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Biomedical subjects

N R Miller

Publications and source records attributed to N R Miller.

At least 55 records · Page 3Linked to original sources
PubMed2000

Bilateral optic neuropathy associated with diffuse cerebral angiomatosis in Sturge-Weber syndrome.

Visual loss in patients with encephalotrigeminal angiomatosis or Sturge-Weber syndrome usually results from secondary glaucoma or from damage to the retrogeniculate pathways by the angiomatous lesions. Optic neuropathy has not been reported as a component of this syndrome. This report describes a patient who developed bilateral optic neuropathy with progressive visual loss associated with diffuse cerebral angiomatosis in the setting of Sturge-Weber syndrome.

Adult↗
PubMed2000

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.

Antidepressive Agents↗
PubMed2000

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.

Adolescent↗
PubMed1999

Visual dysfunction in patients receiving vigabatrin: clinical and electrophysiologic findings.

BACKGROUND: Vigabatrin is an antiepileptic drug that, although relatively well tolerated, is associated with visual field constriction and other visual disturbances of unclear origin. METHODS: We performed a complete neuroophthalmologic examination and electrophysiologic studies on 39 patients receiving vigabatrin and on 11 control patients. RESULTS: Nearly 50% of patients receiving vigabatrin had constricted visual fields compared with control patients. Some of the vigabatrin patients also had reduced visual acuity and abnormal color vision. In addition, most vigabatrin patients had abnormal electroretinographic results, the severity of which correlated strongly with the degree of visual field constriction. CONCLUSIONS: Vigabatrin can cause electrophysiologic evidence of retinal dysfunction and clinically detectable disturbances of visual sensory function.

Adult↗
PubMed1999

Different mutations in the same codon of the proteolipid protein gene, PLP, may help in correlating genotype with phenotype in Pelizaeus-Merzbacher disease/X-linked spastic paraplegia (PMD/SPG2).

Pelizaeus-Merzbacher disease/X-linked spastic paraplegia (PMD/SPG2) comprises a spectrum of diseases that range from severe to quite mild. The reasons for the variation in severity are not obvious, but suggested explanations include the extent of disruption of the transmembrane portion of the proteolipid protein caused by certain amino acid substitutions and interference with the trafficking of the PLP molecule in oligodendrocytes. Four codons in which substitution of more than one amino acid has occurred are available for examination of clinical and potential structural manifestations: Valine165 to either glutamate or glycine, leucine 045 to either proline or arginine, aspartate 202 to asparagine or histidine, and leucine 223 to isoleucine or proline. Three of these mutations, Val165Gly, Leu045Pro, and Leu223Ile have not been described previously in humans. The altered amino acids appear in the A-B loop, C helix, and C-D loop, respectively. We describe clinically patients with the mutations T494G (Val165Gly), T134C (Leu045Pro), and C667A (Leu223Ile). We discuss also the previously reported mutations Asp202Asn and Asp202His. We have calculated the changes in hydrophobicity of short sequences surrounding some of these amino acids and compared the probable results of the changes in transmembrane structure of the proteolipid protein for the various mutations with the clinical data available on the patients. While the Val165Glu mutation, which is expected to produce disruption of a transmembrane loop of the protein, produces more severe disease than does Val165Gly, no particular correlation with hydrophobicity is found for the other mutations. As these are not in transmembrane domains, other factors such as intracellular transport or interaction between protein chains during myelin formation are probably at work.

Codon↗
PubMed1999

Lytic Paget disease as a cause of orbital cholesterol granuloma.

A case of histologically confirmed Paget disease of the orbit produced a lesion that appeared both clinically and histologically similar to a cholesterol granuloma. This case is unique because of the unusual location of the lesion, its presentation in a patient with no other manifestations of Paget disease, and the histological picture produced by the disease.

Cholesterol↗
PubMed1999

Bilateral ocular ischemic syndrome secondary to giant cell arteritis progressing despite corticosteroid treatment.

PURPOSE: To report the development of a bilateral ocular ischemic syndrome despite corticosteroid treatment in a patient with giant cell arteritis. METHOD: Case report. RESULTS: Despite receiving high-dose intravenous methylprednisolone and oral prednisone for biopsy-proven giant cell arteritis that presented as a severe anterior ischemic optic neuropathy in the right eye, a patient developed progressive ocular ischemia in that eye as well as an ocular ischemic syndrome in the fellow eye. CONCLUSIONS: Some patients with giant cell arteritis, possibly patients with other underlying systemic vasculopathies, are refractory to what should be adequate treatment with systemic corticosteroids and may develop a bilateral ocular ischemic syndrome.

Administration, Oral↗
PubMed1999

Efficacy of unilateral versus bilateral temporal artery biopsies for the diagnosis of giant cell arteritis.

PURPOSE: To determine the utility of unilateral versus bilateral temporal artery biopsies in detecting the pathologic changes of giant cell arteritis. METHODS: We performed a retrospective study to determine the utility of unilateral versus bilateral temporal artery biopsies in detecting the pathologic changes of giant cell arteritis. The pathologic reports of consecutive temporal artery biopsy specimens received at the Wilmer Ocular Pathology Laboratory over a 28-year period from 1968 to 1996 were reviewed. RESULTS: Of 908 specimens examined from 758 patients, 300 specimens were simultaneous bilateral biopsies from 150 patients, 72 specimens were bilateral sequential biopsies from 36 patients, and the remaining 536 specimens were unilateral biopsies from 536 patients. Of the 186 patients who had bilateral simultaneous or nonsimultaneous biopsies, 176 had identical diagnoses on both sides. In four patients, no artery was obtained on one side. In each of the remaining six patients, five of whom had bilateral simultaneous biopsies and one of whom had bilateral sequential biopsies performed 8 days apart, the biopsy specimen from one side was interpreted as showing only arteriosclerotic changes with no evidence of active or healed arteritis, whereas the other specimen was interpreted as showing either probable healed arteritis (three specimens) or possible early arteritis (three cases). In none of the six patients with differing diagnoses between the two sides was one side interpreted as showing definite, active giant cell arteritis. Five of the six patients were subsequently determined to have giant cell arteritis, based on a combination of clinical findings, erythrocyte sedimentation rate, and response to treatment with systemic corticosteroids. CONCLUSIONS: The results of this study indicate that performing a bilateral simultaneous or sequential temporal artery biopsy improves the diagnostic yield in at least 3% of cases of giant cell arteritis, whereas in 97% of cases, the two specimens show the same findings. Thus, in patients in whom only one artery can be biopsied, there is a high probability of obtaining the correct diagnosis. Nevertheless, although the improvement in diagnostic yield of bilateral temporal artery biopsies is low, the consequences of both delayed diagnosis and treatment of giant cell arteritis as well as the use of systemic corticosteroids in patients who do not have giant cell arteritis are of such potential severity that consideration should always be given to performing bilateral temporal artery biopsies in patients suspected of having the disease.

Aged↗
PubMed1999

Prevalence of periocular depigmentation after repeated botulinum toxin A injections in African American patients.

Botulinum toxin A (Botox), administered by subcutaneous or intramuscular injection, is the most commonly used and most successful medication for many craniocervical dystonias. Although some patients experience side effects related to the neuroparalytic action of the medication, these side effects are temporary. In 1996, permanent periocular cutaneous depigmentation was reported in three white patients after repeated Botox injections, suggesting that loss or alteration of melanin pigment might be a permanent side effect of long-term Botox injections. The authors examined and photographed 26 African American patients who were receiving periocular Botox injections for hemifacial spasm and essential blepharospasm. The authors found no evidence of periocular cutaneous depigmentation in any of these patients.

Adult↗
PubMed1999

Visual environmental rotation: a novel disorder of visiospatial integration.

A 70-year-old man experienced an unusual disorder of visual perception after undergoing a ventriculoperitoneal shunt for normal-pressure hydrocephalus. The disorder was characterized by transient episodes of 90 degrees rotation of the visual environment, rather than the retinotopic visual field. This phenomenon is different from standard visual allesthesia and may have been caused by disordered integration of vestibular and visual inputs to the posterior parietal cortex or perseveration of a pre-existing environmental memory trace.

Aged↗
PubMed1999

Disseminated histoplasmosis causing reversible gaze palsy and optic neuropathy.

Subacute disseminated histoplasmosis is an uncommon entity. Typical neuro-ophthalmologic manifestations are usually secondary to histoplasmomas or encephalitis. A 45-year-old man noted blurred vision while receiving empiric antituberculosis therapy for fever and diffuse granulomatous disease of unknown origin. Vertical-gaze palsy, right horizontal-gaze paresis, and mild right optic neuropathy were found on neuro-ophthalmologic examination. Further questioning revealed a history of frequent contact with fighting cocks from South America. Magnetic resonance images were consistent with multiple hemorrhagic infarcts, areas of inflammation, or both, and cerebral angiography showed changes consistent with vasculitis. A previously obtained biopsy specimen from the duodenum was restained and found to be positive for fungal elements. Serum antigen titers for Histoplasma capsulatum demonstrated evidence of active infection. This case is a rare example of a supranuclear ocular motility disturbance and optic neuropathy secondary to an occlusive vascular process in a patient with subacute disseminated histoplasmosis.

Diagnostic Errors↗
PubMed1999

Neuro-ophthalmology of arteriovenous malformations.

Intracranial arteriovenous malformations may result in a number of neuro-ophthalmologic signs and symptoms. In some patients, the neuro-ophthalmic findings are the presenting or only manifestations. A multi-disciplinary team approach including neurologists, ophthalmologists, neurosurgeons, interventional radiologists, and radiation therapists is ideal.

Adult↗
PubMed1998

Preparation and EPR studies of lithium phthalocyanine radical as an oxymetric probe.

The electron paramagnetic resonance (EPR) spectrum of the paramagnetic center in solid lithium phthalocyanine, LiPc, exhibits a pO2 (partial pressure of oxygen)-dependent line width. The compound is insoluble in water and is not easily biodegradable and, therefore, is a useful spin probe for quantitative in vivo oxymetry. Because EPR spectrometry is potentially a useful technique to quantitatively obtain in vivo tissue pO2, such probes can be used to obtain physiological information. In this paper, a simple experimental procedure for the preparation of LiPc using potentiostatic electrochemical methods is described. The setup was relatively inexpensive and easy to implement. A constant potential ranging from 0.05 to 0.75 V versus Ag+/AgCl(s) was used for obtaining LiPc. The EPR spectral studies were carried out using spectrometers operating at X-band and at radiofrequency (RF) at different pO2 values to characterize the spectral response of these crystals. The results indicate that, depending on the electrolysis conditions, the products contain mixtures of crystals exhibiting pO2-sensitive and pO2-insensitive line widths. Electrolysis conditions are reported whereby the pO2-sensitive LiPc crystals were the predominant product. The influence of the working surface of the electrode and the electrolysis time on the yield were also evaluated. The crystals of LiPc were also studied using a time-domain RF EPR spectrometer. In time-domain EPR, the signals that survive beyond the spectrometer dead time are mainly the narrow lines corresponding to the pO2-sensitive crystals, whereas the signals arising from the pO2-insensitive component of LiPc were found not to survive beyond the spectrometer dead time. This signal survival makes the time-domain EPR method more sensitive for pO2 measurements using LiPc because the line width becomes very narrow at very low pO2 and, concomitantly, the relaxation time T2 longer, with no modulation or power saturation artifacts that are encountered as in the continuous wave (cw) mode. Further, minimal contributions from object motion in the spectral data obtained using time-domain methods make it an advantage for in vivo applications.

Crystallization↗