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1.Neurobiological Pathophysiology of Attention Deficit Hyperactivity Disorder.

Yeungnam University Journal of Medicine 2000;17(2):108-122

BACKGROUND: Models of attention deficit hyperactivity disorder(ADHD) that have proposed a hypodopaminergic state resulting in hypofunction of the prefrontal circuitry have assumed a unitary dopamine system, which largely ignores the distinct functional differences between mesocortical dopamine system and nigrostriatal dopamine system. PURPOSE: The author's goal was to develop a pathophysiological model for ADHD with greater explanotory power than dopaminergic hypofunction hypothesis in prefronal circuitry. MATERIALS AND METHODS: Published clinical findings on ADHD were integrated with data from genetic, pharmacological, neuroimaging studies in human and animals. RESULTS: Molecular genetic studies suggest that three genes may increase the susceptibility to ADHD. The three candidate genes associated with ADHD are each involved in dopaminergic function, and this consistent with the neurobiologic studies implicating catecholamines in the etiology of ADHD. Pharmacological data also provide compelling support for dopamine and noradrenergic hypothesis of ADHD. Neuroimaging studies lend substantial support for the hypothesis that right-sided abnormalities of prefrontal-basal ganglia circuit would be found in ADHD. CONCLUSIONS: The present hypothesis takes advantage of the major differences between the two pertinent dopamine systems. Mesocortical dopamine system, which largely lacks inhibitory autoreceptors, is ideally positioned to regulate cortical inputs, thus improving the signal-to-noise ratio for biologically valued signals. In this circuit, therapeutic doses of stimulants are hypothesized to increase postsynaptic dopamine effects and enhance executive functions. By contrast, symptoms of hyperactivity/impulsivity in ADHD are hypothesized to be associated with relative overactivity of nigrostriatal circuit. This nigrostriatal circuit is tightly regulated by inhibitory autoreceptoors as well as by long distance feedback from the cortex, and slow diffusion of therapeutic doses of stimulant via oral administration is hypothesized to produce a net inhibition of dopaminergic neurotransmission and improves hyperactivity.
Administration, Oral ; Animals ; Attention Deficit Disorder with Hyperactivity* ; Autoreceptors ; Catecholamines ; Diffusion ; Dopamine ; Dopamine Agents ; Executive Function ; Ganglia ; Humans ; Molecular Biology ; Neuroimaging ; Signal-To-Noise Ratio ; Synaptic Transmission

Partial knee ankylosis is a recognized complication of following open operative procedure, trauma and disease processes about the knee. Intraarticular trauma or surgical procedures such as TKR, synovectomy or patellar fracture were main source of intraarticular or extraarticular soft tissue adhesion and contracture were resulted from distal femoral and proximal tibial fractures. The purpose of this study is to report the value of arthroscopic adhesiolysis of partial knee ankylosis and to evaluate the clinical results of its application in various conditions. From October 1982 to December 1992, 56 cases in 54 patients who had severe limitation of motion in the knee joint following open operative procedure or trauma about the knee were treated by fibroarthrolysis under the arthroscopic control. For release of thick fibrous tissue, we used our designed blunt metal bar. The following results were obtained. There were 30 males and 24 females and the age at the time of release ranged from 20 to 69 years old(average 38.7 years old). The interval between last open operative procedure or trauma and arthroscopic adhesiolysis ranged from 3 months to 6 years(average 16 months). The interval between arthroscopic adhesionlyssis and the last follow up evaluation ranged from 1 year to 9 years(average 49 months), The average preoperative range of knee motion was 42.2 and the postoperative range of motion under the anesthesia was 115.5 and the average final knee range of motion at follow up was 101.3. So the average loss of motion between postoperative and final motion was 14.2. Complications were one case of patellar and tibial condylar fracture respectively. In the author's experience, arthroscopic adhesiolysis seems to be applied to the various condition of the partial knee ankylosis and the results are better than the other surgical procedures when it was performed early enough16).
Anesthesia ; Ankylosis ; Contracture ; Female ; Follow-Up Studies ; Humans ; Knee Joint ; Knee ; Male ; Range of Motion, Articular ; Surgical Procedures, Operative ; Tibial Fractures ; Tissue Adhesions