Role of Optic Nerve Fenestration as an Effective Salvage Therapy in Cerebral Venous Thrombosis: A Case Report and Review of Literature
Abolfazl Rahimi1, Kourosh Karimi Yarandi2, Hoda Aryan3
1 Department of Ophthalmology, Tehran Medical Sciences Branch, Islamic Azad University, Tehran, Iran
2 Department of Neurosurgery, Sina Hospital, Tehran University of Medical Sciences (TUMS), Tehran, Iran
3 Young Researchers and Elite Club, Tehran Medical Sciences Branch, Islamic Azad University, Tehran, Iran
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Abstract Background: Cerebral venous thrombosis (CVT) is an uncommon, unrecognized type of stroke mostly affecting young people. Although a headache is the most common clinical manifestation of CVT, neurological focal signs like diplopia and papilledema are also frequently reported in the patients with such a problem. Currently, specific treatment for CVT involves anticoagulation or thrombolytic therapy. Case Report: In this report, we described a 13-year-old female, who was referred to our clinic with a headache and progressive loss of vision due to increased intracranial pressure. Along with usual anticoagulant therapy, we performed the optic nerve sheath fenestration (ONSF) to improve her vision. The patient visual acuity was improved, and after 11 months’ follow-up, no complication was detected.Conclusion: The ONSF can be safe and beneficial in patients with CVT and who are in immediate danger of visual deterioration despite being treated by other means.[GMJ.2017;6(2):160-65] DOI: 10.22086/GMJ.V6I2.883 Keywords: Cerebral Venous Thrombosis; Optic Nerve Fenestration; Headache; Thrombolytic Therapy |
Introduction
Cerebral venous thrombosis (CVT), as well as thrombosis of the main dural sinuses, affects 3 to 4 cases per million annually [1]. The incidence of CVT increases among individuals younger than 40 years, patients with thrombophilia, during pregnancy, and receiving hormonal contraceptive therapy [1]. The most common clinical findings include focal neurologic signs, partial seizures, and papilledema secondary to increased intracranaial pressure (ICP) [2]. It can further progress into venous infarcts or intracerebral hemorrhage. In some instances, CVT can cause raised ICP due to high venous pressure and consequent impairment of cerebrospinal fluid (CSF) reabsorption in venous sinuses. In such cases, medical therapy with anticoagulants and/or acetazolamide as well as CSF shunting are the primary recommended methods to treat intracranial hypertension. In the presence of sustained intracranial hypertension, the most common treatment of ICP is lumboperitoneal shunt insertion. Raised ICP usually occurs in the presence of normal-sized ventricles, and that is the main philosophy to choose lumboperitoneal shunting systems. Insertion of ventriculoperitoneal (VP) shunt with stereotactic aid or decompressive craniectomy is other valid options for management of raised ICP in those with CVT and signs of pseudotumor cerebri. Nevertheless, treatment of such cases in the presence of rapid visual loss can be challenging.
For the first time, optic nerve sheath fenestration (ONSF) was introduced for treatment of neuro-retinitis [3]. Some authors believe that performing this method is beneficial in the early phase when a rapid visual loss occurs. On the other hand, no clear consensus exists in this regard. Through this report, a case of CVT will be described, in whom early use of ONSF rescued her vision and reversed her progressive visual loss.
Case Presentation
Our patient was a 13-year-old girl whose clinical scenario started with fever and chills on March 16th 2016. With an initial diagnosis of common cold, she was given azithromycin, adult cold tablets, and foot lotion and after 4 days her fever subsided. It is noteworthy to mention that the patient had a long history of sinusitis, which was not eradicated despite previous extensive courses of medical treatment.
After 3 days, headache radiating into the neck and both shoulders urged the patient and her family to visit the doctor again. With an injection of Piroxicam, her pain was temporarily relieved but returned only after a few hours.
After 9 days, the patient developed nausea in addition to a severe headache and shoulder pain and was hospitalized for 24 hours. She was diagnosed to have a digestive problem and was referred for gastrointestinal examination. The medical team became suspicious about meningitis, but before lumbar puncture (LP) the family chose to leave the hospital with informed consent and brought the patient to our medical center.
On physical examination, she had severe pain in her nape and shoulder, nausea, vomiting, dizziness, and strabismus. After that, a progressive decrease in her vision was added to the clinical scenario, being more noticeable in the left eye.
In her check-ups, the visual acuity of the right eye was deteriorated to 3/10, and the count finger (CF) of the left eye was equal to 1m. On ophthalmoscopy, papilledema was detectable in both eyes. Macular edema was also present, and afferent pupillary defect (APD) in the left eye was 3+ to 4+ (Figure-1 A and B). Visual fields in both eyes were also affected and decreased (Figure-2 A and B).
The LP was performed for the patient. The initial pressure was 70cmH2O, and in the second examination, it was 45cmH2O. Each time, 20cc of CSF was drained. According to patient’s LP, increased ICP was diagnosed. Each time, CSF analysis and culture was normal.
No intracranial mass lesion was found on her magnetic resonance imaging (MRI) study. Also, no sign of hydrocephalus and preventricular edema was evident (Figure-3). In magnetic resonance venography (MRV) CVT was detected in the proximal parts of the superior sagittal sinus (Figure-4).
The possible causes of CVT were comprehensively investigated, and since other problems such as thrombophilia, pregnancy, oral contraceptives consumption, and meningitis were not present, the main etiologic factor found to be sinusitis.
Anticoagulant therapy was immediately started. Although headache was subsided after a few days, due to signs of severely increased ICP and profound and progressive loss of visual acuity and visual field, a rescue treatment for her deteriorating vision seemed to be necessary as well. Hence, ONSF was performed for her left eye. Warfarin was changed into heparin. Heparin was also temporarily discontinued hours before the surgery.
The ONSF was done under general anesthesia and through medial limbal orbitotomy approach. In this technique, after medial limbal conjunctival peritomy and extending conjunctiva superiorly and inferiorly, the medial rectus was isolated, secured with suture, and detached from the globe. After retracting the orbital fat away from the optic nerve and with the assistance of the operating microscope, the optic nerve sheath was incised 2mm posterior to the globe. When the CSF flush was noticed, the window was opened by removing a small part of the sheath.
Finally, the medial rectus was reattached to the globe with Vicryl 5/0 using standard strabismus muscle technique. The conjunctiva was closed with 8/0 Vicryl sutures.
In the first follow-up postoperative visits, papilledema was significantly reduced in both eyes (Figure-1 C and D).
The left eye vision improved from CF=1m to 3/10, while the right eye vision improved from 3/10 to 4/10 within two days after the surgery. After two weeks, bilateral visual acuity of 6/10 was achieved. In perimetry, the mean deviation (MD) value was significantly improved as well (Figure-2 C and D). Ultimately, a control MRV revealed the opening of the dural sinus by anticoagulant therapy.
Discussion
In light of recent progress in neuroimaging techniques, our knowledge of CVT has considerably evolved. The CVT is a venous type of stroke, with an insidious onset and a subacute clinical course, often misleading the physician to make a false diagnosis. Although numerous causes are now discovered for this event, still some of the cases have an unknown etiology. The most frequently involved locations in the cerebral venous system are superior sagittal sinus and lateral sinus. Nonetheless, the most common form of septic thrombosis occurs in the cavernous sinus. The clinical picture can contain various focal signs (e.g., seizures or neurological deficits) and general symptoms of raised intracranial pressure (such as a headache).
The presentation can imitate arterial strokes, infectious problems such as abscess and encephalitis, intracerebral hemorrhage, or tumors. It can also cause secondary pseudotumor cerebri as a side effect. In these cases, the venous pressure in cerebral sinus increases and the reabsorption of CSF will be severely disturbed, causing high ICP.
A benign course can be seen in the majority of cases, while a mortality rate of 30% is reported in infectious types of CVT [4].
The CVT was the etiologic factor for the rise of ICP in our case. Anticoagulant (heparin) therapy has been proved to be very helpful [2], but the beneficial effect of such a therapy may occur relatively late. Thus, an additional method for salvage of sensitive neurological organs such as optic nerves may be required. The ONSF is one of the most common therapeutic methods to prevent loss of vision due to increased ICP in idiopathic intracranial hypertension.
This procedure is often used when physical and visual symptoms are obvious [3].
Unlike idiopathic intracranial hypertension, the raised ICP due to CVT has a specific line of treatment; reopening the venous system using anticoagulant therapy or other methods. Accordingly, performing an invasive treatment like ONSF seems to be unnecessary in these cases. In our case, despite the thrombosis of the lateral sinus was eventually vanished; deterioration of visual function continued within the first days of therapy, threatening the visual function of the patient. Due to severe and progressive deterioration of visual acuity, we tried ONSF to immediately save visual function and providing additional time for the main therapy (anticoagulant therapy) to safely continue the course of efficient ICP reduction. The beneficial effect of performing ONSF has been proved in patients with idiopathic intracranial hypertension [5], but it can also be considered in such a case suffering from severe and progressive visual loss, despite anticoagulant therapy, as a treatment to salvage visual function.
Conclusion
We found an acceptable outcome in our patient’s vision, which improved within two days after the operation. It must be noted that our patient did not have any risk factor such as old age, use of specific drugs, or previous disease. Thus, we should mention that this procedure can be safe and beneficial in a subgroup of the patients, who do not have significant risk factors for such a surgery and who are in immediate danger of visual deterioration despite being treated by other means.
More of such cases should be reported to shed more light on our conclusion and the indications to use such a salvage treatment should be more recognized in the future.
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Correspondence to: Abolfazl Rahimi, Department of Ophthalmology, Bouali Hospital, Tehran Medical Sciences Branch, Islamic Azad University, Tehran, Iran Telephone Number: +98 21 88775508 E-mail: aborahimi@hotmail.com |
Figure 1. Fundoscopy of the patient. Before surgery, left eye (A) and right eye (B) papilledema were evident in both eyes. Macular edema was present as well. After surgery, left eye (C) and right eye (D) papilledema were significantly reduced in both eyes.
Figure 2. Perimetry of the patient. Before surgery visual fields of the left eye (A) and right eye (B) were decreased. After surgery, visual fields of the left eye (C) and right eye (D) were improved, and the MD value was increased.
Figure 3. MRI study of the patient. T1-weighted axial views (A) and FLAIR axial views (B) showed no intracranial mass lesion or no sign of hydrocephalus and preventricular edema was evident to justify high CSF pressure detected in LP.
Figure 4. Time of flight MRV of the patient. The initial image (A) and follow-up image after one month (B). Superior sagittal sinus is cut in the anterior third. Lack of visualization of the superior sagittal sinus (a short part after the white arrow), is consistent with thrombosis. More posterior parts of the sinus are filled with intact middle and posterior bridging veins. After sufficient anticoagulant therapy, the sinus was opened in the follow-up image.
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