Intracranial actinomycosis of odontogenic origin masquerading as auto-immune orbital myositis: a fatal case and review of the literature

Abstract

Background: Actinomycetes can rarely cause intracranial infection and may cause a variety of complications. We describe a fatal case of intracranial and intra-orbital actinomycosis of odontogenic origin with a unique presentation and route of dissemination. Also, we provide a review of the current literature.

Case presentation: A 58-year-old man presented with diplopia and progressive pain behind his left eye. Six weeks earlier he had undergone a dental extraction, followed by clindamycin treatment for a presumed maxillary infection. The diplopia responded to steroids but recurred after cessation. The diplopia was thought to result from myositis of the left medial rectus muscle, possibly related to a defect in the lamina papyracea. During exploration there was no abnormal tissue for biopsy. The medial wall was reconstructed and the myositis responded again to steroids. Within weeks a myositis on the right side occurred, with CT evidence of muscle swelling. Several months later he presented with right hemiparesis and dysarthria. Despite treatment the patient deteriorated, developed extensive intracranial hemorrhage, and died. Autopsy showed bacterial aggregates suggestive of actinomycotic meningoencephalitis with septic thromboembolism. Retrospectively, imaging studies showed abnormalities in the left infratemporal fossa and skull base and bilateral cavernous sinus.

Conclusions: In conclusion, intracranial actinomycosis is difficult to diagnose, with potentially fatal outcome. An accurate diagnosis can often only be established by means of histology and biopsy should be performed whenever feasible. This is the first report of actinomycotic orbital involvement of odontogenic origin, presenting initially as bilateral orbital myositis rather than as orbital abscess. Infection from the upper left jaw extended to the left infratemporal fossa, skull base and meninges and subsequently to the cavernous sinus and the orbits.

Keywords: Actinomycosis; Intracranial infection; Intraorbital infection; Odontogenic origin; Orbital myositis.

Fig. 1

a Orthoptic evaluation shows an impaired abduction with over-elevation in adduction of the left eye, suggesting a mechanical component. b CT image (coronal reconstruction) which demonstrates a defect in the left lamina papyracea

Fig. 2

a Orthoptic evaluation now shows impaired elevation and abduction of the right eye. b CT image (coronal reconstruction) which shows enlargement of the right inferior rectus muscle with inflammatory fat infiltration surrounding the muscle

Fig. 3

a T1w fat-suppressed post-gadolineum MRI scan which shows contrast enhancement at the surface of the basal brain structures compatible with basal meningitis (arrow). b Diffusion-weighted image shows high signal, which represents diffusion restriction caused by an acute brain infarct, bilaterally in the thalamus (arrow indicated by asterisk). In addition the high signal posterior in the ventricles is suggestive of ventricular empyema (arrow indicated by double asterisk). c and d Pre and post-gadolineum T1w MRI scan demonstrating a lesion in the right orbit with ring enhancement compatible with an abscess

Fig. 4

Autopsy samples from the brain showed gram-positive filamentous microbes

Fig. 5

Reexamination of imaging studies. a–c T1w MRI scans from 2 months after the initial presentation show (a) a soft tissue mass in the left infratemporal fossa (arrow), with (b) decreased signal intensity in the left central skull base (arrow) and (c) a low signal intensity in the left cavernous sinus (arrow). d–f T1w MRI scan performed at a later stage revealed (d) resolution of the lesion in the infratemporal fossa (arrow), but there is bilateral enlargement of the cavernous sinus (arrows) and involvement of the pituitary gland on the coronal post-gadolinium T1w scan (e) and the T2w Scan (f)