Bazilyarny impressiya — the acquired or congenital vdavleniye in a skull of the site of an occipital bone in the field of kraniovertebralny transition. Arising at a bazilyarny impressiya reduction of volume of a cranium and kranialny (towards a skull) the shift of a backbone are the reason of development of hydrocephaly, cerebellar frustration, violations from craniocereberal nerves, radicular symptoms and signs of defeat of the top cervical departments of a spinal cord. The Bazilyarny impressiya is diagnosed when carrying out a X-ray analysis of kraniovertebralny transition, KT and MPT of a skull and cervical department of a backbone. The bazilyarny impressiya is treated only in the surgical way. However at existence of the easy not progressing clinical changes such treatment is not required.
The Bazilyarny impressiya represents the vdavleniye of a slope of an occipital bone having the funneled form in combination with deepening of edges of a big occipital opening in a cranium. These changes lead to backbone shift closer to a brain and reduction of volume of a back cranial pole. At a bazilyarny impressiya the toothlike shoot of the second cervical vertebra settles down at the level of an occipital opening or even above it — in a skull cavity.
In neurology the bazilyarny impressiya belongs to anomalies of kraniovertebralny transition where also enter a platibaziya, assimilation of the Atlas, atlantoaksialny dislocation and Kiari's anomaly. Often the congenital bazilyarny impressiya is combined with other kraniovertebralny anomalies and malformations of a backbone. Most often the combined defect at which the bazilyarny impressiya and a congenital platibaziya is noted meets.
Causes of a bazilyarny impressiya
Congenital (primary) bazilyarny impressiya is formed during pre-natal development. It is connected both with hereditary predisposition, and with negative impacts on a fruit during pregnancy. To the factors capable to cause malformations including a bazilyarny impressiya, diseases of mother and infections transferred it during pregnancy (clamidiosis, a rubella, measles, a Cytomegaloviral infection, etc.), the radioactive radiation, contact with harmful chemicals belong.
The acquired (secondary) bazilyarny impressiya develops as a result of violation of normal bone structure of an occipital bone. Osteoporosis which is in turn connected with gipoparatireozy, an osteomalyation, heavy rickets, Pedzhet's disease can be its cause. The acquired bazilyarny impressiya is possible as a result of destructive changes of an occipital bone at germination of a tumor in it a back cranial pole or as a result of inflammatory process (syphilis, tuberculosis, actinomycosis, osteomyelitis).
Symptoms of a bazilyarny impressiya
The Bazilyarny impressiya is characterized by emergence of the first clinical symptoms aged up to 30 years, is the most frequent during from 15 to 20 years. Clinical manifestations of a bazilyarny impressiya result from reduction of the volume of a back cranial pole leading to increase in intra cranial pressure, hydrocephaly and a sdavleniye of the anatomic educations located in it: cerebellum, trunk of a brain, backs of craniocereberal nerves. Besides, also the top cervical segments of a spinal cord are exposed to a sdavleniye that leads to emergence of radicular and spinal symptoms.
The general neurologic symptomatology by which the bazilyarny imperssiya is followed comes down to the headaches in occipital area often having pristupoobrazny character and depending on position of the head. Against the background of a headache vegetative violations are possible: cold sense or a heat in a body, tachycardia, , changes of arterial pressure and so forth. In some cases a bazilyarny impressiya unilateral pain in occipital area which can gradually accept bilateral character is observed. Occasionally pain from area of a nape extends kpered in one or both eyes. It can arise as occipital neuralgia, amplify at turns of the head, cough, laughter and a natuzhivaniye.
Cerebellar symptoms which show a bazilyarny impressiya consist in emergence of an ataxy — violations of stability of position of a body and unsteadiness when walking. Defeat of a trunk of a brain is shown nistagmy, poperkhivaniy at food (dysphagy), a voice osiplost, decrease in hearing (relative deafness), dizziness, disorder of sensitivity of face skin. Stem symptoms in cases when the bazilyarny impressiya is combined with assimilation of the Atlas are most expressed.
Quite often bazilyarny impressiya is followed by neck and top extremities pains, and also paresteziya (a sleep, feeling of "crawling of goosebumps") in a nape and a neck. These symptoms are caused by a sdavleniye of the top backs of cervical department of a backbone. In case of a bazilyarny impressiya the compression miyelopatiya in the top cervical department seldom leads to development of spastic tetraparesis. Generally at a bazilyarny impressiya it is observed the moderate dissociated disorders of sensitivity demanding an exception of initial manifestations of a siringomiyeliya.
At survey of patients who have a bazilyarny impressiya, often attract attention a short neck and the underestimated border of growth of hair. Unsteadiness in Romberg's pose, a promakhivaniye is observed when performing koordinatorny tests (knee and calcaneal and a finger - nasal), decrease in sensitivity in the field of cervical dermatom and on a face.
Diagnostics of a bazilyarny impressiya
Complaints of the patient, history of their emergence and development (anamnesis of a disease), results of neurologic survey often suggest to the neurologist an idea of existence of pathology in the field of a back cranial pole and kraniovertebralny transition. At the same time for identification of a bazilyarny impressiya or other anomaly of this area first of all conduct a radiological research. The best, than on the roentgenogram, visualization of bone structures of this area, and also data on other malformations with which the congenital bazilyarny impressiya is often combined can be received by means of KT of a skull and a backbone.
Aim X-ray analysis of a skull in the field of kraniovertebralny transition and a backbone X-ray analysis in cervical department are carried out in direct (fasny) and side (profile) projections. The Bazilyarny impressiya is diagnosed on increase in a corner between a plate of the main bone and a slope more than 130 °, and also on shift of a shoot of the second cervical vertebra up. Definition of location of a shoot is made in relation to conditional lines: Chamberlain's lines (between the rear edge of a hard palate and the rear edge of a big occipital opening) and de la Pti's lines (between tops of the right and left mastoidal shoots). Normal the shoot of the second cervical vertebra is below these lines. The Bazilyarny impressiya is characterized with a shift of shoot at 6-30 mm higher than Chamberlain's line and de la Pti's lines are 10-15 mm higher.
At an oftalmoskopiya at patients with a bazilyarny impressiya stagnant disks of optic nerves can come to light, when carrying out a threshold audiometriya — neurotouch type of relative deafness. Identification of a condition of myagkotkanny structures of a back cranial pole and a spinal cord, assessment of degree of their sdavleniye at a bazilyarny impressiya requires carrying out MRT of a brain and MRT of a backbone.
The Bazilyarny impressiya demands differentiation from other anomalies of kraniovertebralny transition, a siringomiyeliya, Fridreykh's ataxy, a tumor of a cerebellum, Pierre-Mari's ataxy, and also from cortical type of an ataxy.
Treatment of a bazilyarny impressiya
In cases when the bazilyarny impressiya is a casual radiological find and does not cause symptoms of a sdavleniye of brain structures, treatment is not required. Steady progressing of symptoms can be the indication to surgical intervention at a bazilyarny impressiya; clinical signs of a sdavleniye of a spinal cord, trunk of a brain or cerebellum; the expressed liquorodynamic violations with the accruing okklyuzionny syndrome. For the purpose of a decompression during operation make expansion of a big occipital opening.