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Biomedical subjects

Hasan M Bahrani

Publications and source records attributed to Hasan M Bahrani.

3 recordsLinked to original sources

Medical and surgical management of idiopathic intracranial hypertension in pregnancy.

Idiopathic intracranial hypertension (IIH) is a syndrome of increased intracranial pressure without hydrocephalus or mass lesion with elevated cerebrospinal fluid (CSF) pressure but otherwise normal CSF composition. It has been found that pregnancy occurs in IIH patients at about the same rate as in the general population, that IIH can occur in any trimester of pregnancy, that patients have the same spontaneous abortion rate as the general population, and that the visual outcome is the same as for nonpregnant patients with IIH. Although it is also stated that pregnant patients with IIH should be managed and treated the same way as any other patient with IIH, the use of imaging and drug contraindications do make a difference between the two groups. The treatment has two major goals, which are to preserve vision and to improve symptoms. The medical therapy includes weight control, nonketotic diet, serial lumbar punctures, diuretics, steroids, and certain analgesics. When medical therapy fails, surgical procedures should be considered. The two main procedures are optic nerve sheath fenestration and lumboperitoneal shunt. Anesthetic considerations in the pregnant patient are an additional factor when surgeries are contemplated. It is also noted that therapeutic abortion to limit progression of disease is not indicated and that subsequent pregnancies do not increase the risk of recurrence.

Adolescent↗

Photopic ERGs in patients with optic neuropathies: comparison with primate ERGs after pharmacologic blockade of inner retina.

PURPOSE: To determine whether anterior ischemic optic neuropathy and compressive optic neuropathy in humans alter the photopic flash ERG and to investigate the cellular origins of the waves that are affected by pharmacologic agents in primates. METHODS: Photopic flash ERGs were recorded differentially, with DTL electrodes, between the two eyes of 22 patients with diagnosed optic neuropathy (n = 17, anterior ischemic optic neuropathy [AION]; n = 5, compressive optic neuropathy) and 25 age-matched control subjects and in 17 eyes of 13 monkeys (Macaca mulatta). The stimulus consisted of brief (<5 ms) red (lambda(max) = 660 nm) Ganzfeld flashes (energy range, 0.5-2.0 log td-s) delivered on a rod-saturating blue background of 3.7 log sc td (lambda(max) = 460 nm). An eye of the patient with ischemic changes at the disc was classified as symptomatic if it showed visual field defects with a mean deviation (MD) of P < 2%. Recordings in macaque monkeys were made before and after inner retinal blockade with tetrodotoxin (TTX) (1.2-2.1 microM; n = 7), TTX+N-methyl-d-aspartate (NMDA; 1.4-6.4 mM; n = 7), and cis-2, 3 piperidine dicarboxylic acid (PDA; 3.3-3.8 mM; n = 3). RESULTS: The PhNR amplitude was significantly reduced in both symptomatic (P = 3.4 x 10(-8)) and asymptomatic (P = 0.036) eyes of patients with AION or compressive optic neuropathy (P = 0.0054) compared with control subjects. The PhNR amplitude in the symptomatic eye showed a moderate correlation with field defects (P < 0.05) similar to previous findings in open-angle glaucoma. The a-wave also was reduced significantly in the symptomatic eye (P = 0.0002) of patients with AION. The i-wave, a positive wave on the trailing edge of the b-wave peaking around 50 ms, became more prominent in eyes in which the PhNR was significantly reduced. In monkeys, the PhNR was eliminated by TTX. The a-wave at the peak and later times was reduced by TTX, further reduced by NMDA, and eliminated after PDA in response to the red stimuli. PDA also eliminated the i-wave. CONCLUSIONS: PhNR amplitude is significantly reduced in eyes with open-angle glaucoma, AION, and compressive optic neuropathy. Experiments in primates indicate that this reduction reflects loss of a spike-driven contribution to the photopic ERG. There also are small spike-driven contributions to the a-wave elicited by full-field red stimuli. The i-wave, which becomes more prominent when the PhNR is reduced, has origins in the off-pathway distal to the ganglion cells.

Adult↗

Her vision was tied down.

A 50-year-old female presented with progressive painless vision loss in the left eye and was subsequently diagnosed to have a pituitary macroadenoma, consistent with a prolactinoma, which was compressing the chiasm primarily on the left and involving the left cavernous sinus. She was treated with oral bromocriptine, resulting in marked shrinkage of the tumor and significant visual field recovery. Subsequently, she again began noting progressive vision loss in both eyes and was initially thought to have pituitary tumor regrowth. Repeat brain MRI, however, showed chiasmal prolapse with inferior tethering into an empty sella. Surgical fat padding to reposition the chiasm resulted in visual improvement with a different visual field pattern in the left eye. The clinical manifestations and etiopathogenesis of the empty sella syndrome are discussed.

Adipose Tissue↗