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- x-ray computed
- infectious diseases
A 60-year-old woman presented with a 4-week history of unilateral forehead swelling following a coryzal episode. She described frontomaxillary pain and nasal discharge. Examination confirmed a fluctuant non-tender swelling (figure 1A) and ipsilateral mucopurulent rhinorrhoea. Neuro-ophthalmic examinations were unremarkable. A contrast-enhanced CT scan revealed a right-sided pansinusitis (figure 1B), an external subperiosteal collection with an underlying small extradural collection (figure 1C) and an interposed rarefied frontal bone (figure 1D). She underwent endoscopic sinus drainage with external frontal sinus trephine. The intracranial collection was managed conservatively with intravenous antibiotics and serial CT scans.
Pott's puffy tumour describes a subperiosteal abscess overlying frontal bone osteomyelitis. First documented as a sign of intracranial empyema following head injury (1768) and subsequently as a complication of frontal sinusitis (1775),1 fewer than 20 adult cases have been reported in the post-antibiotic era.2 It has also occurred as a late complication of neurosurgery,3 cocaine abuse4 and dental sepsis.5
Both Pott's puffy tumour and its associated complications are facilitated by the system of valveless veins draining the frontal sinus mucosa, which promote septic emboli to seed the adjacent bone, dura and cerebral parenchyma. Extension may also occur via natural foramina or direct bone erosion. Intracranial complications have been reported to occur in as many as 85% of cases6 and include meningitis, epidural or subdural empyema, frontal lobe abscess and cavernous sinus thrombosis in addition to orbital infections.7
While the typical presentation is that of forehead swelling with headache and fever, patients are frequently systemically well and often without a clear history of preceding sinusitis.8 Diagnostic imaging involves a combination of contrast-enhanced CT of the head and paranasal sinuses and MRI with gadolinium enhancement to exclude intracranial complications.9 Gallium-67 scintigraphy has been employed to aid delineation of osteomyelitic bone.10
Causative organisms reflect those seen in chronic rhinosinusitis wherein protracted mucosal oedema obstructs sinus ostia and fosters a polymicrobial microaerophilic and anaerobic growth.11 12 Isolated species have included Streptococci, Staphylococci, Haemophilus influenzae, Enterococci and Bacteroides spp.13
Treatment involves a combination of surgical and medical therapy. Surgical goals are abscess drainage, debridement of osteomyelitic sequestra and obtaining tissue for Gram stain and culture. Simultaneous external or endoscopic drainage of the involved paranasal sinus is advised14 with a breach of the posterior table of the frontal sinus best managed by its cranialisation.15 While bicoronal scalp flaps may provide optimum surgical access, some have achieved clearance through eyebrow incisions16 and occasionally through serial aspiration.17 If craniotomy is performed, care must be taken to avoid damage to the adherent dura under the diseased calvarium as perforation may seed infection into the subarachnoid space.14
A review of contemporary cases supports the early empirical administration of broad spectrum antibiotics with anaerobic and methicillin-resistant Staphylococcus aureus cover and good CNS penetration prior to culture-directed therapy.18 An appropriate combination is ceftriaxone, metronidazole and vancomycin, but consultation with local microbiologists is advised.19 The minimum duration of therapy may be 6 weeks and it may be continued depending upon clinical response.2 Close clinical and radiological follow-up is required to allow the early identification and treatment of recrudescent disease.
Competing interests None.
Patient consent Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.
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