Why Does EpiPen Have to be Injected into the Thigh?

As any severely food allergic patients know, when suffering from a potentially life-threatening anaphylactic reaction, they need to jab an epinephrine needle into the side of their thigh...

But... why the thigh? Why not the arm like most other shots?

Per AAAAI, there have been 3 anatomic sites investigated to determine which location offers the fastest systemic absorption of epinephrine when injected intramuscularly and/or subcutaneously.

• Intramuscular injection in the upper arm (deltoid muscle) just like a flu shot.
• Subcutaneous injection in the upper arm just like an allergy shot.
• Intramuscular injection in the lateral thigh (vastus lateralis muscle).

Of these sites, the intramuscular thigh injection demonstrated the fastest rise in blood epinephrine.

When dealing with a life-threatening anaphylaxis, you need the speed because if the drug is too slow, the person may die before adequate epinephrine levels are achieved... and the thigh muscle provides the speed whereas the other sites do not.

Why might that be?

It's probably because the thigh muscle is large with lots of blood vessels allowing for multiple points of access for the injected epinephrine to enter into the blood circulation.


References:
Epinephrine absorption in children with a history of anaphylaxis. J Allergy Clin Immunology 1998; 101(1):33-37.

Epinephrine absorption in adults: intramuscular versus subcutaneous injection. J Allergy Clin Immunol 2001; 108(5):871-873.

Video on Ear Clogging and What Happens When They Pop Open (or Don't)

A new video has been created describing anatomically how a person pops the ear open when it feels clogged or under pressure. Also explained is what happens anatomically when the clogged ear is very difficult if not impossible to pop open; a condition called eustachian tube dysfunction.

Check the video out here!

Dental X-rays Linked to Brain Tumors

In a study spanning over decades, researchers have found an association between dental x-rays and increased risk of a non-malignant type of brain tumor called meningioma.

Of the four types of dental x-rays, only the full-mouth series was associated with this increased risk. More specifically, the risk was elevated with the aggregate number of full-mouth series in 10-year periods from approximately 15–40 years before diagnosis, with significant elevations in the 10-year periods beginning 22–30 years before diagnosis. The risks in these analyses were even greater when only women were considered.

One needs to be aware that radiation exposure from full-mouth series was much greater in the past than it is now and as such, this risk may be nominal (though not zero) with current dental x-ray technology.

However, it also should be a reminder that x-rays should not be routinely performed unless there is a very good reason to obtain especially in children who are more susceptible to radiation injury... and that applies to not only x-rays, but any kind of testing involving ionizing radiation including CT scans.

Some x-rays should NEVER be performed including sinus x-rays for sinus problems given a nearly 50% error rate in diagnosing the presence OR absence of sinus problems.

X-rays for nasal fractures is not recommended given x-rays rarely change how such fractures are managed.

Soft-tissue lateral x-rays to look for large adenoids should also be discouraged as nasal endoscopy can provide similar if not better information without any radiation exposure.

To know what the cancer risk is with different types of x-rays, check out this website!

Source:
Dental X-rays and the risk of intracranial meningioma. Cancer. Volume 100, Issue 5, pages 1026–1034, 1 March 2004

Tonsil Bad Breath and Tonsil Stones

The Huffington Post published a story on tonsil stones on April 4, 2012 which can lead to bad breath. The author, who is a dentist, gave the perspective of conservative treatment strategies to resolve bad breath whose root cause is due to tonsil stones otherwise known as tonsilloliths.

Such "stones" are produced and ejected from tonsils and consist of mucus, dead cells and other debris that collect in the deep pockets of the tonsils and gradually condense into small, light-colored globs. Bacteria feed on this accumulated matter, giving rise to the odor which is downright foul-smelling (and foul-tasting).

The only known cure for tonsilloliths is tonsillectomy (no tonsils = no tonsil stones), though the article does outline more conservative measures which are encouraged first prior to surgery. More recently, there is a minimally invasive procedure called tonsil cryptolysis which also has the potential to eliminate this problem prior to considering tonsillectomy.

A recent research paper does offer tantalizing clues to address tonsilloliths more conservatively as it found that tonsil stones are more like living biofilms rather than an inert stone. Read the abstract here. 

Source:
The Different Kinds of Bad Breath, Part 2: Tonsil Breath. Huffington Post 4/4/12

How Does Cervical Spine Surgery Potentially Cause Voice and Swallow Problems? [video]

It is not unusual for an ENT surgeon to see patients with swallowing and voice difficulties after cervical spine surgery. In particular, the ACDF surgery (Anterior Cervical Discectomy and Fusion).

The key to understanding these issues is to first understand the anatomy involved.

The cervical spine is located in the back of the neck. In front of this spine is the esophagus (swallowing tube) and voicebox.

As such, when a spine surgeon goes through the FRONT of the neck in order to perform cervical spine surgery located in the BACK of the neck, (s)he has to move the esophagus and voicebox over to the side.

A plate is than fixated to the spine to fuse the cervical vertebral bodies.

Because of such manipulation of the esophagus and voicebox, it is not uncommon for a patient to complain of hoarseness and difficulty swallowing after surgery.

Fortunately, such problems usually dissipate with time, but not always.

Watch the video describing ACDF and how it can affect voice and swallow.