Biomedical subjects

T J McPhee

Publications and source records attributed to T J McPhee.

7 recordsLinked to original sources

PubMed1995

The movement disorder of adult opsoclonus.

We present three cases of the adult opsoclonus-myoclonus syndrome in patients with systemic carcinoma. In addition to opsoclonus and myoclonus, other clinical components of the syndrome can include ataxia, tremor, gait and stance dysfunction, altered mental status, and head and face dyskinesias. The most common etiologies are idiopathic, paraneoplastic, and infectious encephalitis. Radiographic and pathological studies suggest brain-stem dysfunction with associated cerebellar and/or cerebellar pathway dysfunction. In many cases, there is evidence for the involvement of immunologic and/or inflammatory processes in the pathogenesis of this syndrome. The timely recognition of this syndrome is important because of its implications for the underlying etiology and prognosis. The appearance of this syndrome should prompt the search for an occult malignancy.

Adult↗

PubMed1995

Hemangioblastoma of the optic nerve: case report.

An optic nerve hemangioblastoma arising in the optic nerve of a patient with von Hippel-Lindau syndrome is reported. This represents the 10th published example of a hemangioblastoma arising at this site, the second description of the magnetic resonance imaging features of a hemangioblastoma at this location, and the second patient from whom an optic nerve hemangioblastoma has been removed with the goal of preserving the optic nerve as well as vision. A majority of these optic nerve hemangioblastomas have arisen in patients with von Hippel-Lindau syndrome. All patients experienced progressive loss of vision either to blindness or surgical intervention, although a vast majority of the lesions were sharply demarcated from the adjacent nerve and, thus, potentially resectable. Optic nerve hemangioblastomas are a rare cause of blindness but potentially preventable when treated with a conservative surgical approach aided by neuroimaging guidance. The recognition of discordance between the degree of vision loss and the extent or progression of a retinal hemangioblastoma may be an important clue to diagnosis in the patient with von Hippel-Lindau syndrome.

Adult↗

PubMed1993

Electroretinographic findings in iris neovascularization due to acute central retinal vein occlusion.

Electroretinograms (ERGs) were recorded in 94 patients with central retinal vein occlusion (CRVO). Of these 94, 11 had neovascularization of the iris (NVI) at the time of testing, 25 later developed NVI, and 58 did not develop NVI during a follow-up period that varied from 1 1/2 to 5 years. The ERG recorded at the patient's presentation visit predicted the occurrence of NVI in these patients with high sensitivity and specificity. The most predictive ERG parameters were the semi-saturation constant from intensity-response analysis (log K), and the implicit times of the scotopic a- and b-waves and the scotopic 30-Hz flicker response. These parameters were highly correlated, suggesting that the functional mechanism that places eyes at risk for NVI in CRVO is unidimensional. Paradoxically, the most likely candidate for this mechanism is photoreceptor sensitivity loss due to ischemia.

Acute Disease↗

PubMed1993

Visual prognosis in giant cell arteritis.

PURPOSE: The visual prognosis in giant cell arteritis (GCA) was evaluated over a 5-year period. METHODS: The authors reviewed the records of all patients with a diagnosis of GCA established at the Mayo Clinic over a 5-year period regarding visual status. Follow-up data for these patients were obtained 5 years later. RESULTS: Of the 245 patients studied, 34 (14%) permanently lost vision because of GCA. In 32 of these patients, the visual deficit developed before glucocorticoid therapy for GCA was begun; in the 2 other patients, the visual loss occurred after the diagnosis was made and therapy was started. Visual loss progressed in three patients after initiation of oral glucocorticoids, and in five other patients vision improved. After 5 years, the probability of loss of vision developing after initiating oral glucocorticoid treatment was determined to be 1% (Kaplan-Meier technique), and the probability of additional loss was 13% in patients with GCA who had a visual deficit at the time therapy was begun. CONCLUSION: The development or progression of visual loss was rare after the initiation of glucocorticoid therapy.

Aged↗

PubMed1988

Neovascularization in central retinal vein occlusion: electroretinographic findings.

Electroretinograms (ERGs) were measured in 15 patients with central retinal vein occlusion (CRVO). Seven of the patients had neovascularization of the iris (NVI) at the time of testing, and two developed NVI within one month of testing; six did not have NVI or any other form of neovascularization (NV) and were no longer considered to be at risk for NV from their present occlusion. The ERGs were recorded as a function of the stimulus intensity and to a 30-Hz flickering stimulus. A Naka-Rushton-type function was fit to b-wave amplitudes, measured as a function of stimulus intensity, to evaluate changes in ERG amplitude and sensitivity. Compared with eyes in the no-NV group, eyes developing NVI had significantly reduced ERG sensitivity and amplitudes. The distributions of sensitivity values in these two groups did not overlap. All of the eyes with NV showed large a- and b-wave and 30-Hz implicit time delays, but only one eye had a b/a-wave amplitude ratio close to or less than 1. A comparison of ERG sensitivity, amplitude data, and flicker timing data with retinal fluorescein angiography in a two-alternative forced-choice analysis showed that ERG sensitivity and amplitude loss were better than retinal fluorescein angiography at discriminating eyes with CRVO and NVI from eyes with CRVO without NVI.

Electroretinography↗

PubMed1988

Marginal myotomy of the medial rectus with lateral rectus resection as a secondary procedure for esotropia.

Between 1964 and 1982, 89 marginal myotomies were performed, 70 on the medial rectus with lateral rectus resection as a combined secondary procedure for esotropia. Successful realignment was attained in 51% of the cases (for both distance and near measurements); undercorrection occurred in 34% (either distance or near), and overcorrection in 14% (either distance or near). Further operation was required in 17%, of which 4% were for overcorrection. Initial postoperative alignment was maintained at subsequent follow-up. The degree of change in deviation did not correlate with the degree of resection of the lateral rectus or the degree of medial rectus myotomy. Marginal myotomy of the medial rectus with lateral rectus resection is a useful procedure that should be part of the repertoire of all strabismus surgeons.

Adolescent↗

PubMed1985

Location of the stress-bearing layers of the cornea.

In order to determine which layers of the corneal stroma bear the stress of the intraocular pressure, 6.0-mm nonpenetrating trephine incisions were made centrally in one eye of each of 16 adult albino rabbits. After epithelial healing, the central corneal thickness was measured over 3 hr at 50 mmHg intraocular pressure in both eyes of the anesthetized rabbits. The animals were then killed and the uniformity and depth of trephine cut determined histologically. The mean differences in swelling rates between the cut and the opposite uncut eyes for trephine incisions of different depths were as follows: 1 +/- 2 micron/hr for 8-20% depth, 5 +/- 2 micron/hr for 21-40% depth, and 14 +/- 3 micron/hr for 41-60% depth (P less than 0.01 for all groups). These results indicate that the intraocular tension is probably distributed across all the corneal stromal lamellae rather than being borne primarily by the anterior or posterior layers.

Animals↗