Summary: Infectious Complications

Table 31.1 Cardiac conditions associated with the highest risk of endocarditis for which prophylaxis for dental procedures is reasonable

Prosthetic cardiac valve or prosthetic material used for cardiac valve repair

Previous IE

Congenital heart disease (CHD)a

Unrepaired cyanotic CHD, including palliative shunts and conduits

Completely repaired congenital heart defect with prosthetic material or device, whether placed by surgery or by catheter intervention, during the first 6 months after the procedureb Repaired CHD with residual defects at the site or adjacent to the site of a prosthetic patch or prosthetic device (which inhibit endothelialization)

Cardiac transplantation recipients who develop cardiac valvulopathy

aExcept for the conditions listed above, antibiotic prophylaxis is no longer recommended for any other form of CHD bProphylaxis is reasonable because endothelialization of prosthetic material occurs within 6 months after the procedure

Table 31.2 Patients at potential increased risk of experiencing hematogenous total joint infection

All patients during first 2 years following joint replacement

Immunocompromised/immunosuppressed patients Inflammatory arthropathies such as rheumatoid arthritis, systemic

Lupus erythematosus

Patients with comorbidities

Drugor radiation-induced immunosuppression Previous prosthetic joint infections Malnourishment

Hemophilia HIV infection

Insulin-dependent (type 1) diabetes Malignancy

In 2003 the American Dental Association (ADA) and the American Academy of Orthopaedic Surgeons issued an updated consensus statement regarding the prevention of hematogenous total joint infections in patients undergoing dental procedures [10]. The major conclusions of the statement are as follows: (1) Antibiotic prophylaxis is not indicated for patients with pins, plates, or screws. (2) Antibiotic prophylaxis is not routinely advisable in most patients with total joint replacement. (3) It is advisable to consider premedication for a small number of patients with highrisk indications undergoing dental procedures. Patients

at high risk for joint infection are indicated in the table below (Adapted from the 2003 consensus statement) (Table 31.2).

The recent guidelines suggest it is rarely necessary to prophylaxis patients for the prevention of bacterial endocarditis and hematogenous total joint infection, what about for the prevention of surgical site infections?

In a recently published study, Maragh and Brown, reviewed the infection rate in 1,000 consecutive patients who underwent Mohs surgery and were not treated with prophylactic antibiotics [11]. The overall infection rate was 8/1115 or 0.7%. All the cases were performed on an outpatient basis and were a mixture of sterile and clean technique. The authors found the highest risk of infection was associated with surgery on the nose (5/8 infections, 1.7% rate) and with flap closure (7/8 infections, 2.4% rate). The authors concluded that due to the exceedingly low rate of infections following Mohs surgery, the routine use of antibiotic prophylaxis, is not recommended, even in cases involving the nose or flap closure.

In another study, 5,091 lesions were treated in 2,424 patients over a 3-year period with a variety of procedures including curettage, Mohs surgery, simple excisions, and wedge excisions [12]. None of the patients were given prophylactic antibiotics and none ceased taking aspirin or warfarin. The surgeons followed sterile operative techniques. The overall infection rate was an impressively low 1.47%. The authors reported several circumstances that lead to unacceptably high, (>5%), infection rates: procedures below the knee, wedge excisions of the lip or ear, skin grafts, and lesions in the groin. They recommended that prophylactic antibiotics be reserved exclusively for patients in one of the above groups. Interestingly, they reported no increased rate of infection in diabetic patients, smokers or those on anticoagulants. However, in a follow-up study by the same authors involving 7,224 lesions in 4,197 patients, diabetes was shown to increase the risk of wound infection by 66%. Diabetes did not lead to an increase in any other complication [13].

Methicillin Resistant Staphylococcus Aureus (MRSA) infections, both communityand hospitalacquired, have been increasing in incidence recently. It is important to consider an individual patients risk for

MRSA infection on a case-by-case basis (Fig. 31.3). The increasing incidence of MRSA infection highlights the importance of obtaining wound cultures in all suspected infections. If a high index of suspicion exists for an MRSA wound infection, treatment with appropriate antibiotics (i.e., trimethoprim sulfamethoxysole (TMP-SMX), Clindamycin or Doxycycline) should be considered while cultures are pending. A recent publication recommended preoperative MRSA screening and decontamination which included mupirocin ointment for 5–7 days to the nares and 5–7 days of TMP-SMX, starting the day before surgery, to reduce the rate of postoperative infection [14]. The authors were able to reduce the rate of MRSA infection from 0.3% before screening to 0% after the screening and decontamination procedure began.

The issue of whether sterile technique need be followed during Mohs surgery has been evaluated in several recent publications. In one study, 1,400 Mohs cases were performed either with clean or sterile gloves [15]. No statistical difference in infection rates were found between the group treated with sterile gloves and the group treated with clean gloves. The authors concluded that utilizing clean versus sterile gloves could save $0.95 per pair without increasing the risk of infection. In another study an upgraded sterility program including the use of sterile gloves during all phases of the Mohs procedure, along with other changes lead to a decrease in infection rate from 2.5% to 0.9% [16]. The authors concluded that the additional material costs associated with the prevention of one infection were $672.50.

In order to avoid potentially disfiguring motor nerve damage, the Mohs surgeon must be aware of the danger zones encountered in the head/neck regions. There are four important danger zones where motor nerves are relatively superficial and may be at risk for injury.

Three of the danger zones relate to branches of the seventh cranial nerve (facial nerve), the fourth danger zone involves the eleventh cranial nerve (spinal accessory nerve).

The facial nerve exits the skull via the stylomastoid foramen and penetrates the parotid gland. After exiting the parotid gland, it divides into the five facial motor nerve branches: from superior to inferior, temporal, zygomatic, buccal, and marginal mandibular and cervical nerves. The first danger zone frames the temporal branch as it courses superiorly. The temporal branch exits the parotid gland, crosses the zygomatic arch then dips below the frontalis muscle. The danger zone is identified by a triangle covering the area where the nerve is most at risk for damage (Fig. 31.4). The first side of triangle is composed of a line drawn from a point 0.5 cm inferior to the tragus up to a point 2.0 cm lateral and superior to the tail of the eyebrow. The second side is drawn down through the eyebrow to the lateral orbital rim. The triangle is completed by drawing a line horizontally from the lateral orbital rim back to the first side of the triangle. The facial nerve is at greatest danger as it crosses over the zygomatic arch due to its superficial position just below the subcutaneous fat between the superficial and deep temporalis fascia. In order to avoid injuring the temporal nerve, the plane of undermining in the first danger zone

should be in the superficial subcutaneous fat. Injury to the facial nerve results in ipsilateral brow ptosis, diminished forehead rhytids, and a weak frown.

Management of facial nerve injury should include watchful waiting for the first 6 months following surgery, since many motor nerve deficits will improve spontaneously over this time period [17]. Neuropraxia, a temporary conduction deficit due to stretching or trauma of the nerve, resolves spontaneously. If the brow ptosis is mild and the patient is most bothered by a flat forehead, contralateral injection of botulinum toxin can help improve the facial asymmetry [18]. If, after 6 months, significant brow ptosis persists, referral to a facial plastic surgeon should be considered. Techniques which may improve the patients function and appearance include an ipsilateral brow lift or a nerve graft.

The second danger zone involves the zygomatic and buccal branches of the facial nerve. The limits of the second danger zone are defined by a triangle drawn from the angle of the mandible up to the mid zygoma then down to the oral commissure and back to the angle of the mandible (Fig. 31.5). Undermining in this area should be performed above the level of the SMAS. Nerve damage is more likely to occur to the buccal branch and results in ipsilateral lip droop, difficulty eating and an asymmetrical smile.

The third danger zone follows the marginal mandibular branch as it crosses over the mandible proximal to the masseter muscle and travels medially to innervate the depressors of the mouth. The limits of the third danger zone are defined by a circular area centered on the mandible, approximately 2 cm lateral

Fig. 31.6 Danger zone 3 is shown by the circle

and 2 cm inferior to the oral commissure (Fig. 31.6). In this area, the SMAS is very thin and offers little protection to the marginal mandibular nerve. The facial artery is also in jeopardy at the lateral edge of this danger zone. Damage to the marginal mandibular nerve can cause serious functional speech and cosmetic deficits to the patient. The ipsilateral lip tends to be elevated due to weakness of the lip depressors, the patient may also have difficulty fully showing the teeth on the affected side.

The fourth and final danger zone involves the spinal accessory nerve (cranial nerve XI), which is located on the lateral neck in an area known as Erb’s point. Erb’s point, an important landmark in the posterior triangle of the neck, can be located by having the patient turn