Carotid-cavernous fistula: current concepts in aetiology, investigation, and management

A carotid-cavernous fistula (CCF) is an abnormal communication between arteries and veins within the cavernous sinus and may be classified as either direct or dural. Direct CCFs are characterized by a direct connection between the internal carotid artery (ICA) and the cavernous sinus, whereas dural CCFs result from an indirect connection involving cavernous arterial branches and the cavernous sinus. Direct CCFs frequently are traumatic in origin and also may be caused by rupture of an ICA aneurysm within the cavernous sinus, Ehlers-Danlos syndrome type IV, or iatrogenic intervention. Causes of dural CCFs include hypertension, fibromuscular dysplasia, Ehlers-Danlos type IV, and dissection of the ICA. Evaluation of a suspected CCF often involves non-invasive imaging techniques, including standard tonometry, pneumotonometry, ultrasound, computed tomographic scanning and angiography, and/or magnetic resonance imaging and angiography, but the gold standard for classification and diagnosis remains digital subtraction angiography. When a direct CCF is confirmed, first-line treatment is endovascular intervention, which may be accomplished using detachable balloons, coils, liquid embolic agents, or a combination of these tools. As dural CCFs often resolve spontaneously, low-risk cases may be managed conservatively. When invasive treatment is warranted, endovascular intervention or stereotactic radiosurgery may be performed. Modern endovascular techniques offer the ability to successfully treat CCFs with a low morbidity and virtually no mortality.

Investigation of In Vivo skin stiffness anisotropy in breast cancer related lymphoedema

There is a limited range of suitable measurement techniques for detecting and assessing breast cancer related lymphoedema (BCRL). This study investigated the suitability of using skin stiffness measurements, with a particular focus on the variation in stiffness with measurement direction (known as anisotropy). In addition to comparing affected tissue with the unaffected tissue on the corresponding site on the opposite limb, volunteers without BCRL were tested to establish the normal variability in stiffness anisotropy between these two corresponding regions of skin on each opposite limb. Multi-directional stiffness was measured with an Extensometer, within the higher stiffness region that skin typically displays at high applied strains, using a previously established protocol developed by the authors. Healthy volunteers showed no significant difference in anisotropy between regions of skin on opposite limbs (mean decrease of 4.7 +/-2.5% between non-dominant and dominant arms), whereas BCRL sufferers showed a significant difference between limbs (mean decrease of 51.0+/-16.3% between unaffected and affected arms). A large difference in anisotropy was apparent even for those with recent onset of the condition, indicating that the technique may have potential to be useful for early detection. This difference also appeared to increase with duration since onset. Therefore, measurement of stiffness anisotropy has potential value for the clinical assessment and diagnosis of skin conditions such as BCRL. The promising results justify a larger study with a larger number of participants.

Current concepts in the diagnosis, pathogenesis and management of nonarteritic anterior ischaemic optic neuropathy

Nonarteritic anterior ischaemic optic neuropathy (NAION) is the most common acute optic neuropathy in patients over the age of 50 and is the second most common cause of permanent optic nerve-related visual loss in adults after glaucoma. Patients typically present with acute, painless, unilateral loss of vision associated with a variable visual field defect, a relative afferent pupillary defect, a swollen, hyperaemic optic disc, and one or more flame-shaped peripapillary retinal haemorrhages. The pathogenesis of this condition is unknown, but it occurs primarily in patients with structurally small optic discs that have little or no cup and a variety of underlying vascular disorders that may or may not be known at the time of visual loss. There is no consistently beneficial medical or surgical treatment for the condition, but there are now animal models that allow testing of various potential therapies. About 40% of patients experience spontaneous improvement in visual acuity. Patients in whom NAION occurs in one eye have a 15-19% risk of developing a similar event in the opposite eye over the subsequent 5 years.

Diffusion tensor imaging of the optic nerve in multiple sclerosis: association with retinal damage and visual disability

BACKGROUND AND PURPOSE

There is a well-known relationship between MS and damage to the optic nerve, but advanced, quantitative MR imaging methods have not been applied to large cohorts. Our objective was to determine whether a short imaging protocol (< 10 minutes), implemented with standard hardware, could detect abnormal water diffusion in the optic nerves of patients with MS.

MATERIALS AND METHODS

We examined water diffusion in human optic nerves via DTI in the largest MS cohort reported to date (104 individuals, including 38 optic nerves previously affected by optic neuritis). We also assessed whether such abnormalities are associated with loss of visual acuity (both high and low contrast) and damage to the retinal nerve fiber layer (assessed via optical coherence tomography).

RESULTS

The most abnormal diffusion was found in the optic nerves of patients with SPMS, especially in optic nerves previously affected by optic neuritis (19% drop in FA). DTI abnormalities correlated with both retinal nerve fiber layer thinning (correlation coefficient, 0.41) and loss of visual acuity, particularly at high contrast and in nerves previously affected by optic neuritis (correlation coefficient, 0.54). However, diffusion abnormalities were overall less pronounced than retinal nerve fiber layer thinning.

CONCLUSIONS

DTI is sensitive to optic nerve damage in patients with MS, but a short imaging sequence added to standard clinical protocols may not be the most reliable indicator of optic nerve damage.

Neuro-ophthalmologic Aspects of Ameloblastoma

Ameloblastomas are histologically benign tumors derived from the odontogenic apparatus. Although these tumors are locally invasive, they rarely invade the paranasal sinuses, orbits, or intracranial cavity, and, thus, they rarely produce ophthalmologic signs and symptoms. In this report, we describe the neuro-ophthalmologic features of three patients with chronically aggressive ameloblastoma. Two of the patients developed a progressive and recurrent orbital apex and cavernous sinus syndromes. One of these patients is, to our knowledge, the first patient described with orbital and cavernous simus involvement by an ameloblastoma initially arising in the mandible. The other is only the second case described with bilateral orbital involvement. The third patient in this series developed a trigeminal sensory neuropathy as the only sign of the tumor. Although ameloblastomas are benign, slowly growing tumors, they may, often over a long period of time, cause significant neuro-ophthalmologic and orbital manifestutions that can only be partially ameliorated by surgery.

Rate of progression and severity of neuro-ophthalmologic manifestations of cavernous sinus meningiomas

The progression of neuro-ophthalmologic signs and symptoms caused by cavernous sinus meningiomas (CSMs) was evaluated in 24 patients. Ten patients had primary involvement of the cavernous sinus by meningioma, and 14 patients had extension of a sphenoid ridge meningioma into the cavernous sinus. Eighteen patients were followed after intradural meningioma debulking. Two of these patients underwent conventional radiation therapy after surgery. The other six patients were followed without treatment. Optic neuropathy caused by extension of the CSM was the most frequently (67%) seen manifestation at the beginning of the follow-up period. Proptosis (50%), ocular motor nerve palsies (46%), and trigeminal neuropathy (33%) were also common. During a mean follow-up period of 57 months, 14 patients (58%) had no change in neurologic status, four patients (17%) had improvement in one or more parameters and six patients (25%) worsened. The patients who worsened had progression of preexisting cranial nerve palsies (two patients), developed new cranial neuropathies (three patients), or both (one patient). Patients who worsened had a significantly longer mean follow-up (76 months) than patients who remained stable or improved (47 months) (p = 0.01). Although the signs and symptoms of CSMs may worsen with time, the rate is slow and the degree is mild. These factors are important when considering treatment options.

Septo-optic dysplasia

Septo-optic dysplasia is a rare disorder characterized by optic nerve hypoplasia; midline developmental defects including agenesis of the septum pellucidum, thinning or absence of the corpus callosum, or both; and deficiencies of pituitary hormones. The majority of cases are sporadic but rare familial cases occur. The clinical manifestations include poor visual function in one or both eyes, developmental delay, seizures, sleep disturbances, and precocious puberty. A life-long multidisciplinary approach is crucial in the management of these patients to optimize their growth and development and to help them lead as normal lives as possible.

Isolated progressive visual loss after coiling of paraclinoid aneurysms

BACKGROUND AND PURPOSE

The proximity of the paraclinoid segment of the internal carotid artery to the visual pathways may result in visual deficits when patients present with aneurysms in this segment. Although surgical clip ligation of these aneurysms has been the standard of care for decades, the advent of coil embolization has permitted endovascular therapy in those aneurysms with favorable dome-to-neck ratios. Although immediate nonprogressive visual loss after coil embolization of paraclinoid aneurysms has been well described, isolated progressive visual loss immediately or shortly following coil embolization, to our knowledge, has not. We have identified 8 patients who experienced progressive loss of vision, unassociated with any other neurologic deficits, developing immediately or shortly after apparently uncomplicated coil embolization of a paraclinoid aneurysm.

MATERIALS AND METHODS

This study is a retrospective case series of 8 patients seen at 4 separate academic institutions. Inpatient and outpatient records were examined to determine patient demographics, previous ocular and medical history, and ophthalmic status before endovascular embolization. In addition, details of the primary endovascular therapy and subsequent surgical and nonsurgical interventions were recorded. Follow-up data, including most recent best-corrected visual acuity, postoperative course, and duration of follow-up were documented.

RESULTS

Eight patients developed progressive visual loss in 1 or both eyes immediately or shortly after apparently uncomplicated coiling of a paraclinoid aneurysm. MR imaging findings suggested that the visual loss was most likely caused by perianeurysmal inflammation related to the coils used to embolize the aneurysm, enlargement or persistence of the aneurysm despite coiling, or a combination of these mechanisms. Most patients experienced improvement in vision, 2 apparently related to treatment with systemic corticosteroids.

CONCLUSION

Patients in whom endovascular treatment of a paraclinoid aneurysm is contemplated should be warned about the potential for both isolated nonprogressive and progressive visual loss in 1 or both eyes. Patients in whom progressive visual loss occurs may benefit from treatment with systemic corticosteroids.

Cerebrospinal fluid dynamics between the intracranial and the subarachnoid space of the optic nerve. Is it always bidirectional?

CSF is thought to flow continuously from the site of production in the ventricles into interconnected spaces; i.e. cisterns and subarachnoid spaces (SASs). Since the SAS of the optic nerve is defined by a cul-de-sac anatomy, it is not evident how local CSF might recycle from that region to the general SAS. The concept of free communication of CSF has recently been challenged by the description of a concentration gradient of beta-trace protein, a lipocalin-like prostaglandin d-synthase (L-PGDS), between the spinal CSF and that in the SAS of the optic nerve, indicating diminished local clearance or local overproduction of L-PGDS here. In fact, computed cisternography with a contrast agent in three patients with idiopathic intracranial hypertension and asymmetric papilloedema demonstrate a lack of contrast-loaded CSF in the SAS of the optic nerve despite it being present in the intracranial SAS, thus suggesting compartmentation of the SAS of the optic nerve. The concept of an optic nerve compartment syndrome is further supported by a concentration gradient of brain-derived L-PGDS between the spinal CSF and the CSF from the optic nerve SAS in the same patients.

The optic nerve: a new window into cerebrospinal fluid composition?

Cerebrospinal fluid (CSF) pressure and composition are generally thought to be homogeneous within small limits throughout all CSF compartments. CSF sampled during lumbar puncture therefore should be representative for all CSF compartments. On the basis of clinical findings, histology and biochemical markers, we present for the first time strong evidence that the subarachnoid spaces (SAS) of the optic nerve (ON) can become separated from other CSF compartments in certain ON disorders, thus leading to an ON sheath compartment syndrome. This may result in an abnormal concentration gradient of CSF molecular markers determined in locally sampled CSF compared with CSF taken during lumbar puncture.

Feasibility of using ultrasound for real-time tracking during radiotherapy

This study was designed to examine the feasibility of utilizing transabdominal ultrasound for real-time monitoring of target motion during a radiotherapy fraction. A clinical Acuson 128/XP ultrasound scanner was used to image various stationary and moving phantoms while an Elekta SL25 linear accelerator radiotherapy treatment machine was operating. The ultrasound transducer was positioned to image from the outer edge of the treatment field at all times. Images were acquired to videotape and analyzed using in-house motion tracking algorithms to determine the effect of the SL25 on the quality of the displacement measurements. To determine the effect on the dosimetry of the presence of the transducer, dose distributions were examined using thermoluminescent dosimeters loaded into an Alderson Rando phantom and exposed to a 10 x 10 cm2 treatment field with and without the ultrasound transducer mounted 2.5 cm outside the field edge. The ultrasound images acquired a periodic noise that was shown to occur at the pulsing frequency of the treatment machine. Images of moving tissue were analyzed and the standard deviation on the displacement estimates within the tissue was identical with the SL25 on and off. This implies that the periodic noise did not significantly degrade the precision of the tracking algorithm (which was better than 0.01 mm). The presence of the transducer at the surface of the phantom presented only a 2.6% change to the dose distribution to the volume of the phantom. The feasibility of ultrasonic motion tracking during radiotherapy treatment is demonstrated. This presents the possibility of developing a noninvasive, real-time and low-cost method of tracking target motion during a treatment fraction.

Cook detachable coil embolization of a symptomatic, isolated orbital arteriovenous fistula via a superior ophthalmic vein approach

Isolated arteriovenous fistulas of the posterior orbit occur with exceptional rarity, and their evaluation and management are not well characterized. We describe the clinical presentation and treatment of a spontaneous arteriovenous fistula of the right posterior orbit via a superior ophthalmic vein approach for embolization using platinum detachable coils.

Primary tumours of the optic nerve and its sheath

PURPOSE

To describe the clinical, neuroimaging, and pathologic features of primary tumours of the optic nerve and its sheath.

METHODS

Review of published cases and personal series.

RESULTS

The most common primary tumour of the optic nerve is the benign glioma. This low-grade astrocytoma usually can be followed without intervention. Progression of visual symptoms and signs may necessitate either surgery to remove the tumour or radiation therapy. The most common tumour of the optic nerve sheath is the meningioma. The optimum treatment for this lesion is stereotactic or three-dimensional conformal fractionated radiation therapy, which generally results in stabilization or improvement in vision. A variety of other primary tumours may mimic, in both manifestations and imaging appearance, the more common glioma or meningioma. In such cases, the correct diagnosis may not be made until a biopsy is performed or the nerve is removed.

CONCLUSION

Primary tumours of the optic nerve and its sheath are not uncommon. Diagnosis can often but not always be made by the results of a complete examination combined with imaging studies, particularly CT scanning and MR imaging. Management depends on the presumed or histologically verified nature of the tumour.

Long term visual and neurological prognosis in patients with treated and untreated cavernous sinus aneurysms

OBJECTIVE

To determine the long term visual and neurological outcome of patients diagnosed with cavernous sinus aneurysms (CCAs).

METHODS

Prospective follow up for at least five years or until death of 31 retrospectively recruited patients (27 women, 4 men) with treated and untreated CCAs.

RESULTS

There were 40 aneurysms in all. Mean age at diagnosis was 60.4 years (range 25 to 86; median 64). The most common symptoms were diplopia (61%), headache (53%), and facial or orbital pain (32%). Fifteen patients (48%) were diagnosed after they developed cranial nerve pareses, four (13%) after they developed carotid-cavernous sinus fistulas (CCFs), and 12 (39%) by neuroimaging studies done for unrelated symptoms. Twenty one patients (68%) had treatment to exclude the aneurysm from circulation, 10 shortly after diagnosis and 11 after worsening symptoms. Immediate complications of treatment occurred in six patients and included neurological impairment, acute ophthalmoparesis, and visual loss. Ten patients (32%) were observed without intervention. Over a mean (SD) follow up period of 11.8 (7.7) years, eight had improvement in symptoms, five remained stable, and eight deteriorated. Among the 10 patients followed without intervention, none improved spontaneously, three remained stable, and seven worsened.

CONCLUSIONS

Most treated patients in this series improved or remained stable after treatment, but none improved without treatment. The long term prognosis for treated cases is relatively good, with most complications occurring immediately after the procedure. Endovascular surgery has decreased the morbidity and mortality of treatment so should be considered for any patient with a CCA.

Reversible bilateral internuclear ophthalmoplegia associated with FK506

A 50 year old man developed tonic-clonic seizures while receiving cyclosporin A after orthotopic cardiac transplant. The seizures resolved after cessation of cyclosporin A. Thirteen months later, he developed diplopia from bilateral internuclear ophthalmoplegia while receiving intravenous FK506. A temporal association was found between his symptoms and the serum FK506 concentrations. Withdrawal of the intravenous FK506 led to prompt resolution of the bilateral internuclear ophthalmoplegia.

Polarity establishment requires dynamic actin in fucoid zygotes

Previous work has demonstrated that actin plays important roles in axis establishment and polar growth in fucoid zygotes. Distinct actin arrays are associated with fertilization, polarization, growth, and division, and agents that depolymerize actin filaments (cytochalasins, latrunculin B) perturb these stages of the first cell cycle. Rearrangements of actin arrays could be accomplished by transport of intact filaments and/or by actin dynamics involving depolymerization of the old array and polymerization of a new array. To investigate the requirement for dynamic actin during early development, we utilized the actin-stabilizing agent jasplakinolide. Immunofluorescence of actin arrays showed that treatment with 1-10 microM jasplakinolide stabilized existing arrays and induced polymerization of new filaments. In young zygotes, a cortical actin patch at the rhizoid pole was stabilized, and in some cells supernumerary patches were formed. In older zygotes that had initiated tip growth, massive filament assembly occurred in the rhizoid apex, and to a lesser degree in the perinuclear region. Treatment disrupted polarity establishment, polar secretion, tip growth, spindle alignment, and cytokinesis but did not affect the maintenance of an established axis, mitosis, or cell cycle progression. This study suggests that dynamic actin is required for polarization, growth, and division. Rearrangements in actin structures during the first cell cycle are likely mediated by actin depolymerization within old arrays and polymerization of new arrays.

A controlled study comparing visual function in patients treated with vigabatrin and tiagabine

OBJECTIVE

Vigabatrin treatment is frequently associated with irreversible retinal injury and produces retinal electrophysiological changes in nearly all patients. Concern has been raised that tiagabine and other antiepilepsy drugs (AEDs) that increase brain gamma-aminobutyric acid (GABA) might produce similar electrophysiological and clinical changes in visual function. The study compared visual function between groups of patients with epilepsy treated long term with tiagabine, vigabatrin, and patients treated with other AEDs.

METHODS

A cross sectional study comparing visual acuity, colour vision, static and kinetic perimetry, and electroretinograms between groups of patients treated with tiagabine, vigabatrin, and other AEDs (control patients). Patients were adults receiving stable AED treatment for >6 months.

RESULTS

Vigabatrin treated patients had marked visual field constrictions in kinetic perimetry (mean radius 39.6 degrees OD, 40.5 degrees OS), while tiagabine patients had normal findings (mean 61 degrees OD, 62 degrees OS) (differences OD and OS, p=0.001), which were similar to epilepsy control patients (mean 60 degrees OD, 61 degrees OS). Vigabatrin patients had abnormal electroretinographic photopic B wave, oscillatory, and flicker responses, which correlated with visual field constrictions. These electroretinographic responses were normal for tiagabine patients and control patients. Patients were treated with vigabatrin for a median of 46 months compared with 29 months for tiagabine. Patients taking other AEDs that may change brain GABA had normal visual function.

CONCLUSION

Unlike vigabatrin, tiagabine treatment is associated with normal electroretinography and visual fields and ophthalmological function similar to epilepsy control patients. Differences between vigabatrin and other GABA modulating AEDs in retinal drug concentrations and other effects might explain why tiagabine increases in GABA reuptake do not cause retinal injury.

Spontaneous retinal venous pulsation: aetiology and significance

Spontaneous retinal venous pulsation is seen as a subtle variation in the calibre of the retinal vein(s) as they cross the optic disc. The physical principles behind the venous pulsations has been the point of much debate. Initial theories suggested that the pulsation occurred because of the rise in intraocular pressure in the eye with the pulse pressure. This article presents an argument that this is not the case. The pulsations are in fact caused by variation in the pressure gradient along the retinal vein as it traverses the lamina cribrosa. The pressure gradient varies because of the difference in the pulse pressure between the intraocular space and the cerebrospinal fluid. The importance of this is that as the intracranial pressure rises the intracranial pulse pressure rises to equal the intraocular pulse pressure and the spontaneous venous pulsations cease. Thus it is shown that cessation of the spontaneous venous pulsation is a sensitive marker of raised intracranial pressure. The article discusses the specificity of the absence of spontaneous venous pulsation and describes how the patient should be examined to best elicit this important sign.

Choroidal infarction, anterior ischemic optic neuropathy, and central retinal artery occlusion from polyarteritis nodosa

PURPOSE

Ocular ischemia from polyarteritis nodosa (PAN) is rare. The authors present a case of multifocal ocular infarction from PAN.

METHODS AND RESULTS

A 70-year-old woman developed hand and foot numbness followed by intermittent blurred vision and binocular horizontal diplopia. Two weeks later, she suddenly lost vision in the right eye from a central retinal artery occlusion and then developed a left anterior ischemic optic neuropathy and bilateral triangular choroidal abnormalities consistent with infarction. Her erythrocyte sedimentation rate and C-reactive protein were elevated. Although giant cell arteritis was suspected, a multiple mononeuropathy was demonstrated by electromyogram and nerve conduction velocity studies. Biopsy specimens from her sural nerve and biceps muscle showed a necrotizing vasculitis with fibrinoid necrosis, consistent with PAN.

CONCLUSIONS

Polyarteritis nodosa can produce ischemia of a variety of ocular structures, including the retina, choroid, and optic nerve. In our patient, all three structures were affected. To our knowledge, this is the first reported case of the triangular sign of Amalric in PAN.

ALVAC-SIV-gag-pol-env-based vaccination and macaque major histocompatibility complex class I (A*01) delay simian immunodeficiency virus SIVmac-induced immunodeficiency

T-cell-mediated immune effector mechanisms play an important role in the containment of human immunodeficiency virus/simian immunodeficiency virus (HIV/SIV) replication after infection. Both vaccination- and infection-induced T-cell responses are dependent on the host major histocompatibility complex classes I and II (MHC-I and MHC-II) antigens. Here we report that both inherent, host-dependent immune responses to SIVmac251 infection and vaccination-induced immune responses to viral antigens were able to reduce virus replication and/or CD4+ T-cell loss. Both the presence of the MHC-I Mamu-A*01 genotype and vaccination of rhesus macaques with ALVAC-SIV-gag-pol-env (ALVAC-SIV-gpe) contributed to the restriction of SIVmac251 replication during primary infection, preservation of CD4+ T cells, and delayed disease progression following intrarectal challenge exposure of the animals to SIV(mac251 (561)). ALVAC-SIV-gpe immunization induced cytotoxic T-lymphocyte (CTL) responses cumulatively in 67% of the immunized animals. Following viral challenge, a significant secondary virus-specific CD8+ T-cell response was observed in the vaccinated macaques. In the same immunized macaques, a decrease in virus load during primary infection (P = 0.0078) and protection from CD4 loss during both acute and chronic phases of infection (P = 0.0099 and P = 0.03, respectively) were observed. A trend for enhanced survival of the vaccinated macaques was also observed. Neither boosting the ALVAC-SIV-gpe with gp120 immunizations nor administering the vaccine by the combination of mucosal and systemic immunization routes increased significantly the protective effect of the ALVAC-SIV-gpe vaccine. While assessing the role of MHC-I Mamu-A*01 alone in the restriction of viremia following challenge of nonvaccinated animals with other SIV isolates, we observed that the virus load was not significantly lower in Mamu-A*01-positive macaques following intravenous challenge with either SIV(mac251 (561)) or SIV(SME660). However, a significant delay in CD4+ T-cell loss was observed in Mamu-A*01-positive macaques in each group. Of interest, in the case of intravenous or intrarectal challenge with the chimeric SIV/HIV strains SHIV(89.6P) or SHIV(KU2), respectively, MHC-I Mamu-A*01-positive macaques did not significantly restrict primary viremia. The finding of the protective effect of the Mamu-A*01 molecule parallels the protective effect of the B*5701 HLA allele in HIV-1-infected humans and needs to be accounted for in the evaluation of vaccine efficacy against SIV challenge models.

Recurrent ectopic craniopharyngioma

A 66-year-old woman developed an asymptomatic mass in the right frontal lobe 5 years after undergoing a right frontal craniotomy and removal of a craniopharyngioma. The mass progressively enlarged over the next 3 years, during which time it became multiloculated and partially cystic. Repeat craniotomy was performed 8 years after the original operation, at which time the mass was found to be an ectopic craniopharyngioma. The lesion probably resulted from seeding of tumour cells along the surgical tract at the time of the initial surgery.

Optic nerve protection, regeneration, and repair in the 21st century: LVIII Edward Jackson Memorial lecture

PURPOSE

To present the current status and clinical implications of optic nerve protection, repair, and regeneration after experimental injury in mammals, including nonhuman primates.

DESIGN

Optic nerve and neuro-ophthalmology experimental study review.

METHOD

Synthesis of experimental data regarding experimental studies of optic nerve protection, repair, and regeneration.

RESULTS

Under certain conditions, mammalian retinal ganglion cells can be prevented from dying despite injury to the cell bodies or their axons, injured mammalian retinal ganglion cells whose axons have degenerated can be induced to extend new axons, and regenerating axons can reach their correct targets in the central nervous system. In addition, stem cells can be induced to become retinal ganglion cells.

CONCLUSIONS

It may soon be possible to preserve and restore vision in persons whose sight is threatened or has been lost from disease or damage to the optic nerve.

Clinical spectrum of posterior ischemic optic neuropathy

PURPOSE

To describe the systemic and visual characteristics and prognosis in patients with posterior ischemic optic neuropathy (PION).

DESIGN

Observational case series.

METHODS

Retrospective chart review in a multicenter setting. Seventy-two patients (98 eyes) with a clinical diagnosis of PION. Co-morbid systemic diseases and visual function were recorded at both initial presentation and after mean visual follow-up of 4.1 years and systemic follow-up of 5.4 years.

RESULTS

PION occurred in three main settings: in the perioperative period following a variety of surgical procedures (28 patients), associated with giant cell (temporal) arteritis (6 patients), and associated with nonarteritic systemic vascular disease (38 patients). Patients with perioperative and arteritic PION were more likely to have severe, bilateral visual loss that did not improve. Among eyes with nonarteritic PION, 34% experienced improvement in vision, 28% remained stable, and 38% worsened. Among patients with nonarteritic PION, carotid artery disease and a history of stroke (with or without carotid artery disease) were both associated with a statistically significant increased risk of poor final visual outcome.

CONCLUSIONS

There are three distinct subtypes of PION: perioperative, arteritic, and nonarteritic. Patients with PION that is unassociated with surgery should undergo an evaluation for systemic vascular diseases, including giant cell arteritis, that may or may not be apparent at the time of vision loss. The visual prognosis for patients with perioperative or arteritic PION is poor, whereas that for nonarteritic PION is similar to that for patients with nonarteritic AION.

Visual manifestations of temporal arteritis

Visual difficulties are common in patients with temporal arteritis. They may be the presenting manifestation of the disease or may occur at any time during its course. The visual deficits that occur in patients with temporal arteritis are most often loss of visual acuity or visual field; however, some patients develop double vision or other symptoms of ocular motor dysfunction. Knowledge of the visual deficits associated with temporal arteritis can aid in the diagnosis of the disorder, and early diagnosis of temporal arteritis can often prevent such deficits from developing.

Sepsis after Bartholin's duct abscess marsupialization in a gravida

BACKGROUND

Little information exists regarding sepsis following marsupialization of a Bartholin's duct abscess. We report a gravida who became septic after marsupialization.

CASE

A 30-year-old primigravida at 32 weeks' gestation underwent marsupialization of a Bartholin's gland abscess. Postoperatively, she developed fever with maternal and fetal tachycardia. She was admitted to the hospital and started on broad-spectrum antibiotics. Her temperature increased to 39 degrees C, and she became hypotensive. Blood work demonstrated evidence of disseminated intravascular coagulopathy. The patient was stabilized with aggressive fluid resuscitation, antibiotics, transfusion of blood products and oxygen therapy. Within 24 hours, the fever and coagulopathy resolved. She was discharged on postoperative day 5 and gave birth without complications at 38 weeks' gestation.

CONCLUSION

Pregnant women undergoing marsupialization of a Bartholin's gland abscess should be considered at high risk and managed accordingly.

Quantification of optic nerve axon loss associated with a relative afferent pupillary defect in the monkey

OBJECTIVE

To quantify the amount of optic nerve axonal loss associated with the presence of a mild relative afferent pupillary defect (RAPD) in an experimental monkey model.

METHODS

The right macula of 5 rhesus monkeys (Macaca mulatta) was treated with concentrically enlarging diode laser burns until an RAPD was detected using a transilluminator light and measured with neutral density filters. Intervals between treatments were 3 to 7 days over a period of 2 months. Pupillary responses to light stimulation were recorded with a monocular infrared television pupillometer. Two months after detection of an RAPD, 5 treated and 4 control monkeys underwent euthanasia and enucleation. Histopathologic analysis and quantification of optic nerve axon counts using an image analysis system were performed.

RESULTS

No RAPD was observed despite an estimated ganglion cell loss of up to 26%. A 0.6 log unit RAPD was present in 5 monkeys when the laser scar incorporated the entire macula within the temporal vascular arcades. One eye had progressive vitreomacular traction with worsening of the RAPD to 1.8 log units without further laser treatment. Histopathologic evaluation disclosed complete loss of the normal retinal architecture within the macula. The average fiber loss for the 4 treated eyes with 0.6 log unit RAPDs compared with fellow eyes was 53.3% (95% confidence interval [CI], 45.0%-61.6%). The average difference in axon counts between untreated pairs of optic nerves was 12.8% (95% CI, 10.0%-15.6%). Optic nerve axon loss between pairs of experimental and control eyes was statistically significant (P<.001).

CONCLUSION

In rhesus monkeys, an RAPD develops after an approximate unilateral loss between 25% and 50% of retinal ganglion cells.

CLINICAL RELEVANCE

Owing to redundancy in the anterior visual pathways, unilateral retinal ganglion cell loss may occur prior to the observation of an RAPD. The presence of an RAPD measuring 0.6 log units implies that significant retinal ganglion cell injury has occurred.

Peripheral homonymous scotomas from a cavernous angioma affecting fibers subserving the intermediate region of the striate cortex

PURPOSE

To report the case of a pure peripheral homonymous visual field defect and to delineate the representation of the visual field on the striate cortex.

METHODS

Observational case report. Neuro-ophthalmologic and neuroimaging assessment of a patient with a cavernous angioma of the right parieto-occipital lobe.

RESULTS

The patient had left homonymous scotomas located 40 degrees to 60 degrees from the vertical meridian. Neuroimaging indicated that the lesion was affecting the optic radiations at their termination in the intermediate portion of the striate cortex or the striate cortex itself.

CONCLUSION

Homonymous field defects are typically located within 10 degrees of fixation. This patient had a peripheral homonymous field defect from damage to the intermediate striate cortex. Correlation of the neuroimaging findings in this case with the most commonly used maps of the representation of the visual field on the striate cortex suggests that none of the maps correctly predicts the location or extent of lesions that affect the intermediate portion of the cortex.

Traumatic optic neuropathy: a review of 61 patients

The outcome of traumatic optic neuropathy was evaluated following penetrating and blunt injuries to assess the effect of treatment options, including high-dose steroids, surgical intervention, and observation alone. Factors that affected improvement in visual acuity were identified and quantified. Sixty-one consecutive, nonrandomized patients presenting with visual loss after facial trauma between 1984 and 1996 were assessed for outcome. Pretreatment and posttreatment visual acuities were compared using a standard ophthalmologic conversion from the values of no light perception, light perception, hand motion, finger counting, and 20/800 down to 20/15 to a logarithm of the minimum angle of resolution (log MAR). The percentage of patients showing visual improvement and the degree of improvement were calculated for each patient group and treatment method. Measurements of visual acuity are in log MAR units +/- standard error of the mean. Patients who sustained penetrating facial trauma (n = 21) had worse outcomes than patients with blunt trauma (n = 40). Improvement in visual acuity after treatment was seen in 19 percent of patients with penetrating trauma compared with 45 percent of patients with blunt trauma (p < 0.05). Furthermore, patients with penetrating trauma improved less than those with blunt trauma, with a mean improvement of 0.4 +/- 0.23 log MAR compared with 1.1 +/- 0.24 in blunt-trauma patients (p = 0.03). The patients with blunt trauma underwent further study. There was no significant difference in improvement of visual acuity in patients treated with surgical versus nonsurgical methods; however, 83 percent of patients without orbital fractures had improvement compared with 38 percent of patients with orbital fractures (p < 0.05). The mean improvement in patients without orbital fractures was 1.8 +/- 0.65 log MAR compared with 0.95 +/- 0.26 in patients with orbital fractures (p = 0.1). Twenty-seven percent of patients who had no light perception on presentation experienced improvement in visual acuity after treatment compared with 100 percent of patients who had light perception on admission (p < 0.05). The mean improvement in patients who were initially without light perception was 0.85 +/- 0.29 log MAR compared with 1.77 +/- 0.35 in patients who had light perception (p < 0.05). There were no significant differences in improvement of visual acuity when analyzing the effect of patient age and timing of surgery. Patients who sustain penetrating trauma have a worse prognosis than those with blunt trauma. The presence of no light perception and an orbital fracture are poor prognostic factors in visual loss following blunt facial trauma. It seems that clinical judgment on indication and timing of surgery, and not absolute criteria, should be used in the management of traumatic optic neuropathy.

Visual function is stable in patients who continue long-term vigabatrin therapy: implications for clinical decision making

PURPOSE

Vigabatrin (VGB) has been shown to cause visual field constriction and other forms of mild visual dysfunction. We determined the safety of continuing VGB therapy in patients who had received prolonged treatment (>2 years) with the drug by serially monitoring changes in visual function over a 1-year period of continued therapy. We also followed up patients who discontinued VGB to see whether alternative therapies are effective.

METHODS

Fifteen of 17 patients who continued VGB therapy had visual-function testing (visual acuity, color vision, kinetic and static perimetry) every 3 months for 1 year. Eighteen patients who discontinued VGB were given alternative antiepileptic drugs (AEDs); their seizure responses were measured after > or =3 months of treatment.

RESULTS

Patients continuing VGB showed no worsening of visual acuity, color vision, or visual-field constriction beyond that measured in the initial test. Many patients who discontinued VGB had good seizure control with either newer or previously unsuccessful AEDs.

CONCLUSIONS

For patients who have an excellent response to VGB and only mild visual changes, continued therapy may be safe with close visual monitoring. Patients who do not have a significant reduction in seizures or who experience considerable visual dysfunction with VGB may respond well to alternative therapies.

Central disorders of vision in humans

Over the past 20 years, researchers have discovered over 30 separate visual areas in the cortex of the macaque monkey that exhibit specific responses to visual and environmental stimuli. Many of these areas are homologous to regions of the human visual cortex, and numerous syndromes involving these areas are described in the neurologic and ophthalmic literature. The focus of this review is the anatomy and physiology of these higher cortical visual areas, with special emphasis on their relevance to syndromes in humans. The early visual system processes information primarily by way of two separate systems: parvocellular and magnocellular. Thus, even at this early stage, visual information is functionally segregated. We will trace this segregation to downstream areas involved in increasingly complex visual processing and discuss the results of lesions in these areas in humans. An understanding of these areas is important, as many of these patients will first seek the attention of the ophthalmologist, often with vague, poorly defined complaints that may be difficult to specifically define.

A case-control study of tobacco and alcohol consumption in Leber hereditary optic neuropathy

PURPOSE

To determine if tobacco or alcohol consumption is associated with vision loss among sibships harboring pathogenic mitochondrial mutations associated with Leber hereditary optic neuropathy.

METHODS

Retrospective case-control study with questionnaires obtained from both affected and unaffected siblings from 80 sibships with Leber hereditary optic neuropathy. Sibships harbored molecularly confirmed mitochondrial DNA mutations at nucleotide positions 11778 (63), 14484 (10), and 3460 (7). Exposure in affected individuals was calculated based on reported consumption before vision loss.

RESULTS

For male probands (67 sibships), the recurrence risk within a sibship was 10.3% (eight of 78) for males and 3.1% (three of 98) for females. For female probands (13 sibships), the recurrence risk within a sibship was 17.6% (three of 17) for males and 0% (zero of 22) for females. Greater risk of vision loss was associated with male sex (odds ratio [OR] = 6.63; 95% confidence interval [CI] = 2.96 to 14.84; P =.00001) and harboring a 3460 or 14484 in comparison with the 11778 mutation (OR = 2.071; 95% CI = 1.19 to 3.58; P =.0095). No significant association of maximal intensity of smoking or cumulative smoking, whether light or heavy, with vision loss was observed. Light (OR = 0. 31; 95% CI = 0.17 to 0.56; P =.0001) and heavy alcohol consumers (OR = 0.25; 95% CI = 0.11 to 0.58; P =.0011) were less likely to be affected than individuals who did not consume alcohol after adjusting for age, sex, and mutation. In a categorical analysis of sibships with the 3460 or 14484 mutation, no relationship of vision loss with tobacco or alcohol consumption was observed.

CONCLUSION

Unlike previous studies, the present study calculated exposure based on self-reported consumption of tobacco or alcohol before vision loss. No significant deleterious association between tobacco or alcohol consumption and vision loss among individuals harboring Leber hereditary optic neuropathy mutations was observed. Tobacco and alcohol do not appear to promote vision loss in Leber hereditary optic neuropathy.

New therapies with potential neuro-ophthalmologic toxicity

Given the ever-increasing number of drugs available for the treatment of a variety of ocular and systemic disorders, it is not surprising that neuro-ophthalmologic complications are being recognized with increasing frequency. In this chapter, we describe both previously unreported (or rarely described) neuro-ophthalmologic complications produced by well known medications and neuro-ophthalmologic complications produced by new medications. The medications discussed include antidepressants, antiepileptic medications, topical antiglaucoma medications, and chemotherapeutic/immunosuppressive agents. Most of the side effects produced by these medications affect visual sensory function; however, some produce disturbances of ocular motility and alignment. Some of these effects are related directly to drug toxicity, whereas others are related to secondary effects of the drug. The heterogeneity of the pathogenesis of side effects from these drugs explains why some of the side effects are reversible, whereas others are not.

Optic neuropathy associated with laser in situ keratomileusis

PURPOSE

To report 4 cases of optic neuropathy following laser in situ keratomileusis (LASIK).

SETTING

Tertiary Care ophthalmic practices.

METHODS

In this retrospective observational case series, 4 patients who developed acute visual loss following LASIK are reported. All had clinical evidence of optic neuropathy. Two had optic disc edema and 2 had normal appearing optic discs initially. None of the patients experienced significant visual recovery, and all developed optic atrophy in the affected eye.

RESULTS

All patients had evaluations for alternative etiologies of their optic neuropathy, with negative results. All patients were therefore presumed to have experienced an ischemic optic neuropathy following LASIK.

CONCLUSIONS

Patients who have LASIK may experience an acute anterior or retrobulbar optic neuropathy. The etiology is unknown but may be related to the marked increase in intraocular pressure that occurs during a portion of the procedure.

Thresholds for visual detection of Young's modulus contrast in simulated ultrasound image movies

Elasticity imaging (EI) is being developed to allow the evaluation of the mechanical properties of soft tissue, but these properties are already assessed in routine ultrasound breast examination using a method that involves the subjective interpretation of tissue motion seen in real-time B-mode image movies during palpation. We refer to this method as relative motion assessment (RMA). The purpose of this study was to begin a process of learning about the usefulness and limitations of RMA relative to the emerging method of elasticity imaging. Perception experiments were performed to measure Young's modulus contrast thresholds for positive contrast lesions under controlled conditions that could subsequently be repeated to evaluate elasticity imaging for the same task. Observer ability to grade relative lesion contrast using RMA was also assessed. Simulated sequences of B-scans of tissue moving in response to an applied force were generated and used in a two-alternative forced-choice (2-AFC) experiment to measure contrast thresholds for the detection of disc-shaped elastic lesions by RMA in the absence of ultrasound echo contrast. Results were obtained for four observers at a lesion area of about 77 speckle cells and for five observers at lesion areas of about 42 and 139 speckle cells. Young's modulus contrast thresholds were found to decrease with increasing lesion size and were well within the range of contrast values that have been measured for breast tumours in vitro. It was also found that observers were quite skilled at using RMA to grade the relative strain contrast of lesions. The nonlinear relationship between the object contrast (Young's modulus contrast) and the image contrast (strain contrast) prevented observers from detecting very small lesions with 100% accuracy, no matter how high the object contrast. A preliminary comparison of the results for RMA with published thresholds for elastography indicated that elastography is likely to offer great benefit in reducing modulus contrast thresholds, but further study is required to confirm this.

Visual function loss from vigabatrin: effect of stopping the drug

OBJECTIVE

To determine if visual function loss from vigabatrin use recovers after the drug is discontinued.

BACKGROUND

Vigabatrin is an effective antiepileptic drug, but it is known to cause a variety of changes in visual function, including reductions in the visual field, visual acuity, color vision, and in electroretinogram (ERG) and electro-oculogram amplitudes. It is not known whether these changes are reversible.

METHODS

Measurements of static and kinetic visual fields, visual acuity, color vision, and the ERG were recorded while patients were taking vigabatrin and again in 13 patients who had discontinued the drug because of lack of efficacy or reductions in visual field. Most of the patients had been off the drug for 3 to 6 months, although two patients had been drug-free for almost 1 year.

RESULTS

Although ERG cone implicit time improved, most of the patients did not show improvement in either clinical measures of visual function (i.e., visual acuity, color vision, visual fields) or in ERG amplitudes. However, several patients who showed minimal visual field loss while on the drug had substantial recovery of ERG amplitudes. There was no statistical association between recovery of function and either duration of treatment or cumulative dosage. The multifocal ERG showed a diffuse loss of function that was not isolated to the periphery.

CONCLUSIONS

Although the visual deficits in patients taking vigabatrin tend to be mild, most patients do not show improvement after they stop taking the drug. Visual field loss resulting from vigabatrin was not reversible. Visual acuity, color vision, and ERG amplitude loss may be reversible in patients with minimal or no field loss.

Long-term visual outcome after nonradical microsurgery patients with parasellar and cavernous sinus meningiomas

OBJECTIVE

To determine the long-term visual outcome in patients with parasellar and cavernous sinus meningiomas treated with nonradical surgery.

METHODS

Retrospective clinical review of 29 patients with parasellar or cavernous sinus meningiomas and visual sensory or ocular motor dysfunction at presentation, all of whom had at least 10 years of follow-up after initial diagnosis and treatment with nonradical surgery.

RESULTS

Nineteen of 29 patients had a unilateral or bilateral optic neuropathy at presentation, and 7 patients developed a unilateral or bilateral optic neuropathy during a mean follow-up period of 13.6 years. However, 27 (93%) of 29 patients retained vision of 20/40 or better in at least one eye, and 14 patients (48%) retained vision of 20/40 or better in both eyes. New ocular motility deficits developed in 3 (10%) of 29 patients during the follow-up period.

CONCLUSION

Radical surgery is not required to achieve long-term useful visual function for patients with parasellar or cavernous sinus meningiomas.