thereby regaining some movement.
Function electrical stimulation. A device is used to deliver electrical impulses directly into certain muscles that have stopped working. For example, it can help activate muscles in cases of dropped foot to improve walking.
People with HSP should note that stress or cold weather can make muscle stiffness worse.