1,527 articles
Microlissencephaly
Microlissencephaly (MLIS), increasingly called microcephaly with lissencephaly, is a rare, genetically heterogeneous disorder combining lissencephaly with severe congenital microcephaly, presenting in newborns with seizures, spasticity, and severe developmental delay.
Microphthalmia-retinitis pigmentosa-foveoschisis-optic disc drusen syndrome
Microphthalmia-retinitis pigmentosa-foveoschisis-optic disc drusen syndrome, also called nanophthalmos-RP-foveoschisis-optic disc drusen syndrome or MCOP5, is a rare autosomal recessive MFRP-related eye disorder with posterior microphthalmia, retinal dystrophy, foveal schisis, and optic disc drusen.
Microphthalmia, Lenz type
Microphthalmia, Lenz type (Lenz microphthalmia syndrome, OMIM 309800) is a rare X-linked recessive syndromic microphthalmia affecting males, with small or absent eyes, coloboma, ear, dental, skeletal, and urogenital anomalies, and intellectual disability, linked to BCOR and NAA10.
Microphthalmos
Microphthalmos (microphthalmia), abnormally small eye with axial length 2 SD below age mean, part of the MAC spectrum with anophthalmia and coloboma; about 1 in 7,000, often bilateral, SOX2-related, poor vision with corneal diameter under 6 mm.
Microsleep
Microsleep: brief involuntary sleep episode (a few seconds to about 30 s) during wakefulness, caused by sleep deprivation, undetectable to the sufferer, EEG-detectable, and a major factor in drowsy-driving crashes.
Middle cerebral artery occlusion model
The middle cerebral artery occlusion (MCAO) model is a rodent surgical stroke model in which a filament blocks the artery without craniectomy, producing focal cerebral ischemia.
Middle ear myoclonus
Middle ear myoclonus (MEM), also called tensor tympani syndrome, is a rare tinnitus from involuntary contraction of the stapedius or tensor tympani muscles, causing rhythmic clicking or buzzing, treated with medications, botulinum toxin, or tenotomy.
Migraine
Migraine: a primary headache disorder of recurrent one-sided throbbing attacks with nausea and light sensitivity, classified in ICHD-3; global prevalence about 14%, treated with triptans, gepants, and CGRP preventives.
Migraine with aura
Migraine with aura (classic migraine, ICHD-3 code 1.2): recurrent attacks of gradually spreading, fully reversible visual, sensory, or other neurological symptoms lasting 5-60 minutes, usually followed by headache; mechanism linked to cortical spreading depression; carries elevated stroke risk.
Migraine without aura
Migraine without aura (common migraine, ICHD-3 1.1, ICD-11 8A80.0) is the most common migraine form, about 70-75% of cases: recurrent 4-72 hour unilateral pulsating headache with nausea or photophobia/phonophobia, no aura.
Mild vision impairment
Mild vision impairment, mildest WHO/ICD-11 grade of distance vision impairment: presenting visual acuity worse than 6/12 to 6/18 (CDC: 20/32 to >20/80) in the better eye, mostly uncorrected refractive error.
Miller Fisher syndrome
Miller Fisher syndrome (MFS, Fisher syndrome) is a rare variant of Guillain-Barré syndrome defined by the triad of ophthalmoplegia, ataxia, and areflexia, linked to anti-GQ1b antibodies and usually self-limiting recovery.
Misshapen ear
Misshapen ear (ICD-11 LA21.3), abnormal shape or position of the outer ear; congenital or acquired. Treated by early infant ear molding (87-92% success) or otoplasty after age 5.
Mitchell Syndrome
Mitchell syndrome (MITCH, OMIM 618960), also called ACOX1 upregulation, an ultra-rare autosomal dominant peroxisomal neurodegenerative disorder from the de novo ACOX1 p.Asn237Ser gain-of-function variant, causing episodic demyelination, polyneuropathy, and hearing loss; distinct from Mitchell–Riley syndrome.
Mitochondrial membrane protein-associated neurodegeneration
MPAN (NBIA4) is an ultra-rare autosomal recessive neurodegenerative disorder caused by C19orf12 mutations, with brain iron accumulation, spasticity, dystonia, cognitive decline, and optic atrophy, onset usually in childhood.
Moderate vision impairment
Moderate vision impairment: ICD-11 distance vision category with presenting acuity worse than 6/18 (20/70) but 6/60 (20/200) or better; also called part of MSVI; mainly caused by uncorrected refractive error and cataract.
Moebius syndrome
Moebius syndrome (Möbius syndrome), a rare congenital cranial dysinnervation disorder with nonprogressive facial weakness and limited eye abduction, sporadic in most cases, no unifying genetic cause, managed supportively by multidisciplinary care.
Mohr-Tranebjaerg syndrome
Mohr-Tranebjaerg syndrome (DDON, deafness-dystonia-optic neuronopathy) is a rare X-linked recessive TIMM8A disorder: childhood deafness, adolescent dystonia or ataxia, adult visual loss, dementia; BTK deletions add XLA (XLA-MTS).
Monocular elevator palsy
Monocular elevator palsy, also called monocular elevation deficiency or double elevator palsy (ICD-11 9C83.02), is inability of one eye to elevate equally in adduction and abduction, caused by inferior rectus restriction, elevator weakness, or a supranuclear lesion, and treated surgically by inferior rectus recession or Knapp transposition.
Mononeuritis multiplex
Mononeuritis multiplex (mononeuropathy multiplex, multiple mononeuropathy) is a multifocal peripheral neuropathy damaging two or more separate nerve trunks, usually from vasculitis; other causes include diabetes, sarcoidosis, Lyme disease, HIV, and leprosy.
Mooren ulcer
Mooren ulcer (ulcere de Mooren), also called rodent ulcer, is a rare idiopathic autoimmune peripheral ulcerative keratitis of the cornea, diagnosed by exclusion, bilateral in about one third of cases, treated with a stepladder immunosuppressive approach.
Morvan syndrome
Morvan syndrome, or Morvan fibrillary chorea, is a rare life-threatening autoimmune VGKC-complex (CASPR2/LGI1) channelopathy with neuromyotonia, dysautonomia, severe insomnia, and often thymoma.
Mosaic neurofibromatosis type 1
Mosaic neurofibromatosis type 1 (MNF1, mosaic NF1, formerly segmental NF1) is a postzygotic NF1 gene variant form of NF1 with segmental or generalized, usually milder features; confirmed by VAF under 50% in blood or identical variants in two lesions, with under 50% transmission risk.
Mosaic NF2-related schwannomatosis
Mosaic NF2-related schwannomatosis (mosaic NF2, ORPHA:634475) is a postzygotic NF2 variant form of NF2-related schwannomatosis causing multiple schwannomas, often asymmetric or segmental, milder than germline disease, with VAF under 50% in blood.
MRCS syndrome
MRCS syndrome, short for microcornea-rod-cone dystrophy-cataract-posterior staphyloma syndrome, is a rare inherited retinal dystrophy inherited dominantly, causing night blindness in childhood and progressive vision loss.
Mucosal cyst of postmastoidectomy cavity
Mucosal cyst of postmastoidectomy cavity (ICD-11 AB91, ICD-10 H95.13, formerly ICD-9 383.31): a mucosa-lined cyst forming in the mastoid after mastoidectomy, presenting with discharge and hearing loss, treated by complete cyst wall removal.
Multifocal cerebral infarctions
Multifocal cerebral infarctions (ICD-11 8E64, postprocedural) are multiple ischemic brain infarcts in several arterial territories; 13% of strokes, usually cardioembolic, common after cardiac surgery, with vasculitis a key differential.
Multifocal motor neuropathy
Multifocal motor neuropathy (MMN), also called MMNCB, is a rare immune-mediated purely motor neuropathy with asymmetric distal upper-limb weakness, motor conduction block, anti-GM1 IgM antibodies in 40-50%, and IVIg as first-line therapy.
Multiple mitochondrial dysfunctions syndrome type 3
Multiple mitochondrial dysfunctions syndrome type 3 (MMDS3, IBA57 deficiency, OMIM 615330) is a rare autosomal recessive mitochondrial leukoencephalopathy from biallelic IBA57 variants, causing infantile developmental regression, hypotonia, hyperglycinemia, lactic acidosis, and cavitating leukoencephalopathy.
Multiple mitochondrial dysfunctions syndrome type 4
Multiple mitochondrial dysfunctions syndrome type 4 (MMDS4, ISCA2-related mitochondrial disorder) is a rare autosomal recessive infantile leukodystrophy causing neuroregression, nystagmus, optic atrophy, and defective mitochondrial [4Fe-4S] cluster assembly.