The new research, led by neurosurgeon Michael Egnor at Stony Brook Medicine and published in the Journal of Neurosurgery: Pediatrics, questions the century-old idea that hydrocephalus is caused mainly by cerebrospinal fluid (CSF) malabsorption. The authors propose that hydrocephalus is better explained as a disorder of pulsatile dynamics: the brain fails to absorb the pulsatile energy of the heartbeat, and the cerebral windkessel system that normally removes these pulsations is impaired.
Using an electrical circuit model of pulsatile CSF dynamics, the researchers simulated hydrocephalus produced by subarachnoid obstruction. Their model reproduces key features of the condition and, they argue, shows that the older malabsorption theory is inconsistent with a wide range of experimental and clinical evidence. They describe the impairment as high impedance of pulsatility in CSF pathways, which prevents the windkessel from smoothing inflowing pulses and disturbs capillary blood flow.
Hydrocephalus can affect people of any age; according to the Hydrocephalus Association, about one million Americans and some 25 million people worldwide live with the condition. Common causes include congenital forms, bleeding in prematurity, head trauma, aneurysms, strokes, tumors, and normal pressure hydrocephalus in older adults. Symptoms range from life-threatening pressure to walking difficulty, loss of bladder control, and memory problems.
Treatment remains surgical and often lifelong, typically involving a CSF shunt from the brain to the abdomen. Shunt devices have high malfunction rates and frequently lead to repeat operations. The authors welcome scrutiny of the windkessel hypothesis and call for further work, including imaging research and development of new shunt designs.
Difficult words
- hydrocephalus — condition with excessive fluid in brain cavities
- cerebrospinal fluid — clear fluid that surrounds brain and spinal cord
- neurosurgeon — doctor who performs brain and spine surgery
- malabsorption — failure to absorb a substance properly
- pulsatility — regular variation in pressure or blood flow
- windkessel — elastic system that buffers blood flow pulsations
- impedance — resistance that reduces movement or flow
- shunt — tube that diverts fluid from one placeCSF shunt, Shunt devices
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Discussion questions
- How might a focus on pulsatile dynamics change the design or use of shunts?
- What are the possible benefits and risks of replacing the malabsorption theory?
- What kinds of imaging research could help test the windkessel hypothesis?
- How could repeated shunt malfunctions affect patients' lives and healthcare needs?
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