Among them, mitochondrial encephalomyopathy includes: MELAS syndrome; MERRF syndrome; KSS syndrome; Pearson syndrome; Albers disease; Lee syndrome; Menke's disease; LHON； NARP； Volfram's syndrome. The clinical features of major syndromes are summarized as follows:
1. meras syndrome
That is, a group of clinical symptoms such as mitochondrial encephalomyopathy with lactic acidemia and stroke-like attack are mostly maternal inheritance. 10 years old develops normally. 10 ~ 40 years old, the first symptom is exercise intolerance, stroke-like attack, hemiplegia, aphasia, cortical blindness or deafness. There are limb weakness, convulsion or paroxysmal headache, mental retardation, dementia and lactic acidemia. Muscle biopsy showed RRF, abnormal mitochondria and lattice-like inclusions. CT showed 30% ~ 70% globus pallidus calcification, and MRI cortex showed layered abnormal signal. Gene detection showed 3243 or 327 1 nucleotide point mutation. In the acute phase of stroke-like attack in MELAS patients, the temporal parietal lobe or temporal occipital lobe is mainly involved, and the lesions may involve cortex and deep white matter. Different from ischemic cerebral infarction, the distribution of MELAS infarction focus is different from that of cerebral artery perfusion blood supply area, mainly concentrated in the microvascular area with strong metabolism, and the surrounding edema is not obvious, accompanied by astrocyte proliferation. Other common symptoms of MELAS patients involving nervous system include nervous deafness, migraine, cognitive impairment, peripheral neuropathy, depression and some mental symptoms. The latent attack of nervous deafness is often the early manifestation of MELAS, which is often inherited in the family and can also occur in the relatives of patients who are not ill. Follow-up study found that more than half of MELAS patients had hearing loss and maternal diabetes and/or deafness (MIDD). Secondly, irregular migraine before onset is also a common symptom of early MELAS patients. Headaches often occur in the intermission of diseases, which may be due to the impairment of mitochondrial energy metabolism, which on the one hand increases the excitability of neurons, on the other hand reduces the threshold for inducing headaches. Thirdly, patients with MELAS may have different degrees of cognitive impairment, including language, memory, orientation and so on. The most common is the damage of frontal lobe executive function, which is characterized by ischemic changes in the back of brain stem and cingulate gyrus on MRI, which may be related to the degeneration of cortical neurons. In addition, a small number of patients may have peripheral neuropathy, manifested as mild sensory abnormalities and sock numbness. The onset is insidious and progressive, often involving distal limbs.
2. Melf syndrome
That is, myoclonic epilepsy, cerebellar ataxia, lactic acidemia and RRF, a small number of mental retardation and dementia, as well as neurological deafness, short stature, arch of foot and other deformities. Electroencephalogram showed the synthesis of spinous slow waves, and muscle biopsy showed RRF, abnormal mitochondria and inclusion bodies. CT and MRI showed cerebellar atrophy and white matter lesions. Gene detection showed 8344 or 8356 nucleotide point mutations.
3.KSS syndrome
Retinitis pigmentosa, heart block and extraocular muscle paralysis. Most of them started before the age of 20. Other symptoms may include headache, limb weakness, short stature and mental retardation. A few of them have endocrine dysfunction, hypoparathyroidism, globus pallidus calcification, abnormal signals in cortex and white matter on MRI. A few muscle biopsies showed RRF and abnormal mitochondria, and some CT and MRI showed calcification and white matter lesions in basal ganglia. Gene detection is characterized by mtDNA deletion or massive rearrangement.
4.CPEO syndrome
It can occur at all ages, especially in children or early adulthood. In addition to the gradual aggravation of extraocular muscle paralysis, a few may be accompanied by limb weakness, emaciation or atrophy. Muscle biopsy of RRF, abnormal mitochondria and inclusion bodies. The variation of gene detection is great, and mtDNA deletion or a large number of rearrangements can be seen.
5. Leishmaniasis
That is to say, subacute necrotizing encephalomyelitis is mainly caused by the deficiency of cytochrome oxidase in complex ⅳ, most of which have maternal genetic history and onset at the age of 2 months to 3 years, and a few also have juvenile onset. The common clinical manifestations are eating difficulty, ataxia, hypotonia and pyramidal tract sign. If the brain stem is involved, it will cause ophthalmoplegia and decrease vision and hearing. A few people may have psychomotor seizures, and pathology shows bilateral symmetrical basal ganglia and brain stem gray matter nuclei damage. Magnetic resonance imaging has characteristic findings. Muscle biopsy RRF and mitochondrial inclusion bodies are rare. Visible cytochrome c oxidase deficiency.
6. Alpers's disease
Familial primary progressive gray matter atrophy. Most of them get sick a few months after birth, a few get sick after 8 years old, and most of them have family history. The first symptoms are seizures, decreased vision and hearing, cortical blindness and cortical deafness, and mild hemiplegia, aphasia and mental retardation-dementia can be seen. Pathological features: degeneration and loss of neurons in gray matter of cerebral cortex, proliferation and stratification of small vessels and astrocytes, and characteristic abnormal signals of stratification can be seen on MRI. Some muscle biopsies showed RRF and abnormal mitochondria.
7. Mencke's disease
Most of them began to get sick a few months after birth and died at the age of 3. There are also reports that children are late. The clinical manifestations are curly hair, seizures, ataxia, extrapyramidal system or pyramidal tract sign, mental retardation and developmental retardation. Pathological features: brain atrophy with nerve cell loss and white matter lesions, the characteristic change of Purkinje cells in cerebellum is large and long branched dendrites. The copper content in blood decreased and the copper content in intestinal mucosa increased. Muscle biopsy occasionally showed RRF and abnormal mitochondria.
8. Leber's hereditary optic neuropathy (LHON)
Sudden bilateral vision loss and loss. The peak age of onset is 20 ~ 24 years old, and the youngest is 5 years old. Most of them are bilateral vision loss. A few people get sick at first sight, and the other eye gets sick weeks or months later. Most of them are blindness, macular edema and retinopathy caused by retrobulbar optic nerve injury. Men are more common, and at least 85% of them are young men with X-linked genetic characteristics. Optic nerve injury is the main cause of this disease. There are few other symptoms and signs of nervous system, and only a few reports are accompanied by ataxia, tendon hyperreflexia, pathological symptoms and hereditary peripheral neuropathy (CMT). CT, MRI and muscle biopsy have no characteristic manifestations.
9. Retinitis pigmentosa ataxia peripheral neuropathy (NARP)
Holt reported three generations and four family cases in 1990. Its clinical features are retinitis pigmentosa, ataxia, developmental delay dementia, convulsion, proximal limb weakness with sensory peripheral neuropathy and other different symptoms. Most of them are about 3 years old, and there are reports of maternal inheritance and Leigh's disease. CT and MRI have characteristic changes. Muscle biopsy did not confirm RRF.
10. Others
(1)Wolfram syndrome is diabetes with neurological deafness. Like MELAS, the point mutation of mtDNA is nt3243.
(2) Detection of mtDNA deletion in the gene of peripheral mitochondrial neuropathy complicated with gastrointestinal encephalopathy (MNGIE). The clinical features are gastrointestinal symptoms of childhood onset, extraocular muscle paralysis, sensorimotor neuropathy and pseudointestinal obstruction.