In the acute stage, lasting a few weeks, the affected eye demonstrates an oedematous appearance of the nerve fiber layer, especially in the arcuate bundles and enlarged or telangiectatic and tortuous peripapillary vessels (microangiopathy). The main features are seen on fundus examination, just before or after the onset of visual loss. A pupillary defect may be visible in the acute stage as well. Examination reveals decreased visual acuity, loss of color vision and a cecocentral scotoma on visual field examination. LHON with demyelinating lesions or LHON Plus
LHON Plus is a rare variant of the disorder with eye disease together with other conditions. Its symptoms include loss of the brains ability to control the movement of muscles, tremors, and cardiac arrhythmia. Many cases of LHON plus have been compared to multiple sclerosis because of the lack of muscular control and the presence of demyelinating lesions in the CNS. It is therefore a subtype of MS, according to McDonalds definition. Genetics
Leber hereditary optic neuropathy is a condition related to changes in mitochondrial DNA. Although most DNA is packaged in chromosomes within the nucleus, mitochondria have a distinct mitochondrial genome composed of mtDNA.Mutations in the MT-ND1, MT-ND4, MT-ND4L, and MT-ND6 genes cause Leber hereditary optic neuropathy. These genes code for the NADH dehydrogenase protein involved in the normal mitochondrial function of oxidative phosphorylation. Oxidative phosphorylation uses a series of four large multienzyme complexes, all embedded in the inner mitochondrial membrane, to convert oxygen and simple sugars to energy.
The alveoli still appear consolidated, but grossly the color is paler and the cut surface is drier. This is when death typically occurs in severe cases. Resolution (complete recovery): The exudate is digested by enzymatic activity, and cleared by macrophages or by cough mechanism. Enzymes produced by neutrophils will liquify exudates, and this will either be coughed up in sputum or be drained via lymph. In children
The openings between the alveoli known as the pores of Kohn, and the collateral airways of the canals of Lambert, are undeveloped in children. Spread of infection that would otherwise occur is prevented and can result in round pneumonia, most commonly caused by S. pneumoniae. This clinically presents with an initial mild respiratory infection, followed by fever. On imaging it presents an opaque pulmonary consolidation which is unusually round, and can resemble a lung mass. However it quickly resolves with antibiotics. Diagnosis
The most common organisms which cause lobar pneumonia are Streptococcus pneumoniae, also called pneumococcus, Haemophilus influenzae and Moraxella catarrhalis. Mycobacterium tuberculosis, the tubercle bacillus, may also cause lobar pneumonia if pulmonary tuberculosis is not treated promptly. Other organisms that cause lobar pneumonia are Legionella pneumophila and Klebsiella pneumoniae.Like other types of pneumonia, lobar pneumonia can present as community acquired, in immune suppressed patients or as nosocomial infection. However, most causative organisms are of the community acquired type.