Ординатура / Офтальмология / Английские материалы / Oculoplasty and Reconstructive Surgery Made Easy_Garg,Touky, Nasralla_2009
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Infections of the Orbit 319
Figures 5A to D: (A) Clinical photograph of patient with tubercular osteomyelitis left orbit, showing left proptosis, fullness of superior sulcus, and discharging sinus. (B) Axial CT scan of the same patient, showing well-circumscribed soft-tissue density mass in left superolateral orbit.
(C) Acid fast bacillus detected with Ziehl Nielson staining. (D) Healed orbital tuberculosis after treatment. The site of the sinus is scarred
Investigation
Orbital biopsy: the biopsy shows caseating or non-caseating granulomatous inflammatory changes. Histopathological examination of biopsied material may rarely reveal acid fast bacilli. The biopsied material inoculated on culture media may rarely grow AFB. It may be useful to subject biopsied material to Polymerase chain reaction (PCR) for Mycobacterium
tuberculosis DNA.
Concomitant active tuberculosis elsewhere in the body may or may not be present. A chest X-ray may be helpful. Strongly positive tuberculin test in presence of an orbital lesion may be corroborative evidence.
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Management
Management of orbital tuberculosis is systemic therapy with antitubercular drugs.
Inference
Diagnosis of orbital tuberculosis requires a high index of suspicion. If the evidence is subtle, a therapeutic trial with anti-tubercular drugs may be beneficial.
ORBITAL FUNGAL INFECTION
Orbital fungal infection is by predominantly two classes of fungi—Mucor and Aspergillus.
ORBITAL MUCORMYCOSIS
Introduction
Orbital mucormycosis, by species of rhizopus, is commonly seen in debilitated, immunocompromised patients. Uncontrolled diabetics are a susceptible group of patients, as are patients on chemotherapy for hematological malignancies. Orbital disease is frequently associated with sinus or cerebral disease
Sign and Symptoms
The condition is painful in about 40% of patients, with ocular as well as facial pain. The patient may be febrile. There is facial and periocular edema. Vision is diminished; there may be proptosis and ptosis. Orbital apex involvement will cause total ophthalmoparesis. Other cranial nerves involved are the fifth and seventh nerves. Inflammatory signs such as conjunctival congestion and chemosis are present. The pupil
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Figures 6A and B: (A) Clinical photograph of patient with uncontrolled diabetes, with pain, proptosis, ptosis, complete ophthalmoparesis and diminished vision. (B) Axial contrast-enhanced T1-weighted MRI scan of same patient, showing soft tissue density shadows in the ethmoid sinus and orbital apex
may have relative afferent pupillary defect. Blackened areas of necrosis and eschar are visible in the external nares or palate. The periocular and facial skin shows necrosis with advanced disease (Figures 6A and B).
Investigations
Suspected mucormycosis warrants orbital imaging, preferably with CT scan. CT scan shows homogenous, well circumscribed or diffuse irregular soft tissue density mass in the orbit, extending to paranasal sinus or intracranially. The imaging will also show any bone erosion. MRI scan better visualizes intracranial extension into the frontal lobe or into the carotid artery siphon.
Diagnosis is by biopsy from the affected tissue, the biopsy specimen showing fungal filaments on staining, or growing mucor species on inoculation into culture media. Biopsy material may be obtained by endoscopic sinus surgery or from the orbit, and stained by both hematoxylin-eosin and specific fungal stains.
Investigations also demonstrate the underlying systemic condition:historically,mucormycosishasbeenassociatedwith
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diabetic ketoacidosis. Appropriate investigations should be undertaken for diabetes, hematological malignancies, chronic renal failure and other immunosuppressed states.
Treatment
Mucormycosis is best treated by a multi-specialty team of infectious disease specialist, orbital surgeon, neurosurgeon and ENT surgeon. Patients with rhino-orbito-cerebral mucormycosis require extensive and repeated debridation of thesinuses,orbitandotherinfectedareas.Theaimistoremove all unhealthy tissue. Orbital extension may be required in nearly half the patients with severe orbital disease.
The mainstay of treatment is intravenous amphotericin B, at the dose of 1 to 1.5 mg/kg body weight per day. Prolonged treatment may be required. Liposomal amphotericin B has been shown to be more effective. Newer systemic antifungals such as posaconazole and voriconazole have been used in addition. Hyperbaric oxygen may aid in the treatment. Supportive therapy is required for the concurrent systemic conditions.
ORBITAL ASPERGILLOSIS
Introduction
The saprophyte Aspergillus can infect the orbit insidiously, and affects both immunocompetent and immunocompromised individuals. It may also be related to drug addiction, renal transplants, alcoholism and diabetes mellitus.
Signs and Symptoms
Orbital aspergillosis presents with a slowly progressive mass extending into the orbit from the adjacent paranasal sinus. The patient may have progressive proptosis and globe
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Figures 7A and B: (A) Clinical photograph of patient with maxillary sinus fungal granuloma extending into the orbit. There is left eye proptosis, hyperglobus, chemosis and inferior orbital palpable mass. (B) Coronal CT scan shows bilateral maxillary sinus opacity, with diffuse soft tissue mass extending from left maxillary sinus into the orbit, eroding orbital floor, and involving the inferior rectus
displacement. There may be an orbital apex syndrome, with visual loss, ptosis and ophthalmoparesis. The patient has orbital pain and headache. The orbital inflammatory signs are less marked. The vision is relatively better preserved unless there is orbital apex involvement. Occasionally there may be abscess formation. Rarely, the condition may be rapidly progressive.
In the disseminated form, endophthalmitis may occur.
(Figures 7A and B).
Investigation
CT scan imaging of the orbit and paranasal sinuses will detect localized mass from a sinus with bony erosion and infiltrating into the orbit. Rarely there may be an isolated orbital mass. An MRI scan will help early detection of cranio-cerebral spread of the disease.
Biopsy of the sinus or orbital mass will show septate fungal filaments by hematoxylin-eosin and special fungal stains. The confirmation of the diagnosis is by culture of aspergillus from the biopsy material.
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The patient should undergo an evaluation for any underlying predisposing factor-systemic conditions mentioned earlier, or pre-existing sinus disease such as polyps.
Differential Diagnosis
Aspergillosis should be differentiated from other mass lesions arising from the sinus and extending into the orbit. A fulminant presentation of aspergillosis may mimic mucormycosis. Secondary orbital invasion by paranasal sinus malignancies can also have a similar presentation.
Treatment
Disseminated aspergillosis responds poorly to treatment. Local disease can be managed by surgical debridement and irrigation with amphotericin B. The patient needs adjuvant systemic therapy with amphotericin B, ketoconazole or itraconazole. The patients may be followed up with endoscopy and CT scan to detect recurrences early.
ORBITAL CYSTICERCOSIS
Introduction
Orbital infection with cysticercosis is not uncommon in endemic areas of the world. The cysts occur in the extra-ocular muscles and may migrate anteriorly and sub-conjunctivally. Depending on the exact location, the clinical presentation is varied. The inflammatory signs may be moderate or severe.
Signs and Symptoms
The patient may present with axial or non-axial proptosis; the pain may be only mild or more severe. Visual acuity may be diminished due to rare involvement of the optic nerve by
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a cyst, or due to compression. There may be limitation of ocular motility; the restriction of ocular motility is often worst in the direction opposite the muscle involved. Presentation may be that of an isolated rectus weakness; acquired Brown syndrome has been reported in cysticercosis involving the superior oblique. A cyst in the levator palpebraesuperior rectus complex would present with ptosis and restricted elevation of the globe. Cysticercosis in the area of the lacrimal gland presents with a picture like dacryoadenitis. A cyst which has migrated subconjunctivally may present at the insertion of the muscle. Occasionally a cyst may migrate anteriorly and be palpable in the periorbital region as a cystic mass. A cyst may extrude spontaneously. If the cyst ruptures within the orbit, it sets up an intense inflammatory reaction, with pronounced signs and symptoms (Figures 8A and B).
Investigation
Orbital imaging is the mainstay of diagnosis in orbital myocysticercosis.
Figures 8A and B: (A) Clinical photograph of patient with right inferior rectus myocysticercosis. The patient had pain, limitation of depression and diplopia. (B) Axial CT scan of same patient, showing cystic lesion with low internal density, with single high density area representing the scolex. The soft tissue density shadow surrounding the cyst is inflammatory in nature
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An ultrasound B scan of the orbit is a sensitive tool. It will show a low-echo reflective cystic structure with an internal high-echo reflective area of the scolex. A CT scan or MRI scan of the orbit will also detect a cyst with a scolex.
If only the cyst is visualized, but no scolex, a good clinical response to the appropriate therapeutic trial will confirm the diagnosis.
Serum ELISA test for cysticercus antigens has a low sensitivity, but may be corroborative if a cyst without a scolex is detected on imaging.
Management
Medical management comprises the use of oral anthelminthic, albendazole, 15 mg/kg body weight/day, for two weeks. Systemic corticosteroids, 1-2 mg/kg body weight/ day is started concurrently to reduce the inflammatory effects. The steroid is tapered over 6 weeks. Serial USG B scan imaging can document the collapse and ultimately the disappearance of the cyst.
Surgical excision of the cyst is rarely required. The cyst should be removed in toto; rupturing the wall would cause an intense inflammatory response.
Inference
Any patient with proptosis, with mild inflammatory signs and an unusual pattern of ocular motility restriction should be suspected of having orbital myocysticercosis, particularly if the patient has been residing or travelling in the endemic geographical distributions.
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ORBITAL HYDATID CYST
Introduction
Involvement of the orbit by Echinococcus cysts is found in the endemic areas of the world. Orbital hydatid cyst comprises about 1% of all hydatid cysts.
Signs and Symptoms
The patient presents with progressive proptosis, axial or nonaxial. There may be associated pain, diminished vision, limitation of ocular movements and chemosis in addition. There may be edema of the optic disc, and even loss of vision in long-standing cases (Figures 9A and B).
Figures 9A and B: (A) Clinical picture of patient with orbital hydatid cyst, presenting with proptosis, chemosis and periocular edema. (B) Coronal CT scan of same patient, showing multiple cystic lesions in orbit, with low internal density and rim enhancing with contrast
Investigation
An ultrasound B scan will identify a single cyst or multilobulated cysts with echo-lucent centers. MRI scan CT scan will identify clear cystic structures, which may have some calcification on the cyst wall. Additional supportive evidence is from a positive indirect hemagglutinin test (IHA) and eosinophilia.
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Hydatid cysts may involve multiple locations in the body, particularly in children. The common sites are liver, lung and brain, and USG abdomen and CT scan brain may be helpful.
Treatment
The cyst is to be removed surgically by orbitotomy. Care is to be taken not to rupture the cyst during removal. Accidental spillage of the cyst contents into the orbit may cause seeding.
Sytemic albendazole at the dose of 15 mg/kg body weight has been used of recurrent hydatid cysts.
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