Introduction
Necrotising fasciitis (NF) is a life-threatening infection which can
affect the skin, subcutaneous tissue, superficial and deep fascia with
muscular extension1. Predisposing factors for
developing NF include chronic immunocompromised states, prolonged
corticosteroid use, diabetes mellitus and intra-venous drug
use1.
NF originating in and affecting the head and neck region is
rare1. NF has been documented in patients with dental
infections, traumatic neck wounds and deep space neck
infections1. Peri-ocular NF is very rare, with a rate
of 0.24 cases per million per annum2. Mortality rates
of NF can exceed 50%, with peri-ocular NF mortality ranging from
3-10%2,3.
The pathophysiological mechanism behind NF includes the seeding and
proliferation of a bacterial pathogen in the subcutaneous tissue and
fascial layers. This pathogen triggers the release of inflammatory
mediators, including toxins and cytokines2. This
inflammatory cascade results in microthrombi formation heralding
ischaemic necrosis of tissue. Severe pain, erythema, bullae formation,
and surgical emphysema with systemic sepsis are hallmark features which
should raise suspicion.
Four types of necrotising fasciitis have been described in the medical
literature, with types 1 and 2 the most prevalent3.
Type 1 NF is a polymicrobial infection usually consisting of mixed
anaerobes and aerobes acting in a synergistic
fashion3. Type 1 can account for up to 80% of all
necrotising fasciitis cases3. Type 2 usually has a
monomicrobial aetiology, with Group A beta-haemolyticStreptococcus (GAS) as the most prevalent
pathogen3. Type 2 NF accounts for 20-30% of all cases
of necrotising fasciitis, and can present as aggressive and rapidly
progressing. GAS can induce a large inflammatory response by reducing
phagocytic function and interferon secretion. Type 2 NF is more likely
to produce bacteraemia with streptococcal toxic shock
syndrome4. Type 3 NF is mono-microbial and usually
gram negative in origin with Type 4 NF occurring in immunocompromised
patients and is usually fungal in nature4.
Management of necrotising fasciitis requires prompt recognition,
intravenous anti-microbials and urgent surgical debridement.