treatment plan

A Cautious Approach to Penetrating Injuries

BY WILLIAM D. TOWNSEND, OD
DECEMBER 1999

A45-year-old feedyard worker presented with blurry vision and photophobia after experiencing sudden pain and discomfort in his right eye while hammering on a transmission. Visual acuities without correction were 20/30 OD and 20/20 OS. His pupils were round and reactive, and slit lamp evaluation showed an entry wound near the upper lid margin of his right eye. Lid eversion revealed the apex of a metal fragment protruding from the underside of the wound. The patient's cornea was badly scratched, with multiple foreign body tracks in random directions extending over most of the corneal surface. Conjunctival injection was present, as were Grade I+ flare and cells in the anterior chamber.

A topical anesthetic was applied and the foreign body was carefully removed. The margins of the wound were cleaned with an antimicrobial scrub, and the wound, which extended through the full lid thickness, was irrigated with sterile saline to remove any particulate matter. No penetration of the globe was noted.

We instructed the patient to begin using ciprofloxacin drops every two hours and arranged for his primary care provider to administer a tetanus booster shot the same day. We then called to confirm that the shot was administered. Over the next few days, the patient's visual acuity improved to 20/20 bilaterally.

The Importance of Persistence

Our insistence on ordering a tetanus shot for the patient may seem excessive until you consider the potential morbidity if tetanus had actually developed. This condition, fatal in 50 percent of cases, is caused by the bacteria Clostridium tetani, which can revert from the normal vegetative bacterial form to a spore form that is highly resistant to alcohol, boiling and other common means of disinfection. Only systems that sterilize (e.g., autoclave, ethylene oxide and glutaraldehyde) are capable of destroying spores.

Clostridium tetani is found in soil, lives as a saprophyte in the gastrointestinal tract of herbivorous animals and is present in their fecal material (this patient worked in a feedlot). It thrives in dead or necrotic tissue, or in tissue with very low oxygen concentrations such as a penetrating wound or infected tissue.

Tetanus Symptoms

The initial symptoms of tetanus, exaggerated reflexes, muscle rigidity and uncontrolled muscle spasms, occur anywhere from three to 21 days after exposure and are caused by the release of the toxin tetanospasmin from the bacteria Clostridium tetani. Clostridium tetani is not an aggressive agent, but its toxins enter the blood and are carried to central nervous tissue, where they bind to neurons and then block the release of the inhibitory mediator glycine in spinal synapses. This results in hyperactivity of the motor neurons and constriction of the jaw muscles, otherwise known as "lockjaw." Other manifestations include respiratory failure due to effects on the diaphragm, and tachycardia and sweating due to increased sympathetic activity.

When you encounter a patient with a penetrating wound or a case where there is potential for contamination via soil or fecal material, it's imperative that you demand that the patient have a tetanus shot. This one extra step ensures that your patients are protected from the ravages of this devastating disease.

Dr. Townsend is in private practice in Canyon, Texas, and is a consultant at the Amarillo VA Medical Center. (drbill@1s.net)

A special thanks to Dr. Kevin Appel for allowing us to work with this patient.