Commentary

Myth of the Month: Retired myths from yesteryear


 

I appreciate the opportunity to share medical myths each month, hopefully to highlight topics where new knowledge and data may help change ways we approach common problems in medicine. I have been researching medical myths since the early 1990s, and some have actually evolved in such a way that they are no longer myths – that is, accepted practice now is very different than it was decades ago, and has incorporated updated research.

Some myths are timeless. The vitamin B12 myth I shared in this column last year continues to this day, despite evidence that has been present since the 1960s.

Dr. Douglas S. Paauw

Dr. Douglas S. Paauw

I will share with you two of my all-time favorite myths that have now been retired, where current practice now does not perpetuate these myths.

When I was in medical school, I was taught that the best way to treat a corneal abrasion was to patch the affected eye.1 Pretty much everyone who was seen in an emergency department for a corneal abrasion before the 1990s left the ED with an eye patch. This standard approach was not based on any evidence of benefit of healing or decreased pain.

Dr. Harold Jackson reported in a study of patients with corneal abrasions published in 1960 that there was no difference in healing between eyes that were patched and eyes that were left unpatched.2 The largest published study on eye patches for corneal abrasions involved 201 patients who were evaluated for corneal abrasions.3 The patients who did not receive an eye patch had less pain and quicker healing of the corneal abrasions. Other studies all showed no benefit to eye patches.4,5

A Cochrane Review published in 2006 concluded: “Treating simple corneal abrasions with a patch does not improve healing rates on the first day post-injury and does not reduce pain. In addition, use of patches results in a loss of binocular vision. Therefore, it is recommended that patches should not be used for simple corneal abrasions.”6

A more recent study by Dr. Moreno Menghini and colleagues showed no differences in healing of traumatic corneal abrasions between groups who received an eye patch, a contact lens, or no eye covering.7

Another longstanding myth that is less commonly seen now is the avoidance of use of narcotics for the treatment of acute, severe abdominal pain.

The long-term teaching was that by treating abdominal pain with narcotics, you could mask the important physical exam findings in patients presenting with an acute abdomen. The source of this myth wasn’t hard to uncover. The following are quotes from Cope’s Early Diagnosis of the Acute Abdomen 15th and 16th editions (these were the editions available back when I was a medical student in the early 1980s).

From the 15th edition: “If morphine be given, it is possible for a patient to die happy in the belief that he is on the road to recovery, and in some cases the medical attendant may for a time be induced to share the elusive hope.”8

An even stronger position was taken in the next edition of Cope’s text: “The patient cried out for relief, the relatives are insistent that something should be done, and the humane disciple of Aesculapius may think it is his first duty to diminish or banish the too obvious agony by administering a narcotic. Such a policy is a mistake. Though it may appear cruel, it is really kind to withhold morphine until a reasonable diagnosis has been made.”9

No controlled trials ever questioned this long-held belief until a study done by Dr. Alex Attard and colleagues published in 1992.10 In this study, 100 patients were evaluated by an admitting officer and given an intramuscular injection of either a narcotic or saline. Surgeons who subsequently followed the patients felt equally confident in diagnosis and management in both groups. The decision to operate or observe was incorrect in two patients in the narcotic group and nine in the saline group.

Dr. H. A. Amoli and colleagues studied whether administering morphine changed exam findings in patients with acute appendiciits.11 In a randomized, double-blind study design, half the patients received morphine and half received saline. Patients were examined by surgeons not involved in their care before and after drug administration, and their pain intensity and signs were recorded at each visit. The administration of morphine did not alter clinical signs or physician management plans.

In a study by Dr. Steven Pace and colleagues of patients presenting with acute abdominal pain, intravenous morphine or placebo was administered in 71 patients early in their presentation to the ED.12 There were no differences in accuracy of diagnosis between groups. Three diagnostic or management errors were made in each group.

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