What is the value of temporal artery biopsy in the diagnosis of GCA?

Giant cell arteritis (GCA) is a nasty inflammatory disorder that affects the large arteries. Because it characteristically involves the temporal artery, this form of vasculitis is also referred to as temporal arteritis. It usually affects people over the age of 50 years and manifests with sudden onset headache, scalp pain, and a thick, tender temporal artery. GCA is often accompanied by polymyalgia rheumatica (PMR) , a painful condition of the joints and muscles. The active systemic inflammation in GCA is often detected by the erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) tests. These distinguishing features constitute most of the diagnostic criteria for GCA.

By National Institute of Standards and Technology – https://www.flickr.com/photos/usnistgov/5828207621/, Public Domain, Link

Most people with GCA however do not have all the ‘classical’ features of the disease. A high index of suspicion is therefore required to sniff out the duplicitous miscreant. It is particularly imperative to make the diagnosis as early as possible to prevent the dreaded complications of GCA, sudden blindness and stroke. The treatment of GCA, implemented according to established treatment guidelines, involves several months of oral steroids, drugs which cause immune suppression and a host of other side effects. It is therefore essential that the diagnosis of GCA is made correctly to avoid putting the patient on a long, risky, and unnecessary treatment.

By Henry Vandyke CarterHenry Gray (1918) Anatomy of the Human Body (See “Book” section below)Bartleby.com: Gray’s Anatomy, Plate 508, Public Domain, Link

The conventional method of establishing the definitive diagnosis of GCA is by performing a temporal artery biopsy. This involves taking a short segment of the temporal artery as it traverses the temple. This procedure however only confirms the diagnosis of GCA in 1335% of people with the condition. One reason the biopsy has such a poor sensitivity is that it is often performed after treatment has already commenced. Another reason the biopsy is often normal is that the inflammation in GCA occurs in patches, sparing large segments of the artery. Don’t even think about it-taking a longer biopsy segment does not increase the yield of temporal artery biopsy. Put another way, “specimen length is not associated with diagnostic yield of temporal artery biopsy.

By NephronOwn work, CC BY-SA 3.0, Link
What then is the value of the temporal artery biopsy in the diagnosis of GCA? This is the question posed by Bowling et al in their incisive paper titled Temporal artery biopsy in the diagnosis of giant cell arteritis: does the end justify the means? They reviewed 129 temporal artery biopsies and found that the clinical diagnosis of GCA was confirmed in only 13% of cases. Furthermore, the outcome of the biopsy rarely ever influenced the treatment; 87% of those with a normal biopsy result still continued their treatment. The miffed authors therefore rhetorically, and indignantly, asked: “can we justify invasive surgery to all patients on histological grounds when the results may not alter management?” 
Ipswich, Waterfront, Ipswich Campus, The Big Question Mark Sculpture. Martin Pettitt on Flikr. https://www.flickr.com/photos/mdpettitt/8671901426

This is an entirely reasonable question especially because there are other more accurate and less invasive ways of establishing the diagnosis of GCA. These include:

But the answer to the authors’ rhetorical question is anyones guess. It is a sad tradition of medicine that studies such as these take ages to change practice. Indeed I predict the the temporal artery biopsy will sidestep this minor hurdle and simply continue its long and agonising reign. Despair!
By No machine-readable author provided. Spekta assumed (based on copyright claims). – No machine-readable source provided. Own work assumed (based on copyright claims)., Public Domain, Link
You can at least read more on GCA in my previous blog post titled Advances in the management of giant cell arteritis. You may also explore these comprehensive neurochecklistsGiant cell arteritis (GCA): clinical featuresand Giant cell arteritis (GCA): diagnosis and management.

 

FDG. TRIUMF Lab on Flikr. https://www.flickr.com/photos/triumflab/8232448893

 

What are the obstacles to creating reliable neurology checklists?

This is a follow up to my previous blog post on the value of checklists in medical practice. That post explored how checklists improve clinical practice and promote patient safety. It also cited Atul Gawande‘s call to Medicine to “seize the opportunity” and produce checklists for all aspects of clinical practice.

Neurology. MV Maverick. https://www.flickr.com/photos/themvmaverick/11396461045
Neurology. MV Maverick. https://www.flickr.com/photos/themvmaverick/11396461045

 

Picking up this gauntlet for neurology comes with peculiar challenges. Here are the 7 hurdles to overcome.

1. The challenge of a diverse specialty

Legume diversity. Global Crop Diversity Trust on Flikr. https://www.flickr.com/photos/croptrust/3594324633
Legume diversity. Global Crop Diversity Trust on Flikr. https://www.flickr.com/photos/croptrust/3594324633

Neurology consists of an astonishing diversity of sub-specialities. Any neurology checklist must exhaustively cover the major neurological categories such as stroke, epilepsy, movement disorders, headache, dementia, neuromuscular diseases, sleep disorders, neuro-inflammation, nervous system tumours, and neurological infections. These topics must be thoroughly covered with emphasis on their clinical features, investigations, and treatments. A useful database must also include rare neurological diseases, of which neurology has quite a few. This is reflected in my previous blog on the most perplexing diseases that excite neurologists.

2. The challenge of multiple associated specialties

jelly-baby-631848_1920

Neurological disorders cut across many diverse allied neurological specialties. Any dependable checklist database must cover these specialised fields which include neurosurgery, neuroradiology, neuroophthalmology, neuropsychiatry, neuropaediatrics, and pain management. It must also include important diseases which straddle neurology and general medicine. These include a long list of cardiovascular, nutritional, endocrine and gastrointestinal disorders. Furthermore, neurologists often have to deal with surgical complications especially in orthopaedics and following transplant surgery. Neurologists are also frequently called upon to attend to neurological problems that are unique to pregnancy. Any practical checklist application must therefore thoroughly address these areas.

Brain Cells Created From Skin Cells in Landmark Study. Day Donaldson on Flikr. https://www.flickr.com/photos/thespeakernews/15656329862
Brain Cells Created From Skin Cells in Landmark Study. Day Donaldson on Flikr. https://www.flickr.com/photos/thespeakernews/15656329862

3. The challenge of reliable content

books-education-school-literature-48126

It goes without saying that the most important feature of any database is reliable content which alone will engender trust and confidence. A reliable checklist must obtain its material from dependable sources. Neurology is replete with reliable textbooks and reference websites, . Neurology is also bursting at the seams with journals such as Neurology, Brain, the JNNP, and Journal of Neurology, each churning out a bewildering array of neurology guidelines, review articles, ground-breaking studies, and fascinating case reports. The challenge is to keep a regular handle on these sources, sifting through for practical and established material. As important for the user is that any checklist must be fully referenced and hyperlinked to the source material.

magazines-1108801_1920

4. The challenge of practical functionality

Any practical checklist database must be available on the move, easily accessible and searchable. In other words, it must be in the form of a mobile application. The app must have a reliable search functionality. More importantly for users is the requirement that the application must serves as a prompt to remember important points across the breadth of neurological practice: history taking, investigations, differential diagnosis, and treatment. For the administrator, the technology must make it easy to update and edit content, keeping the content consistently up-to-date.

app-1013616_1920 (1)

5. The challenge of varied target groups

Toy_balls_with_different_Colors

In developing any form of medical resource, it is a challenge to define the target audience. The primary aim of a neurology checklist application is to ease the challenges medical professionals face in accessing relevant and practical information about neurology in a timely way. This may be on a busy ward round or clinic, but also when researching a topic or preparing a presentation. The core users of a neurology application will therefore clearly be neurologists and neurology trainees.

By SpinningSpark real life identity: SHA-1 commitment ba62ca25da3fee2f8f36c101994f571c151abee7 - Created with Superliminal's Magic Cube 4D, CC BY-SA 3.0, https://en.wikipedia.org/w/index.php?curid=17492843
By SpinningSpark real life identity: SHA-1 commitment ba62ca25da3fee2f8f36c101994f571c151abee7 – Created with Superliminal’s Magic Cube 4D, CC BY-SA 3.0, https://en.wikipedia.org/w/index.php?curid=17492843

In many places however other cadres of medicine cater for people with neurological diseases. Psychiatrists, neurosurgeons, paediatriciansgeneral physicians, obstetricians, ophthalmologists, specialist and general nurses, would likely access the database. Other health care professionals may also find areas of interest such as speech therapists, physiotherapists and occupational therapistsMedical students and researchers also require vast amounts of neurological information, often within restricted time frames.

A Tangle of Different Colours 001. Christina Quinn on Flikr. https://www.flickr.com/photos/chrisser/7909899736
A Tangle of Different Colours 001. Christina Quinn on Flikr. https://www.flickr.com/photos/chrisser/7909899736

6. The challenge of public access

people-309099_1280

Specialised medical application are never aimed at non-medically trained people. The reality however is that the general public are closely involved in their care today, seeking reliable information to address their medical concerns. It is inevitable that patients and their families will access the checklist database. For this reason the language must be simple and clear, avoiding any sort of ambiguity.

7. The challenge of resources and pricing

calculator-385506_1920

A checklist application, to be most beneficial, should ideally be free to use. A Wikipedia model would be a model to adapt. But creating a checklist database, with all the features mentioned above, would surely stretch resources in terms of time and funding. There will also be great demands on resources to maintain and enhance it. A balance must be struck between beneficence and realism. Such a balance should have, as with most applications, a free version with sufficient access of some sort, and a premium version with unlimited access. The developer must also be aware that potential users have limited resources to spread round their conflicting demands. Any premium account should be affordable, perhaps not more than the equivalent cost of a cup of coffee and a cake a month.

Muffin and coffee. Phil Gyford on Flikr. https://www.flickr.com/photos/philgyford/6534958441
Muffin and coffee. Phil Gyford on Flikr. https://www.flickr.com/photos/philgyford/6534958441 

 

___________0____________0_____________0______________0____________

Is there any neurology checklist application that has taken the above challenges into consideration? This will be revealed in my next blog post, How simple checklists unlock excellent neurological practice?

Screen Shot 2016-06-18 at 10.00.30