What Are Brain Stem Lesions?

Brainstem injury is a serious and even fatal injury, with about 10% to 20% of severe brain injury accompanied by brainstem injury. The brainstem includes the midbrain, pontine and medulla oblongata, which is located at the bottom of the central axis of the brain. The dorsal side is connected to the cerebellum and cerebellum. The ventral side is the bony skull base, just like a snail lying on a slope. Brainstem injury is usually divided into two types: primary brainstem injury, brainstem injury caused by external violence; secondary brainstem injury secondary to other severe brain injury, due to cerebral hernia or cerebral edema Causes brain stem damage. Severe brain stem injury has very poor curative effect, and its death rate accounts for almost one third of the death rate of craniocerebral injury. If the medullary plane is damaged, there is little hope for treatment.

Basic Information

English name

brain stem injury

Visiting department

neurosurgery

Common causes

Direct or indirect violence causes collisions and movements of brain tissue

Common symptoms

"Disorder of consciousness, decortical rigidity

Causes of brain stem injury

Simple brainstem injuries are rare. The brainstem includes the midbrain, pons and medulla. When external force acts on the head, whether direct or indirect violence will cause the brain tissue to collide and move, which may cause brainstem damage.

Clinical manifestations of brain stem injury

Disturbance of consciousness

In patients with primary brain stem injury, coma often occurs immediately after the injury. The light can respond to painful stimuli. The severe can have a deep coma and all reflexes disappear. If the coma lasts for a long time, and there is little intermediate awakening or intermediate improvement, you should think of secondary brain stem injury caused by intracranial hematoma or other reasons.

2. Pupil and eye movement

Changes in eye movements and pupil adjustment are managed by brain nerves such as eye movement, tackle, and abduction. Their nerve nuclei are located in the brainstem. Corresponding changes can occur during brainstem injury, which has clinical significance. When the midbrain is injured, the pupils on the two sides are different, the pupils on the injured side are dilated, the light reaction disappears, and the eyes are tilted downward and outward. When the two sides are injured, the pupils on both sides are enlarged and the eyes are fixed. When the pontine is injured, the two pupils can be extremely narrowed, the light reflection disappears, the sides of the eyes are inclination, the same deviation, or the sides of the eyes are separated.

3. Cortical rigidity

It is one of the important manifestations of midbrain injury. Because there is a center in the midbrain vestibular nucleus level that promotes extensor contraction, the midbrain red nucleus and its surrounding reticular structure are the centers that inhibit extensor contraction. When cut off between the two, decortical rigidity occurs. It is manifested by increased extensor tone, hyperextension of both upper limbs and internal rotation, excessive extension of the lower limbs, and an arch of the back of the head in the form of an angled bow. Less severe injuries may be paroxysmal, and severe ones may persist.

4. Cone bundle sign

It is one of the important signs of brain stem injury. Including limb paralysis, increased muscle tone, hypertenoid reflexes and pathological reflexes. In the early stage of brainstem injury, due to various factors, the appearance of pyramidal tract signs is often not constant. However, when the base is damaged, the signs are often constant. For example, one side of brainstem injury is manifested as cross paralysis, including limb paralysis, increased muscle tone, hypertenoid reflex, and positive pathological reflex. When the severe injury is in the acute shock phase, all reflexes can disappear, and it can only appear after the condition is stable.

5. Changes in vital signs

(1) Respiratory dysfunction Respiratory dysfunction often occurs immediately after injury. Disturbances in respiratory rhythms, such as Chen-Shi breathing, occur when the respiratory regulation centers in the lower midbrain and upper pontine are damaged; when the long inhalation center in the lower part of the pontine is damaged, sobbing breathing can occur; When the exhalation center is damaged, respiratory arrest occurs. In the early stages of secondary brainstem damage, such as the formation of cerebellar notch hernias, respiratory rhythm disorders first occur, and Chen-Shi breathing, in the later stages of cerebral hernia, intracranial pressure continues to rise, cerebellar tonsil hernias appear, compressing the medulla oblongata , Breathing stops first.

(2) Cardiovascular dysfunction When the medulla oblongata is severe, the respiratory heartbeat stops quickly and the patient dies. Respiratory and circulatory disturbances that occur during higher brainstem injury often have a period of excitement. At this time, the pulse is slow and strong, the blood pressure rises, the breathing is deep or wheezing, and then it turns into failure, pulse frequency, blood pressure drops, breathing. Tide-like, finally the heartbeat and breathing stopped. Generally, the breathing stops first. Under the condition of artificial respiration and medication to maintain blood pressure, the heartbeat can still be maintained for several days or months, and finally it often died of heart failure.

(3) Changes in body temperature Sometimes high fever can occur after brainstem injury, which is mostly due to impaired sympathetic nerve function and sweating dysfunction, which affects body heat dissipation. When brainstem failure occurs, body temperature can drop below normal.

6. Visceral symptoms

(1) Upper gastrointestinal bleeding is caused by acute gastric mucosal lesions caused by stress on brain stem injury.

(2) Stubborn hiccup

(3) Neurogenic pulmonary edema is caused by sympathetic nerve excitement, which causes increased resistance to systemic circulation and pulmonary circulation.

Brain stem injury examination

Laboratory inspection

Lumbar puncture, normal or slightly increased cerebrospinal fluid pressure, mostly bloody.

2. Other auxiliary inspections

(1) The incidence of skull fractures on plain X-ray plain radiographs is high. It is also possible to infer the situation of brain stem injury based on the location of the fracture and the injury mechanism.

(2) The primary brainstem injury of CT and MRI scans of the brain showed swelling of the brainstem, a little patchy area of increased density, compression and occlusion of the inter-foot pool, bridge pool, quadrilateral pool and fourth ventricle. In addition to showing signs of secondary lesions, the brainstem injury of secondary brain hernia can also be seen as displacement of the brainstem under compression and distortion. MRI can show small bleeding lesions and contusions in the brainstem. The effect of sexual artifacts is clearer than CT.

(3) Intracranial pressure monitoring is helpful to identify primary or secondary brainstem injury. The secondary may have a significant increase in intracranial pressure, but the primary does not increase significantly.

(4) Brainstem auditory evoked potential (BAEP) is an electrophysiological activity on the brainstem auditory pathway, which is transmitted to the far-field potential through the cerebral cortex to the scalp. The electrophysiological activity reflected by it is generally not disturbed by other external lesions, and can more accurately reflect the level and extent of brain stem injury.

Brain stem injury diagnosis

Primary brainstem injury and other craniocerebral injuries often overlap with clinical symptoms, making differential diagnosis difficult. The diagnosis of primary brainstem injury is basically established in patients who are immediately comatose with progressive exacerbation, with variable pupil size, early onset of respiratory and circulatory failure, decortical rigidity, and positive bilateral pathological signs.

Differential diagnosis of brain stem injury

The difference between primary brainstem injury and secondary brainstem injury lies in the appearance of symptoms and signs sooner or later. Symptoms and signs of secondary brain stem injury gradually develop after injury. Continuous monitoring of intracranial pressure can also be identified: the primary intracranial pressure is not high, and the secondary is significantly increased. At the same time, CT and MRI are also effective means of differential diagnosis.

MRI is significantly better than CT in showing small hemorrhages or contusions in the brain parenchyma, especially minor damage to the corpus callosum and brain stem. Brainstem auditory evoked potentials can more accurately reflect the level and extent of brainstem injury. Usually the waves below the lesion of the auditory pathway are normal, and the level of the lesion and the waves above it show abnormality or disappearance. Continuous pressure measurement of intracranial pressure monitoring can also identify primary or secondary brain stem injury, although The clinical manifestations were the same, but the intracranial pressure was normal in the primary and significantly increased in the secondary.

Brain stem injury treatment

Severe primary brainstem injuries with a longer duration of coma require tracheotomy, ventilator-assisted breathing, and mild hypothermia as early as possible. For patients with mild brainstem injury, they can be treated according to cerebral contusion and laceration, and some patients can get good results. For severe patients, the mortality rate is very high, so the treatment work should be careful, long-term plans, and nursing Work is particularly important, and at the same time, pay close attention to prevention and treatment of various complications.

1. Protect the central nervous system, use hibernation therapy to reduce brain metabolism as appropriate; actively fight cerebral edema; use hormones and neurotrophic drugs.

2. Whole body supportive therapy to maintain nutrition, prevent and correct water and electrolyte disorders.

3. Actively prevent and manage complications. The most common are lung infections, urinary tract infections, and pressure ulcers. Intensive care, close observation, early detection, and timely treatment. For patients with severe conscious disturbance and respiratory dysfunction, early tracheotomy is necessary, but after tracheotomy, care should be strengthened to reduce the chance of infection.

4. For secondary brain stem injury, a clear diagnosis should be made as soon as possible, and the cause should be removed in time. If the delay is too long, the effect is not good.

5. The recovery period should focus on the improvement of brainstem function. It can be treated with wakeful medicine and hyperbaric oxygen chamber to enhance the body's resistance and prevent complications.