Periorbital necrotising soft tissue infection in a 12-year-old patient

Introduction

Periorbital necrotising soft-tissue infection (NSTI) is uncommon, with a paucity of cases reported in the medical literature. ¹ In addition, paediatric NSTI (of any anatomical site) is also a rarity, with an annual incidence in economically developed countries of around 2.93 cases per million children. ²

Periorbital NSTI is a fulminant bacterial infection: commencing with a superficial cellulitis, spreading deeper and horizontally, resulting in necrosis of soft tissue layers. ¹ Complications include sepsis, requirement for eye exenteration, meningitis and – as is often the case – mortality. ³ NSTI is often initiated by a relatively innocuous soft tissue injury. ²

The infection tracks along avascular fascial planes, where antibiotic penetration is limited. NSTI often does not abide by anatomical boundaries and thus requires wide surgical excision of the advancing front.^2,4 As is especially the case in the head and neck region, the aggressive surgical management can mean that reconstructive surgery is necessary following eradication of the infection and stabilisation of the patient systemically.

This case report documents the management of periorbital NSTI in a paediatric patient.

Case

A 12-year-old male patient presented to accident & emergency (A&E) with a 2.5-cm linear partial-thickness laceration involving his left eyebrow after slipping on ice that morning. There was no loss of consciousness and no bony injury. Vision was recorded as being normal. The wound was cleaned with saline and closed with five simple ethilon sutures. The patient was discharged from A&E and advised to return to his general medical practice for suture removal in 5–7 days.

The following afternoon the patient returned to A&E complaining of significant swelling, pain, redness and pus discharging from the affected area. In addition, the patient was unable to open his left eye and had vomited multiple times that day.

With the exception of a pulse rate of 144 bpm, vital signs were normal.

Clinical examination revealed significant erythema and oedema involving the left upper and lower eyelids, with erythema extending periorbitally and extreme tenderness of the region. Significant proptosis was evident, with a tense orbit and suppuration from the original wound.

Blood tests undertaken in A&E indicated a leukocytosis of 46.2 (×10⁹/L) (reference range 4.5–13.0 ×10⁹/L) and a C-reactive protein of 28 (mg/L) (reference range 0–10 mg/L).

Intravenous antibiotic therapy was commenced promptly – benzylpenicillin (2.4 g QID), flucloxacillin (2 g QID), cefotaxime (3 g QID), metronidazole (450 mg TID).

A lack of response to antibiotic therapy and rapid spread of surface erythema led to the suspicion of NSTI. Intravenous clindamycin (600 mg QID) was prescribed.

Twenty-two hours after admission, the patient was taken to theatre by oral and maxillofacial surgery (OMFS) for surgical exploration and subsequent wide local excision of the area.

Necrotic, non-bleeding soft tissue was encountered; upper eyelid skin and orbicularis oculi were resected and the area was irrigated copiously with saline. A diagnosis of periorbital NSTI was made.

A planned return to theatre 6 h later revealed extension of the erythema beyond the previously demarcated borders. Further debridement of the left eyelid revealed advancement of the necrotic margin. Ophthalmology accompanied OMFS in theatre to assess eye involvement.

A third planned return to theatre the following morning revealed no further progression; however, an unplanned return to theatre that evening was necessary as there was further extension of erythema on the contralateral side (Figure 1). There was further debridement of necrotic tissue carried out and a one-off dose of gentamicin (300 mg) was added to the antibiotic regimen on the advice of microbiology, following culture of Group A Streptococcus pyogenes. OPEN IN VIEWER

Following eradication of infection and stabilisation of the patient systemically, reconstruction of the left eyelid with a forehead rotational flap was undertaken.

On outpatient follow-up with OMFS and ophthalmology it was noted that good skin coverage has been achieved with the flap. Residual function of levator palpebrae superioris was observed with revision/flap debulking being a planned possibility in the near future (Figure 2). OPEN IN VIEWER

Discussion

NSTI can be classified microbiologically: type I NSTI is a polymicrobial infection, consisting of aerobes and anaerobes, typically seen in immunocompromised adults; type II NSTI is associated with Group A Streptococcus alone and is mostly seen in medically fit and well patients. Type II is less common in the population as a whole (25–45% of cases) ⁵ ; however, it predominates in paediatric cases (88% of cases). ⁴ This is a case of type II NSTI.

An early marker for NSTI is a severe level of pain, disproportionate to the clinical appearance. ² This must serve as a red flag when assessing a patient with a soft tissue infection. However, obtaining an accurate pain history in a paediatric patient is notoriously challenging. ⁶

Later clinical evidence characteristic of NSTI includes changes in skin colour, presence of crepitus and absence of bleeding. ⁴ Signs of sepsis must also be monitored, and intensive medical care sought if necessary.

Blood investigations (often characterised by a markedly elevated white cell count), microbiological and histopathological analysis will aid diagnosis, but NSTI is a clinical diagnosis and should be acted upon immediately.^1–4

A diagnostic tool for distinguishing NSTI from other soft tissue infections was developed by Wong et al. ⁷ in 2004: the laboratory risk indicator for necrotising fasciitis (LRINEC) score (Table 1). This tool includes six parameters and has a reported positive predictive value of 92.0% and negative predictive value of 96.0%. ⁷ However, the patient in this case was not positive as per the LRINEC score.

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Table 1.

LRINEC ⁷ diagnostic tool.

Laboratory test	Result	Score
White cell count (×109/L)	<15	0
	15–25	1
	>25	2
C-reactive protein (mg/L)	<150	0
	≥150	4
Haemoglobin (g/dL)	>13.5	0
	11–13.5	1
	<11	2
Serum sodium (mmol/L)	≥135	0
	<135	2
Glucose (mmol/L)	≤10	0
	>10	1
Serum creatinine (µmol/L)	≤141	0
	>141	2
Total score (≥6 is positive for NSTI)

Results upon admission: White cell count = 46.2 (×10⁹/L); C-reactive protein = 28 (mg/L); Hb = 15.4 (g/dL); serum sodium = 139 (mmol/L); glucose = not recorded at admission; creatinine = 61 (µmol/L).

A modified paediatric LRINEC tool (P-LRINEC) exists, which has been shown to have a greater diagnostic accuracy in paediatric cases of NSTI. ⁸ The P-LRINEC score uses only laboratory values for C-reactive protein and serum sodium. Again, however, this index would fail to detect this case as positive for NSTI. Clearly, the accuracy of LRINEC and P-LRINEC remains to be fully validated with a suggestion of differences between UK metropolitan and international populations. ⁹ A retrospective study of 47 NSTI cases in California found that only 63.8% of cases were positive as per the LRINEC score. This case emphasises that refinement and validation of the laboratory-based diagnostic tools may be required. ¹⁰

The cornerstone of NSTI investigation and treatment is surgical exploration. Timing of initial surgical intervention is the most important prognostic determinant in NSTI.^1–9 Nisbet et al. ¹¹ reported in a case series of 82 adult patients that a 43% mortality rate existed when surgical input was greater than 24 h from recognition of infection; when surgery occurred within 24 h, this figure decreases to 16%. Early identification is clearly crucial in management of NSTI; however, it has been shown that NSTI is correctly diagnosed prior to admission to hospital only 14% of the time. ¹² Early recognition is clearly imperative in order that surgical management can commence without delay – late intervention means further pathologic spread, and thus surgery that is increasingly more drastic and disfiguring. Despite the rarity of NSTI, patients presenting with relatively innocuous wounds should be informed by medical staff to look out for malaise, increasing levels of pain, redness, discharge and swelling around the injury. Patient awareness of NSTI may prompt earlier presentation to the appropriate surgical service.

As an adjunct to surgery, prompt, appropriate antimicrobial therapy has an important role in NSTI. Lazzeri et al., ¹ in their 2010 review of 104 periorbital NSTIs, identified that S. pyogenes was implicated in 84% of cases. Clindamycin is known to inhibit the synthesis of streptococcal toxins and other virulence factors and should be empirically included in patients with suspected NSTI. ¹³

Concluding learning points

A suspicion of NSTI must be present when examining any soft tissue infection.