Arnold-Chiari malformation is a malformation of the brain. It is also known as Chiari malformation. It is a downward displacement of the cerebellar tonsils through the foramen magnum (the opening at the base of the skull). This may cause obstruction of cerebrospinal fluid and hydrocephalus.
Types
I
This is most common form. A congenital malformation which is asymptomatic during childhood, but often manifests with headaches and cerebellar symptoms. Herniation of cerebellar tonsils occurs.
Syndrome of occipitoatlantoaxial hypermobility is an acquired Chiari I Malformation in patients with hereditary disorders of connective tissue.
II
It is usually accompanied by a myelomeningocele leads paralysis below the spinal defect. Abnormal development of the cerebellar vermis and medulla oblongata occur, and they both descend into the foramen magnum. Hydrocephalus is frequently present.
III
It is associated with encephalocele and causes severe neurological defects.
IV
It is characterized by a lack of cerebellar development.
Other conditions sometimes associated with Chiari Malformation include hydrocephalus, syringomyelia, spinal curvature, tethered spinal cord syndrome, and connective tissue disorderssuch as Ehlers-Danlos syndrome and Marfan Syndrome.
Presentation
* Headaches which are aggravated by Valsalva maneuvers, such as yawning, laughing, crying, coughing, sneezing or straining.
* Tinnitus (ringing in the ears)
* Dizziness and vertigo
* Nausea
* Nystagmus (irregular eye movements)
* Facial pain
* Muscle weakness
* Impaired gag reflex
* Sleep Apnea
* Dysphagia (difficulty swallowing)[18]
* Impaired coordination
* Dysautonomia: tachycardia (rapid heart), syncope (fainting), polydipsia (extreme thirst), chronic fatigue [19]
The blockage of Cerebro-Spinal Fluid flow may also cause a syrinx to form, eventually leading to syringomyelia [Dilatation of spinal canal]. Central cord symptoms such as hand weakness, dissociated sensory loss, and, in severe cases, paralysis may occur.[20]
Diagnosis
Diagnosis is based on patient history, neurological examination, and Magnetic Resonance Imaging (MRI).
Treatment
Decompression surgery is the desired treatment in which the lamina of the first, second or even third cervical vertebrae and part of the occipital bone of the skull is removed to relieve pressure.
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