Arnold Chiari Anomaly
Arnold Chiari anomaly - a congenital defect in the development of hindbrain. Manifest this anomaly size mismatch posterior cranial region and cerebral components located therein. This eventually leads to the fact that part of the tonsils and cerebellum of the brain is lowered into the foramen magnum where they are restrained.
The causes of the anomalies Arnold Chiari
According to statistics, the pathology seen in 3-8 out of every 100 thousand.
To date, the exact cause of Chiari abnormalities were found. Most likely, the manifestation of the disease is accompanied by the following three factors:
- traumatic wedge-occipital and sphenoid-ethmoid part of the slope as a result of birth trauma;
- congenital osteonevropatii with hereditary factor;
- hydrodynamic shock of cerebrospinal fluid in the wall of the central canal of the spinal cord.
What anatomical changes occur in the Arnold Chiari anomaly?
If this disease is the cerebellum in the posterior fossa.
Normally, the lower part of the cerebellum (the tonsils) must be located above the foramen magnum. When anomalies Arnold Chiari tonsils are located in the spinal canal, that is under the foramen magnum.
Foramen magnum is a kind of boundary between the spine and skull, as well as between the spinal cord and brain. Over this hole is the posterior cranial fossa, and under it - the spinal canal.
Lower Division of the brain stem (medulla oblongata) goes into the spinal cord at the level of the foramen magnum. Normally, CSF (cerebrospinal fluid) must circulate freely in the subarachnoid space of the spinal cord and brain. These subarachnoid spaces are interconnected at the level of the foramen magnum, which ensures free outflow of cerebrospinal fluid from the brain.
When anomalies Arnold Chiari tonsils are located at the foramen magnum, which hinders the free flow of cerebrospinal fluid between the brain and spinal cord. Cerebellar tonsils block the foramen magnum like a cork, which significantly violates the outflow of cerebrospinal fluid and leads to the development of hydrocephalus.
The types of anomalies Arnold Chiari
In 1891 Chiari identified four main types of pathology and a detailed description of each. Doctors use this classification to the present day.
- 1 type. It is characterized by the omission of the posterior fossa structures below the plane of the foramen magnum.
- Type 2, which is characterized by caudal dislocation of the lower divisions of the skull, the 4th ventricle and the medulla oblongata. This is often accompanied by hydrocephalus.
- 3 type. This type of disease is quite rare and it is characterized by gross caudal displacement of all the structures of the posterior fossa.
- 4 type, when hypoplasia of the cerebellum occurs without bias down.
The third and fourth types of anomalies Arnold Chiari not be disinfected, and usually leads to death.
In the large majority of patients (80%), Arnold Chiari malformation with syringomyelia combined - pathology of the spinal cord, which is characterized by the formation of cysts in it, contributing to the development of progressive myelopathy. These cysts are formed in the deletion of the posterior fossa structures and as a result of compression of the cervical spinal cord.
Symptoms anomalies Arnold Chiari
For this disease characterized by the following clinical signs:
- loss of thermal and pain sensitivity of the upper extremities;
- pain in the neck and occipital region, worse when you sneeze and cough;
- loss of visual acuity;
- loss of muscle strength of the upper extremities;
- frequent dizziness, fainting;
- spasticity of the lower and upper extremities.
In more advanced stages of the disease the symptoms of Arnold Chiari anomaly join weakening the pharyngeal reflex, episodes of apnea (temporary cessation of breathing) and involuntary rapid eye movement.
The disease is fraught with the development of the following complications:
- Cranial nerve palsy, impairment of the cervical spinal cord, cerebellar dysfunction, occurring against a background of progressive signs of intracranial hypertension.
- It happens that this pathology is connected with the defects of the skeleton: oktsipitalizatsiey atlas or basilar Impress (funnel-shaped impression craniospinal junction and the ramp).
- Foot deformities, abnormalities of the spine.
Sometimes Arnold Chiari malformation are asymptomatic and detected only during a general study of the patient.
Diagnosis of anomalies Arnold Chiari
The main method of diagnosis of this disease is by far the MRI breast and cervical spinal cord and brain MRI. MRI of the spinal cord do mainly with a view to identifying syringomyelia.
Treatment of anomalies Arnold Chiari
If the disease has only one symptom - pain in the neck, the treatment of anomalies Arnold Chiari mostly conservative. Therapy includes various circuits using relaxants and nonsteroidal antiinflammatory drugs.
If the effect of conservative treatment is insufficient or non-existent during the 2-3 months of treatment, and if the patient has symptoms of neurological impairment (weakness and numbness in the extremities, etc..), The doctor usually provides the operation with the anomalies Arnold Chiari .
The main objective of the operation at the Arnold Chiari anomaly is to minimize the infringement of the nerve endings and tissues, and the normalization of the outflow of cerebrospinal fluid, for which the size of the posterior fossa little increase in volume. As a result of the operation when Arnold Chiari anomaly disappears completely or decreases headache, partially restored motor function and sensitivity of the limbs.