The effect of sildenafil on ocular blood flow.

Sildenafil is a potent phosphodiesterase (PDE) 5 inhibitor that is used for patients with erectile dysfunction. Sildenafil induces vasodilation in selected smooth muscle via increased levels of guanosine 3', 5' cyclic monophosphate and increase in nitric oxide. The vasodilatory effects of the PDE 5 inhibitors led us to review its effect on the ocular vasculature. Sildenafil appears to increase blood flow velocity significantly in the retrobulbar and choroidal circulation. Most studies suggest an increase in choroidal blood flow, with a lesser effect on the retinal vasculature.

Isolated IVth (trochlear) nerve palsy due to basilar artery dolichoectasia.

BACKGROUND: Dolichoectasia (elongation, dilatation and tortuosity) of the basilar artery can cause an isolated cranial neuropathy. The trigeminal nerve and facial nerve are most frequently affected. Dysfunction of one of the ocular motor cranial nerves due to basilar artery dolichoectasia is uncommon, and an isolated IVth (trochlear) nerve palsy has not been previously described in the literature. HISTORY AND SIGNS: Two men, ages 70 and 59 years, respectively, presented with vertical diplopia due to a IVth nerve palsy. In one patient, the onset of the IVth nerve palsy was painless and gradual and in the other patient, the onset was acute and associated with periorbital pain. Neuroimaging in both patients revealed pathological tortuosity of the basilar artery around the midbrain and displacement of the artery toward the side of the affected trochlear nerve. THERAPY AND OUTCOME: The patients were observed clinically. One patient had gradual worsening of his palsy for three and one-half years then suffered a stroke. The second patient whose IVth nerve palsy had an acute onset experienced spontaneous resolution of his palsy but later developed dysfunction of other cranial nerves. CONCLUSIONS: Basilar artery dolichoectasia should be considered in the differential diagnosis of an isolated IVth nerve palsy. The clinical course may be variable, and the prognosis is not always benign.

Dolichoectatic arterial compression of the anterior visual pathways: neuro-ophthalmic features and clinical course.

AIM: To characterise the clinical findings and natural history of anterior visual pathway compression by dolichoectatic intracranial vessels. METHODS: A retrospective case review of patients evaluated in an outpatient neuro-ophthalmology clinic. RESULTS: 10 patients with this condition were identified. Dolichoectatic compression was confirmed by magnetic resonance scanning in all patients. The average age at presentation was 70.6 years and eight of the 10 were female. The carotid artery was involved in seven patients and the basilar in three. Patterns of visual loss varied depending on the site of compression. The most common pattern in patients with optic neuropathy was nasal field loss. In most patients visual loss showed little progression over time. Over an average follow up interval of 2.8 years, progressive visual loss was documented in only three cases. In one of these, neurosurgical intervention was undertaken with subsequent improvement of vision. CONCLUSIONS: Visual loss resulting from compression of the visual pathways by dolichoectatic arteries is usually mild and only slowly progressive. Most patients are elderly, with other forms of vascular disease. Conservative management is thus usually appropriate in this disorder. In occasional cases with more rapid progression, surgical intervention may be beneficial.

Optic perineuritis: clinical and radiographic features.

BACKGROUND: Optic perineuritis is an uncommon variety of orbital inflammatory disease that is distinct from demyelinating optic neuritis. OBJECTIVE: To describe the clinical and radiographic features of idiopathic optic perineuritis, with particular emphasis on those features that help to distinguish this condition from optic neuritis. METHODS: We reviewed the medical records of 14 patients with optic perineuritis who were seen in 2 neuro-ophthalmology clinics. RESULTS: Patients ranged in age from 24 to 60 years; 5 were older than 50 years. All patients had visual loss, eye pain, or both. The visual acuity was 20/20 or better in 8 of the 15 eyes. The results of visual field testing were normal in 2 eyes, and a paracentral scotoma or an arcuate defect was seen in 7. Magnetic resonance imaging scans demonstrated circumferential enhancement around the optic nerve, sometimes with intraorbital extension. Response to corticosteroids was dramatic; however, 4 patients had a relapse with lowering of the dose. CONCLUSIONS: In contrast to those with optic neuritis, patients with optic perineuritis are often older at onset and are more likely to show sparing of central vision. Magnetic resonance imaging scans demonstrate enhancement around, rather than within, the optic nerve. Response to corticosteroids is more dramatic than in patients with optic neuritis, and patients are more likely to experience recurrence after stopping treatment.

Patterns of extraocular muscle weakness in vasculopathic pupil-sparing, incomplete third nerve palsy.

OBJECTIVE: To determine the pattern of extraocular muscle (EOM) paresis in incomplete vasculopathic third nerve palsies (3NP) that have normal pupillary function. METHODS: A retrospective study in a private practice and academic neuro-ophthalmic practice. Patients diagnosed with vasculopathic 3NP within 4 weeks of symptom onset were identified. The chart of each patient was reviewed to determine pupillary function and the pattern and degree of EOM and levator palpebrae paresis at the time of presentation. RESULTS: Of 55 patients with vasculopathic 3NP, 42 (76%) had normal pupillary function. Of these 42, 23 (55%) demonstrated an incomplete EOM palsy, defined as partially reduced ductions affecting all third nerve-innervated EOMs and levator (diffuse pattern) or partially reduced ductions that involved only some third nerve-innervated EOMs and levator (focal pattern). Twenty (87%) of these 23 patients showed a diffuse pattern of paresis; only three (13%) showed a focal pattern of paresis, one that affected only the superior rectus and levator muscles (superior division weakness). CONCLUSIONS: Based on our series, most patients with EOM/levator involvement in pupil-sparing, incomplete 3NP of vasculopathic origin have a diffuse pattern of paresis. In contrast, our review of the literature suggests that pupil-sparing 3NP of aneurysmal origin usually have a focal pattern of paresis. We propose that distinguishing these two patterns of EOM paresis may be helpful in differentiating between vasculopathic and aneurysmal 3NP. Future studies will be needed to confirm the clinical utility of this hypothesis.

Papilledema and obstructive sleep apnea syndrome.

OBJECTIVES: To characterize the pathogenesis and clinical features of optic disc edema associated with obstructive sleep apnea syndrome (SAS). METHODS: A series of 4 patients with SAS and papilledema (PE) underwent complete neuro-ophthalmologic evaluation and lumbar puncture. In 1 patient, continuous 24-hour intracranial pressure (ICP) monitoring was also performed. RESULTS: All 4 patients had bilateral PE that was asymmetric in 2. Three patients had optic nerve dysfunction, asymmetric in 1, unilateral in 2. Daytime cerebrospinal fluid pressure measurements were within normal range. Nocturnal monitoring performed in one patient, however, demonstrated repeated episodes of marked ICP elevation associated with apnea and arterial oxygen desaturation. CONCLUSIONS: We propose that PE in SAS is due to episodic nocturnal hypoxemia and hypercarbia resulting in increased ICP secondary to cerebral vasodilation. In these individuals, intermittent ICP elevation is sufficient to cause persistent disc edema. These patients may be at increased risk for developing visual loss secondary to PE compared with patients with obesity-related pseudotumor cerebri because of associated hypoxemia. The diagnosis of SAS PE may not be appreciated because daytime cerebrospinal fluid pressure measurements are normal and because patients tend to present with visual loss rather than with symptoms of increased ICP.

Optic neuropathies for the neurologist.

Before embarking on expensive ancillary testing, it is crucial for the neurologist to distinguish visual loss due to optic nerve dysfunction from other causes of visual loss. This can usually be accomplished based on specific features of the history and bedside examination. Once it has been established that a patient has some form of optic neuropathy, several clinical features are helpful in determining the etiology. The most important of these is the time course. Other factors include presence or absence of pain, pattern of visual loss (particularly visual field defects), and funduscopic appearance. In most cases, by using this information it is possible to differentiate among the common forms of optic neuropathy: papilledema, ischemic optic neuropathy, optic neuritis, compressive lesions, toxic/nutritional deficiencies, and hereditary forms. This article also reviews recent information concerning the evaluation and treatment of optic neuritis, how to recognize conditions that mimic optic neuritis (e.g., neuroretinitis, papillophlebitis), distinguishing arteritic from non-arteritic AION, and new developments in the genetics of Leber's Hereditary Optic Neuropathy. There is also a discussion of various forms of toxic/nutritional visual loss including Cuban Epidemic Optic Neuropathy and visual loss due to commonly prescribed medications.

Hyperhomocysteinaemia in young patients with non-arteritic anterior ischaemic optic neuropathy.

BACKGROUND/AIM: Elevated plasma homocysteine is a newly identified vascular risk factor among patients under age 55 years with cerebrovascular, cardiovascular, or peripheral vascular disease. This study sought to evaluate retrospectively the plasma homocysteine status among healthy younger patients with ischaemic optic disc disease. METHODS: 12 non-diabetic patients who had been diagnosed with non-arteritic anterior ischaemic optic neuropathy (NAION) before the age of 50 years were identified from chart review. None had experienced previous ischaemic cerebrovascular, cardiovascular, or peripheral vascular events. Plasma homocysteine, CBC, renal function, vitamin B6, vitamin B12, and folate levels were sampled in the fasting state. RESULTS: Two of 12 patients (17%) had hyperhomocysteinaemia. Both had experienced NAION in both eyes with recurrent episodes. Neither patient was hypertensive nor had a smoking history. One of these two patients had mild hypercholesterolaemia which did not warrant medication. CONCLUSIONS: Elevated plasma homocysteine may be associated with NAION. An evaluation for hyperhomocysteinaemia should be considered in patients with NAION who do not have the typical risk factor such as older age, diabetes, hypertension, or tobacco use. It should also be considered in young patients with bilateral or recurrent attacks of NAION.

Cancer-associated retinopathy in a patient with advanced epithelial ovarian carcinoma.

BACKGROUND: Paraneoplastic phenomena, such as retinopathy, may herald an unsuspected gynecologic malignancy. CASE: A 75-year-old woman presented to a neuro-ophthalmologist with abrupt onset of unilateral visual loss. A diagnosis of branch retinal artery occlusion was made and she was treated with aspirin. An echocardiogram subsequently revealed atrial dilation and she was placed on coumadin therapy. Her vision worsened and a cancer-associated retinopathy was entertained. A serum cancer-associated retinopathy antibody was detected; subsequent computed tomographies of the abdomen and pelvis revealed findings consistent with a primary ovarian carcinoma. CONCLUSION: Patients with unexplained ophthalmologic symptoms may harbor an underlying gynecologic cancer.

Through a shade darkly.

A 43-year-old man complained of difficulty seeing in dim light (nyctalopia). A prolonged photostress test and abnormal electroretinogram confirmed retinal rather than optic nerve dysfunction. Vitamin A deficiency secondary to remote ileal-jejunal bypass was diagnosed, and his visual symptoms and signs reversed with oral vitamin A supplementation.

Unilateral optic disc edema following trabeculectomy.

Two cases of a benign form of optic disc edema after successful trabeculectomy are reported. In both patients, optic disc edema was noted 2 to 4 weeks after trabeculectomy. The edema occurred without loss of visual acuity or field. The absolute intraocular pressure and intracranial pressure were normal--that is, the edema was not a syndrome of hypotony or pseudotumor cerebri. However, both patients had intracranial pressure in the high-normal range. The decrease in intraocular pressure into the low normal range after trabeculectomy may have altered the intracranial pressure:intraocular pressure ratio at the lamina cribrosa enough to produce optic disc edema.

Ocular neuromyotonia: three case reports with eye movement recordings.

The objective of this article was to evaluate the etiologies, findings, and treatment of ocular neuromyotonia (ONM) in three case reports. The etiologies of ONM were determined by the histories, neuroradiologic tests, or biopsies. Clinical observations, videotaping, and electronic eye movement recordings documented the eye movement abnormalities. Intermittent diplopia developed several years after myelography with thorium dioxide (Thorotrast), radiation treatment for a pituitary tumor, and radiotherapy for medulloblastoma of the posterior fossa. All of the patients had intermittent, variable tropias that occurred spontaneously or were induced by eccentric gaze. One patient had a partial third nerve palsy, and another had a unilateral internuclear ophthalmoplegia (INO). ONM involved the paretic third nerve, extraocular muscles, and ipsilateral lateral rectus muscle in one patient, the paretic medial rectus muscle (INO) in one patient, a lateral rectus muscle (INO) in one patient, and a lateral rectus muscle in the last patient. Eye movement recordings were consistent with spasms of the involved muscles. Carbamazepine (Tegretol) abolished the ONM in two patients. The other patient had been taking carbamazepine for seizures and developed ONM when the dose was decreased. Increasing the dose abolished the ONM. ONM is an unusual cause of intermittent diplopia and strabismus, but its distinctive history and signs identify it easily. Damage to the peripheral cranial nerves might produce segmental demyelination, axonal hyperexcitability, and a self-perpetuating, reverberating circuit that causes spasms of the extraocular muscles.

Bilateral anterior ischemic optic neuropathy following influenza vaccination.

Optic neuritis is an occasional complication of vaccination. Visual loss can be unilateral or bilateral, and most patients recover substantially without treatment. The presumptive mechanism is an immune-mediated demyelinating injury of the optic nerve. We report two patients who had permanent visual loss following influenza vaccination. Their pattern of visual loss, segmental optic disc changes, and failure of visual recovery were atypical for demyelinating optic neuritis and reminiscent of a primary ischemic injury to the optic nerve. We speculate that an immune complex-mediated vasculopathy following vaccination can cause anterior ischemic optic neuropathy. Clinicians should be aware of this entity because of the less favorable prognosis for visual recovery in these cases.

Optic neuritis.

Advances in magnetic resonance (MR) orbital imaging using fat suppression techniques and contrast enhancement have increased our ability to visualize the area of inflammation in patients with optic neuritis. Our understanding of the natural history of optic neuritis continues to expand. The high risk of developing multiple sclerosis (MS) after an episode of optic neuritis has been confirmed with longitudinal studies. The most important predictive factor for the future development of MS continues to be an abnormal MR image at presentation. Treatment with intravenous steroids temporarily reduces this risk but has no effect on visual outcome. Although subjective visual complaints are common, objective measures of vision show only mild loss in most patients.

Unilateral headache and ptosis in a 30-year-old woman.

A 30-year-old woman developed left-sided headaches and ipsilateral oculosympathetic paresis (Horner's syndrome) secondary to carotid dissection. Although she initially denied preceding trauma, further questioning revealed a pattern of physical abuse by her boyfriend, including an attempted strangulation shortly before onset of symptoms. This case highlights the need for increased awareness of domestic violence among health care providers.

Lumboperitoneal shunting for pseudotumor cerebri.

To clarify the appropriate role of lumboperitoneal (LP) shunting in the surgical management of pseudotumor cerebri (PTC), we retrospectively analyzed the clinical data from 30 patients who underwent this procedure. We found LP shunting to be an effective means of acutely lowering intracranial pressure. Symptoms of increased intracranial pressure improved in 82% of patients. Among 14 eyes with impaired visual acuity, 10 (71%) improved by at least two lines. Worsening of vision occurred in only one eye. Of 28 eyes with abnormal Goldmann perimetry, 18 (64%) improved and none worsened. The incidence of serious complications was low. The major drawback of LP shunting was the need for frequent revisions in a few patients. The reason for poor shunt tolerance in certain individuals is unclear. In PTC, LP shunting should be considered as the first surgical procedure for patients with severe visual loss at presentation or with intractable headache (with or without visual loss). After shunting it is important to identify patients who are shunt intolerant.

Progressive visual loss and motility deficit.

A 63-year-old female with known stage III, low grade non-Hodgkin's lymphoma presented with progressive visual loss in the left eye and binocular diplopia in all positions of gaze. The left globe was almost immotile. Two MRI's of the orbit were interpreted as normal. Lumbar puncture did not reveal abnormal cytology. Although orbital apex involvement is uncommon in non-Hodgkin's lymphoma, the patient's clinical findings clearly indicated a lesion in this area, which was confirmed by a third MRI. Review of one of the initial films showed evidence of orbital apex involvement. To prevent diagnostic delay and unnecessary repeat imaging, the clinical diagnosis of orbital apex syndrome should be clearly communicated to the radiologist. Prompt recognition of orbital apex syndrome may improve visual outcome.

Migraine precipitated by head trauma in athletes.

PURPOSE: To present the clinical features of a case of migraine precipitated by head trauma. METHODS: Detailed history was obtained and ophthalmic and neurologic examinations were performed. RESULTS: This patient's history of transient loss of vision followed by severe headache precipitated by a direct blow to the top of the head is characteristic of this phenomenon. Normal neurologic and opthalmic examination findings, normal magnetic resonance imaging, and a history of similar episodes are all consistent with this diagnosis. CONCLUSION: Familiarity with this entity can obviate an expensive examination for patients with these classic symptoms.

Persistent palinopsia following ingestion of lysergic acid diethylamide (LSD).

OBJECTIVE: To identify a distinctive chronic visual complication of lysergic acid diethylamide (LSD) use. DESIGN: Description of the clinical findings in three patients with this disorder. SETTING: A neuro-ophthalmology referral center. RESULTS: All three patients experienced prolonged afterimages (palinopsia) during LSD intoxication and have continued to be symptomatic up to 3 years after they ceased to ingest the drug. Results of neuro-ophthalmologic and neurologic examinations and neuroimaging and electrophysiologic studies were normal. CONCLUSIONS: We have described three patients in whom persistent palinopsia developed following ingestion of LSD. Clinicians should inquire about past LSD use in all patients who initially have seemingly spontaneous, isolated palinopsia. Recognition of this distinctive clinical syndrome associated with LSD use might avoid unnecessary anxiety and excessive diagnostic tests for patients with this disorder.

Intermittent diplopia and strabismus caused by ocular neuromyotonia.

PURPOSE: Two cases illustrate the symptoms, signs, etiologies, and treatment of ocular neuromyotonia (ONM). METHODS: The histories, neuroradiologic tests, and/or biopsy revealed the etiologies of ONM in both patients. Clinical observations, videotaping, and electronic eye movement recordings documented the eye movements. RESULTS: A 72-year-old man with chronic arachnoiditis following myelography with thorium dioxide (Thorotrast) developed intermittent diplopia and a partial right third nerve palsy. Left gaze induced spasm of the right medial rectus. Right gaze produced right lateral rectus spasm. A 66-year-old woman, who had radiation treatment for a pituitary tumor and acromegaly, had intermittent spasm of the left medial rectus muscle and left esotropia. The episodes occurred spontaneously and were induced by right gaze. A left internuclear ophthalmoplegia was also found. Carbamazepine (Tegretol) abolished the ONM in both patients. CONCLUSIONS: Although ONM is an unusual cause of intermittent diplopia and strabismus, its distinctive clinical features identify it. Injury to the peripheral cranial nerves probably leads to segmental demyelination, axonal hyperexcitability, and a self-perpetuating, reverberating circuit, which causes spasms of the extraocular muscles.