Assimilation of the Atlas
Assimilation of the Atlas — a partial or full union of the I cervical vertebra and occipital bone of a skull. Assimilation of the Atlas can not be followed by clinically significant violations. In other cases it leads to a sdavleniye of structures of kraniovertebralny area (the top cervical department of a spinal cord and a medulla), restriction of mobility in the top cervical department of a backbone and to development of instability of segments of the lower cervical department. Assimilation of the Atlas by a radiological research of cervical department of a backbone and kraniovertebralny transition is diagnosed, Ekho-EG, REG, EEG, MRT and KT of a brain, MRT of cervical department of a backbone is in addition carried out. Assimilation of the Atlas is treated by generally conservative methods. Surgical interventions are carried out for the purpose of a decompression of brain structures.
Assimilation of the Atlas
Together with Kimerli's anomaly and Kiari's anomaly assimilation of the Atlas in neurology and a vertebrologiya belongs to congenital anomalies of development of a backbone. Assimilation of the Atlas approximately in 1-2% of cases meets and it is most often shown aged from 20 up to 30 years. As a rule, development of a backbone happens up to 20-22 years, and the cervical department ossifitsirutsya first of all. Normal articulate shoots of the I cervical vertebra (Atlas) adjoin condyles of an occipital bone. Assimilation of the Atlas is characterized by a dense increment of the Atlas to an occipital bone. Often assimilation of the Atlas is combined with his underdevelopment and the displaced situation in relation to the II cervical vertebra, and also with a bazilyarny impressiya — shift up of bazilyarny department of an occipital bone which leads to reduction of volume of a back cranial pole and a sdavleniye of the anatomical structures located in it.
Etiology and pathogenesis of assimilation of the Atlas
Assimilation of the Atlas is violation of formation of kraniovertebralny structures in the course of an embryonal development. Somewhat similar violations are genetically determined. Big frequency of occurrence of assimilation of the Atlas in families which members have these or those anomalies of development of TsNS testifies to it (to the meningotsela, a platibaziya, a gidromiyeliya, Kiari's anomaly, etc.). Treat the factors causing violations in the course of pre-natal development: radioactive radiation, a serious illness of mother (diabetes, heart disease, heart failure, bronchial asthma and so forth), the complicated course of pregnancy: toxicosis, a nephropathy and the pregnancies of an infection transferred to the period (measles, a rubella, a cytomegalic inclusion disease, clamidiosis and so forth).
Development of pathological changes by which assimilation of the Atlas is followed can happen in two ways. The first way is connected with the fact that assimilation of the Atlas causes narrowing and violation of a configuration of a big occipital opening therefore there is a sdavleniye of structures of a medulla and the top segments of cervical department of a spinal cord. The second pathogenetic mechanism is caused by the fact that assimilation of the Atlas leads to reduction of amplitude of movements in verkhnesheyny department of a backbone. Restriction of movements in the top department at the expense of compensatory mechanisms leads to development of the increased mobility in the lower department of a cervical segment of a backbone. As a result of hyper mobility load of CIV-CV and CV-CVI intervertebral disks increases. So there can be their excess wear leading to formation of instability of a backbone at this level.
Symptoms of assimilation of the Atlas
Unsharply expressed assimilation of the Atlas is characterized by an asymptomatic current and can not have an effect throughout all life of the patient. Clinically significant assimilation of the Atlas debuts usually after 20 years. Its manifestations depend on degree of an union of the Atlas with an occipital bone and combinations to other congenital anomalies.
Assimilation of the Atlas is shown by headaches which can have pristupoobrazny character and be followed by vegetative reactions: the increased perspiration, tachycardia, fluctuations of arterial pressure, feeling of heat in a body or on the contrary a chill. At violation of outflow of tserebrospinalny liquid assimilation of the Atlas is shown by pressure sense on eyeballs, nausea and vomiting. Sleep disorders and neck pains are possible. The pain syndrome with localization of pains in cervical department of a backbone often appears if assimilation of the Atlas is followed by instability of nizhnesheyny segments. Intensity of pain can increase after physical activity. At survey at such patients the raised tone of muscles of a neck comes to light.
The assimilation of the Atlas leading to a sdavleniye of the top segments of a spinal cord usually is not followed by the expressed compression miyelopatiya with heavy motive violations. As a rule, it is shown by the easy dissociated disorders of sensitivity in the field of the lower cervical dermatom for which identification careful neurologic survey is necessary. If assimilation of the Atlas leads to a sdavleniye of structures of a medulla, then signs of damage of the craniocereberal nerves leaving it are observed. Sdavleny the IX-XII steam is shown by violation of swallowing with a poperkhivaniye during food, a dezartriya, a voice osiplost, decrease in flavoring feelings. Defeat of the VIII pair of craniocereberal nerves (a preddverno-ulitkovy nerve) is followed by relative deafness development, dizziness and emergence of a nistagm, the VII couples — neuritis of a facial nerve.
Diagnostics of assimilation of the Atlas
The clinical manifestations accompanying various options of assimilation of the Atlas and data of neurologic survey allow the neurologist to suspect the violations which are localized in cervical department of a backbone and kraniovertebralny area. Identification of assimilation of the Atlas requires carrying out a X-ray analysis of a backbone in cervical department with capture of an occipital bone. Such research in direct and side projections allows to visualize the place of an union. On standard and functional roentgenograms signs of instability of CIV-CV and CV-CVI by which assimilation of the Atlas is followed often are found: change of height of intervertebral disks, shift of vertebras and violation of parallelism of their articulate surfaces.
During standard primary inspection (EEG, Ekho-EG and REG) at patients only the increased intra cranial pressure usually decides on assimilation of the Atlas. In cases when assimilation of the Atlas is followed by symptoms of damage of a medulla, the exception of other cerebral pathology is necessary: tumors of a brain, siringomiyelichesky cyst, abscess. It is for this purpose carried out by brain KT or MPT which in case of assimilation of the Atlas can reveal symptoms of hydrocephaly. MRT of a backbone allows to judge degree of a sdavleniye of a spinal cord.
Treatment of assimilation of the Atlas
Assimilation of the Atlas at existence of clinical manifestations needs performing symptomatic treatment. It can be carried out by joint efforts of neurologists, vertebrolog and orthopedists. Apply analgetics, nonsteroid resolvents to knocking over of a pain syndrome (, to meloksika, diclofenac), reflexotherapy. For decrease in intra cranial pressure to patients appoint diuretic medicines (acetazoleamide, , a mannitol). In treatment of instability of a backbone carrying a collar of Shants, LFK and massage, an electrophoresis, is applied. For removal of the expressed pain syndrome paravertebralny blockade can be carried out.
Surgically assimilation of the Atlas is treated only in cases of a considerable sdavleniye back or a medulla. Operation can include expansion of an occipital opening and a decompression of a spinal cord by a laminektomiya. Operations of a forward and back spondilodez are applied for the purpose of stabilization of cervical department of a backbone.