Treatment of pseudotumor cerebri by primary and secondary optic nerve sheath decompression

Optic nerve sheath decompression saves sight in severe papilloedema: results from 81 eyes in 56 patients with pseudotumor cerebri

PURPOSE

To report the outcome of optic nerve sheath decompression (ONSD) for papilloedema in a teaching hospital in western Turkey.

METHODS

The charts of 56 patients who had ONSD surgery between April 2007 and September 2019 were collated; and a total of 81 operated and 31 fellow eyes were included. Pre- and postoperative ophthalmologic examination including best-corrected visual acuity (BCVA), colour vision (CV), visual field (VF) analysis, fundoscopic examination and demographic and medical characteristics of the patients were noted and outcomes after surgery were investigated.

RESULTS

Of all study eyes, 49 (43.7%) eyes had BCVA 0.2 or less and 62 (55.3%) eyes had mean deviation (MD) below - 20.0 dB. 62 (55.3%) eyes had Frisen grade 4 or 5 papilloedema. Almost half of the eyes had severe vision loss. After ONSD, BCVA, CV and MD in both operated and fellow non-operated eyes improved significantly (p < 0.001, p = 0.009 and p < 0.001 for operated, p < 0.001, p = 0.007 and p < 0.001 for fellow eyes, respectively). Earlier surgery and higher cerebrospinal fluid opening pressure were related to better outcomes. None of the patients had major operative complications.

CONCLUSION

Optic nerve sheath decompression can safely improve vision not only of the operated but also of the non-operated eye, even in cases with severe vision loss from severe bilateral papilloedema. Regardless of initial VA and VF, patients may benefit from ONSD; the earlier it is done the more likely the better outcome.

Optic nerve sheath fenestration via a supero-medial eyelid skin crease approach for the treatment of idiopathic intracranial hypertension in a UK population

BACKGROUND/AIMS

Optic nerve sheath fenestration (ONSF) is a surgical intervention in the management of idiopathic intracranial hypertension (IIH) infrequently performed in the United Kingdom. Numerous surgical approaches have been described, including medial transconjunctival, lateral and endoscopic. We describe our outcomes and complications from ONSF via a supero-medial eyelid skin crease incision in patients with IIH.

METHODS

We performed a retrospective review of consecutive patients undergoing ONSF for IIH between January 2011 and December 2017 by a single surgeon.

RESULTS

Thirty patients were included in the analysis with a median follow-up of 14.5 months. Bilateral ONSFs were undertaken in 27 (90%). The data from one eye per patient were analysed. The mean kinetic perimetry score in mean radial degrees of the I4e isopter improved from 27.3° to 35.7°, p = 0.04. After removing cases with optic atrophy, the median modified Frisén grade of papilloedema improved from 2.5 to 1.0, p = 0.007. A total of 5/30 (17%) patients had complications: two (7%) had recurrence/late failure (one managed medically and one with cerebrospinal fluid [CSF] diversion surgery), one had transient cotton wool spots post-operatively, one had transient retinal haemorrhages and one patient had a transiently oval pupil. No patients had repeat ONSF, but CSF diversion surgery was subsequently carried out in 4/30 (13%) patients.

CONCLUSIONS

ONSF via a supero-medial eyelid skin crease approach is effective at improving visual function in patients with IIH. The complication rates are low when compared with CSF diversion surgery and other surgical approaches for ONSF.

Fulminant Idiopathic Intracranial Hypertension

PURPOSE OF REVIEW

The goal of this review is to describe the presenting features of fulminant idiopathic intracranial hypertension (IIH) and outline the multimodal approach to its treatment.

RECENT FINDINGS

Venous sinus stenting may be an appropriate alternative to optic nerve sheath fenestration or cerebrospinal fluid shunting in select patients with fulminant IIH. Prompt surgical intervention maximizes the chance of visual recovery in patients with fulminant IIH. "Fulminant IIH" is defined as intracranial hypertension with no secondary cause, severe vision loss within 4 weeks of symptom onset, and progressive vision loss over days. Rapid recognition of the fulminant phenotype of IIH by emergency department physicians, neurologists, and ophthalmologists is critical. Without appropriate triage and rapid medical and surgical intervention, patients with fulminant IIH are at high risk for profound, permanent vision loss. Prompt surgical intervention with optic nerve sheath fenestration, cerebrospinal fluid shunting, or venous sinus stenting minimizes the chance of poor visual outcome. If a delay is anticipated, serial lumbar punctures or temporary cerebrospinal fluid drainage and medical therapy may forestall irreversible vision loss.

Update on the application of optic nerve sheath fenestration

BACKGROUND

With the ongoing development of surgical procedures and instruments, the safety of optic nerve sheath fenestration (ONSF) has been improved.

OBJECTIVE

Through the past three decades, progress has been made in preventing visual loss from chronic optic nerve swelling in idiopathic intracranial hypertension (IIH), secondary intracranial hypertension and local optic nerve diseases. We now review the updated application of ONSF in those diseases.

METHODS

The application of ONSF in papilledema due to IIH, secondary intracranial hypertension to cerebral venous sinus occlusion, Cryptococcal meningitis, and intracranial mass or tumors is reviewed. Additionally, the potential benefits of ONSF in local optic neuropathy from optic nerve sheath meningioma, optic nerve drusen, traumatic optic neuropathy and optic nerve/sheath biopsy are also described.

RESULTS

Although ONSF has little or no effect on intracranial pressure, it is a safe, relative easy and effective surgical procedure to prevent or reverse visual loss in IIH. When other treatment modalities fail to timely protect vision, ONSF can be useful in protecting visual function or delay visual loss in secondary intracranial hypertension.

CONCLUSION

We recommend that ONSF should be considered as a meaningful alternative or an adjunct therapy to reduce or delay the visual morbidity of these diseases, although the use of ONSF for some of them remains controversial.

Optic nerve sheath fenestration: a revised lateral approach for nerve access

Idiopathic intracranial hypertension (IIH), also known as pseudotumor cerebri, describes a disease of poorly understood pathophysiology with a specific set of signs and symptoms including potentially irreversible and blinding visual loss. Optic nerve sheath fenestration (ONSF) is a well-described surgical treatment for patients with IIH and progressive visual loss despite maximally tolerated medical therapy. A number of optic nerve access procedures have been described including medial transconjunctival, superomedial lid crease, and lateral orbitotomy with and without bone takedown. The purpose of this report is to describe a revised lateral approach for temporal optic nerve access that obviates the need to traverse through the intraconal fat of the central surgical space in the previously described lateral approach techniques.

A 15-year review of secondary and tertiary optic nerve sheath fenestration for idiopathic intracranial hypertension

PURPOSE

Optic nerve sheath fenestration (ONSF) is a common surgical option for patients with idiopathic intracranial hypertension (IIH) with vision loss refractory to medical management. Little is known about the visual benefit of repeated ONSF. The authors aimed to assess the efficacy of secondary and tertiary ONSF in patients with IIH.

METHODS

A retrospective chart review was performed on all patients with repeat ONSF for IIH at Emory University from 1999 to 2016. Primary outcome measures included visual acuity, optic nerve head findings, and visual field results.

RESULTS

A total of nine eyes in seven patients (five females and two males) with repeat ONSF were identified. Two of the seven patients had repeat ONSF in both eyes, while the remaining five patients had only one eye repeated. Five of seven patients (five eyes) improved or remained stable after the secondary ONSF. Two patients (three eyes) continued to worsen despite the secondary fenestration surgery and underwent tertiary ONSF at an average of 13.2 months (SD 5.5 months) after the failed secondary ONSF. Both patients that underwent the tertiary fenestration showed improvement. Six of the patients had either improvement or stability in their clinical findings at their last documented follow-up, but one continued to worsen despite intervention.

CONCLUSIONS

This study suggests that secondary and tertiary nerve sheath fenestration is a viable management option for patients with progressive vision loss from IIH. Repeat ONSFs do not appear to have increased complication or failure rates compared to prior documented studies regarding primary fenestrations.

Endoscopic endonasal optic nerve decompression in a patient with pseudotumor cerebri

Pseudotumor cerebri (idiopathic intracranial hypertension) is a syndrome characterized by intracranial pressure elevation and associated signs and symptoms in the absence of a space-occupying intracranial lesion. The most common symptoms are visual loss and headache. Sometimes, surgical therapy is needed in patients who have no apparent response to medical therapy and exhibit a progressive course. Optic nerve decompression is an effective and recommended treatment approach for patients with pseudotumor cerebri in whom visual loss predominates. With the growing experience with endoscopic skull base approaches, this method has begun to be used as an alternative and effective treatment modality. In this study, we aimed to present the outcome of endoscopic endonasal optic nerve decompression and to review the literature on this treatment modality in 2 patients diagnosed with pseudotumor cerebri that was unresponsive to medical therapy and associated with progressive visual loss.

Papilledema: epidemiology, etiology, and clinical management

Papilledema is optic disc swelling due to high intracranial pressure. Possible conditions causing high intracranial pressure and papilledema include intracerebral mass lesions, cerebral hemorrhage, head trauma, meningitis, hydrocephalus, spinal cord lesions, impairment of cerebral sinus drainage, anomalies of the cranium, and idiopathic intracranial hypertension (IIH). Irrespective of the cause, visual loss is the feared morbidity of papilledema, and the main mechanism of optic nerve damage is intraneuronal ischemia secondary to axoplasmic flow stasis. Treatment is directed at correcting the underlying cause. In cases where there is no other identifiable cause for intracranial hypertension (ie, IIH) the available options include both medical and surgical modalities. Weight loss and diuretics remain the mainstays for treatment of IIH, and surgery is typically reserved for patients who fail, are intolerant to, or non-compliant with maximum medical therapy.

Meta-Analysis of CSF Diversion Procedures and Dural Venous Sinus Stenting in the Setting of Medically Refractory Idiopathic Intracranial Hypertension

BACKGROUND AND PURPOSE

In medically refractory idiopathic intracranial hypertension, optic nerve sheath fenestration or CSF shunting is considered the next line of management. Venous sinus stenosis has been increasingly recognized as a treatable cause of elevated intracranial pressure in a subset of patients. In this article, we present the results of the largest meta-analysis of optic nerve sheath fenestration, CSF shunting, and dural venous sinus stenting. This is the only article that compares these procedures, to our knowledge.

MATERIALS AND METHODS

We performed a PubMed search of all peer-reviewed articles from 1988 to 2014 for patients who underwent a procedure for medically refractory idiopathic intracranial hypertension.

RESULTS

Optic nerve sheath fenestration analysis included 712 patients. Postprocedure, there was improvement of vision in 59%, headache in 44%, and papilledema in 80%; 14.8% of patients required a repeat procedure with major and minor complication rates of 1.5% and 16.4%, respectively. The CSF diversion procedure analysis included 435 patients. Postprocedure, there was improvement of vision in 54%, headache in 80%, and papilledema in 70%; 43% of patients required at least 1 additional surgery. The major and minor complication rates were 7.6% and 32.9%, respectively. The dural venous sinus stenting analysis included 136 patients. After intervention, there was improvement of vision in 78%, headache in 83%, and papilledema in 97% of patients. The major and minor complication rates were 2.9% and 4.4%, respectively. Fourteen additional procedures were performed with a repeat procedure rate of 10.3%. Three patients had contralateral stent placement, while 8 had ipsilateral stent placement within or adjacent to the original stent. Only 3 patients required conversion to CSF diversion or 2.2% of patients with stents.

CONCLUSIONS

Patients with medically refractory idiopathic intracranial hypertension have traditionally undergone a CSF diversion procedure as the first intervention. This paradigm may need to be re-examined, given the high technical and clinical success and low complication rates with dural venous sinus stenting.

Optic nerve sheath decompression: a surgical technique with minimal operative complications

BACKGROUND

The purpose of this study was to determine the safety and efficacy of optic nerve sheath decompression (ONSD) with a medial transconjunctival approach for a variety of indications in a larger population of patients than has previously been reported.

METHODS

A retrospective chart review was performed on consecutive patients who underwent ONSD between January 1992 and December 2010. Before ONSD, all patients had documented evidence of progressive loss of visual acuity or visual field, or both. Postoperative follow-up visits were scheduled at 1 week, 1 month, and then every 3-6 months. Main outcome measures were visual acuity, visual fields, and surgical complications.

RESULTS

Five hundred seventy-eight eyes of 331 patients underwent ONSD for progressive vision loss due to various indications, which included but were not limited to idiopathic intracranial hypertension (IIH), progressive nonarteritic ischemic optic neuropathy, and optic nerve drusen (OND). During a mean follow-up of 18.7 months (range, 1 week to 10 years), postoperative visual acuity remained stable or improved in 536 of 568 eyes (94.4%) and progressively worsened in 32 of 568 eyes (5.6%). Visual fields remained stable or improved in 257 of 268 eyes (95.9%) and progressive visual field loss occurred in 11 of 268 eyes (4.1%). There were no reported intraoperative complications. The most common postoperative complication was diplopia (6.0%).

CONCLUSIONS

To our knowledge, this review represents the largest series of patients who have undergone ONSD for any indication. Our data are consistent with current literature supporting ONSD as a safe and effective procedure for IIH. Other indications for ONSD, such as progressive visual field loss associated with OND, warrant further study. Regardless of the indication, complications following ONSD with the technique described in this report are infrequent.

Long-Term Results of Optic Nerve Sheath Fenestration for Idiopathic Intracranial Hypertension: Earlier Intervention Favours Improved Outcomes

The role of optic nerve sheath fenestration (ONSF) in the management of idiopathic intracranial hypertension remains controversial, with indications, risks, and benefits compared to cerebro-spinal fluid diversion procedures not fully elucidated. We report a retrospective record review of 37 patients (50 eyes) which had undergone ONSF by a single surgeon. Visual acuity (VA) improved in 22% of operated eyes and 17% of fellow eyes; stabilized in 54% of operated and 74% of fellow eyes; and deteriorated in 24% of operated and 9% of fellow eyes. Better pre-operative VA (p = 0.01), colour vision (p = 0.002), and earlier intervention (p = 0.04) were associated with stabilization. We conclude that ONSF often stabilizes vision and visual fields. Our results were best in patients with better pre-operative vision and in those with earlier intervention.

Papilledema: are we any nearer to a consensus on pathogenesis and treatment?

Papilledema is a term generally reserved (at least in the English language use of the term) by neuro-ophthalmologists for optic disc edema due to increased intracranial pressure. The etiology for the intracranial hypertension may be known (e.g., brain tumor, meningitis, cerebral venous sinus thrombosis) or may be idiopathic (idiopathic intracranial hypertension [IIH]). IIH is a disorder that predominantly affects overweight women of childbearing age and these epidemiologic factors should offer clues to pathogenesis. The main morbidity of papilledema is visual loss and the major mechanism for permanent optic nerve damage is axoplasmic flow stasis and resultant intraneuronal ischemia. The current initial management of papilledema in IIH includes weight loss and medical therapy (e.g., acetazolamide or furosemide). Patients who fail, are intolerant to, or noncompliant with maximum tolerated medical therapy might require optic nerve sheath fenestration or cerebrospinal fluid diversion (i.e., shunting) procedures.

Resolution of headache and papilledema in idiopathic intracranial hypertension associated with inhibition of Na+-K+-2Cl- cotransport

Medical treatment of idiopathic intracranial hypertension is often ineffective. Cerebrospinal fluid diversion or optic nerve sheath fenestration is employed when medical therapy fails. Here, we describe a case of a 13-year-old girl with idiopathic intracranial hypertension refractory to long-term trials of acetazolamide and furosemide at maximally tolerated doses. After declining surgical intervention despite progression of her visual symptoms, a trial of bumetanide (0.25 mg daily) monotherapy was successful in resolution of the patient's symptoms. These results suggest bumetanide could be effective in the treatment of idiopathic intracranial hypertension, perhaps by restoring the balance between cerebrospinal fluid formation and absorption and/or by altering the volume or ionic composition of the brain's extracellular fluid compartment.

Clinical review: the surgical treatment of idiopathic pseudotumour cerebri (idiopathic intracranial hypertension)

To review the literature on the surgical treatment of idiopathic pseudotumour cerebri (PTC) [idiopathic intracranial hypertension (IIH)]. When medical therapy fails or when visual dysfunction deteriorates, surgical therapies for PTC should be considered. The main procedures performed include lumboperitoneal shunt (LPS), ventriculoperitoneal shunt (VPS) and optic nerve sheath fenestration (ONSF). Recently, venous sinus stenting procedures have been performed on selected patients with PTC, especially those with venous sinus occlusive disease. The literature is summarized and appraised in the form of a narrative review. It is evident that ONSF, LPS, VPS and, in selected cases, venous sinus stenting may improve vision and prevent deterioration of vision in patients with PTC. All of the procedures have their advantages and disadvantages and may fail with time no matter what procedure is used. Various authorities have vehemently advocated one or the other of these procedures. Until a prospective, randomized study comparing ONSF with LPS or VPS for PTC is performed, and until the role of venous sinus obstruction as the aetiology of PTC is better defined, the question of which surgical procedure is best for the treatment of PTC remains unanswered.

Optic nerve sheath decompression for visual loss in intracranial hypertension: report from a tertiary care center in South India

AIM

Severe visual loss is the only serious complication of intracranial hypertension secondary to idiopathic intracranial hypertension (IIH) and some cases of cerebral venous thrombosis (CVT). Optic nerve sheath decompression (ONSD) has been shown to improve or stabilize visual function in patients with IIH, while its role in CVT is yet to be established. We report our experience with optic nerve sheath decompression for visual loss in IIH and CVT.

MATERIALS AND METHODS

In this prospective noncomparative, interventional study, 41 eyes of 21 patients with IIH and CVT and visual loss underwent ONSD. The main outcome measures included best-corrected visual acuity (BCVA), visual fields, pupillary light reflex, optic nerve sheath diameter on B-scan and resolution of papilledema which were evaluated preoperatively and at follow-up at four days, two weeks, one month, three months and final follow-up. In 7/41 eyes with absent light perception preoperatively, the functional outcome was analyzed separately.

RESULTS

Following ONSD BCVA and visual fields stabilized or improved in 32/34 (94%) eyes. Statistically significant improvement in BCVA, visual fields and pupillary light reflex occurred over the three month follow-up period. Surgical success was indicated by reduction in optic nerve diameter and papilledema resolution occurred in all patients. The outcome in the IIH and CVT groups was comparable. Four eyes with absent light perception showed marginal improvement in visual acuity. Four eyes had transient benign complications.

CONCLUSION

Optic nerve sheath decompression is an effective and safe procedure to improve or stabilize vision in patients with visual loss caused by IIH and CVT.

Mechanisms of visual loss in papilledema

The term "papilledema" indicates swelling of the optic discs secondary to increased intracranial pressure. Papilledema can be caused by an intracranial mass lesion or by other factors. Visual symptoms frequently accompany papilledema, which can lead to permanent visual loss if left untreated. Starting with an illustrative case, the authors review the pathophysiology of the visual signs and symptoms of papilledema. They also briefly review potential treatment options, focusing on the role of the neurosurgeon in the treatment of patients with papilledema.

Visual outcomes comparing surgical techniques for management of severe idiopathic intracranial hypertension

Object

The object of this study was to compare surgical techniques for management of visual loss in idiopathic intracranial hypertension (IIH) unresponsive to medical treatment.

Methods

The published literature was reviewed using electronic and manual search techniques. Articles were categorized based upon the surgical procedure performed, including optic nerve sheath decompression (ONSD), also called optic nerve sheath fenestration; intracranial venous sinus stent placement; ventriculoperitoneal (VP) shunt placement; and lumboperitoneal (LP) shunt placement. Demographic data and visual outcome of the cumulative experience were compiled and compared for each type of surgical intervention.

Results

Seventeen patients treated by stent placement, 31 by VP shunt placement, 44 by LP shunt placement, and 252 patients by ONSD were identified in the literature; average follow-up ranged from 11.8 months for patients treated with stents to 57.2 months for those treated with LP shunts. Improved or resolved vision deficit was noted in 38.7% of patients after VP shunt placement, 47% of patients after stent placement, 44.6% of patients after LP shunt placement, and 80% of eyes after ONSD. Visual worsening was rare for all procedures evaluated.

Conclusions

There is a paucity of information regarding visual outcomes from intracranial venous stent placement and cerebrospinal fluid diversion procedures. Visual outcomes from ONSD are better documented and appear to be superior to other surgical techniques for management of IIH. Further studies with improved data collection regarding visual outcomes are needed for surgical procedures other than ONSD in order to assess their possible value as treatments for visual loss in IIH.

Visual outcomes for optic nerve sheath fenestration in pseudotumour cerebri and related conditions

BACKGROUND

To determine the efficacy and safety of optic nerve sheath fenestration, and to identify factors predicting visual field (VF) and visual acuity (VA) in patients with progressive pseudotumour cerebri syndrome.

METHODS

This retrospective observational case series studied 51 eyes of 32 patients with pseudotumour cerebri syndrome, by chart review and comparison of preoperative and postoperative examinations. Main outcome measures included VF, VA and complications.

RESULTS

Postoperative VF mean deviation scores improved (P = 0.03) within 6 months when compared with preoperative VF. Multiple regression analysis demonstrated that eyes with mean deviation > or = -20 dB were associated with improved or stabilized VA at 6 months, odds ratio 7.5 and confidence interval (1.2, 46.1), P = 0.03. Eyes with VF defects outside 10 degrees of fixation were associated with improved or stabilized VF at 6 months odds ratio 9.7, 95% confidence interval 1.1, 85.9, P = 0.04. Five patients developed self-limiting complications from surgery.

CONCLUSIONS

Optic nerve sheath fenestration is safe and effective in stabilizing or improving VF and VA in the short to medium term. Patients with mild VF loss improved following surgery, and patients with severe VF loss stabilized following surgery.

Optic nerve disorders: role of canal and nerve sheath decompression surgery

Optic nerve sheath decompression (ONSD) maintains a role in the management of visual loss complicating papilloedema in selected patients primarily with idiopathic intracranial hypertension. The evidence base for this intervention is reviewed and audit data on visual outcomes for patients with acute, chronic, and atrophic forms of papilloedema are contrasted. Optic canal decompression has a role in the management of compressive optic neuropathies complicating mass lesions arising from paranasal sinuses and intracranially and can be achieved by transethmoidal, transbasal, and open craniotomy routes. The evidence base supporting this intervention in traumatic optic neuropathy and in primary bone disease causing canal stenosis (in particular fibrous dysplasia) is reviewed where the indications are more controversial.

Idiopathic intracranial hypertension

OBJECTIVE

The history, diagnosis, and therapy of idiopathic intracranial hypertension (IIH) (pseudotumor cerebri) are reviewed. Theories of pathogenesis are considered, the clinical presentation is described, and potential diagnostic and therapeutic challenges are explored.

METHODS

An extensive literature review of IIH and related conditions (secondary pseudotumor syndromes) was performed. The history of and rationale for the diagnosis and medical and surgical approaches to treatment are reviewed. Available outcome studies are presented.

RESULTS

Diagnosis of IIH requires that the modified Dandy criteria be satisfied. Multiple potential contributing causes of intracranial hypertension must be identified or excluded. The clinical presentation most often includes headaches and papilledema, but many other findings have been described. The most important goal of therapy is to prevent or arrest progressive visual loss. Medical therapies include alleviation of associated systemic diseases, discontinuation of contributing medications, provision of carbonic anhydrase inhibitors, and weight loss. Surgical therapies include lumboperitoneal shunting, ventriculoperitoneal shunting, and optic nerve sheath fenestration. On the basis of the advantages and disadvantages of these treatment modalities, a suggested treatment paradigm is presented.

CONCLUSION

Idiopathic intracranial hypertension is the term to be adopted instead of pseudotumor cerebri. IIH remains an enigmatic diagnosis of exclusion. However, prompt diagnosis and thorough evaluation and treatment are crucial for preventing visual loss and improving associated symptoms.

Idiopathic Intracranial Hypertension

The syndrome of intracranial hypertension without structural brain or cerebrospinal fluid abnormalities and without identifiable cause, now most appropriately termed idiopathic intracranial hypertension, was described over a century ago. Although the pathogenesis of this condition remains unknown, diagnostic and therapeutic developments during the past two decades have substantially advanced patient management.

Pseudotumor cerebri

Pseudotumor cerebri is a perplexing syndrome of increased intra-cranial pressure without a space-occupying lesion. The terminology for the disorder has changed over the years and the diagnostic criteria revised to reflect advances in diagnostic technology and insights into the disease process. The classification and nomenclature depend on the presence or absence of an underlying cause. When the diagnostic criteria are followed, a secondary etiology is unlikely. When no secondary cause is identified, the syndrome is termed "idiopathic intracranial hypertension."

Idiopathic "benign" intracranial hypertension: case series and review

Idiopathic "benign" intracranial hypertension is an uncommon but important cause of headache that can lead to visual loss. This study was undertaken to review our experience in the diagnosis and management of idiopathic intracranial hypertension, giving special attention to treatments used. A retrospective chart review was conducted on 32 patients diagnosed with idiopathic intracranial hypertension between 1984 and 1995. Subjects included 23 females and ranged in age from 2 to 17.5 years. Headache was the most common symptom, followed by nausea and vomiting, double vision, and visual loss. Papilledema was the most common sign. Others were VIth cranial nerve palsy and compromised visual acuity at or within 3 months of presentation. Management included administration of acetazolamide or corticosteroids, lumboperitoneal shunt, optic nerve fenestration, and repeat lumbar puncture. Treatment combinations were used in 40% of cases. During follow-up, headache, papilledema, and decreased visual acuity persisted for longer than 10 months in a significant number of patients. We conclude that idiopathic intracranial hypertension causes significant short- and long-term morbidity with no proven effective treatment available. A prospective study is needed to establish the indications for treatment and the efficacy of the treatments used.

The contribution of macular changes to visual loss in benign intracranial hypertension

PURPOSE

To describe the significance of macular changes to visual outcome in benign intracranial hypertension (BIH).

METHOD

The clinical and photographic records of 24 patients with BIH who required optic nerve sheath fenestration were analysed.

RESULTS

Macular changes were found in 21 of 48 (44%) eyes. These were: choroidal folds 9; circumferential lines (Paton's lines) 4; nerve fibre layer haemorrhage 3; macular stars 5; macular oedema 6; retinal pigment epithelial changes 4; subretinal haemorrhage leading to a macular scar 1. Significant visual loss attributable to the macular changes was found in 5 eyes in the short term and 3 in the long term. The 2 eyes that improved had macular stars. Of the 3 eyes that did not improve, 2 eyes had retinal pigment epithelial changes and 1 a large subretinal haemorrhage that led to a macular scar. These 3 cases had long-standing BIH.

CONCLUSIONS

The majority of macular changes resolve and do not add to visual loss from optic nerve damage. Patients with marked macular oedema are at most risk of permanent visual loss and should be considered for early treatment such as optic nerve sheath fenestration.

Breakdown of the meningeal barrier surrounding the intraorbital optic nerve after experimental subarachnoid hemorrhage

PURPOSE

The intraorbital optic nerve sheath meninges contain a perineural subarachnoid space lined by meningeal cell layers and intercellular fibrous tissue. We sought to determine whether functional or structural characteristics, or both, of the optic nerve sheath are influenced by the increased intracranial pressure after the rupture of cerebral aneurysms.

METHODS

We infused the great cisterns of cats with either x-ray contrast medium or autologous blood. The cisternal infusions were done under the experimental condition of a sudden 2.5-minute increase in intracranial pressure similar to that recorded after the rupture of cerebral aneurysms in humans.

RESULTS

Digital subtraction radiographs of the optic nerves taken during the cisternal infusion of contrast medium at the start showed the opacification of the optic nerve subarachnoid space. After 2 minutes, the contrast medium leaked into the orbit, indicating the breakdown of the meningeal fluid barrier. Ultrastructural investigation of the optic nerve sheath after high-pressure cisternal infusions showed the arachnoid cell layers scattered. The flattened arachnoid cells displayed mainly intracellular and some intercellular, porelike openings. After infusion of blood into the great cistern, erythrocytes were found within porelike openings of the arachnoid cells.

CONCLUSIONS

The meningeal fluid barrier of the optic nerve sheath can be destroyed by pressure changes associated with subarachnoid hemorrhage. This disruption might be regarded as a natural optic nerve sheath fenestration that allows outflow of cerebrospinal fluid into the orbit to protect the optic nerve from increased intracranial pressure after aneurysmal rupture.

Effect of mitomycin C on the optic nerve in rabbits

AIM

To prevent scarring after surgical optic nerve sheath decompression, it has been suggested that treating the area of fenestration with mitomycin C (MMC) might be effective. An animal model was used to test whether this toxic substance may cause optic neuropathy.

METHODS

The optic nerves of 15 rabbits were exposed to balanced salt solution (BSS) or mitomycin C (MMC) in a concentration of 0.2 or 0.5 mg/ml. The unoperated fellow eyes and the eyes that received BSS served as controls. Steady state visual evoked potentials (VEPs) at 40, 50, and 60 Hz were recorded before and 4 weeks after surgery. The nerves were examined by light and electron microscopy after 5 weeks.

RESULTS

VEPs in all non-operated eyes and eyes treated with BSS before and 4 weeks after surgery demonstrated responses at all three stimulus frequencies tested. Eyes operated with MMC had extinguished responses for one, two, or all the different temporal frequencies after 4 weeks with marked reduction in VEP amplitude. Eyes operated with MMC at a concentration of 0.5 mg/ml had significantly more reduced VEP responses than those where MMC 0.2 mg/ml was used. On histopathological examination, special stains for myelin and axons showed normal axons and myelin. On electron microscopy, no distinct abnormalities were seen among nerves operated with MMC and controls.

CONCLUSION

The data from this study suggest that in rabbits, the application of MMC to the optic nerve has a dose dependent toxic effect in the short term postsurgical follow up period. While a functional alteration could be demonstrated reproducibly by steady state VEPs, the extent was not obvious on histopathological examination of the nerves.

All-trans-retinoic acid and pseudotumor cerebri

Pseudotumor cerebri or idiopathic intracranial hypertension is a neurological syndrome characterized by signs and symptoms of intracranial hypertension without clinical and radiological evidence of infective or space occupying lesions. Iatrogenic factors are frequent; in particular, cases of Pseudotumor cerebri associated with all-trans-retinoic acid treatment in acute promyelocytic leukemia (APL) have been frequently described in pediatric patients. We review the literature and give diagnostic and therapeutic guidelines.

Long-term results using adjunctive mitomycin C in optic nerve sheath decompression for pseudotumor cerebri

PURPOSE

Up to 35% of patients undergoing optic nerve sheath decompression (ONSD) for pseudotumor cerebri who show initial improvement in visual function later show deterioration in visual field and acuity. Although repeat surgery can result in subsequent visual improvement, these procedures are technically difficult because of scarring and fibrosis. Attempting to improve the long-term success of ONSD, the authors sought to analyze the long-term success of ONSD by pretreating optic nerve sheaths with mitomycin C before incision.

METHODS

Using a standard transconjunctival medial orbitotomy, optic nerve sheaths were exposed and treated for 5 minutes with mitomycin C (0.5 mg/ml)-soaked neurosurgical cottonoids before incision.

RESULTS

Both eyes undergoing repeat ONSD with adjunctive mitomycin C had initial improvement and stable visual function for follow-up of more than 3 years. Four eyes that underwent primary ONSD all initially showed improvement in visual field. Three eyes with large cysts or fistulas remained stable. Another eye had gradual decline in visual function. Repeat ONSD in this eye showed no orbital scarring, and lysis of adhesions between dura-arachnoid and optic nerve resulted in improved, stable visual function for 31 months of follow-up.

CONCLUSION

Mitomycin C appears to be a safe adjunct to ONSD in a series of six patients followed between 20 and 37 months. Fistulization and cyst formation are associated with improved visual function. Closure of cysts and fistulas may result in worsening visual function due to intersheath adhesions. Repeat surgery shows significantly less orbital scarring and allows for easier and successful repeat surgery. Adjunctive mitomycin C leads to less orbital scarring after ONSD, allowing for easier repeat surgery.

Idiopathic intracranial hypertension

Although the cause of IIH remains obscure, it has become clear that loss of visual function is common and patients may progress to blindness. Diagnosis should adhere to the modified Dandy criteria. Recent case-control studies cast doubt on the validity of many frequently cited conditions associated with IIH. Valid associations include obesity, recent weight gain, female gender, vitamin A intoxication, and steroid withdrawal. IIH patient management should include serial perimetry using a sensitive disease-specific strategy. This is done so the proper therapy can be selected and visual loss prevented or reversed.

Management of visual loss after optic nerve sheath decompression in patients with pseudotumor cerebri

PURPOSE

To determine the appropriate management of patients with pseudotumor cerebri with early, progressive visual loss after optic nerve sheath decompression (ONSD).

METHODS

The records of all patients with pseudotumor cerebri who underwent ONSD were reviewed retrospectively. Patients who showed visual loss within 1 month of surgery were studied.

RESULTS

Five patients with pseudotumor cerebri, including two with renal failure and hypertension, had visual loss within 1 month of ONSD. The first patient had an abrupt decrease in vision 6 days after ONSD. In this patient, a vessel on the nerve sheath bled into the surgical site. At the time of ONSD, this patient had a visual acuity of 20/20 1 day after surgery. Six days later, visual acuity decreased to 20/200. After high-dose intravenous corticosteroids failed to improve vision, emergency lumboperitoneal shunt resulted in full visual recovery. An apparent infectious optic neuropathy developed in the second patient 3 days after surgery. After 72 hours of intravenous antibiotics, visual acuity improved from 20/600 to 20/15. The other three patients had gradual visual loss after ONSD, which stabilized after lumboperitoneal shunts.

CONCLUSIONS

Avoidance of bleeding during ONSD may prevent fibrous occlusion of the surgical site. Patients with no identifiable cause for visual loss after ONSD, who do not respond to intravenous corticosteroids, should be evaluated for emergency lumboperitoneal shunting. Postoperative infectious optic neuropathy should be considered in the differential diagnosis of abrupt visual loss after ONSD.

Measurement of the subarachnoid pressure of the optic nerve in human subjects

PURPOSE

We measured the subarachnoid pressure of the optic nerve in 16 patients scheduled for ocular enucleation or evisceration.

METHODS

We measured the subarachnoid pressure of the optic nerve directly with an electronic digital manometer in 16 patients scheduled for enucleation or evisceration for various blinding conditions. The nerve was exposed via a medial orbitotomy, and the subarachnoid pressure of the optic nerve was measured 5 mm posterior to the optic nerve head. The subarachnoid pressure of the optic nerve was also measured in five patients who were placed in the Trendelenburg position (head declined at a 30-degree angle) for three minutes.

RESULTS

The subarachnoid pressure of the optic nerve varied from 4 to 14 mm Hg in the 16 patients tested. The mean subarachnoid pressure of the optic nerve was 8.5 mm Hg in the 16 patients tested. An increase of 1 to 2 mm Hg in the subarachnoid pressure was observed in all five patients placed in the Trendelenburg position.

CONCLUSIONS

Subarachnoid pressure of the optic nerve can be measured in vivo in humans. The values obtained are consistent with the known physiologic range of intracranial pressure. There was no statistically significant correlation between subarachnoid pressure of the optic nerve and age or cause of blindness. The subarachnoid pressure of the optic nerve varies over a wide range.

Choroidal infarction after optic nerve sheath fenestration

PURPOSE

To describe a visual complication of optic nerve sheath fenestration.

METHODS

Case review of two patients who underwent seemingly uncomplicated optic nerve sheath fenestration.

FINDINGS

Both patients had a surgical complication that resulted in significant depression of their temporal visual field and development of a wedge-shaped region of subretinal pigmentation in the nasal fundus.

CONCLUSIONS

Both patients had choroidal infarctions as a complication of optic nerve sheath fenestration. Choroidal infarction should be considered in cases of unexpected loss of visual field after this type of surgery, although the funduscopic signs that assist in making the diagnosis may not be evident for several weeks after surgery.

Idiopathic intracranial hypertension

OBJECTIVE

This review was undertaken to summarize the significant progress that has been made in the epidemiology of idiopathic intracranial hypertension (IIH), the changing nosology, and the diagnostic criteria and therapeutic strategy.

DESIGN

We reviewed the pertinent literature on IIH published in major English-language journals for the last 20 years.

MATERIAL AND METHODS

The diagnosis, epidemiology, pathophysiology, complications, and treatment of IIH are described.

RESULTS

IIH occurs at an average annual incidence rate per 100,000 persons of 1 to 2 for the total population and 19 to 21 in obese females of the reproductive age-group. IIH is a recognized cause of reversible vision loss in adult obese women. The diagnosis of IIH requires a documented elevation of intracranial pressure, normal cerebrospinal fluid (CSF) composition, and normal findings on neuroimaging studies. At least two primary mechanisms for the development of increased CSF pressure in IIH have been postulated and supported by experimental data: vasogenic extracellular brain edema and a low conductance of CSF outflow at the arachnoid villi. This condition may be secondarily exacerbated by compression of intracranial venous sinuses by the increased intracranial pressure, resulting in a further reduction of flow across the arachnoid villi. The therapeutic strategy is determined by visual status, which needs close monitoring.

CONCLUSION

Although medical measures to lower the intracranial hypertension are successful in the majority of patients, surgical therapy should not be delayed in those with significant or progressive vision loss. Based on recent advances, a practical approach has been described for the diagnosis, early detection of visual impairment, and targeting therapy to preserve the vision or to reverse recent loss of vision in patients with IIH.