In addition to all of the above, primidone can cause arthralgia.Granulocytopenia, agranulocytosis, and red-cell hypoplasia and aplasia, and megaloblastic anemia are rarely associated with the use of primidone. Megaloblastic anemia is actually a group of related disorders with different causes that share morphological characteristics—enlarged red blood cells with abnormally high nuclear-cytoplasmic ratios resulting from delayed maturation of nuclei combined with normal maturation of cytoplasm, into abnormal megakaryocytes and sometimes hypersegmented neutrophils; regardless of etiology, all of the megaloblastic anemias involve impaired DNA replication. The anticonvulsant users who get this also tend to eat monotonous diets devoid of fruits and vegetables.This antagonistic effect is not due to the inhibition of dihydrofolate reductase, the enzyme responsible for the reduction of dihydrofolic acid to tetrahydrofolic acid, but rather to defective folate metabolism.In addition to increasing the risk of megaloblastic anemia, primidone, like other older anticonvulsants also increases the risk of neural tube defects, and like other enzyme-inducing anticonvulsants, it increases the likelihood of cardiovascular defects, and cleft lip without cleft palate. Epileptic women are generally advised to take folic acid, but there is conflicting evidence regarding the effectiveness of vitamin supplementation in the prevention of such defects.Additionally, a coagulation defect resembling Vitamin K deficiency has been observed in newborns of mothers taking primidone.
A laryngocele is a congenital anomalous air sac communicating with the cavity of the larynx, which may bulge outward on the neck.It may also be acquired, as seen in glassblowers, due to continual forced expiration producing increased pressures in the larynx which leads to dilatation of the laryngeal ventricle (sinus of Morgagni). It is also seen in people with chronic obstructive airway disease. Additional images
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