Introduction 

Imagine being fully awake, aware of the surroundings, understanding conversations, able to feel pain and emotions — yet completely unable to move or speak. This is the daily reality for those living with Locked-In Syndrome (LIS), a rare condition often confused with disorders of consciousness (DoCs) like vegetative or minimally conscious states. 

While these conditions may look very similar in appearance, marked by extremely limited movement or lack of response, differences between them are profound and critical, drastically affecting care and treatment. So how can we tell them apart? 

In this article, we will explore the difference between LIS and disorders of consciousness and explain the essence of their accurate identification. This is important, not just for medical treatment, but for preserving the dignity and voice of those who may still be very much aware and their families and surroundings to lessen the unnecessary emotional toll. 

What is locked-in syndrome? 

Locked-In Syndrome (LIS) is a rare neurological condition in which almost all voluntary muscles are paralysed, resulting in quadriplegia, an inability to speak (anarthria), chew, or swallow, except for limited eye movements. However, patients remain fully conscious with intact cognitive abilities (i.e. thinking, memory, understanding), hearing, and potential sensations for touch and pain.  

While most people with LIS can still blink or move their eyes vertically (up and down), these 

movements would become their primary means of communication. They can either spell out words through yes/no questions via blinking or the use of assistive eye-tracking devices for more complex communication needs or emotional expressions.  

LIS is most commonly caused by either an ischemic or hemorrhagic stroke in the (anterior or ventral) pons of the brainstem, an area that specifically sends voluntary motor signals from the brain to the body. Other causes include traumatic brain injury (TBI), infections, tumours, or any damage to the pons, as well as advanced demyelination conditions like multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and Guillain-Barre Syndrome (GBS)¹.  

Since people with LIS cannot move or speak and appear unable to react, especially those with total locked-in syndrome (TLIS), who may even lose vertical eye movements, they are often mistaken for being in a coma or vegetative state.  

What are disorders of consciousness? 

Disorders of consciousness (DoCs) or impaired consciousness occur when a person is unconscious (not awake or aware) or semi-conscious, resulting from a variety of severe brain injuries. These include vegetative state (VS), minimally conscious state (MCS), and coma.²

It is called a prolonged disorder of consciousness (PDoC) whenever it lasts more than a month. 

Coma

Coma is a state of complete unconsciousness without wakefulness induced by widespread damage to all brain regions3. Lasting for days to a few weeks, most cases will begin to recover within 2-4 weeks if they survive, either awake or falling into vegetative or minimally conscious states.⁴

Vegetative state (VS)

Vegetative state (VS), aka unresponsive wakefulness syndrome (UWS), is when a person is awake, has regular eye opening, closure, sleep-wake cycles, yet no signs of awareness of themselves and their surroundings.

Although reflexive movements like teeth grinding, swallowing, grunting, and involuntary heartbeat and breathing regulations may be intact due to an active brainstem. Resulting from the severely damaged cerebral cortex, no purposeful responses exist to external voices, touch, or commands; signs of emotional experiences and cognitive functioning are also absent.^3,4,5 

Minimally conscious state (MCS)

Minimally conscious state (MCS) describes the severely altered consciousness of intermittent, limited, yet definite, purposeful signs of awareness. 

As a recovery transition from coma or VS in some cases, those in MCS may inconsistently follow simple commands, make eye contact, and even verbalise.

Diagnosis is generally very difficult as these purposeful responses may come and go, varying from day to day, even moment-to-moment.^3,4

Key clinical differences

Consciousness 

In LIS, the person is fully conscious and aware of their surroundings but unable to move or speak. Conversely, there is no wakefulness or awareness in a coma. Someone in VS is awake yet lacks awareness, while those in MCS show limited yet inconsistent, brief periods of awareness on occasion.  

Eye movements

People with LIS can usually retain some vertical eye movements and blinking, which becomes the key to communication. Individuals in a coma have their eyes closed without any movements. Eye movements are non-purposefully, reflexive, or random in VS; those in MCS may track moving objects or stimuli with sustained fixation inconsistently.  

Communication 

Individuals with LIS can often communicate voluntarily through vertical eye movements or blinking. Those in a coma are totally unable to communicate. Those in VS cannot communicate purposefully, despite occasional moaning or grunting; MCS may still exhibit inconsistent and limited responses through gestures, facial expressions, or sometimes verbalisation, though these are brief and unreliable. 

Motor function 

LIS often leads to near-total paralysis, where residual motor functions are limited to eye movements. Those in a coma are typically unable to move. VS retains only non-purposeful, reflexive, automatic movements like eye opening, heartbeat and breathing. MCS can occasionally involve brief voluntary smiling, crying, eye movements, sustained fixation, and even reaching for objects. 

Brain activity

The EEG is usually normal in LIS, as cognitive functions are not affected. It is significantly reduced or suppressed in a coma. Brain waves are severely slowed and disorganised in VS; they become variable and may potentially show higher-level processing sometimes in MCS.⁶

Prognosis and recovery 

Although there is little chance of physical recovery in LIS, people may still have stable or slow improvements with proper care and assistive communication aids. A coma can either lead to recovery, VS, or MCS. Vegetative states typically have a poor prognosis, especially if they persist for more than a year, despite the possibility of transiting to MCS. Minimally conscious state generally offers a potential for partial recovery, yet progress is often slow with varying outcomes. 

Diagnosis and challenges 

Diagnostic tools 

Diagnosing Locked-In Syndrome and disorders of consciousness requires a combination of clinical and technological tools:

• Neurological examination in assessing the level of consciousness, cognition, eye movements, and reflexes
• Brain imaging, like computed tomography (CT), magnetic resonance imaging (MRI), and even cerebral angiogram, to “look” into the brain for structural damage, especially in the brainstem for LIS. 
• An electroencephalogram (EEG) measures brain activity to detect potential awareness through monitoring neuronal communications 
• Evoked potentials measure the brain’s response to sensory inputs 
• Functional MRI (fMRI) and Positron Emission Tomography (PET) scans are used to detect hidden signs of awareness that are not visible through external behaviours alone 
• Coma-Recovery Scale-Revised (CRS-R) to track and assess subtle signs of consciousness and reproducible responses 
• Communicating Test to ask yes/no questions and observe either vertical gaze or eye blinking responses to confirm awareness for LIS⁷

Why is diagnosis so difficult?

Differentiating between Locked In Syndrome, coma, vegetative state, and minimally conscious state can be exceptionally challenging, as patients often have little or no ability to move or speak, making it harder to assess awareness. 

Some may appear unresponsive even if they are conscious, such as in LIS, where individuals are fully aware but unable to move any muscles except those of the eyes, even losing eye movements for the most severe TLIS subtype. 

Signs of awareness can be subtle and inconsistent in MCS, such as brief tracking of objects or a small gesture that can be easily missed during a routine exam. Reflexive behaviours in VS can also mimic purposeful actions, causing confusion. 

Ethical risks of misdiagnosis 

Misdiagnosis of a person with Locked-In Syndrome or a disorder of consciousness can have serious ethical consequences. 

If someone with LIS is mistaken as unconscious, they may be denied the chance to communicate, participate in decision-making, or even receive appropriate care, despite being fully aware. In turn, intensifies the immense inner fear and isolation.

Similarly, mislabeling a minimally conscious state vegetative could also lead to withdrawal of life-sustaining treatment, even when potential recovery is still possible.

These errors not only affect the patient’s dignity and basic rights, but also escalate the emotional strain on families making life-altering decisions. Highlighting the necessity of testing for voluntary eye movements and awareness.  

Clinical and ethical implications 

Treatment approaches 

Locked-in syndrome

Despite being incurable, management of LIS typically focuses on communication training and complication prevention. This often includes specialised coding systems, communication boards, eye-tracking devices, and supportive therapies like pneumonia, urinary tract infections (UTIs), thrombosis, bedsores prevention, physical therapy for minor movements recovery, even chest PT, and tracheostomy care to prevent further complications, support mobility and daily function. 

Vegetative/minimally conscious states 

Due to severe cerebral damage, treatments for VS and MCS are mainly supportive, such as ensuring proper nutrition and hygiene through feeding tubes and catheters, and preventing infections. However, individuals in MCS may still benefit from neurorehabilitation, including sensory stimulation (e.g., Coma Arousal Therapy) and functional communication establishment.

Ethical considerations 

Ethical challenges arise when patients are incapable of expressing their wishes clearly.  Preserving autonomy is foremost for LIS cases through communication tools and assistive technology like eye-tracking or blinking to allow for informed decisions about their care. 

Patients in vegetative or minimally conscious states, in contrast, are unable to make informed decisions due to uncertainty or absence of awareness. The difficulty in determining their preferences further complicates the decision about continuation or withdrawal of life-sustaining treatment. This highlights the need for careful, repetitive assessments, as well as supporting the emotional stability of families and caregivers. 

Support to families and caregivers 

Families and caregivers of individuals with LIS, vegetative state, or minimally conscious state often face overwhelming emotional and practical challenges. 

While understanding the diagnosis is the most critical step for setting realistic expectations and reducing confusion.. Access to psychological interventions and counselling services, such as grief counselling, stress management, trauma-informed therapy, and peer support groups, can help navigate through the complex treatment and end-of-life care decisions. Moreover, clear communication with healthcare professionals can also empower families to make informed decisions and feel more supported in the care process. 

Summary 

Locked-In Syndrome (LIS) and disorders of consciousness (DoC), such as coma, vegetative state (VS), and minimally conscious state (MCS), are often confused due to overlapping physical symptoms. However, they are significantly different in terms of awareness, communication, and prognosis: individuals with LIS are fully conscious yet unable to move or speak, while VS and MCS involve varying degrees of impaired consciousness. 

A combination of various tools, including neurological examination, brain imaging, and advanced tools, is used to avoid misdiagnosis. Ethical decisions and support for families vary according to the correct identification of each condition. Raising awareness for accurate diagnosis of these conditions is not only clinically important for providing more compassionate care and support, but also crucial for maintaining the autonomy and dignity of the affected individuals and their families.

FAQs 

How is akinetic mutism different from LIS, vegetative state, and minimally conscious state? 

Akinetic mutism is when a person is awake and aware but cannot move or speak due to a severe lack of motivation or drive, often resulting from frontal brain damage. Unlike LIS, where patients are fully conscious and try to communicate through the eyes, those with akinetic mutism have little or no effort to respond. This is also different from vegetative and minimally conscious states, that which awareness may be fine, albeit extremely limited or absent, of purposeful behaviour. 

Can someone wake up from a coma into locked-in syndrome? 

Yes, it is, especially after severe brain stem injury, such as a pontine stroke. The person regains consciousness by remaining nearly totally paralysed, often only able to move their eyes, easily being mistaken for continued unconsciousness.