From Nature Outlook, 13 November 2014:
At first glance, a child with sickle-cell disease may appear healthy. But what you cannot see — and what dominates the child’s life — are bursts of searing, crippling pain that strike without warning. These episodes require trips to hospital, and even the highest doses of the most powerful opioid drugs typically provide only temporary, incomplete relief1.
As children with sickle-cell disease grow older, the pain worsens. They continue to have intense and debilitating acute attacks, and by the time they reach adulthood nearly one-third of them will also experience steady, unrelenting, background pain every day of their lives.
Sickle-cell pain has been thought of as a distress cry of oxygen-starved tissues, as the blood vessels supplying them become blocked and damaged by distorted blood cells. But in the past five years, a proliferation of pre-clinical and early clinical research is forcing a rethink of this assumption. Each new discovery is revealing a jigsaw puzzle in which damaged blood vessels, oxygen-deprived tissues, inflammation, opioid tolerance and hyper-sensitivity are intrinsically connected. Together, these processes present a much more complex picture of sickle-cell pain than researchers had previously believed, one of a damaged and persistently activated nervous system. Read more.