Kính hiển vi điện tử thường cho thấy một sự gia tăng đáng kể về số lượng của ty thể trong các perikaryon tế bào Purkinje, và đến một mức độ ít hơn trong các tế bào thần kinh của vỏ não và hạch đáy | 768 773 . Electron microscopy often shows a marked increase in the number of mitochondria in the perikaryon of Purkinje cells and to a lesser degree in the neurons of cerebral cortex and the basal ganglia 774 . Mitochondria are enlarged and intramitochondrial electron-dense bodies are present. The pathogenesis of these changes is a matter of controversy but they are believed to result from a reduction in the activity of the mitochondrial copper-containing enzymes. Clinical Manifestations KHD is not a rare disorder its frequency has been estimated at 1 in 114 000 to 1 in 250 000 live births 774 . Baerlocher and Nadal have provided a comprehensive review of the clinical features 775 . Symptoms appear during the neonatal period. Most commonly hypothermia poor feeding and impaired weight gain are observed. Seizures soon become apparent. Marked hypotonia poor head control and progressive deterioration of all neurologic function are seen. The facies has a cherubic appearance with a depressed nasal bridge and reduced movements 776 . The optic discs are pale and microcysts of the pigment epithelium are seen 777 . The most striking finding is the appearance of the scalp hair it is colorless and friable. Examination under the microscope reveals a variety of abnormalities most often pili torti twisted hair and trichorrhexis nodosa fractures of the hair shaft at regular intervals 768 . Radiography of long bones reveals metaphyseal spurring and a diaphyseal periosteal reaction reminiscent of scurvy 778 . On MR arteriography the cerebral vessels are markedly elongated and tortuous. Similar changes are seen in the systemic vasculature 779 . The urinary tract is not spared. Hydronephrosis hydroureter and bladder diverticula are common 780 . Neuroimaging discloses cerebral atrophy and cortical areas of encephalomalacia. A progressive tortuosity and enlargement of intracranial vessels also can be shown by MRI 781 . Asymptomatic subdural hematomas are almost invariable. EEGs show .
