Focal dehiscnece of lamina papyracea

Above axial CT images show focal dehiscence / absence of lamina papyracea in the right orbit with herniation of orbital fat into the right ethmoid sinus. The medial rectus muscle on this side is slightly thickened and irregular although it does not herniate through the bony defect.
This was an incidental finding in the above young patient.

Dehiscence of lamina papyracea may be congenital or acquired( post traumatic/ post-surgical).
There may either be a focal bony defect or inward displacement of the the lamina papyracea.
The defect is usually small with focal herniation of orbital fat and/ medial rectus muscle into the ethmoid bulla.
However, there may be herniation of the optic nerve or the entire  globe.

IMPORTANCE: This defect provides a direct route for sinus surgery instruments which can cause orbital injuries like medial rectus muscle laceration, orbital hematoma, orbital fibrosis, perforation of the orbital wall, damage to globe etc. Hence, it should be highlighted to the otolaryngologist to avoid possible complications during FESS( functional endoscopic sinus surgery).
It may also cause mild diplopia.

REFERENCES:
Hoang JK, Eastwood JD, Tebbit CL, Glastonbury CM. Multiplanar sinus CT:A Systematic Approach to Imaging Before Functional Endoscopic Sinus Surgery. AJR; 194:W527-W536
Radiology picture of the day. Dr Ahmed Haroun.

INTRAOCULAR CYSTICERCOSIS

T2WI of right orbit showing an intraocular cystic lesion abutting the optic nerve head

T1 W sequence showing a hypointense lesion in the posterior part of the globe

FLAIR image showing subretinal cyst with suggestion of a hyperintense scolex posteriorly

FLAIR axial image showing Co-existent cysticercosis in the brain

FLAIR axial image showing co-existent cysticercosis lesions in brain

A 22 year old young man presented with epilepsy and blurring of vision in right eye. An MRI of his brain showed neurocysticercosis with an intra-ocular cystic lesion in right globe in keeping with ocular cysticercosis.

INTRODUCTION: Cysticercosis is a parasitic infection caused by the larval form of pig tapeworm, T solium. The humans act as an intermediate host in the life cycle of the worm and contracts the disease following ingestion of eggs in contaminated water or food. After ingestion, the eggs form primary larvae which disseminate to different parts of the body( central nervous system and skeletal muscles). Once intracranial, the primary larvae develop into secondary larvae, cysticerci..
Ocular disease is reported to occur in a significant number of patients with cysticercosis.

CLINICAL PRESENTATION:
-Blurring/ loss of vision
-Distorsion of images
-Sensation of light flashes
-Periorbital pain
-Diplopia
-Ptosis

DISCUSSION:
The human eye is vulnerable to many infectious diseases. It is important to identify and timely treat these diseases to prevent loss of vision.

Most parasitic infections of the eye arise from blood borne carriage of the micro-organisms to the eye.
The extra-ocular muscles form the most common type of orbital cysticercosis.
In the ocular form, vitreous and subretinal space are the preferential sites. Anterior chamber presentation is very rare.

Diagnosis is usually by direct ophthamoscopic demonstration.
Ultrasound, CT and MRI are imaging modalities described in establishing the diagnosis.
MRI is the best imaging tool for intraocular as well as neurocysticercosis.
If not clearly identified on routine MR sequences, high resolution CISS sequence has been found to be helpful in identifying the ocular lesions.

REFERNCES:
-Nijjar IBS, Singh JP, Arora V, Abrol RA, Sandhu PS, Chopra R, Roopa. MRI in intraocular cysticercosis- A Case Report. IJRI 2005; 15:3