Preseptal and orbital cellulitis — formative SAQs

SAQ 1 (10 marks)

A 5-year-old child presents to the emergency department with a two-day history of right eyelid swelling and erythema following a viral upper-respiratory infection. On examination the child is febrile to 38.8 degrees Celsius and irritable. The right eye is proptotic, with marked chemosis, limited eye movement in all directions of gaze, and pain on attempted movement. Visual acuity is reduced compared with the left eye, and there is a relative afferent pupillary defect on the right. [1]

Question: Outline the diagnosis, the immediate investigations and the stepwise management of this child, including the medical-versus-surgical decision. (10 marks) [1]

Model answer

Diagnosis and recognition (2 marks). The diagnosis is orbital (postseptal) cellulitis. The proptosis, chemosis, ophthalmoplegia, pain on eye movement, reduced visual acuity and relative afferent pupillary defect, in a febrile unwell child, are the classic orbital signs indicating that infection has crossed the septum and involved the orbital contents. The likely source is ethmoid sinusitis spreading through the thin lamina papyracea. This is a sight- and life-threatening emergency requiring immediate admission and senior review. [1]

Immediate investigations (2 marks). Take blood cultures and inflammatory markers before antibiotics. Obtain urgent contrast-enhanced computed tomography of the orbits and paranasal sinuses to define the sinus source and to look for a subperiosteal or orbital abscess or intracranial extension. Do not delay intravenous antibiotics while waiting for imaging. Assess and document visual acuity, colour vision and the pupillary reaction at presentation and serially thereafter, because deterioration is the trigger for urgent surgical decompression. [6] [1]

Immediate management and intravenous antibiotics (2 marks). Admit, establish intravenous access, and start broad-spectrum intravenous antibiotics immediately after blood cultures. Give ceftriaxone 50 mg per kilogram (maximum 2 g) once daily intravenously plus flucloxacillin 25 to 50 mg per kilogram (maximum 2 g) every six hours intravenously, covering the Staphylococcus aureus and streptococci that dominate paediatric orbital disease. Add metronidazole 7.5 mg per kilogram (maximum 400 mg) every eight hours if anaerobic or dental concern is present, and vancomycin or clindamycin if MRSA is suspected. Refer urgently to ophthalmology and ear-nose-and-throat surgery. [8] [11]

The medical-versus-surgical decision (2 marks). The contrast CT, together with the visual compromise (reduced acuity and a relative afferent pupillary defect), mandates urgent surgical drainage if an abscess is demonstrated. The age-based criteria allow a trial of intravenous antibiotics only for a medial subperiosteal abscess in a child under nine years with normal vision; this child has visual compromise, which is an absolute indication for surgery regardless of age or abscess site. Any deterioration in vision pending surgery is the trigger for immediate surgical decompression, because optic nerve ischaemia becomes irreversible within hours. [7] [8]

Disposition and safety-netting (2 marks). Admit to a monitored bed under combined paediatric, ophthalmology and ENT care. Continue intravenous antibiotics, monitor vision and orbital signs serially, and drain the abscess urgently. Transition to oral antibiotics on clinical improvement to complete a total course guided by severity and culture results. At discharge, arrange ophthalmology follow-up, address any underlying sinus disease, and give a clear safety-net for spreading redness, fever, pain on eye movement or visual change. The prognosis is good with prompt recognition and treatment, but delayed surgery risks permanent visual loss. [1] [11]

SAQ 2 (10 marks)

Question: A 3-year-old child is brought to the general practitioner with a one-day history of left eyelid swelling and redness after an insect bite. The child is afebrile and well, the eye is white and quiet, eye movements are full and painless, and the vision is normal. (a) What is the diagnosis and how does it differ from orbital cellulitis? (b) Outline the management and follow-up. (c) What feature would prompt urgent reassessment for orbital disease? (10 marks) [3]

Model answer

(a) Diagnosis and distinction from orbital cellulitis (4 marks). The diagnosis is preseptal (periorbital) cellulitis — infection of the eyelid and periorbital soft tissues anterior to the orbital septum, here following an insect bite as the portal of entry. The child is well and afebrile, the eye is white and quiet, and crucially there is no proptosis, no chemosis, no limitation of eye movement, no pain on eye movement and no visual disturbance. These normal findings confirm the septum is intact and distinguish preseptal from orbital cellulitis, in which infection posterior to the septum produces the orbital signs: proptosis, ophthalmoplegia, pain on movement, decreased visual acuity and a relative afferent pupillary defect. The two are distinct diseases with different sources, severities and management pathways. [3]

(b) Management and follow-up (3 marks). Manage the well child in the community with oral antibiotics covering Staphylococcus aureus and streptococci — co-amoxiclav (child one to five years five millilitres of 250/62 suspension twice daily), or cephalexin 25 mg per kilogram (maximum 500 mg) twice daily, or flucloxacillin (child one to five years 125 mg four times daily) for five to seven days. Advise hygiene and warm compresses to the eyelid. Review at 24 to 48 hours to confirm improvement, and give a clear safety-net to return urgently if any orbital sign develops. No imaging or blood tests are needed for uncomplicated preseptal cellulitis. [3]

(c) The feature prompting urgent reassessment (3 marks). Any sign that the septum has been crossed warrants urgent reassessment and imaging: proptosis, limitation of eye movement (ophthalmoplegia), pain on eye movement, decreased visual acuity, impaired colour vision or a relative afferent pupillary defect. Fever and systemic upset are additional warning signs. The family should be told specifically to return if the child develops a bulging eye, cannot move the eye normally, complains of pain on looking around, has blurred or changed vision, or becomes febrile and unwell. The onset of any orbital sign transforms the management from oral antibiotics and review to admission, intravenous antibiotics and contrast CT. [1] [3]