The cutting-edge applications of ultrasound in neurology
Imaging is central to neurological practice. It doesn’t take much to tempt a neurologist to ‘order’ or ‘request’ an MRI or a CT. In appropriate circumstances the imaging is a DAT scan, and with a bit more savvy, exciting imaging modalities such as amyloid scans and tau PET scans. In the playpen of the neurologist, the more ‘high tech’ the imaging technology, the more cutting-edge it feels-even if it doesn’t make much of a difference to the patient. Ultrasound on the other hand is the mongrel of imaging technologies. Too simple, too cheap, too available, too unsophisticated-not better than good old X-rays. It is safe to assume that the pen of the neurologist hardly ever ticks the ultrasound box. What for?
And yet, ultrasound has an established, even if poorly appreciated, place in neurological imaging. It is perhaps best known for its usefulness in assessing carpal tunnel syndrome at the wrist. But, for the neurologist, CTS is sorted out by wrist splints, steroid injections, and decompression surgery-forgetting that there may just be a ganglion, a cyst, or a lipoma lurking in there. Ultrasound also has a place in the assessment of muscle disorders, picking up anomalies and detecting distinctive muscle disease patterns. The only problem is that, even when radiologists and neurologists put their heads together, they struggle to understand what the patterns actually mean. And since the first pass of this blog post, I was reminded of the place of ultrasound-guided lumbar puncture in improving the safety and accuracy of this otherwise blind procedure. And there are even guidelines to help takers. My guess is that most neurologists prefer the thrill of hit-and-miss that goes with conventional LP. For many reasons therefore, the ultrasound box remains un-ticked.
Despite these limitations, the place of ultrasound remains entrenched in neurological practice. Indeed, ultrasound has been spreading its wings to exotic places, broadening its range, and asserting its presence. Perhaps it is time to reconsider the humble ultrasound, and to catch up with what it has been up to. Here then are 3 emerging roles of ultrasound in neurology
The blood brain barrier is a rigidly selective barricade against most things that venture to approach the brain-even if their intentions are noble. This is a huge impediment to getting drugs to reach the brain where they are badly needed. It is therefore humbling that it is the simple ultrasound that is promising to smuggle benevolent drugs across the blockade to aid afflicted brains. This was reported in the journal Science Translational Medicine, and the article is titled Clinical trial of blood-brain barrier disruption by pulsed ultrasound. The trial subjects were people with the notorious brain tumour, glioblastoma. They were injected with their conventional chemotherapy drugs, delivered along with microbubbles. The blood brain barrier was then repeatedly ‘pelted’ with pulsed ultrasound waves; this seem to leapfrog the drugs into the brain in greater than usual concentrations, enough to do a much better job. This surely makes films such as Fantastic Voyage and Inner Space not far-off pipe-dreams.