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Biomedical subjects

Y T So

Publications and source records attributed to Y T So.

35 records · Page 2Linked to original sources
PubMed1990

A comparison of thermography and electromyography in the diagnosis of cervical radiculopathy.

We studied 20 asymptomatic control subjects and 14 patients with clinically unequivocal cervical radiculopathy to compare the diagnostic value of thermography with that of electromyography. We measured the average skin temperature of designated regions over the neck, shoulder, and upper extremities. We then compared the temperature between corresponding regions of the two limbs, and between fingers innervated by different roots in the same hand. Thermography was abnormal in 6 patients (43%), whereas electromyography was abnormal in 10 (71%). Thermographic abnormalities were seen only in the hands and fingers, and the pattern did not follow the dermatome of the clinically involved cervical root. When compared to electromyography, thermography provided no additional diagnostic information. Thus, thermography does not have an established role in the evaluation of patients with cervical radiculopathy.

Arm↗
PubMed1990

The recent development and evaluation of a medical expert system (ABVAB).

A medical expert system for the diagnosis of abnormal vaginal bleeding named as ABVAB had been reported. This paper will describe the recent development of ABVAB and its clinical evaluation. The overall testing results are quite satisfactory in spite of the limitations of time and small domain. This expert system, by using the fuzzy and certainty factor concepts, is able to handle imprecise and incomplete medical knowledge which has become informative. The paper also analyses the relative degrees of importance of the history and physical examination data in making a medical diagnosis.

Data Interpretation, Statistical↗
PubMed1989

New-onset seizures associated with human immunodeficiency virus infection: causation and clinical features in 100 cases.

PURPOSE: We attempt to define the significance and most common causes of new-onset seizures in patients with human immunodeficiency virus (HIV) infection. In addition, we review the seizure type, neurologic examination, and other clinical features to better address diagnostic and management issues in these patients. PATIENTS AND METHODS: We reviewed 100 cases of new-onset seizures in HIV-infected patients who underwent complete evaluations at the University of California, San Francisco, hospitals. RESULTS: Seizures were the presenting symptom of HIV-related illness in 18 patients, six of whom developed no other HIV-related illness until at least four months after the first seizure. Common causes in the 100 patients included mass lesions, HIV encephalopathy, and meningitis. No cause for the seizures was found in 23 patients despite a complete evaluation. An underlying cause was found in all patients with focal neurologic deficits but in only two of 24 who had normal results on an interictal neurologic examination. Focal ictal features were not predictive of cause. A cause was found in all 12 patients with status epilepticus or medically refractory seizures. A total of 12 of the 87 (14%) patients who received phenytoin developed a hypersensitivity reaction. Despite the brevity of follow-up in some patients, many patients, including those with no definable cause, had multiple seizures prior to the administration of anticonvulsants. CONCLUSION: The direct effects of HIV on the brain may be the single most common cause of seizures in this population. We favor treatment of a single seizure in patients with HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Evaluation of thermography in the diagnosis of selected entrapment neuropathies.

We studied 20 normal subjects, 22 patients with carpal tunnel syndrome, and 15 with ulnar neuropathy at the elbow to compare the diagnostic accuracy of infrared thermography with that of conventional electrodiagnostic studies. We found abnormal thermograms in 55% of patients with carpal tunnel syndrome and 47% with ulnar neuropathy, using 2.5 SD from the normal mean as criteria for abnormality. The abnormalities consisted of either an increase in interside temperature difference in the fingers and hands or an alteration of the normal thenar-hypothenar temperature gradient in the fingers. The sensitivity of thermography was considerably lower than that of conventional electrodiagnostic methods. Moreover, the thermographic abnormalities were nonspecific, and could be misleading as they did not reliably identify the side of lesion or distinguish between median or ulnar nerve involvement. Thus, thermography is not helpful in the diagnosis of these two common entrapment neuropathies.

Carpal Tunnel Syndrome↗
PubMed1989

The role of thermography in the evaluation of lumbosacral radiculopathy.

We studied 27 normal subjects and 30 patients with low back pain to evaluate the diagnostic accuracy of thermography in the diagnosis of lumbosacral radiculopathy. Thermographic abnormality was defined as the presence of either interside temperature difference exceeding 3 standard deviations from the normal mean, or an abnormal heat pattern overlying the lumbosacral spine. In patients with clinically unequivocal radiculopathy, thermography and electrophysiologic study were similar in diagnostic sensitivity, and the 2 methods agreed on the presence or absence of abnormality in 71% of cases. However, the thermographic findings had limited localizing value. Relative limb warming was often seen in patients with acute denervation on EMG, and limb cooling in those with more chronic lesions, but the side of the root lesion could not be identified confidently by thermography alone. Moreover, thermographic abnormalities appeared not to follow a dermatomal distribution and failed to identify the clinical or electrophysiologic level of radiculopathy in most cases. Thus, the thermographic findings are nonspecific, of little diagnostic value, and of uncertain prognostic relevance.

Adult↗
PubMed1988

Subacute structural myopathy associated with human immunodeficiency virus infection.

An unusual myopathy characterized by selective loss of thick filaments and widespread formation of rod bodies is described in two men, both seropositive for human immunodeficiency virus. We were unable to find any previous reports documenting this combination of morphological abnormalities, which we believe may be related to human immunodeficiency virus infection. Both patients responded to treatment: one, to steroid therapy; the other, to plasmapheresis.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Peripheral neuropathy associated with acquired immunodeficiency syndrome. Prevalence and clinical features from a population-based survey.

We prospectively studied 40 hospitalized patients who had well-established diagnoses of acquired immunodeficiency syndrome. Patients with confounding risk factors for neuropathy were excluded; none of the study patients had known vitamin deficiency, alcoholism, or any metabolic, drug, or toxic factor. Clinical and electrophysiologic evidence of a distal symmetric polyneuropathy was found in 35% (13/37) of the patients. Symptoms and signs of neuropathy were usually mild, and painful dysesthesias were uncommon. Amplitude reduction of sural nerve action potentials distinguished all patients with from those without clinical neuropathy. Results of other electrophysiologic studies of sural, peroneal, and median nerves were typically normal. These results provide evidence of distal axonal degeneration. Neuropathy occurred only in patients with systemic illness longer than five months' duration. When compared with patients without neuropathy, these patients had more severe weight loss and a higher incidence of clinical dementia. Follow-up evaluation showed no evidence of clinical progression over a six-month period. The pathogenesis of this common distal axonal polyneuropathy is unknown and warrants further investigation.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Primary central nervous system lymphomas in patients with AIDS.

Primary central nervous system non-Hodgkin's lymphomas are observed in approximately 1.9% of all patients with acquired immunodeficiency syndrome (AIDS). The yearly incidence of AIDS-associated tumors has surpassed the yearly incidence from all other causes and could become as frequent as low-grade astrocytomas by 1991. Patients' signs, symptoms, and radiographic studies are not specific for this lesion; brain biopsy usually is necessary to make a definitive diagnosis. Most tumors are high-grade lymphomas and are pathologically similar to the primary central nervous system lymphomas observed before the AIDS epidemic. AIDS-associated tumors respond readily to radiation therapy. However, patient survival remains limited owing to other manifestations of the syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Primary central nervous system lymphoma in acquired immune deficiency syndrome: a clinical and pathological study.

Twenty cases of primary lymphoma of the central nervous system associated with acquired immune deficiency syndrome were seen over a period of four years and were studied clinically and pathologically. Biopsy established the diagnosis in 11 cases, and autopsy confirmed it in 9. Multicentricity was demonstrated in all cases for which there was adequate autopsy material. Both large-cell immunoblastic and small noncleaved lymphomas were seen, and marker studies in 5 patients established that the lymphomas were of B-cell origin. Neurological symptoms and signs, cerebrospinal fluid characteristics, and radiographic appearance were reviewed. The clinical and radiographic picture is nonspecific and histological confirmation is essential for diagnosis. Although the tumor appears to be radiosensitive, prognosis is extremely poor, with an average survival of less than two months.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Eosinophilic vasculitis leading to amaurosis fugax in a patient with acquired immunodeficiency syndrome.

A 49-year-old bisexual man with generalized lymphadenopathy and antihuman T lymphocyte virus, type III, (HTLV-III) antibodies presented with recurrent, unilateral amaurosis fugax. A temporal artery biopsy specimen showed eosinophilic vasculitis. The patient then developed acquired immunodeficiency syndrome with Kaposi's sarcoma. We describe this patient because of the unusual association of large vessel vasculitis and acquired immunodeficiency syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1980

Is there an effect of monocular deprivation on the proportions of X and Y cells in the cat lateral geniculate nucleus?

The proportions and receptive properties of X and Y cells in the A and A1 layers of the lateral geniculate nucleus (LGN) were studied in monocularly deprived cats. Contrary to previous reports, we found that there was no change in the relative number of Y cells in the geniculate layers driven by the deprived eye. There was also no marked change in the spatial resolution of X or Y cells driven from the deprived eye as compared to the cells driven from the normally experienced eye. In these same cats, the visual evoked potential from stimulation of the deprived eye with grating patterns was markedly reduced in amplitude. Furthermore, the cell bodies of the cells in the LGN driven by the deprived eye had shrunk. Therefore, these usual consequences of monocular deprivation are not necessarily associated with a loss of geniculate Y cells.

Animals↗
PubMed1979

Spatial properties of X and Y cells in the lateral geniculate nucleus of the cat and conduction veolcities of their inputs.

Visual neurons in the lateral geniculate nucleus (LGN) of the cat may be separated into distinct X and Y classes based on a test of the linearity of spatial summation. Y cells produce nonlinear responses especially when the visual stimulus is a fine spatial grating. X cells exhibit mainly linear summation properties. X cells respond mainly at the fundamental modulation frequency of a contrast reversal grating while Y cells respond at the fundamental and at the second harmonic of the modulation frequency. The spatial resolution of X cells' fundamental responses and Y cells' second harmonic responses is about the same, and both are two to eight times higher than the spatial resolution of the Y cells' fundamental response. The conduction velocity of the Y optic tract afferents is greater than that of the velocity of the X afferents. However, the LGN latencies of the responses of the two classes of cells to optic chiasm stimulation overlap considerably.

Animals↗
PubMed1979

Effects of dark adaptation on spatial and temporal properties of receptive fields in cat lateral geniculate nucleus.

1. We studied the effect of dark adaptation on the spatial organization of receptive fields of single cells in the lateral geniculate nucleus l.g.n. of the cat. 2. Contrary to previous reports, we found that in many l.g.n. cells the ability of the receptive field surround to suppress the response of the centre was diminished following dark adaptation. 3. The degree of reduction of the surround antagonistic strength varied from cell to cell, and was independent of the various classifications of visual neurones (X/Y, ON/OFF, layer, A/layer, A1 and central/peripheral). 4. Most cells also showed an increase in the apparent size of the excitatory centre upon dark adaptation. On the average, the width of the most effective bar stimulus located at the centre of the receptive field increased more than twofold. 5. We also studied the effect of dark adaptation on the temporal properties of l.g.n. receptive fields. In many cells dark adaptation changed the temporal modulation transfer function: it flattened the amplitude function, and changed the phase relationship between the centre response and the surround response. 6. Retinal ganglion cells showed qualitatively similar behaviour to that of l.g.n. neurones. 7. Our data do not support the notion that retinal ganglion cell centres converge on l.g.n. cells to form their surround mechanism.

Action Potentials↗