Phenotypes associated with the disease Chiari malformation type II (OMIM:207950):
- Opisthotonus (HP:0002179): Opisthotonus is defined as a dramatic abnormal posture due to spastic contraction of the extensor muscles of the neck, trunk, and lower extremities that produces a severe backward arching from neck to heel. In most cases, the trunk is elevated off the ground by a few inches. It is usually sudden in onset and can be sustained or repetitive. It can be considered a variant of decerebrate posturing involving a hyperextension of the neck, back, and limbs. Evidence: IEA. (OMIM:207950)
- Inspiratory stridor (HP:0005348): Inspiratory stridor is a high pitched sound upon inspiration that is generally related to laryngeal abnormalities. Evidence: IEA. (OMIM:207950)
- Dysphagia (HP:0002015): Difficulty in swallowing. Evidence: IEA. (OMIM:207950)
- Myelomeningocele (HP:0002475): Protrusion of the meninges and portions of the spinal cord through a defect of the vertebral column. Evidence: IEA. (OMIM:207950)
- Bulbar signs (HP:0002483). Evidence: IEA. (OMIM:207950)
- Feeding difficulties (HP:0011968): Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it. Evidence: TAS. (OMIM:207950)
- Syringomyelia (HP:0003396): Dilated, glial-lined cavity in spinal cord. This cavity does not communicate with the central canal, and usually is between the dorsal columns unilaterally or bilaterally along the side of the cord. Evidence: IEA. (OMIM:207950)
- Hypotonia (HP:0001252): Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist. Evidence: IEA. (OMIM:207950)
- Agenesis of corpus callosum (HP:0001274): Absence of the corpus callosum as a result of the failure of the corpus callosum to develop, which can be the result of a failure in any one of the multiple steps of callosal development including cellular proliferation and migration, axonal growth or glial patterning at the midline. Evidence: IEA. Frequency: Frequent (HP:0040282). (OMIM:207950)
- Ataxia (HP:0001251): Ataxia refers to impaired coordination of voluntary muscle movement. Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly). Evidence: IEA. (OMIM:207950)
- Generalized hypotonia (HP:0001290): Generalized muscular hypotonia (abnormally low muscle tone). Evidence: TAS. (OMIM:207950)
- Gray matter heterotopia (HP:0002282): Heterotopia or neuronal heterotopia are macroscopic clusters of misplaced neurons (gray matter), most often situated along the ventricular walls or within the subcortical white matter. Evidence: IEA. (OMIM:207950)
- Limb muscle weakness (HP:0003690): Reduced strength and weakness of the muscles of the arms and legs. Evidence: IEA. (OMIM:207950)
- Occipital neuralgia (HP:0012318): A distinct type of headache characterized by piercing, throbbing, or electric-shock-like chronic pain in the upper neck, back of the head, and behind the ears, usually on one side. Evidence: TAS. (OMIM:207950)
- Nystagmus (HP:0000639): Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms. Evidence: IEA. (OMIM:207950)
- Chiari malformation (HP:0002308): Chiari malformation consists of a downward displacement of the cerebellar tonsils and the medulla through the foramen magnum, sometimes causing hydrocephalus as a result of obstruction of CSF outflow. Evidence: TAS. (OMIM:207950)
- Hydrocephalus (HP:0000238): Hydrocephalus is an active distension of the ventricular system of the brain resulting from inadequate passage of CSF from its point of production within the cerebral ventricles to its point of absorption into the systemic circulation. Evidence: IEA. (OMIM:207950)
- Non-Mendelian inheritance (HP:0001426): A mode of inheritance that depends on genetic determinants in more than one gene. Evidence: IEA. (OMIM:207950)
- Cervical myelopathy (HP:0002318): A collection of pathologic conditions that result from progressive spinal cord dysfunction secondary to cord compression in the cervical spine. Evidence: IEA. (OMIM:207950)
- Cyanosis (HP:0000961): Bluish discoloration of the skin and mucosa due to poor circulation or inadequate oxygenation of arterial or capillary blood. Evidence: IEA. (OMIM:207950)
- Spina bifida (HP:0002414): Incomplete closure of the embryonic neural tube, whereby some vertebral arches remain unfused and open. The mildest form is spina bifida occulta, followed by meningocele and meningomyelocele. Evidence: IEA. (OMIM:207950)