Arnold–Chiari malformation (or sometimes also known asChiari malformations or CM) is a structural malformation in the part of the brainthat controls balance, called cerebellum.
In this illness, there is a displacement of cerebellartonsils and both cerebellum and the brainstem are pushed downward. There isalso a potential danger of hydrocephalus, accumulation of the cerebrospinalfluid in the brain that might cause many symptoms and even be life threateningcondition.
There are four different types of Chiari malformations,rated from I to IV, and the type IV is the most serious form. One of every 1.000to 5.000 people is suffering from Chiari malformation type 1, which is the mostcommon of these malformations.
Type I is a congenital malformation, which usually doesn’t showany symptoms during the childhood. In some cases, patients experiencecerebellar symptoms and headaches. There is also the acquired type I Chiarimalformation, associated with Marfan and Ehlers-Danlos syndromes (hereditaryproblems of connective tissue). The acquired type I malformation is hard todiagnose and treat.
Type II might cause partial or total paralysis, below thedefect of the spine. Sometimes, it can be difficult to differentiate Chiarimalformation type II from Dandly Walker syndrome.
Types II and IV are severe Chiari malformations. Patients sufferingfrom type III experience serious neurological problems, and in type IV there is a lack of cerebellar development.
The diagnosis is established after the neurologicalexamination, MRI (magnetic resonance imaging), 3D CT (computer tomography) imaging or cine imaging ofthe brain. To confirm the diagnosis for Arnold-Chiari malformation, doctorsmight use invasive cranial traction. Prenatal diagnosis can be established throughthe ultrasound.
Many symptoms might indicate AC malformation of the brain. Patientsexperience headaches, which get worse with sneezing, crying, laughing or evenyawning. There are also ringing in the ears, irregular eye movements, problemswith the gag reflex, swallowing difficulties, dizziness, nausea and facialpain. Many patients have problems with muscle weakness and sleep apnea, orsuffer from restless leg syndrome, coordination difficulties and chronictiredness, extreme thirst, fainting or tachycardia.
Other potential symptoms include: syrinx, syringomyelia, weaknessof the hands, sensory loss or even paralysis.
Treatment and Prognosis
The most common treatment is the decompression surgery,after which patients might have also installed the shunt. Some surgeons suggestan alternative procedure, which includes the dethering of the spinal cord, andthe newest approach is minimally invasive trans-nasal surgery.
The prognosis mainly depends on the type of the disease. Patientssuffering from Arnold-Chiari malformation type 1 are usually adults. Their conditioncan’t be cured, but it’s not a life threat and can be treated.
Type II is more common in babies, and can be diagnosedeither before the birth (prenatally) or at birth. Some 15% of these patients diebefore the second birthday. The mortality in general is about 33% in, with the respiratoryfailure as the most common cause of death.
Patients suffering from types III and IV of Arnold-Chiarimalformation (extremely rare conditions) usually do not survive more than 3years.