"Using magnetic resonance imaging (no ionizing radiation involved and much cheaper than nuclear medical techniques), we identified a specific imaging feature which has great similarity to a tail of a swallow and therefore decided to call it the 'swallow tail sign,'" says Stefan Schwarz. "This sign is absent in Parkinson’s disease." (Credit: Zebarnabe/Flickr)

Missing ‘swallow tail’ is a sign of Parkinson’s

In Parkinson’s disease, cells in a sub-region of the brain, the substantia nigra, aren’t shaped like a swallow’s tail, as they are in the brains of healthy people.

A new study describes how the absence of this imaging sign can help to diagnose Parkinson’s disease using standard clinical magnetic resonance scanners.

The brain region labeled number 7 in the diagram is the substantia nigra, which resembles the swallow's tail in healthy brains. (Credit: PLOS ONE 9(4): e93814. doi:10.1371/journal.pone.0093814)
The brain region labeled number 7 in the diagram is the substantia nigra, which resembles the swallow’s tail in healthy brains. (Credit: PLOS ONE 9(4): e93814. doi:10.1371/journal.pone.0093814)

“This is a breakthrough finding as currently Parkinson’s disease is mostly diagnosed by identifying symptoms like stiffness and tremor,” says Stefan Schwarz of the School of Medicine at the University of Nottingham.

“Imaging tests to confirm the diagnosis are limited to expensive nuclear medical techniques, which are not widely available and associated with potentially harmful ionizing radiation.

“Using magnetic resonance imaging (no ionizing radiation involved and much cheaper than nuclear medical techniques), we identified a specific imaging feature which has great similarity to a tail of a swallow and therefore decided to call it the ‘swallow tail sign.’ This sign is absent in Parkinson’s disease.”

Parkinson’s disease is a progressive neurodegenerative disorder that destroys brain cells that control movement. Around 127,000 people in the UK have the disease. Currently there is no cure but drugs and treatments can be taken to manage the symptoms.

The diagnosis can be challenging early in the course of the condition and in tremor dominant cases. Other non-licensed diagnostic techniques offer a varying range of accuracy, repeatability, and reliability, but none of them has demonstrated the required accuracy and ease of use to allow translation into standard clinical practice.

Using high resolution, ultra high filed 7T magnetic resonance imaging, the research team had already pinpointed the characteristic pathology of Parkinson’s with structural change in a small area of the mid brain known as the substantia nigra.

This latest study, published in PLOS ONE, shows that these changes can also be detected using 3T MRI technology.

They reviewed a total of 114 high-resolution scans, and in 94 percent of cases, the diagnosis was accurately made using this technique.

Schwartz and Professor Dorothee Auer led the study, which took place at the Queen’s Medical Centre in collaboration with Nin Bajaj, an expert in movement disorder diseases at the Nottingham University Hospitals NHS Trust.

The University of Nottingham, the Sarah Matheson Trust, and the Medical Research Council supported the study. The National Institute for Health Research UK funds Schwarz’s academic clinical lectureship. The funders had no role in study design, data collection, and analysis.

Source: University of Nottingham

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