Chin-Ho Wong

Necrotizing Fasciitis: Clinical Presentation, Microbiology, and Determinants of Mortality

BACKGROUND Necrotizing fasciitis is a life-threatening soft-tissue infection primarily involving the superficial fascia. The present report describes the clinical presentation and microbiological characteristics of this condition as well as the determinants of mortality associated with this uncommon surgical emergency. METHODS The medical records of eighty-nine consecutive patients who had been admitted to our institution for necrotizing fasciitis from January 1997 to August 2002 were reviewed retrospectively. RESULTS The paucity of cutaneous findings early in the course of the disease makes the diagnosis difficult, and only thirteen of the eighty-nine patients had a diagnosis of necrotizing fasciitis at the time of admission. Preadmission treatment with antibiotics modified the initial clinical picture and often masked the severity of the underlying infection. Polymicrobial synergistic infection was the most common cause (forty-eight patients; 53.9%), with streptococci and enterobacteriaceae being the most common isolates. Group-A streptococcus was the most common cause of monomicrobial necrotizing fasciitis. The most common associated comorbidity was diabetes mellitus (sixty-three patients; 70.8%). Advanced age, two or more associated comorbidities, and a delay in surgery of more than twenty-four hours adversely affected the outcome. Multivariate analysis showed that only a delay in surgery of more than twenty-four hours was correlated with increased mortality (p < 0.05; relative risk = 9.4). CONCLUSIONS Early operative débridement was demonstrated to reduce mortality among patients with this condition. A high index of suspicion is important in view of the paucity of specific cutaneous findings early in the course of the disease.

The LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis) score: a tool for distinguishing necrotizing fasciitis from other soft tissue infections.

Objective:Early operative debridement is a major determinant of outcome in necrotizing fasciitis. However, early recognition is difficult clinically. We aimed to develop a novel diagnostic scoring system for distinguishing necrotizing fasciitis from other soft tissue infections based on laboratory tests routinely performed for the evaluation of severe soft tissue infections: the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score. Design:Retrospective observational study of patients divided into a developmental cohort (n = 314) and validation cohort (n = 140) Setting:Two teaching tertiary care hospitals. Patients:One hundred forty-five patients with necrotizing fasciitis and 309 patients with severe cellulitis or abscesses admitted to the participating hospitals. Interventions:None. Measurements and Main Results:The developmental cohort consisted of 89 consecutive patients admitted for necrotizing fasciitis. Control patients (n = 225) were randomly selected from patients admitted with severe cellulitis or abscesses during the same period. Hematologic and biochemical results done on admission were converted into categorical variables for analysis. Univariate and multivariate logistic regression was used to select significant predictors. Total white cell count, hemoglobin, sodium, glucose, serum creatinine, and C-reactive protein were selected. The LRINEC score was constructed by converting into integer the regression coefficients of independently predictive factors in the multiple logistic regression model for diagnosing necrotizing fasciitis. The cutoff value for the LRINEC score was 6 points with a positive predictive value of 92.0% and negative predictive value of 96.0%. Model performance was very good (Hosmer-Lemeshow statistic, p = .910); area under the receiver operating characteristic curve was 0.980 and 0.976 in the developmental and validation cohorts, respectively. Conclusions:The LRINEC score is a robust score capable of detecting even clinically early cases of necrotizing fasciitis. The variables used are routinely measured to assess severe soft tissue infections. Patients with a LRINEC score of ≥6 should be carefully evaluated for the presence of necrotizing fasciitis.

Alternative vascular pedicle of the anterolateral thigh flap: the oblique branch of the lateral circumflex femoral artery.

Background: The anterolateral thigh flap is known for variations of its vascular pedicle. This is a prospective intraoperative analysis of the vascular anatomy of the lateral thigh that focuses on clinically important variations that impact flap harvest. Methods: Eighty-nine consecutive anterolateral thigh flaps were harvested. A detailed intraoperative analysis was performed of the vasculature anatomy and variations of the pedicle encountered during dissection. Results: Fasciocutaneous flaps were harvested in 82 percent (73 of 89) and myocutaneous flaps were harvested in 17 percent of cases (15 of 89). Sizable perforators were absent in 1 percent of the cases (one of 89). A mean of 1.9 sizable cutaneous vessels were identified. Musculocutaneous perforators were noted in 85 percent of cases and septocutaneous vessels were seen in 15 percent. Most septocutaneous vessels were located in the proximal thigh. In the midpoint of the thigh, musculocutaneous perforators predominate. Those located within 1 cm of the septum characteristically have a short, direct intramuscular course. In contrast, those located more laterally and distally in the thigh characteristically have a tortuous intramuscular course. An oblique branch of the lateral circumflex femoral artery was noted to be present in 35 percent of cases (31 of 88), and the dominant perforator supplying the anterolateral thigh was noted to originate from this branch in 14 percent of cases (12 of 88). Conclusions: This study further clarified the vascular pedicle anatomy of the anterolateral thigh. The existence of the oblique branch of the lateral circumflex femoral artery in a proportion of patients and its reliability when used as the flap pedicle were demonstrated.

Reconstruction of complex abdominal wall defects with free flaps: indications and clinical outcome.

Background: Free flaps have a distinct role in a select group of patients with large abdominal wall defects. They offer a completely autologous reconstructive solution in a single stage for difficult abdominal wounds for which pedicled flaps would be inadequate. Methods: From 1996 to 2005, five patients with complex abdominal wall defects underwent reconstruction using free flaps. All patients had multiple comorbidities, making the use of alloplastic materials relatively contraindicated. Flaps used included a free radial forearm flap in one patient, a tensor fasciae latae myocutaneous flap in two patients, a free anterolateral thigh myocutaneous flap in one patient, and free conjoined tensor fasciae latae and anterolateral thigh myocutaneous flaps in the last patient. Results: The mean defect size was 470 cm2 (range, 136 to 875 cm2). The femoral artery and long saphenous vein reliably provided recipient vessels in cases for which suitable vessels could not be located within the abdomen. A temporary arteriovenous shunt of the long saphenous vein to the femoral artery could be created. This was later divided to provide a recipient artery and vein. Flap complications were wound edge necrosis, hematoma, infection, and venous thrombosis. All were successfully managed and there were no flap failures. The average length of hospitalization was 64 days (range, 41 to 128 days). Lateral thigh flaps based on the lateral circumflex femoral system are our preferred donor site. A large amount of soft tissue, strong fascia, and innervated muscle are available, enabling single-stage autologous reconstruction of the entire anterior abdominal wall. Conclusions: Free flaps offer a reliable single-stage solution to complex abdominal wall defects. With these techniques, even the most challenging defects can be reconstructed with completely autologous tissue.

Four cases of necrotizing fasciitis caused by Klebsiella species.

Presented here are four cases of necrotizing fasciitis caused by Klebsiella spp. that were treated at one hospital over a 2-year period. Klebsiella necrotizing fasciitis can occur via direct inoculation, local trauma or, more commonly, hematogenous spread from other septic foci. Early, aggressive, surgical debridement and appropriate antimicrobial treatment are the cornerstones of treatment for this condition. Necrotizing fasciitis due to Klebsiella spp. is unique in that it is commonly associated with multiple septic foci. While liver abscesses and endogenous endophthalmitis are better-known associations of disseminated Klebsiella infection, necrotizing fasciitis is increasingly recognized as one of the manifestations of this syndrome. When treating Klebsiella necrotizing fasciitis, awareness of the potential for multiorgan involvement should prompt a thorough search for associated foci of infection.

The perforator-sparing buttock rotation flap for coverage of pressure sores.

Background: The rotation fasciocutaneous flap for buttock pressure sore coverage has the distinct advantage of allowing rerotation in the event of ulcer recurrence. The authors describe their approach of preserving and incorporating musculocutaneous perforators into the conventional rotation design. Methods: The skin incision is the same as that for the conventional gluteal rotation flap. The flap is elevated subfascially until one or two large musculocutaneous perforators of the superior or inferior gluteal arteries are encountered. Intramuscular dissection by splitting fibers of the gluteus maximus muscle is then performed to free the perforator down to its emergent point at the level of the piriformis muscle to enable the perforator to pivot freely with the rotation of the skin flap. Further elevation of the flap beyond the location of the perforator is then performed as necessary to enable tension-free rotation of the skin flap into the defect. Muscle to fill dead space when needed is raised as a separate flap. Seven patients underwent closure of buttock pressure sores in the sacral, ischial, and trochanteric areas using this technique. Results: All wounds healed, with no recurrence, at a mean follow-up of 30 months. This technique can be used to cover pressure sores over the sacral, trochanteric, and ischial regions. Conclusions: This modification of the conventional rotation flap affords the flexibility of rerotation in the event of ulcer recurrence while providing the flap with enhanced blood supply. This is an ideal flap for patients in whom the risk of ulcer recurrence is high.

Recurrent necrotizing fasciitis caused by methicillin-resistant Staphylococcus aureus

Reported here is a rare case of recurrent necrotizing fasciitis due to methicillin-resistant Staphylococcus aureus (MRSA). A 46-year-old female with poorly controlled diabetes and chronic ingestion of steroid-containing medications was admitted for treatment of necrotizing fasciitis of the right thigh. Three months following hospital discharge she was readmitted with necrotizing fasciitis of the left hand. On both occasions, MRSA was isolated from tissue cultures obtained during surgical debridement. Patients who develop necrotizing fasciitis are predisposed to severe soft tissue infections due to associated comorbid conditions such as diabetes mellitus. Recurrent soft tissue infection in a patient with previous MRSA-related necrotizing fasciitis should therefore be treated with a high index of suspicion.

Symptomatic spinal epidural varices presenting with nerve impingement: report of two cases and review of the literature.

Study Design. Two cases of symptomatic epidural varices are presented and the literature was reviewed on this entity. Objective. To raise awareness of this rare condition in the interpretation of preoperative magnetic resonance imaging scans and to assess the results of surgical treatment. Background. Symptomatic epidural varices presenting with radiculopathy are extremely rare, and the diagnosis is often missed in the preoperative evaluation. This condition commonly masquerades as a herniated nucleus pulposus. Diagnosis is often only made intraoperatively. Materials and Methods. Case 1 is a 40-year-old man presenting with acute exacerbation of lower back pain associated with radiculopathy down his right lower limb. Magnetic resonance imaging showed a paracentral disc prolapse. At operation, a congested epidural vein impinging on the L5 nerve root was noted with no intervertebral foramens stenosis. Excision of the vein was performed. The second case, a 50-year-old man with previous spinal instrumentation, was admitted for acute onset of radiculopathy down his left lower limb. At operation, an epidural varix compressing on the L4 nerve root was noted. Retrospectively, features of epidural varices were noted in the preoperative magnetic resonance imaging scans. Both patients reported resolution of symptoms after surgery. Results. Excision was done for the first patient, and coagulative ablation was done in the second patient. Both patients had symptomatic relief and neurologic recovery on follow-up. Conclusion. Our experience and the literature demonstrated that a favorable outcome with resolution of neurologic symptoms can often be achieved after excision or ablation of the epidural varices.

Use of the soleus musculocutaneous perforator for skin paddle salvage of the fibula osteoseptocutaneous flap: anatomical study and clinical confirmation.

Background: The skin paddle of the fibula osteoseptocutaneous flap is reliably vascularized by septocutaneous perforators from the peroneal artery. However, in 5 to 10 percent of lower limbs, these perforators are absent. This anatomical study evaluated use of the soleus musculocutaneous perforator for skin paddle salvage in such situations. Methods: Latex injection studies were performed on 20 cadaveric lower limbs. The presence, prevalence, and location of the musculocutaneous perforators in the distal leg were documented. The perforators were traced proximally to determine their origins. Results: Of the 20 cadaveric limbs, one or more musculocutaneous perforators of at least 0.5 mm in diameter were noted in 18 specimens (90 percent). They were located within 6 cm of the junction of the middle and lower thirds of the fibula. The soleus musculocutaneous perforators originated in the peroneal artery in 10 specimens (50 percent), the posterior tibial artery in seven (35 percent), and the tibioperoneal trunk in one (5 percent). This information was successfully used to salvage the skin paddle in two of our clinical cases. Conclusions: Use of the soleus musculocutaneous perforator depends on its origin. When it arises from the peroneal artery, a single set of anastomoses is all that is necessary for flap revascularization, with the skin paddle serving as a monitor for the bone flap. When it originates from the posterior tibial artery or tibioperoneal trunk, a second set of anastomoses is needed and the skin paddle cannot monitor the bone flap. The authors propose that one or two soleus musculocutaneous perforators be preserved during harvest until existence of the septocutaneous perforator is confirmed.

Perforator-Sparing Transposition Flaps for Lower Limb Defects Anatomic Study and Clinical Application

The local fasciocutaneous flap has the advantage of low donor-site morbidity when used for the coverage of lower limb defects. However, flap reliability remains a major problem with its use. The purpose of this study was to determine the feasibility of preserving perforators to the tip of conventional local fasciocutaneous flaps to improve its vascularity. The technical considerations of raising these flaps were examined in cadaveric specimens. Twenty-one local perforator-sparing transposition flaps were raised in 12 specimens. The leg was divided into knee/proximal-third, middle-third, and lower-third/ankle regions. We raised 7 flaps in each region. Success was defined as ability to transpose flaps to cover defects without tension on the perforators. In the knee/upper-third and middle-third regions of the leg, all wounds were successfully closed. However in the lower-third and ankle region, we were unable to close wounds in 3 of 7 cases. The reasons for this were the inadequate length of the perforator and the presence of tendons in the distal leg that interfered with perforator transposition. We successfully employed this flap in 6 clinical cases. This flap represents a technical advancement over conventional lower limb skin flaps because of its improved vascularity. It can safely be performed in the knee and upper and middle-thirds of the leg and can potentially be a valuable alternative to local muscle flaps for wounds in these areas.