MYELENCEPHALON

From Big Medical Encyclopedia

MYELENCEPHALON [medulla oblongata (PNA, JNA, BNA); synonym: bulbus, myelencephalon, bulbus] — the part of a brain trunk which is a part of a rhombencephalon. In P. the m located the vital centers regulating breath, blood circulation, exchange.

The item of m develops from back primary brain bubble (see. Brain ). The newborn has a weight (weight) of P. of m in comparison with other departments of a brain more, than at the adult. In it the back kernel of a vagus nerve is well developed and the double kernel is accurately segmented. To 7-year age nerve fibrils P. of m become covered by a myelin cover.

Anatomy

Fig. 1. Diagrammatic representation of a front surface of a brain trunk and places of an exit of roots of cranial nerves: 1 — a third cranial nerve; 2 — a block nerve; 3 — a trigeminal node; 4 — a trifacial (a motive root); 5 — a trifacial (a sensitive root); 6 — the taking-away nerve; 7 — a facial nerve; 8 — an eighth cranial nerve; 9 — a glossopharyngeal nerve; 10 — a vagus nerve; 11 — a hypoglossal nerve; 12 — an eleventh cranial nerve; 13 — a root of the first cervical spinal nerve; 14 — a lower surface of a cerebellum; 15 — a front median crack; 16 — a front lateral furrow; 17 — decussation of pyramids; 18 — a pyramid of a myelencephalon; 19 — an olive; 20 — a bulbar and bridge furrow; 21 — the bridge; 22 — a leg of a brain.
Fig. 2. Diagrammatic representation of a back surface of a brain trunk: 1 — a rhomboid pole; 2 — a block nerve; 3 — a facial nerve; 4 — an intermediate nerve; 5 — an eighth cranial nerve; 6 — a glossopharyngeal nerve; 7 — a vagus nerve; 8 — an eleventh cranial nerve; 9 — a hillock of a wedge-shaped kernel; 10 — a hillock of a thin kernel; 11 — a back lateral furrow; 12 — a wedge-shaped bunch; 13 — an intermediate furrow; 14 — a posterior pyramid; 15 — a back median furrow; 16 — a latch; 17 — brain strips; 18 — the lower cerebellar leg.

The item of m is located between bridge of a brain (see) and spinal cord (see), in a form he reminds the truncated cone 25 — 30 mm long. The longitudinal size P. of m — 12 — 15 mm, cross — 10 — 12 mm; weight of 6 — 7 g. The reinforced upper part of P. of m is considerably delimited from the bridge of a brain (a varoliyev of the bridge) in front at the expense of a cross small crack (a bulbar and bridge furrow), behind, in the field of a rhomboid pole, the border corresponds to the level of an arrangement of brain strips of the fourth ventricle.

As the lower bound of P. of m serves the bottom edge of decussation of pyramids or the place of an exit of ventral and back roots of the I pair of cervical nerves that corresponds to the level of a big occipital opening. Being direct continuation of a spinal cord, P. the m in many respects keeps lines of its structure.

The item of m has a lobby (ventral), back (dorsal) and the side (lateral) surfaces bearing a number of the longitudinal furrows which are continuation of the corresponding furrows of a spinal cord. The front surface of P. of m convex, is turned forward and down, prilezhit on an internal base of skull to a slope (fig. 1). Along its middle there passes the deep front median crack [fissura mediana ventralis (anterior)] limited from sides to powerful tyazha — the pyramids of a myelencephalon (pyramides medullae oblongatae) proceeding in front cords of a spinal cord. Pyramids are formed by fibers of pyramidal ways (see. Pyramidal system ), most of which part at border with a spinal cord throughout 6 — 8 mm comes over in the depth of a front median crack to the opposite side, forming decussation of pyramids — motive decussation [decussatio pyramidum (decussatio motoria)]. Knaruzhi from a pyramid on a lateral surface of P. of m is located an oval eminence — an olive (oliva). The pyramid and an olive are delimited from each other by a front lateral furrow [sulcus ventrolateralis (anterolateralis)], in depth a cut there are roots hypoglossal nerve (see). Behind an olive the back lateral furrow [sulcus dorsolateralis (posterolateralis)] consistently leave roots glossopalatine, wandering and additional craniocereberal (cranial, T.) nerves (see. Vagus nerve , Eleventh cranial nerve , Glossopharyngeal nerve ). On a lateral surface of P. of m there is a side cord (funiculus lat.), proceeding in the lower cerebellar leg [pedunculus cerebellaris caudalis (inferior)]. The back surface of P. of m is covered with a cerebellum. Its bottom significantly reminds the surface of a spinal cord on a relief, upper — is developed and turned into a cavity of the fourth ventricle (fig. 2). It forms the lower half of a bottom of a rhomboid pole. Along the middle of a back surface of P. of m the back median furrow [sulcus medianus dorsalis (posterior)] follows. On each side it there are back cords which in the direction up disperse in the parties and are a part of the lower cerebellar legs limiting the lower half of a rhomboid pole from sides. Each back cord is subdivided by an intermediate furrow (sulcus intermedius) into a posterior pyramid (fasc. gracilis), the located knutr, and a wedge-shaped bunch (fasc. cuneatus), lying lateralno. At a bottom corner of a rhomboid pole thin and wedge-shaped bunches come to an end with the thickenings of the same name — hillocks of thin and wedge-shaped kernels (tuberculum gracile et cuneatum). Knaruzhi from a wedge-shaped kernel is located Monakov's kernel surrounded around with yarns, creating the lower cerebellar leg.

Fig. 1. A section at the level of transition of a spinal cord to oblong.
Fig. 2. A section at the level of decussation of pyramids.
Fig. 3. A section at the level of decussation of medial loops.
Fig. 4. A section at the level of disclosure of the IV ventricle.
Fig. 5. A section at the level of emergence of the lower cerebellar leg.
Fig. 6. Section at the level of emergence of a back cochlear kernel. 1 — the central channel; 2 — a reticular formation; 3 — decussation of pyramids; 4 — a front median crack; 5 — a front cord; 6 — a front horn; 7 — a side cord; 8 — a back horn; 9 — jellylike substance; 10 — a back cord; 11 — a back median furrow; 12 — a thin kernel; 13 — a wedge-shaped kernel;/4 — a back spinomozzhechkovy way; 15 — a front spinomozzhechkovy way; 16 — a pyramid; 17 — a spinal way of a trifacial; — wedge-shaped bunch; 19 — a posterior pyramid; 20 — decussation of medial loops; 21 — a back kernel of a vagus nerve; 22 — internal arc-shaped fibers; 23 — a kernel of an eleventh cranial nerve; 24 — a single way; 25 — a kernel of a hypoglossal nerve; 26 — a back longitudinal bunch; 27 — a medial loop; 28 — the lower olive kernel; 29 — a medial additional olive kernel; 30 — an additional wedge-shaped kernel; 31 — the lower cerebellar leg; 32 — a hypoglossal nerve; 33 — fibers of a glossopharyngeal nerve; 34 — an upper vestibular nucleus; 35 — the IV ventricle; 36 — a back cochlear kernel.

The item of m consists of gray and white matter. White matter occupies preferential perednebokovy P.'s department of m (See color illustrations 1 — 6: Cross sections of a myelencephalon at its various levels). Gray matter lies in the form of accumulations of nervous cells — kernels of cranial nerves (V, VIII, IX, X, XI, XII) and kernels of a reticular formation which differ from each other but a form and size. Kernels of cranial nerves are symmetrized at the bottom of a rhomboid pole under an ependyma (in a dorsal part of a myelencephalon). At the same time is closer to the centerline motive kernels are located, sensitive kernels are displaced most lateralno, and in an interval between them there are vegetative kernels. The kernel of a hypoglossal nerve (nucleus nervi hypoglossi) is located in a bottom corner of a rhomboid pole, in the depth of a triangle of a hypoglossal nerve, only his small lower part lies in front from the central channel passing into a cavity of the fourth ventricle. Lateralny in the field of a triangle of a vagus nerve the parasympathetic back kernel of a vagus nerve (nucleus dorsalis nervi vagi) is projected. Slightly more deeply and above the last in reticular formation (see) the large motive double kernel (nucleus ambiguus), the general with a kernel of a glossopharyngeal nerve is put. The lower end of a double kernel is adjoined by a motive kernel of an eleventh cranial nerve, and more naturally between a double kernel and the lower kernel of an olive the parasympathetic lower slyunootdelitelny kernel [nucleus salivatorius caudalis (inferior)] is located. Knaruzhi: from the last the sensitive kernel of a single way (nucleus solitarius) and a sensitive kernel (lower) of a spinal way of a trifacial [nucleus spinalis (inferior) nervi trigemini] lie. In a lateral corner of a rhomboid pole in the field of the vestibular field (area vestibularis) kernels of an eighth cranial nerve are projected (upper, lower, medial and lateral vestibular nuclei; front and back cochlear kernels). Kzadi and knaruzh from pyramids is located the lower kernel of an olive [nucleus olivaris caudalis (inferior)] presented by the gyrose plate of gray matter opened medially [gate of the lower kernel of an olive, hilus nuclei olivaris caudalis (inferioris)], P. forming on a lateral surface to m protrusion — an olive. Kzadi from this kernel lies a back additional kernel of an olive [nucleus olivaris accessorius dorsalis (posterior)], and knutr — a medial additional kernel of an olive (nucleus olivaris accessorius medialis). In the central region of P. of m the reticular formation representing network is located, in a cut are disseminated, and places grouped in the form of reticular kernels multipolar neurons. On a surface of a pyramid of P. of m the arc-shaped kernels (nuclei arcuati) lie. About the centerline of P. of m occupied with a median seam there are kernels of a median seam [nuclei raphae (medianae)].

Fig. 7. Conduction paths of a myelencephalon and their communication with its various educations (the ascending ways are designated in lilac, yellow and green color, descending — red and blue): 1 — a pyramidal bunch; 2 — a medial loop; 5 - and wedge-shaped kernels; 4 — decussation of medial loops; 5 — a front cortical and spinal (pyramidal) way; 6 — a ventral root; 7 — thin and wedge-shaped bunches; 8 — a front horn; 9 — a chest kernel; 10 — a back root; 11 — a front spinomozzhechkovy way; 12 — a lateral spinotalamichesky way; 13 — a back spinomozzhechkovy way; 14 — a lateral cortical and spinal (pyramidal) way; 15 — decussation of pyramids; 16 — an olivocerebellar way; 17 — the lower cerebellar leg.

White matter P. of m is presented by short and long bunches of own fibers and bunches of the long fibers passing tranzitno. The last provide a two-way communication of a spinal cord with the above-located departments of a brain trunk and with a great brain (tsvetn. silt., fig. 7). From the efferent pathways passing tranzitno the major are cortical and spinal (cortical and spinal fibers, T.), krasnoyaderno-spinal, pokryshechno-spinal ways; from afferent — front and lateral spinnotalamichesky ways, front and back spinnomozzhechkovy ways, a spinnopokryshechny way.

Short own fibers connect P.'s kernels of m among themselves, and long — with the next departments of a brain (a preddverno-spinal way, an olivocerebellar way, olivospinnomozgovy a way, a spinnoolivny way, a reticular and spinal way). Fibers of proprioceptive sensitivity belong to own fibers P. of m. The first neuron of this way comes to an end at cells of thin and wedge-shaped kernels of the party. Shoots of cells of these kernels, being dugoobrazno bent (internal arc-shaped fibers), go on the opposite side, crossing in front from the central channel with similar fibers of the opposite side. After formation of decussation of medial loops (decussatio lemniscorum medialium) they go to to a thalamus (see), being located dorsalny pyramids between olives. T. about. decussation of medial loops (sensitive decussation) in P. is located with m above and dorsalny decussation of pyramids.

Blood supply The item of m is carried out at the expense of vertebrata, back lower cerebellar, front spinal and initial department basilar arteries. Outflow of blood of m comes from P. to the median venous highway of the bridge and a myelencephalon.

Physiology

Extensive functional linkages in the ascending and descending directions and close interrelation with a reticular formation allow P. to m to carry out system integration and coordination of a wide range of the vital physiological functions. The item of m is under the influence of mezentsefalny, di-en of tsefalny and cortical departments of a brain. It performs important touch functions. The afferent impulses bearing information from receptors of face skin, mucous membranes, respiratory tracts, from internals and the acoustic analyzer come to P. of m. These afferentation are a basis of formation of the corresponding reflex reactions. Thanks to them the m provides to P. protective reflexes of eyes (blinking), the movements of language, motive function of face muscles (mimicry), secretion salivary, gastric and pancreatic glands.

Providing these sensomotor fiziol, functions is caused by occupying of P. of m of kernels of cranial nerves. With participation of these kernels of P. of m carries out regulation not only somatosensory, but also vegetative functions.

Big fiziol. the descending ways beginning in P. m, such as reticular and spinal, preddverno-spinal, olivospinnomozgovy which regulate functions of motor-neurons of the corresponding segments of a spinal cord (see matter. Conduction paths ).

Besides, in P. the cortical and nuclear fibers of a pyramidal way bearing impulses from various layers of neurons of a neocortex to kernels of the corresponding couples of cranial nerves reach a limit with m. These ways cause the regulating influence of a cerebral cortex on fiziol, the reactions connected with activity of kernels of cranial nerves.

Along with conduction function P. of m carries out regulation of compound vital instinctive reflexes, such as suction, chewing, swallowing, sneezing, cough, vomiting, dacryagogue, salivation. These reflexes, as a rule, have protective and physiological character. Especially important physiological, and also diagnostic value has an emetic reflex (see. Vomiting ), the m

of P. of m which is entirely depending on a functional condition of P. participates in a pneumotaxis (see. Respiratory center ) and cardiovascular system (see. Vasomotor center ).

According to Rossi and Tsanketti (G. Bossi, A. Zanchetti, 1960), X. Megun (1960, 1965), P.'s physiology of m it is impossible to consider without a role of the reticular formation exerting the tonic and modulating impact on a functional condition of segments of a spinal cord.

Basic researches of X. Megun, R. Granita and other neurophysiologists it was shown that P.'s neurons of m, the bridge of a brain, the tires of a mesencephalon integrated into uniform system by a reticular formation exert the continuous regulating impact on pulse activity gamma efferentov, alpha motor-neurons and muscle spindles that causes adequate redistribution of a muscle tone. Comparison of the spinal and decerebrated animals (see. Decerebration , Spinal cord ) shows that after correctly made interkolla of kulyarny section there is a disinhibition of both the static, and dynamic gamma fibers going to razgibatel that leads to a cerebrate rigidity (dominance of a tone of razgibatel) whereas at spinal animals no signs of activity of static and dynamic fusimotor gamma neurons are observed.

In P. of m there are vital vegetative centers. The electric irritation of these centers causes clear reactions in all areas of a body in experimental animals. They are expressed in increase of cordial reductions, increase in the ABP, a mydriasis, reduction of the third century, a piloerektion, sweating, weakening of a vermicular movement of intestines and increase in a sugar content in blood.

Activity of the vegetative centers P. of m increases also in response to reflex or their direct chemical irritation. At inhalation of air with the increased content of carbon dioxide gas or the lowered oxygen content the animal has characteristic symptoms of excitement autonomic nervous system (see). Asphyxia during the crossclamping of a trachea causes the powerful category in the vegetative centers as a result of the combined influence hypercapnias (see) and hypoxias (see). After high section of a spinal cord asphyxia (see) the same degree very slightly affects function of the bodies having a sympathetic innervation. The obtained data demonstrate that functions of these bodies are almost entirely mediated by the centers lying above a spinal cord i.e. in a myelencephalon. It is established that carbon dioxide gas renders direct irritant action on the vegetative centers P. of m; decrease in the oxygen content is expressed in direct suppression of their excitability. However, according to Gellgorn and Lufborrou (1963) if tension of oxygen in liquids of an organism falls very low, chemoceptors of a carotid sine are excited that leads to reflex activation of the vegetative centers P. of m in spite of the fact that their excitability in the conditions of a hypoxia is lowered.

Dynamic disturbances of blood supply of P. of m cause a so-called vertebralno-basilar syndrome. Insufficiency of blood supply (hypoxia) is characterized by oppression of functional activity of the centers P. of m and kernels of the corresponding cranial nerves that is shown by emergence patol. types of breath: periodic breathing, breath like Cheyn — Stokes (see. Cheyna — Stokes breath ), biotovsky breath (see), and also disappearance corneal, deglutitory, sneezing and other reflexes.

The item of m plays an important role in regulation of difficult vital functions, and disturbances of its activity have, as a rule, dangerous effects. Timely definition of a functional condition of P. of m it is necessary for acceptance urgent to lay down. died. It is determined by shifts in fiziol. the reactions connected with activity of certain educations and systems P. of m, kernels of cranial nerves (disturbance of corneal and chewing reflexes, acts of swallowing, suction, a condition of sensitivity in the head and a neck, tussive, sneezing, emetic reflexes, respiratory movements, etc.)

Methods of a research

For diagnosis of defeats of P. of m use two groups of methods of a research: clinical and tool and laboratory. Refer all receptions to the first group nevrol. inspections of the patient (see): research of functions of cranial nerves, autokinesias of extremities and coordination of these movements, sensitivity, vegetative and visceral functions. Tool and laboratory methods include spinal puncture (see) and suboktsipitalny puncture (see) with the subsequent laboratory research cerebrospinal liquid (see), a X-ray analysis of a skull (see. Kraniografiya ), pneumoencephalography (see), vertebralny angiography (see), ekhoentsefalografiya (see), radio isotope research (see), a computer tomography of a brain (see. Tomography computer ), etc.

By the main methods of studying of a condition of P. of m are electro-fiziol. registration of bioelectric activity of its certain zones, kernels, the centers, and also registration of neyronalny pulse activity of the motive reflexes and other reflex reactions connected with activity of cranial nerves. The important place in P.'s studying m is taken also by registration of rhythmic activity of the automatic centers with the help electroencephalography (see), electrocardiography (see) and pneumography (see).

Pathology

the Symptomatology

At dysfunction of P. of m arise various a wedge. syndromes which character depends from lo a kalization and the sizes patol. center. The most characteristic is the bulbar syndrome consisting of symptoms of dysfunction IX, X and XII cranial nerves (see. Vagus nerve , Hypoglossal nerve , Glossopharyngeal nerve ), which kernels are located in P. with m. Sharply or gradually there are dysphagias and speeches. Because of paresis of muscles of a soft palate and a throat there is a poperkhivaniye, liquid food pours out through a nose, the voice gets a nasal shade (twang). At full denervation of these muscles swallowing of food and saliva is broken. Owing to paresis of muscles of a throat there is an incomplete smykaniye of phonatory bands and the voice becomes hoarse or silent (see. Aphonia , Dysphonia ). Damage of muscles of language leads to a smazannost of the speech (see. Dysarthtia ), lip and tooth concordants («mushmouth») are badly said, movement of a lump of food during the chewing is at a loss. Later 1,5 — 2 weeks at acute development bulbar paralysis (see) the atrophy of muscles of language therefore its volume decreases joins, there is a skladchatost of a mucous membrane, there are fascicular twitchings. At hemilesion of bulbar cranial nerves language deviates towards defeat, and a uvula of a soft palate (a uvula, T.) — in the healthy party. At bilateral dysfunction of the IX—XII cranial nerves there is an aphagia (see. Dysphagy ), an anarthria (see. Dysarthtia ), an aphonia, expectoration, yawning are complicated, there is a threat of aspiration pneumonia. Unlike similar on clinic pseudobulbar paralysis (see) in the paralyzed muscles at bulbar paralysis reaction of degeneration is observed (see. Elektrodiagnostika , Electromyography ), and also there are no palatal and gag reflexes.

Defeat of a ventral part an upper half of P. of m it is shown by a bulbar alternating syndrome of Jackson (see. Alternating syndromes ), the characterized flaccid paralysis of muscles of language on the party of the center of defeat and the central paralysis of extremities on the opposite side. Defeat of the lower olive (the lower olive kernel) is followed by disturbance of balance of a body and a myoclonia of a soft palate.

Defeat of a dorsal part an upper half of P. of m leads to paralysis of muscles of a soft palate, a throat, language and voice muscles on the party of the center of defeat. Besides, on the same party the dissociated segmented anesthesia of face skin, disturbance of deep sensitivity in a hand and a leg with a sensitive ataxy in them is observed (see. Ataxy ), a cerebellar hemiataxia, Bernard's syndrome — Horner (see. Bernard — Horner a syndrome ). On the party opposite to the center, owing to defeat of a spinnotalamichesky way (see. Conduction paths ) the conduction superficial hemianaesthesia which is not extending to the person — Wallenberg's syndrome — Zakharchenko comes to light (see. Alternating syndromes ).

Defeat of kernels of a reticular formation is followed by disorders of breath (it becomes frequent, irregular, any changes of a respiration rate), cardiovascular activity are impossible (tachycardia, cyanochroic spots on extremities and a trunk, cold sweat), thermal and vasculomotor asymmetry (in an acute phase of defeat on the party of the center temperature of skin increases on 1 — 1,5 °, in the subsequent it fluctuates depending on ambient temperature, pallor of skin, delay of capillary pulse is noted), decrease in emotional and mental activity.

For defeats of the right or left half of an upper part The item of m the combination of above-mentioned symptom complexes to lines of an alternating syndrome of Babinsky — Nazhotta is characteristic (see. Alternating syndromes ).

Defeat of a ventral part of the lower half The item of m is shown by asymmetric central tetra-paresis, against the background of to-rogo the cross hemiparesis (paresis prevails in one hand and an opposite leg) owing to defeat of a part of decussation of pyramids sometimes is defined. On the party of the center peripheral paresis grudino - clavicular and mastoidal and partially trapezoid muscles comes to light that is caused by defeat of a bulbar part of a kernel of the XI couple of cranial nerves.

Defeat of a dorsal part of the lower half The item of m is characterized by emergence on the party of the center of the segmented dissociated anesthesia in caudal dermatomas of Zelder on a face (see. Trifacial ), decrease in deep sensitivity in a hand and a leg, a cerebellar and sensitive hemiataxia and Bernard's syndrome — Horner. On the party opposite to the center, the conduction hemianaesthesia with the upper bound at the level of upper cervical segments is noted (With II \CIII ).

At the limited centers of defeat in limits of one half of P. of m various options noted above a wedge develop. pictures, sometimes with lines of an alternating syndrome of Avellis, Schmidt, Volestein, etc. Total destruction of P. of m is incompatible with life.

Malformations myelencephalon meet seldom, their pathogeny is various (see. Brain ). The item of m is surprised for the second time at kraniovertebralny anomalies more often. Among malformations the syringobulbia is quite widespread (see. Myelosyringosis ), characterized by formation of cavities and growth of a glia in gray matter P. of m Klin. displays of this disease arise at adults and first of all kernels of a spinal way of a trifacial are a consequence of defeat that leads to disturbance painful and temperature, but with preservation of tactile sensitivity on a face (the dissociated segmented anesthesia). Then gradually bulbar frustration (a dysphagy, a dysphonia, a dysarthtia) join, and also ataxy (see), nystagmus (see), vestibular symptom complex (see), sometimes vegetative crises in the form of tachycardia, disturbances of breath, vomiting (see. Crises, cerebral ). Symptomatic treatment.

Damages in the form of the isolated P.'s bruise of m or hemorrhage are rare, they are observed at heavy to a craniocereberal injury (see) are also, as a rule, combined with damage of other departments of a brain. At the same time suddenly there comes the loss of consciousness, the deep coma with sharp oppression of all reflex defense reactions and a full obezdvizhennost develops. Disorders of breath and cardiovascular activity are observed. Breath becomes periodic, like Cheyn — Stokes, the Biota or terminal with separate arrhythmic breaths and the subsequent apnoea (see. Breath ). Disorders of cardiovascular activity are characterized by falling of the ABP at the expressed cordial weakness or arterial hypertension. Often tachycardia develops, is more rare than bradycardia. Symptoms of ischemia and hypoxia of a brain are noted (see. Hypoxia , Stroke ), disturbances of fabric metabolism and permeability of cellular membranes with edematization of a brain (see. Swelled also swelling of a brain ). Disturbances develop thermal controls (see), shown tendency to a hypothermia. In some cases there can be trunk spasms which are characterized by a tonic muscle tension, is more often than extremities, a picture cerebrate rigidity (see).

At less heavy damages of P. of m the spontaneous nystagmus, decrease corneal and pharyngeal reflexes, decrease or increase in tendon jerks with bilateral patol can be observed. reflexes (see. Reflexes pathological ).

Treatment of traumatic defeats of P. of m is directed first of all to recovery of disturbances of system blood circulation and breath. Correction of oxidizing processes, an acid-base, electrolytic, proteinaceous and water balance is at the same time carried out. If recovery and stabilization of breath under the influence of conservative treatment does not occur, urgently make an intubation of a trachea (see. Intubation ) or tracheostomy (see) using artificial ventilation of the lungs (see. Artificial respiration ). Apply a combination of the funds allocated for elimination of a hypovolemia to elimination of arterial hypotension (hemotransfusion, Polyglucinum, reopoliglyukin), with the drugs normalizing cardiovascular activity (strophanthin, Korglykonum). For correction of the shifts caused by a hypoxia and quickly developing metabolic acidosis intravenously enter 4% solution of hydrosodium carbonate (100 — 200 ml). For normalization of balance of potassium effectively intravenous administration glyukozo - potassium and insulin mix. At disorders of water and electrolytic balance apply the pharmaceuticals raising a diuresis and removal of sodium — Spironolactonum (Aldactonum, veroshpiron). For strengthening of diuretic effect use of lasixum (furosemide), hypothiazid (dichlothiazide) is shown. The forecast depends on weight of damage of P. of m, timeliness and completeness of the carried-out treatment.

Diseases

Dysfunctions of P. of m can arise at vascular and infectious diseases of a brain. Among vascular diseases ischemic defeats of P. of m in the form of passing disturbances of blood circulation in the vertebralno-basilar pool and focal heart attacks meet more often. Allocate two main options of a heart attack of P. of m. One is connected with obstruction of a vertebral artery and occlusion of the lower back cerebellar artery departing from her leading to a heart attack of dorsolateral departments of P. of m. It is followed by the so-called lateral syndrome which is a wedge. manifestation of one of options of an alternating syndrome of Wallenberg — Zakharchenko (see. Alternating syndromes ). At obstruction of lateral and medial brain branches (branches to a myelencephalon) vertebrata and the main of arteries develops a so-called medial syndrome, for to-rogo are characteristic paralysis of muscles of language on the party of a heart attack and the central hemiplegia on the opposite side (an alternating syndrome of Jackson). Less often the hemiplegia is combined with cross paralyzes of muscles of a soft palate and a throat or is noted only spastic gemi-or a tetraplegia (see. Paralyses, paresis ).

Hron. the circulatory unefficiency of m can develop in P. at the expressed atherosclerosis of vertebrata and the main of arteries, is frequent in combination with cervical osteochondrosis and the deforming spondylarthrosis. At the same time insultoobrazny episodes periodically appear and gradually the bulbar syndrome forms. Hron. P.'s ischemia of m is differentiated with amyotrophic side sclerosis (see), at Krom only motive kernels of cranial nerves in P. m and the varoliyevy bridge are surprised.

Hemorrhages in P. of m are rare, usually are continued from a varoliyev of the bridge or a traumatic origin. They quickly lead to a lethal outcome.

Infectious diseases of P. of m happen primary and secondary. Among primary neurovirus defeats meet more often, e.g. poliomyelitis (see), poliomiyelitopodobny diseases (see), and also infectious and allergic, napr, a bulbar form of a polyradiculoneuritis of Giyen — Barret — Shtrolya (see. Polyneuritis ). At the same time against the background of a serious general condition and meningeal symptoms signs of defeat of the IX—XII cranial nerves from one or both parties and change in cerebrospinal liquid (a pleocytosis or proteinaceous and cellular dissociation appear at Giyen's disease — Barret — Shtrolya). The bulbar form of neuroviral diseases is most dangerous since it often leads to an apnoea and cardiovascular activity.

Secondary defeats of P. of m can be observed at syphilis, tuberculosis, flu owing to an endarteritis, and also at a nodular periarteritis. In such cases not only bulbar cranial nerves and their kernels, but also pyramidal ways, conductors of sensitivity, koordinatorny systems suffer. At the expressed form botulism (see) there are dysphagias, speeches, salivation decreases. At epidemic encephalitis (see) along with oculomotor disturbances occasionally there are also passing bulbar paralyzes.

The item of m can be surprised at multiple sclerosis (see) with development of symptoms of dysfunction of conduction and nuclear structures of this part of a brain.

The general principles of treatment of patients at the diseases which are followed by P.'s defeat in m have etiological and pathogenetic character. If necessary hold also special events for correction of respiratory insufficiency (including artificial ventilation of the lungs), cardiovascular frustration (using a phenylephine hydrochloride, adrenaline, Cordiaminum) and feeding by nutritious mix via the probe. Prevention of aspiration pneumonia is carried out (a toilet of an oral cavity with suction of slime). The forecast is defined by the nature of a disease and efficiency of the carried-out treatment.

Tumors myelencephalon meet seldom, preferential at children's age. Are more often observed ependymomas (see), astrocytomas (see). oligodendrogliomas (see), more rare glioblastoma (see), medulloblastomas (see), gemangioretikuloma. Ependymomas strike the central departments of P. of m, other tumors can asymmetrically be located, occupying its half, or extend to all diameter of P. of m. Sometimes growth of a tumor is followed by formation of cysts.

Idiosyncrasy wedge. courses of tumors of P. of m early emergence and gradual increase of signs of focal defeat and late development of a syndrome of intracranial hypertensia is (see. Hypertensive syndrome ). In connection with the considerable density of an arrangement in P. of m of kernels of cherepnomozgovy nerves, the vital centers, motive, sensitive and cerebellar conduction paths for a wedge. pictures of tumors of P. of m the variety of focal symptoms which sequence of development depends on the place of emergence and the direction of preferential spread of a tumor is typical. In an early stage of a disease hemilesion of kernels of cranial nerves and conduction paths of P. of the m which are followed by alternating syndromes is more often noted. However soon defeat becomes bilateral, being combined with increase of the general weakness, progressive emaciation of the patient. In a late stage of a disease appear and accrue a cardiac disturbance and breath which often are a cause of death. They can be combined with the gipertenzionno-gidrotsefalny phenomena, disturbances of outflow of cerebrospinal liquid from cerebral cavities. Separate symptoms of defeat of P. of m can arise at extra brain tumors (a meningioma, a neurinoma, a chordoma, an epidermoida) which are localized in the field of an occipital and cervical dural funnel.

Treatment of tumors of P. of m usually conservative. Carry out radiation therapy in a total dose 5000 — 6000 I am glad (50 — 60 Gr) usually for 2 — 3 courses. At emergence in a wedge. to a picture of a disease of gipertenzionno-gidrotsefalny symptoms make eksplorativny trepanation in the field of a back cranial pole with obligatory opening of an atlantozatylochny membrane and firm cover of a brain. In case of detection of a cyst of P. of m its emptying by a careful puncture is possible. Compact tumors of P. of m usually neudalima. Asher (R. of W. Ascher, 1977) provides data on successful removal of a glioma of P. of m by means of the laser on carbon dioxide gas blocked with an operative microscope. Usually operation is directed to recovery of the broken outflow of cerebrospinal liquid in the field of Marangdi's opening (a median aperture of the fourth ventricle, T.), in this connection the section of lower parts of a worm of a cerebellum is made. If this action is insufficient or weight of a condition of the patient excludes performing trepanation, likvoroshuntiruyushchy operations using the ventrikuloatrialny or ventrikuloperitonealny shunting systems are shown.

At an uncomplicated postoperative current carry out radiation therapy.

Forecast at intra trunk tumors of P. of m, irrespective of them gistol. structures, adverse. Combined (operational and beam) treatment prolongs life of patients, but does not provide recovery.


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A. A. Skoromets; F. P. Vedyaev (physical.), Yu. A. Zozulya (neyrokhir.), V. V. Turygin (An.).

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