Arnold-Chiari malformation is a developmental disorder that displaces parts of the cerebellum from the brain space. Patients often do not experience initial symptoms until their teenage years, which usually correspond to nonspecific complaints such as dizziness. Therapy is intended to prevent progressive damage to the central nervous system.
What is an Arnold-Chiari malformation?
Malformations are deformities that are usually congenital. Accordingly, the group of Chiari malformations is also called the Chiari malformation group and involves the rhombencephalon. This is the unit of myelencephalon and metencephalon affected by cogenital displacements in the malformations. The group of Chiari malformations is, in the broadest sense, a group consisting of [developmental disorders in children|developmental disorders]] that displace cerebellar parts into the spinal canal and are simultaneously associated with a reduced occipital fossa. Modern medicine distinguishes four different types of malformation, known as type I through type IV. The effects and manifestations of the malformation differ depending on the type. The malformation group is named after the pathologist von Chiari, who first described malformations in the 19th century. Later, the students of the German pathologist Arnold propagated the malformations, most notably Chiari malformation type II, which has since been known as Arnold-Chiari malformation.
Causes
Depending on the expression and localization, medicine distinguishes four types of Chiari malformation, which have different causes. In type II, and thus Arnold-Chiari malformation, there is caudal displacement of the medulla oblongata. In addition, the inferior portions of the vermis cerebelli and the fourth cerebral ventricle are displaced caudally. The cause of the malformation is a malformation of the brain stem. Primarily, this malformation is triggered by an embryonic developmental disorder that affects approximately the period between the sixth and tenth weeks of gestation. The skull rim undergoes bony malformations. The same applies to the first cervical vertebrae. The posterior parts of the brain, such as the cerebellum or the cerebellar tonsils, do not find sufficient space under the skullcap and shift to the transition between the skull and the spinal column due to lack of space. For this reason, the brain parts protrude from the occipital hole into the spinal canal after displacement. Exactly what circumstances cause the developmental disorder during pregnancy has not yet been conclusively determined. Exposure to toxic substances is considered as well as possible shortages of nutrients in the maternal nutrition, trauma or infections. Familial clusters have been observed, so genetic factors are also considered causative.
Symptoms, complaints, and signs
Patients with Arnold-Chiari syndrome, or Chiari malformation type II, suffer from mild to severe displacements of the cerebellum that occur in combination with a malformation of the brainstem. The cerebellar tonsils, the cerebellar vermis or even the brain stem of the patients deviate into the spinal canal due to lack of space. The occipital orifice of affected individuals is usually greatly dilated. Cell death of neurons occurs in the displaced nervous tissue. In this way, the patients lose portions of their functioning brain mass. In many patients, the ventricles of the brain are also affected by changes, in which the so-called cerebrospinal fluid (CSF) is formed as cerebral and neural fluid. These pathological changes in the ventricles often cause a CSF congestion. In this way, hydrocephalus can be favored. The skull thus grows in volume. Not all affected individuals suffer from hydrocephalus. Sometimes there are no symptoms until adulthood. Conceivable symptoms are non-specific complaints such as neck pain, disturbances of balance, muscle weakness. Also sensory disturbances, visual disturbances or difficulty swallowing. Ringing in the ears to hearing loss, nausea with vomiting, insomnia or depression and pain can also be associated with Chiari malformation.
Diagnosis and course
The diagnosis of an Arnold-Chiari malformation is usually made by chance. Radiologic studies, computed tomography, or magnetic resonance imaging are the common imaging modalities that prove an Arnold-Chiari malformation.In most cases, imaging is not ordered because there is already a suspected diagnosis of the malformation. However, especially from MRI, the displacements of the brain substance can undoubtedly be detected and the basis for a diagnosis is given. In most cases, a favorable prognosis applies to patients of the malformation. This is especially true for people who have remained nearly or completely asymptomatic until diagnosis. Symptomlessness may persist throughout life in some circumstances.
Complications
Different complications and symptoms occur with Arnold-Chiari malformation, depending on the type of disease. In type 1, there is usually only headache or pain in the neck. If parts of the brain are affected, there is often unsteadiness of gait or other balance problems. In type 2 Arnold-Chiari malformation, malformations may occur in the brain. These often lead to speech disorders, impaired thinking and other defects. In type 3 and type 4, disability occurs due to underdevelopment of the brain. However, the type of disability cannot be universally predicted. Due to Arnold-Chiari malformation, the patient’s life becomes relatively limited. In many cases, it is no longer possible for the patient to cope with everyday life on his own, so that he is dependent on the help of family and caregivers. Treatment itself can only be given if the Arnold-Chiari malformation is not congenital. In most cases, however, the brain cannot recover to its usual state, so disabilities can still be expected. However, the severity of these disabilities varies among people.
When should you see a doctor?
Arnold-Chiari malformation is most often detected during a routine physical examination. A specific medical evaluation is useful if there are external symptoms such as muscle twitching or hydrocephalus. In the case of severe external changes, the examination and diagnosis usually take place immediately after birth. In its weak manifestation, an Arnold-Chiari malformation can run relatively symptom-free until adolescence and remain unnoticed. In later life, however, the disease manifests itself in the form of increasing swallowing difficulties, visual disturbances, sensory disturbances, hearing loss and depression. Affected individuals who suddenly experience one or more of these symptoms should speak with their primary care physician or a developmental disabilities specialist. Although Arnold-Chiari malformations are rare, the symptoms mentioned above are at least based on another condition that needs to be clarified. If an Arnold-Chiari malformation is present, medical treatment should not be delayed any longer. Especially symptoms such as nausea, insomnia and increasing intracranial pressure require immediate treatment, otherwise severe physical and psychological complications may occur. Usually, lengthy follow-up and therapeutic measures are required following treatment.
Treatment and therapy
Causal therapy does not exist for patients with Arnold-Chiari malformation. Symptomatic treatment can be given and is indicated, especially if intracranial pressure increases. For example, after hydrocephalic congestion due to herniated cerebellar tonsils, decompression must be performed using a suboccipital approach. If pain persists or symptoms such as nausea, insomnia, and depression occur, symptomatic treatment usually consists of drug therapy. Functional disturbances caused by the malformation can only be corrected surgically. Such corrections are indicated, for example, when damage to the central nervous system threatens to progress. The surgical intervention can take place, for example, at the posterior fossa. By this measure, the surgeon creates more space for the cerebellum and at the same time reduces the pressure on the spinal cord. In some cases, small portions of the skull base are also removed for this purpose. All abnormal bone structures can be surgically corrected. Removal of the back at the first cervical vertebra is also an option. This procedure enlarges the spinal canal and protects the nerve tissue that has passed through from pressure damage. The most common treatment procedure for hydrocephalus is detour to another body cavity, such as the abdominal cavity. For this purpose, a subcutaneous tube is placed between the brain and the abdomen.The most important goal of all treatment steps is to relieve pressure on the nerve tissue. Compression of the neurons can, in the worst case, cause the nerves to die. This phenomenon should be prevented as far as possible by the therapeutic steps in order to reduce secondary damage caused by the malformation.
Outlook and prognosis
The prospects for cure of Arnold-Chiari malformation are unfavorable. The condition cannot be cured with existing medical options and therapeutic approaches. The patient’s treatment is aimed at reducing the accompanying symptoms. In addition, a deterioration of the general state of health should be prevented. Without treatment, developmentally disabling consequences may occur. Complications arise within the normal growth process that can cause dysfunction or system failure. If sudden hemorrhages begin to occur in cortical regions due to the lack of space in the tissue below the skull, a stroke is imminent. This is associated with lifelong consequences and can lead to the premature death of the patient. With treatment, surgical interventions can create the conditions so that the growth process does not lead to any threatening disturbances. The treatment aims to create as much space as possible for organs and vital tissue. Vascular detour are created and pressure damage to muscles as well as nerve fibers is to be avoided. In addition, various therapeutic approaches are used to treat the individual sequelae. Corrective surgery may be performed on the spine, or psychological impairments may be treated. The disease has a progressive course until the end of the physical growth process. Therefore, this is usually stopped at an early stage by hormonal treatment. Subsequently, there is no further increase in the malformations of the body.
Prevention
To date, little is known about the factors that cause Arnold-Chiari malformation. For this reason, there are no preventive measures for the malformation to date.
Follow-up
First and foremost, Arnold-Chiari malformation must be examined and treated by a physician. The options for follow-up care are very limited in this regard, so affected individuals are primarily dependent on medical treatment. Self-healing cannot occur with the Arnold-Chiari malformation, and the possibilities for self-help are also severely limited. In most cases, the increasing pressure in the brain is treated by surgery. Affected persons should rest after such an operation. Physical exertion and sports activities should be avoided in order to accelerate the healing process. Stress should also be avoided in Arnold-Chiari malformation. In general, a healthy diet with a balanced lifestyle also has a very positive effect on the course of the disease. The earlier the disease is detected, the higher the chance of a complete cure of Arnold-Chiari malformation. In some cases, the disease can also reduce or limit the life expectancy of the affected person. Contact with other Arnold-Chiari malformation sufferers can also have a positive effect on the course of the disease, as information can be exchanged.
What you can do yourself
Patients with Arnold-Chiari malformation suffer from increasing symptoms, especially from puberty onwards, which often delay diagnosis due to their diffuse character. Symptoms such as dizziness, weak muscles, or disturbances of the sense of balance impair the patients’ quality of life and everyday life. In addition, there are often complaints of visual function as well as sensory disturbances. Some patients develop sleep problems, which in turn have a negative impact on their well-being and health. Under certain circumstances, the disease may impair speech, so that logopedic therapy is advisable. The treatment either improves the condition or delays further deterioration to a certain extent. Basically, the medical therapy of the disease is in the foreground, whereby the medicinal treatment plays an important role. Medical examinations at regular intervals monitor the patient’s condition in order to intervene in the event of complications or acute deterioration.Nevertheless, due to the enormous mental stress, in some cases the disease results in psychological complaints and even depression. This affects not only the patients but also, under certain circumstances, the parents of the patients, who suffer from the stress of caring for the sick child. In such cases, a psychological therapist is the correct person to contact.
