Locked-in Syndrome

Locked-in Syndrome
Body Parts: Head
Medical Subjects: Nervous System Brain

What Is A Locked-in Syndrome?

Locked-in syndrome refers to a special type of brain injury syndrome, in which patients can't swallow and talk, have no facial expression, can't turn their heads and shrug their shoulders, and have quadriplegia and weakness. However, they have clear consciousness, normal hearing, can sense pain, can receive external information through audio-visual, and can signal by opening eyes, closing eyes and moving eyes up and down.

Therefore, locked-in syndrome is also known as "lost state", "pseudocoma" and "alertness coma". This disease is mostly caused by bilateral infarction or hemorrhage at the base of the pons.

Is locked-in syndrome common?

This syndrome is rare.

Is locked-in syndrome and "vegetative state" a condition?

No, locked-in syndrome patients with clear consciousness, can accept outside information through visual and auditory. The brain's ability to integrate information and thinking is normal. Can express ideas through eye movements and other movements, but cannot move limbs or speak.

Vegetative state usually refers to that the patient only retains some instinctive neural reflex and metabolic ability of material and energy. The cognitive ability of the brain (including the ability to receive and process information and thinking ability) has been completely lost without any active activity.


What Are The Causes Of Locked-in Syndrome?

The vast majority of locked-in syndrome is caused by infarction of the basal part of the pons due to bilateral occlusion of the paracentral arteries from the basilar artery. Other possible causes of locked-in syndrome (e.g. trauma, abscess, tumor, etc.) are rare.

The infarction at the base of the pons caused the damaged corticospinal tract from the cerebral cortex to the anterior horn of each segment of the spinal cord to be unable to control the movement of the trunk and limbs, thus leading to quadriplegia. At the same time, the corticobulbar tract, which runs from the cerebral cortex to the medulla oblongata, is damaged, making it impossible for the patient to turn his head, shrug, swallow and pronounce. At the same time, the facial nucleus located in the pons and the nucleus controlling eyeball movement were damaged, resulting in the loss of facial expression and inability to move eyeball horizontally.

However, the functions of the reticular activation system of the pons tegmentum, the supranuclear eyeball movement conduction pathway, the spinothalamic tract, and the advanced cerebral cortex were not damaged, so the patient had a clear consciousness, and the eyeball could open and close its eyes as well as move up and down, with sensation retention, and cognitive functions such as memory, calculation, and thinking retention.

There are many causes of arterial occlusion, which may originate from hypertension, hyperglycemia, hyperlipidemia, smoking and drinking, advanced age and other related atherosclerosis, or may originate from arterial embolism or small vessel lesions.


What Are The Symptoms Of Locked-in Syndrome?

Patients with locked-in syndrome are characterized by inability to move their limbs, trunk, head and neck, inability to swallow and speak, and no facial expression, but they have clear consciousness, normal hearing, and the ability to sense pain. They can receive external information through audio-visual, and can indicate by opening and closing their eyes, as well as by moving their eyeball up and down, but their eyeball cannot move horizontally.

Where does locked-in syndrome often occur?

Locked-in syndrome involved bilateral corticospinal tracts and corticospinal tracts. In addition, the nerve nuclei and conduction pathways that control eye movement will also be affected (mainly including the medial longitudinal fascia and the lateral visual center of the pons). The lesion is usually located in the pons, and occasionally the internal capsule and the feet of the brain.

What diseases are the symptoms of locked-in syndrome similar to?

Locked-in syndrome needs to be distinguished from other conditions that cause tetraplegia, such as high-segment spinal cord lesions, coma, vegetative state, motor inability to mutism, tension, or psychogenic non-response.


How To Check For Locked-in Syndrome?

Usually, doctors need to consider according to the typical clinical manifestations and signs of patients, and the diagnosis of locked-in syndrome needs to meet two conditions:

  1. Patient's alertness and cognitive function are preserved.
  2. Because of limb paralysis and facial nerve paralysis, patients can't communicate with the outside world by using limbs and language.

Combined with cranial imaging, it can be confirmed that there is infarct focus in pons, internal capsule or midbrain consistent with the symptoms, which can lead to the definite diagnosis.

What tests do patients with locked-in syndrome need to do? Why do these tests?

  • Cranial imaging including cranial CT or MRI Craniography helps to identify the lesion and MRI has a higher resolution than CT for lesions in the brain stem.
  • Cranial vascular imaging, including CTA or MRA, which helps to clarify the location and etiological classification of vascular infarction.

Can Locked-in Syndrome Be Prevented?

In most cases, the prevention of locked-in syndrome is the same as that of cerebral infarction.

For those with high risk factors of cerebrovascular disease, such as old age, smoking and drinking, hypertension, hyperlipidemia, hyperglycemia, obesity, hyperhomocysteinemia, genetic history, etc. We should actively control these risk factors, regularly check the cardiovascular and cerebrovascular conditions, and insist on primary prevention, which can effectively prevent the occurrence probability of cerebral infarction.


How To Treat Locked-in Syndrome?

The treatment of locked-in syndrome should give priority to the identification of the etiology. Most of them are a special type of cerebral infarction, which is consistent with the treatment of general acute cerebral infarction, including acute stage treatment, secondary prevention treatment and complication treatment.

Acute phase treatment

Cerebral infarction within 6 hours of onset belongs to the disease of ultra early, should actively strive for intravenous thrombolysis treatment, commonly used drugs for alteplase or urokinase, for more than time or cases such as large artery stenosis can also consider intravascular treatment.

For patients who are not suitable for thrombolytic therapy or intravascular therapy, antithrombotic, lipid-lowering and plaque-stabilizing therapy should be used, supplemented by drugs such as improving circulation, scavenging oxygen free radicals and protecting brain, and actively managing blood pressure and blood sugar. Once the condition is stable, rehabilitation treatment can be started as soon as possible.

Prevention and treatment of complications

Patients are more likely to have complications due to serious damage of nervous system function, including pulmonary infection, urinary tract infection, bedsore, deep vein thrombosis, water, salt and electrolyte disorder, nutrition imbalance. Active prevention and treatment of complications is particularly critical for the treatment of patients.

Secondary prevention and treatment

According to the etiological classification of cerebral infarction, choose appropriate antithrombotic scheme to prevent recurrence of cerebral infarction.

What is the prognosis of patients with locked-in syndrome?

Most of them have poor prognosis, which easily leads to death, and some survivors are still in a long-term locked state or have severe functional impairment. However, many patients will recover part of their motor function over time, and a few patients will recover well.


What Should Patients Pay Attention To In Their Lives?

Patients with locked-in syndrome rely entirely on others for their lives because of severe dyskinesia. Accompanying staff should regularly turn over and pat the back, massage and move the limbs of the patient to reduce the risk of hypostatic pneumonia and venous thrombosis. At the same time, attention should be paid to the mental health of patients, and necessary communication should be given. Electronic equipment can also be used to assist communication.


Patients with locked-in syndrome should be provided with nasal feeding tube to ensure nutritional support due to dysphagia. Attention should be paid to balanced nutrition in liquid diet to ensure a certain amount of heat and protein.

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