Rugby champion Joost van der Westhuisen died on Monday after suffering a six-year battle with motor neuron disease (MND), a rare and incurable degenerative condition.
MND, also known as amyotrophic lateral sclerosis (ALS), progressively damages parts of the nervous system.
The condition develops when nerve cells in the brain and spine called motor neurons stop working properly -- a process known as neurodegeneration. Over time, this disease causes difficulty in doing just about everything -- breathing, swallowing, speaking, walking etc. When the disease has reached a critical stage, these activities become impossible, as was the case with Van der Westhuisen.
Motor neuron disease is a very rare condition of which there is no single test to diagnose. Diagnosis is made by a neurologist through what is effectively a process of elimination -- several tests are conducted to rule out other conditions with similar symptoms.
The disease can affect people of any age, but in most cases the disease developed after the age of 40. Van der Westhuisen was 39 at the time of his diagnosis and 45 at the time of his passing.
Other well-known people who suffered from the condition include Chinese military and political leader Mao Zedong and jazz musician Charles Mingus. British scientist Stephen Hawking also has the disease.