Studies have shown that x-rays delivered as arrays of parallel microplanar beams (microbeams), 25-to 90-m thick and spaced 100 -300 m on-center, respectively, spare normal tissues including the central nervous system (CNS) and preferentially damage tumors. However, such thin microbeams can only be produced by synchrotron sources and have other practical limitations to clinical implementation. To approach this problem, we first studied CNS tolerance to much thicker beams. Three of four rats whose spinal cords were exposed transaxially to four 400-Gy, 0.68-mm microbeams, spaced 4 mm, and all four rats irradiated to their brains with large, 170-Gy arrays of such beams spaced 1.36 mm, all observed for 7 months, showed no paralysis or behavioral changes. We then used an interlacing geometry in which two such arrays at a 90°angle produced the equivalent of a contiguous beam in the target volume only. By using this approach, we produced 90-, 120-, and 150-Gy 3.4 ؋ 3.4 ؋ 3.4 mm 3 exposures in the rat brain. MRIs performed 6 months later revealed focal damage within the target volume at the 120-and 150-Gy doses but no apparent damage elsewhere at 120 Gy. Monte Carlo calculations indicated a 30-m dose falloff (80 -20%) at the edge of the target, which is much less than the 2-to 5-mm value for conventional radiotherapy and radiosurgery. These findings strongly suggest potential application of interlaced microbeams to treat tumors or to ablate nontumorous abnormalities with minimal damage to surrounding normal tissue.
Abstract-Objective:The purpose of this article is to review the use of serum prolactin assay in epileptic seizure diagnosis. Methods: The authors identified relevant studies in multiple databases and reference lists. Studies that met inclusion criteria were summarized and rated for quality of evidence, and the results were analyzed and pooled where appropriate. Results: Most studies used a serum prolactin of at least twice baseline value as abnormal. For the differentiation of epileptic seizures from psychogenic nonepileptic seizures, one Class I and seven Class II studies showed that elevated serum prolactin was highly predictive of either generalized tonic-clonic or complex partial seizures. Pooled sensitivity was higher for generalized tonic-clonic seizures (60.0%) than for complex partial seizures (46.1%), while the pooled specificity was similar for both (approximately 96%). Data were insufficient to establish validity for simple partial seizures. Two Class II studies were consistent in showing prolactin elevation after tilt-test-induced syncope. Inconclusive data exist regarding the value of serum prolactin following status epilepticus, repetitive seizures, and neonatal seizures. Recommendations: Elevated serum prolactin assay, when measured in the appropriate clinical setting at 10 to 20 minutes after a suspected event, is a useful adjunct for the differentiation of generalized tonic-clonic or complex partial seizure from psychogenic nonepileptic seizure among adults and older children (Level B). Serum prolactin assay does not distinguish epileptic seizures from syncope (Level B). The use of serum PRL assay has not been established in the evaluation of status epilepticus, repetitive seizures, and neonatal seizures (Level U). NEUROLOGY 2005;65:668-675 Prolactin (PRL) release from the pituitary is controlled by the hypothalamus via a PRL inhibitory factor, now believed to be dopamine.1 It has been hypothesized that ictal epileptic activity in the mesial temporal structures may propagate to the hypothalamus, altering the hypothalamic regulation of PRL release. 2Trimble first demonstrated that generalized tonicclonic seizures, but not nonepileptic seizures (NESs), could raise serum PRL.3 Despite subsequent confirmatory findings, the sensitivity and specificity of serum PRL assay for diagnosis of epileptic seizures (ESs) remain uncertain. Utility of PRL assays for diagnosis of seizures depends upon the study design, standard of seizure classification, and criteria for abnormal PRL elevation. Additional uncertainty arises from the circadian fluctuations of serum PRL, demonstrating surges of 50 to 100% prior to awakening from sleep, although PRL serum levels otherwise are stable during the waking state.4 PRL concentrations usually are higher in females than in males, 5 and higher in persons with epilepsy than in healthy individuals. 6 In a study that measured baseline PRL every 20 minutes over 24 hours in 20 healthy controls and 17 people with epilepsy, 5 no female had baseline PRL exceeding 700 U/mL, and no ...
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