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Locked-in Syndrome

Locked in Syndrome

Locked-in syndrome is a rare condition usually caused by ischemic stroke, trauma or hemorrhage, affecting the corticospinal, corticopontine and corticobulbar tracts in the brainstem. It is characterized by quadriplegia and anarthria with preservation of consciousness.


The following are the characteristic signs and symptoms of LiS:

  • Inability to control movements of the lower face
  • Inability to chew, swallow and speak
  • Difficulty in breathing
  • Lower limbs become immobile 
  • Lateral movement of eye is not possible [7]
  • Individuals can only blink eyes a number of times and vertically move their eyes.
  • Hearing ability is intact and patients respond by blinking their eyes.
Diastolic Murmur
  • On physical examination, she had a 40-point difference in blood pressure between her left and right arms, and a loud diastolic murmur.[ncbi.nlm.nih.gov]
  • Thus, trismus may be associated with locked-in syndrome due to megadolichobasilar artery thrombus, although yawning is still possible.[ncbi.nlm.nih.gov]
  • In pontine lesions with tetraplegia and cranial-nerve disturbances--including trismus--and with speech disability paralytic akinesia and loss of reactivity may be misinterpreted as coma.[ncbi.nlm.nih.gov]
Dry Eyes
  • This impairment is multifactorial including mostly binocular diplopia or oscillopsia but also refractive errors, dry eye syndrome, keratitis or visual field defect.[ncbi.nlm.nih.gov]
  • An abnormal visual field was observed in 17% of patients, and abnormal pupillary light response leading to photophobia was present in 22% of patients.[ncbi.nlm.nih.gov]
Ear Discharge
  • Streptococcus pneumoniae and Haemophilus influenzae were cultured from the purulent ear discharge. CONCLUSION: The final diagnosis was locked-in syndrome consecutive to inflammatory changes compressing the basilar artery.[ncbi.nlm.nih.gov]
  • Locked-in syndrome is characterized by quadriplegia, lower cranial nerve paralysis, and mutism but with maintenance of consciousness, as well as vertical eye movements and eyelid blinking.[ncbi.nlm.nih.gov]
  • Quadriplegia is one of the most serious clinical manifestations in patients with LIS. However, little is known about the motor recovery mechanism of quadriplegia in patients with LIS.[ncbi.nlm.nih.gov]
  • BACKGROUND: The locked-in syndrome is defined as quadriplegia and anarthria (loss of articulate speech) with the preservation of consciousness. It is typically caused by a lesion to the ventral pons.[ncbi.nlm.nih.gov]
  • BACKGROUND: Basilar artery occlusion can cause locked-in syndrome, which is characterized by quadriplegia, anarthria, and limited communication via eye movements.[ncbi.nlm.nih.gov]
  • OBJECTIVE AND IMPORTANCE: Locked-in syndrome is a state of preserved consciousness in the setting of quadriplegia, anarthria, and usually also includes lateral gaze palsy.[ncbi.nlm.nih.gov]
  • Our patient's neglect prevented the use of augmentative communication devices based on a computerized eye-tracker system. For this reason, we adapted a visual scanning training for neglect rehabilitation.[ncbi.nlm.nih.gov]
  • The outpatient therapy group was associated with complete UE/LE hemiplegia, unilateral neglect, impaired proprioception, and urinary incontinence.[emedicine.com]
  • The EEG oscillations were analyzed using average power over the 15 s answering period, neglecting the temporal dynamics of the EEG across the answering period.[journals.plos.org]
Unresponsive to Pain Stimuli
  • […] to painful stimuli (inability to withdraw an extremity from painful stimuli) No horizontal eye movements Cannot consciously chew food, swallow, breathe, speak, or move voluntary muscles Must rely on caregivers for most basic functions (body movements[medicinenet.com]
Upbeat Nystagmus
  • To our knowledge, the change from ocular bobbing to upbeat nystagmus has not been previously reported in the Locked-in syndrome. Bilateral involvement of the lateral lemniscus might have contributed to its appearance in our patient.[ncbi.nlm.nih.gov]
  • In pontine lesions with tetraplegia and cranial-nerve disturbances--including trismus--and with speech disability paralytic akinesia and loss of reactivity may be misinterpreted as coma.[ncbi.nlm.nih.gov]


The diagnosis of LiS often becomes difficult as the signs and symptoms of the syndrome often mimic other diseases as well. In many cases, it takes as long as 2.5 years to appropriately diagnose the disease. Various neuroimaging tests should be carried out to rule out other disease conditions [8]. In addition, imaging studies such as CT scan and MRI should be done to detect the location of the brain lesion.

Angiographic studies of the basilar veins using contrast enhanced imaging may effectively localize the lesions [9]. In addition, confirmatory tests such as PET or functional MRI need to be carried out examine the cerebral functioning. EEG is also done that shows sleep wake patterns which is a characteristic feature for patients with LiS.


Locked-in syndrome cannot be cured and there is no standard treatment regime to treat the condition. Depending on the cause of the syndrome and nature of severity of the symptoms, treatment is tailor made for each individual.

The primary goal is to treat the underlying cause and employ methods to restore cognitive and motor functioning [10]. Electrodes are used for stimulation of the muscle reflexes. In addition, Dasher technology is used for helping the individuals communicate. Recent advancements in the treatment methods have introduced mechanisms such as direct brain interface that helps patients answer yes–no questions. Treatment methods should also be channelized to prevent the onset of various systemic complications.


With appropriate initiation of treatment, the neurological functions such as horizontal eye movements begin to restore within the first four weeks. Younger individuals have a better prognosis than the adults. It has also been seen that, about 85% of affected individuals have a better survival rate with effective treatment and rehabilitation program. However, affected individuals often suffer from muscle stiffness and tightness also known as spasticity for the rest of their life.


The following are the several complications associated with Locked-in Syndrome:


Development of acute brainstem lesions is the most potential cause of Locked-in Syndrome. The lesions develop as a result of arterial thrombosis accompanied by obstruction of the affected artery. The other causes of LiS include the following:

In addition to the above mentioned causes, there have been certain pieces of evidence suggesting an association between cervical manipulation and artery dissection. However, such a kind of relation is not sufficiently backed up with research studies.


The exact incidence of Locked-in Syndrome is not recorded. However, with the available literature, it can be estimated that the onset of acute infections in patients with LiS was the cause of death in about 40% of the cases. The development of stroke was the primary cause of death in 25% of individuals with LiS.

Sex distribution
Age distribution


Locked-in Syndrome is basically divided into 3 categories:

  • Total LiS characterized by complete paralysis of the limbs, facial muscles including the eyes.
  • Incomplete LiS wherein there are some limb movements with eye blinks and movements.
  • Classical LiS wherein only eye movements are present.

LiS occurs due to damage to the lower portion of the brain along with the brainstem. The development of brainstem lesion is known to be the major cause of this syndrome. These lesions gravely affect the corticospinal tracts and cranial nerves IV and VI. When the facial nerves and lower cranial nerves are affected it specifically leads to paralysis of the facial muscles causing impaired speech with disruption of swallowing function.


So far no guidelines have been designed to prevent the onset of LiS. However, if the disease is diagnosed in its early stages and treatment initiated then complications can be prevented and significant restoration of cognitive and motor functions can be achieved.


Locked-in Syndrome, abbreviated as LiS, is a disease characterized by a state wherein the affected individual is awake and fully aware of the surroundings but is unable to react or communicate due to paralysis of the limbs and facial muscles [1]. Such a syndrome is also known as pseudocoma and was first described in the year 1966 by Fred Plum and Jerome Posner.

In this condition limbs and facial muscles are paralyzed except the eyes. However, in total Locked-in Syndrome, the individuals are unable to move the eyes as well. Functions of breathing, phonation and swallowing may all be interrupted due to LiS.

Patient Information


Locked-in Syndrome (LiS) is a state of wakefulness wherein the patient is awake and aware of the surroundings but is unable to communicate due to paralysis of the limbs and facial muscles.


The development of brain lesions either due to stroke, brain hemorrhage or other disease conditions gives rise to LiS. In some cases, drug overdose can also lead to LiS.


LiS precipitates as paralysis of the lower limbs and the facial muscles that greatly impairs the cognitive as well as motor functioning. Patients with LiS are unable to use their lower facial muscles which in turn cause inability to swallow, eat, talk and breathe. Eyes of the affected individuals are wide opened and can communicate only through vertical eye movements. 


Diagnosis is made by carefully studying the clinical features followed by determination of the location of the brain lesion through imaging studies. Neuroimaging studies are also carried out to rule out the possibility of other disease conditions. EEG tests shows sleep wake pattern that confirms LiS.


Treatment of LiS is done by employing methods to treat the underlying disease conditions. Various methods such as Dasher technology and use of electrodes can be employed for restoring the cognitive and motor functioning. Patients are also given speech therapy to help regain their speaking ability.



  1. Laureys S, Pellas F, Van Eeckhout P, Ghorbel S. The locked-in syndrome: what is it like to be conscious but paralyzed and voiceless? Prog Brain Res. 2005; 150:495-511 
  2. Bauer G, Gerstenbrand F, Aichner F. Locked-in syndrome: pseudocoma from pons sections. Psychiatr Neurol Med Psychol Beih. 1983; 29:139-45
  3. Rizzo MA, Fisher M, Lock JP. Hypermagnesemic pseudocoma. Arch Intern Med. 1993; 153(9):1130-2 
  4. Flügel KA, Fuchs HH, Druschky KF. The "locked-in" syndrome: pseudocoma in thrombosis of the basilar artery (author's transl) Dtsch Med Wochenschr. 1977; 102(13):465-70 
  5. Shaibani A, Sabbagh MN. Pseudoneurologic syndromes: recognition and diagnosis. Am Fam Physician. 1998; 57(10):2485-94
  6. Chaves CJ, Caplan LR, Chung CS, et al. Cerebellar infarcts in the New England Medical Center Posterior Circulation Stroke Registry. Neurology. Aug 1994; 44(8):1385-90.
  7. Wall M, Wray SH. The one-and-a-half syndrome--a unilateral disorder of the pontine tegmentum: a study of 20 cases and review of the literature. Neurology. Aug 1983; 33(8):971-80.
  8. Kim D, Liebeskind DS. Neuroimaging advances and the transformation of acute stroke care. Semin Neurol. Dec 2005; 25(4):345-61.
  9. Sylaja PN, Puetz V, Dzialowski I, et al. Prognostic value of CT angiography in patients with suspected vertebrobasilar ischemia. J Neuroimaging. Jan 2008; 18(1):46-9.
  10. Bahouth MN, LaMonte MP. Acute ischemic stroke: evaluation and management strategies. Top Adv Pract Nurs. 2005; 5(4).

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Last updated: 2018-06-22 05:14