CA S E S TU DY
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A case of locked-in syndrome complicated
by central deafness
Colette M Smart*, Joseph T Giacino, Tara Cullen, Diana Rodriguez Moreno, Joy Hirsch, Nicholas D Schiff
and Martin Gizzi
S U M M ARY
Background A 53-year-old male with a history of hypertension, diabetes

mellitus, and factor V deficiency presented to an emergency room with
progressively increasing headache, slurred speech, and left upper extremity
weakness. Over the previous 3 months, he had been receiving warfarin
for prophylaxis of deep venous thrombosis following knee surgery. After
presentation and an initial period of coma, he became tetraplegic and
anarthric, requiring intubation and ventilatory assistance.
Investigations Neurological examination, CT scan, electroencephalogram,
brainstem auditory and visual evoked potential studies, neuropsychological
assessment and functional MRI studies.
Diagnosis Locked-in syndrome following ventral pontine hemorrhage,
complicated by central deafness secondary to extension of the lesion to the
inferior colliculus.
Management Development of an augmentative communication system
designed to exploit the patient’s preserved cognitive and motor functions.
keywords central deafness, disorders of consciousness, locked-in syndrome,
neuropsychological testing, stroke

cme

CM Smart is a Postdoctoral Fellow in Clinical Neuropsychology at the JFK
Johnson Rehabilitation Institute and the New Jersey Neuroscience Institute,
JFK Medical Center, Edison, NJ, JT Giacino is an Associate Professor in the
Department of Neuroscience at Seton Hall University, South Orange, NJ, and
Associate Director of Neuropsychology at JFK Johnson Rehabilitation Institute
and the New Jersey Neuroscience Institute, JFK Medical Center, Edison, NJ,
T Cullen is a Speech-Language Pathologist at the JFK Johnson Rehabilitation
Institute, Edison, NJ, D Rodriguez Moreno is a Postdoctoral Fellow in the
fMRI Research Center at Columbia University, New York City, NY, J Hirsch
is a Professor in the Departments of Radiology, Neuroscience and Psychology,
and Director of the fMRI Research Center at Columbia University, New York
City, NY, ND Schiff is Associate Professor of Neurology and Neuroscience
in the Department of Neurology and Neuroscience at Weill Cornell
Medical College, New York, NY, and M Gizzi is Professor and Chairman of
Neuroscience, Seton Hall University School of Graduate Medical Education,
South Orange, NJ, and Chairman of the New Jersey Neuroscience Institute,
JFK Medical Center, Edison, NJ, USA.
Correspondence
*New Jersey Neuroscience Institute, JFK Medical Center, 65 James Street, Edison, NJ 08818, USA
csmart@solarishs.org
Received 30 November 2007 Accepted 16 April 2008 Published online 27 May 2008
www.nature.com/clinicalpractice
doi:10.1038/ncpneuro0823

448 nature clinical practice NEUROLOGY

Continuing Medical Education online
Medscape, LLC is pleased to provide online continuing
medical education (CME) for this journal article,
allowing clinicians the opportunity to earn CME credit.
Medscape, LLC is accredited by the Accreditation
Council for Continuing Medical Education (ACCME) to
provide CME for physicians. Medscape, LLC designates
this educational activity for a maximum of 0.5 AMA PRA
Category 1 CreditsTM. Physicians should only claim credit
commensurate with the extent of their participation in the
activity. All other clinicians completing this activity will
be issued a certificate of participation. To receive credit,
please go to http://www.medscape.com/cme/ncp
and complete the post-test.
Learning objectives
Upon completion of this activity, participants should be
able to:
1 Identify the most common cause of locked-in
syndrome.
2 Describe the diagnostic assessment of suspected
locked-in syndrome.
3 List clinical elements of classic locked-in syndrome.
4 Identify effective therapies for patients with locked-in
syndrome.
Competing interests
The authors and the Journal Editor H Wood declared no
competing interests. The CME questions author CP Vega
declared that he has served as an advisor or consultant
to Novartis, Inc.

THE CASE

A 53-year-old right-handed male with a history of
hypertension, diabetes mellitus, hyper­lipidemia,
and factor V deficiency presented to an emergency room with headache, slurred speech, and
left upper extremity weakness and numbness, all
of which had progressively increased in severity
over a period of several hours. At the time of
presentation, the patient was receiving warfarin
(4 mg/day) for prophylaxis of deep venous thrombosis following knee surgery 3 months previously.
His initial Glasgow Coma Scale score was 12, but
his level of consciousness declined sharply in the
emergency room (Glasgow Coma Scale score = 4),
ultimately resulting in the need for ventilator
insertion. On admission to an intensive care unit
the following morning, the patient was comatose,
with no spontaneous eye opening or response
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to command, and without oculocephalic and
corneal reflexes. His spontaneous eye movements
were limited to intermittent periods of ocular
bobbing. Twenty-four hours later, the patient
recovered spontaneous eye opening but still had
no response to command and demonstrated
decerebrate posturing to noxious stimuli. An
initial head CT scan in the emergency department
revealed a ventral midline hemorrhage extending
from the pontomedullary junction to the upper
pons (hemorrhaging was greater on the right than
on the left). It was presumed that the patient had
suffered a hemorrhagic stroke secondary to use
of warfarin for deep venous thrombosis prophy­
laxis. At 36 h, there was further rostral exten­sion
of the hemorrhage to the inferior midbrain
and expansion into the left pons and midbrain. A
repeat CT scan on day 3 (Figure 1) revealed
an additional small area of hemorrhage that
involved the dorsal pontomesencephalic region,
including the inferior colliculi (particularly on
the right), in addition to tegmental edema.
By day 7, vertical pursuit eye movements and
eye movements in response to command were
noted, although these behaviors were difficult to
discern because of near-constant ocular bobbing.
The patient remained tetraplegic and anarthric.
Assessment of the patient’s voluntary eye movement on day 10 by use of the JFK Coma Recovery
Scale–Revised1 confirmed intact vertical pursuit
and reproducible eye movement to command.
These behaviors were consistent with the diagnostic
criteria for a minimally conscious state (MCS),2
although the results from electroencephalogram,
brainstem auditory evoked response (BAER)
and visual evoked response studies, conducted
approximately 5 weeks following the stroke, were
normal, which is unusual during an MCS. In view
of the large pontine lesion, a diagnosis of locked-in
syndrome (LIS) was considered.
At approximately 4 months following the stroke,
improved arousal and recovery of lateral head
movements enabled further investigation of the
patient’s cognitive status. Over a period of 2 weeks,
in up to 3 sessions per day, the patient was exposed
to simple situational orientation questions,
accompanied by visual cues. The patient’s yes or
no responses were obtained by use of shouldermounted toggle switches that were activated by
lateral head movements. Overall response consistency and accuracy during this assessment period
were 99% and 98%, respectively (Box 1).
At approximately 6 months after the stroke,
verbally presented questions that required access

Figure 1 CT scans of the brain at 3 days following stroke in a patient with
locked-in syndrome. Four axial scans show a hemorrhagic infarct of the
brainstem interrupting the auditory processing pathway at the level of the inferior
colliculi (arrows).

Box 1 Neurobehavioral assessment of a patient
with locked-in syndrome at 4 months following
onset of the condition.
■

Question type: situational orientation (verbal
and visual)

■

Sample questions: “Am I clapping my hands
right now?”; “Am I touching my nose right now?”

■

Total number of trials: 29 sessions × 12 trials
= 348 trials

■

Across-trial consistency: 344 out of 348
(4 failures to respond) = 99%

■

Accuracy of responses: 336 out of 344
(8 incorrect responses) = 98%

to semantic knowledge were added to the cognitive assessment protocol. The patient’s accuracy
and consistency of responses to simple situational
orientation questions remained high, but response
accuracy was unexpectedly poor on verbally
presented semantic knowledge questions (Box 2).

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Box 2 Neurobehavioral assessment of a patient
with locked-in syndrome at 6 months following
onset of the condition.
■

Question types: situational orientation (verbal
and visual); verbally presented semantic
knowledge

■

Sample questions: “Is a rose a flower?”; “Is
ice hot?”

■

Total number of trials: 20 sessions × 18
trials = 360 trials

■

Across-trial consistency: 358 out of 360
(2 failures to respond) = 99%

■

Accuracy of verbal situational question responses:
117 out of 119 (2 incorrect responses) = 98%

■

Accuracy of visual situational question responses:
112 out of 120 (8 incorrect responses) = 93%

■

Accuracy of verbal semantic question responses:
65 out of 119 (54 incorrect responses) = 55%

To clarify the reason for the patient’s poor
performance on semantic knowledge questions,
visually based semantic knowledge questions were
added to the cognitive assessment protocol (e.g. the
examiner showed a picture of ice cream and asked,
“Is this hot?”) at 7 months following the stroke. The
patient’s performance accuracy was 92% on visually based semantic knowledge items as compared
with 67% on verbally based questions.
Contemporaneous to the assessment of
the patient’s semantic knowledge, at around
6 months after the stroke, the patient began
using a spelling board. By use of this communication device, he reported that his sense of
hearing seemed distorted (e.g. “all is loud”)
and that speech sounded muffled, although
he had no premorbid hearing deficit. He also
reported being able to understand verbal information much better when provided in written
form. Neurobehavioral assessment was, therefore, repeated at 7 months after the stroke, with
verbal semantic items presented with or without
a written transcript. The findings revealed high
accuracy on verbal semantic items presented
both with and without a written transcript
(100% and 95%, respectively). However, the
patient’s response accuracy to yes or no questions
was poor without the aid of written transcripts
during interactions conducted outside the formal
assessment protocol. It was unclear whether
the general inconsistency between the patient’s
response to verbal versus visual questioning
450 nature clinical practice NEUROLOGY

was attributable to cognitive impairment or a
disturbance in auditory processing.
At approximately 10 months following the
stroke, the patient underwent neuro­psychological
testing based on a protocol proposed by Neumann
and Kotchoubey for cognitive assessment of
severely paralyzed patients.3 Specifically, the
patient’s general fund of knowledge, receptive
language, memory, and executive functioning were
examined. All test instructions were presented in
visual form, and the patient used a spelling board
during tests that required open-ended responses.
Premorbid intellectual function was estimated to
be in the average range. On tests of discrete cognitive functions, the patient’s performance was
within normal limits on all measures except rate of
new learning (Table 1), indicating that higher-level
cognitive functions were essentially intact.
At approximately 1 year following the stroke,
functional MRI (fMRI) studies were performed
to assess the integrity of the patient’s neural
networks that underlie auditory and visual
processing.4–6 In a hierarchical scanning
paradigm, the patient was exposed to passive
auditory stimulation under two conditions
(intelligible speech and unintelligible, reversed
speech) followed by passive visual stimulation under two conditions (landscapes and
faces). Instructions for all tasks were presented
in written form. Standard blood oxygen leveldependent (BOLD) signal analyses were
performed by use of the statistical parametric
mapping package SPM2 (Wellcome Department
of Imaging Neuroscience, Institute of Neurology,
University College London, London, UK).
The passive speech paradigm failed to elicit
the expected activation of the superior temporal
gyrus (the primary structure responsible for
mediating language comprehension) during the
normal speech condition (Figure 2A). Moreover,
activation of the primary auditory cortex, which
is responsible for basic sound reception, was weak
and inconsistent across both language conditions, suggesting impaired discrimination of
speech from background scanner noise. Findings
from the passive visual paradigm revealed activation of the primary visual cortex with selective
activation of the fusiform gyrus and para­
hippocampal place areas during the face and
landscape conditions, respectively (Figure 2B).
These results were indica­tive of well-preserved
visual processing pathways. After completion
of the fMRI studies, the patient’s medical status
deteriorated, preventing further assessment.
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DISCUSSION OF DIAGNOSIS

The weight of the evidence obtained from the
patient—presentation with anarthria and tetraplegia in the context of a brainstem stroke;
normal performance on neuropsychological
measures administered nonverbally; and failure
to activate auditory cortices, coupled with
normal activation of visual association areas,
on fMRI—was suggestive of LIS complicated by
central deafness.
The term “locked-in syndrome” was initially
coined by Plum and Posner in 1966,7 although
the condition has been variously referred
to as cerebromedullospinal disconnection,
de-efferented state, pseudocoma, and ventral
pontine syndrome. The most frequently reported
premonitory symptoms of LIS include headache,
dizziness, vertigo, and hemiparesis.7 LIS most
commonly occurs after lesions of the ventral
pons, although other etiologies such as trauma,
tumor, and encephalitis have been documented
(Box 3).8 The cardinal signs of LIS include tetraplegia, lower cranial nerve palsy, and anarthria,
with preserved consciousness.
Accurate diagnosis of LIS in the early stages is
critical for establishing a prognosis and appropriate management strategies. However, patients
with LIS might initially be comatose, which can
delay the diagnosis.9 Injury to tegmental regions
of the upper pons and midbrain increases the
likelihood of initial disturbances in consciousness,
but CT scans completed in the acute stage of
injury are limited in their capacity to detect edema
or regional infarction in these brain structures.
In the present patient, the lesions evident in the
inferior colliculi suggested that there was an interruption of the tegmental reticular system, which
might account for the arousal fluctuations noted
in the acute post-coma phase.
Following emergence from coma, most
patients transition to a vegetative state or an
MCS before normal consciousness is regained.
Patients with LIS might be mis­diagnosed
as being in a vegetative state because of the
attendant anarthria and tetraplegia. It might
also be difficult to differentiate LIS from an
MCS when the patient exhibits fluctuating
arousal and oculomotor dysfunction, which can
interfere with vertical eye-movement control,
a feature that is often the best early sign of
preserved consciousness in LIS. Assessment can
be further confounded by the fact that patients
with LIS do not retain sufficient strength or
motor control to meet existing criteria for
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Table 1 Results of neuropsychological assessment in a patient with
locked-in syndrome.
Neuropsychological domain

Raw score

Interpretation

97.87

Average

11 out of 12

T = 46 (normal)

24 out of 29

SS = 13 (normal)

Trials 1–4 total

15

T = 24 (impaired)

Short delay free recall

4

Z = –2 (impaired)

Long delay free recall

6

Z = 0 (normal)

Hits

9

Z = 0.5 (normal)

False positives

1

Z = 0.5 (normal)

Recognition discriminability

3.2

Z = 0.5 (normal)

Categories completed

1

6–10th percentile (normal)

Trials to first

27

11–16th percentile (normal)

Total errors

27

10th percentile (normal)

Perseverative responses

16

21st percentile (normal)

Perseverative errors

15

16th percentile (normal)

Nonperseverative errors

12

10th percentile (normal)

Conceptual level responses

30

7th percentile (normal)

Premorbid function
Barona IQ
Receptive language
Complex Ideation from the BDAE
Current intellectual function
Information from the WAIS-R NI
Memory
CVLT-II SF

Executive function
WCST-64

Abbreviations: BDAE, Boston Diagnostic Aphasia Examination; CVLT-II SF, California Verbal
Learning Test Second Edition, Short Form; SS, scaled score; T, T-score; WAIS-R NI, Wechsler
Adult Intelligence Scale-Revised as a Neuropsychological Instrument; WCST-64, Wisconsin
Card Sorting Test-64 card version; Z, Z-score.

emergence from an MCS (i.e. demonstration
of functional communication and object use).
Bauer and colleagues have categorized LIS
as classical, incomplete, or total (Box 4).10
According to this classification, the present
patient emerged from a coma into classical LIS.
The only behavioral evidence of conscious awareness he retained was the ability to execute vertical
eye movements to command. However, this
behavior also technically satisfies the diagnostic
criteria established for an MCS. Although it was
possible to elicit reproducible eye movements
to command, the patient’s fluctuations in
arousal and persistent ocular bobbing notably
compromised the consistency of the responses.
It was not until the arousal disorder and ocular
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A

3

4

2.5

3

2

2

1.5
1

1

B

0.5

0

0

5

4
3.5
3
2.5
2
1.5
1
0.5
0

4
3
2
1
0

Figure 2 Functional MRI images of a patient with locked-in syndrome. The
images were acquired according to standard clinical procedures for passive
stimulation techniques.5,6 Instructions to the patient were given before each
run in the form of written text. (A) Colored voxels indicate BOLD responses
elicited by exposure to an auditory narrative (normal forward speech, left
panel), and the same narrative presented as filtered sound (reversed speech,
right panel). The primary auditory cortex shows a weak unilateral signal (arrow)
in response to the forward speech. There is no clear evidence of activity in
the left hemisphere superior temporal gyrus (putative Wernicke’s area) in any
of the conditions. (B) Colored voxels indicate BOLD responses elicited by
exposure to visually presented black and white pictures of faces (left panel)
and black and white pictures of landscapes (right panel). The activities in the
right inferior temporal gyrus (face fusiform area, left panel, arrow) and the right
parahippocampal gyrus (parahippocampal place area, right panel, arrow) are
consistent with preserved specificity of the visual system. Color bars reflect
the range of BOLD signal intensity changes with corresponding T-values.
Abbreviation: BOLD, blood oxygen level-dependent.

Box 3 Common etiologies of locked-in syndrome.8
Vascular etiologies
■
Basis pontis infarct
■

Pontine hemorrhage

■

Midbrain infarction

■

Transient ischemia

■

Basilar artery occlusion

■

Hypoxic–ischemic events

Nonvascular etiologies
■
Trauma
■

Central pontine myelinolysis

■

Tumor

■

Encephalitis

■

Toxins

■

Multiple sclerosis affecting the ventral pons

bobbing resolved that he was able to consistent­ly
follow eye-movement commands. Over time, the
patient’s condition was deemed to have evolved
into incomplete LIS on the basis of his recovery
of lateral head movements, but it was not
possible to reliably determine cognitive status
until 10 months after stroke onset.
The assessment of hearing is of critical importance in LIS, as speech and gestural modes of
communication are either severely compromised or unavailable. Unfortunately, there is
a paucity of literature available on auditory
processing in individuals with LIS. Aside from
Jean-Dominique Bauby’s autobiographical
account of distorted hearing after a brainstem
stroke,11 we could find only one reported case
documenting “deafness” subsequent to LIS.12
In that case, the patient showed no response to
pure tones of any frequency or loudness and no
response to speech.12
In the present case, the patient’s difficulty in
comprehending spoken language was probably attributable to central deafness, as indicated by the normal results from BAER studies
(an observation that has been reported previously in patients with central deafness arising
from brainstem lesions involving the inferior
colliculi13,14), the patient’s yes or no responses
to questioning, neuro­psychological test results,
and the lack of activation in primary auditory
cortices as observed in the fMRI studies. The
structural and functional neuroimaging findings in this patient suggest that the mechanism
underlying the central deafness is best explained
by a disconnection syndrome in which the inferior collicular lesion interrupted the auditory
pathway from the mesodiencephalic region to
the primary auditory cortices.
Access to paralinguistic aspects of speech in
the form of visual cues might explain why the
patient did so well on initial situational orientation items (all of which were accompanied by a
visual stimulus) and why his response accuracy
to verbal semantic questions improved over a
3-month period (this improvement might have
been mitigated by lip-reading practice effects15).
In view of the high margin of error for early
misdiagnosis of LIS, serial neurological examinations combined with neuropsychological
assessments adapted for use in nonverbal
patients with quadriparesis are essential to
accurately ascertain the level of consciousness and cognition. In the present patient,
underarousal, oculomotor disturbance, and

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Box 4 Classification of locked-in syndrome.10
Classical
■
Follows Plum and Posner’s7 original
description of LIS, characterized by anarthria,
tetraplegia, and lower cranial nerve palsy,
with voluntary vertical eye movements and
preserved consciousness
Incomplete
■
Includes all the features of classical LIS, with
some additional motor recovery (e.g. distal
limb movement, horizontal eye movements)
Total
■
Similar to classical LIS, but without voluntary
vertical eye movements
Abbreviation: LIS, locked-in syndrome.

impaired auditory processing conspired to
confound diagnostic assessment. Thus, serially conducted assessments of possible diagnostic confounders are necessary to accurately
characterize cognitive function in LIS.
TREATMENT AND MANAGEMENT

Although there are instances in which LIS is
reversible, there is no treatment known to alter the
pace of recovery or final outcome for individuals
with this condition. Regardless, establishment of
a functional communication system should be
a priority for all patients with LIS. The present
patient relied on a spelling board, but a range of
other augmentative communication devices is
also available. These include eye-gaze computer
systems9 and speech-generating devices that
can be utilized by patients with residual motor
recovery. The present patient learned to activate
shoulder-mounted toggle switches connected to
an assistive communication device, enabling him
to independently initiate discourse and communicate his needs and feelings. Unfortunately, as
illustrated here, undetected auditory processing
impairment can confound the assessment
of cognition and the capacity for functional
communication. Simple bedside screening procedures can be employed to mitigate this problem,
including comparing a patient’s response consistency and accuracy to verbal questions presented
within versus outside the patient’s field of vision.
If impaired auditory processing is suspected,
audiometry studies should be conducted and
appropriate accommodations prescribed, such
as provision of information in a written format
to facilitate communication.
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CONCLUSIONS

Acknowledgments

LIS, which is typically caused by lesions in the
ventral pons, manifests as anarthria and quadri­
plegia with preserved vertical eye movements.
Patients with LIS retain consciousness and, with
intensive early management, can survive for
many years. This report highlights the importance of conducting serial neurological examinations and of adapting neuropsychological
assessment measures for use in nonverbal
patients with quadriparesis, and the article
illustrates the emerging role of neuroimaging
in differential diagnosis and in the investigation of higher-level cognitive functions. Such
an approach to assessment might help to
avoid underestimation of a patient’s cognitive
capacity, a situation which can have a negative
impact on the patient’s quality of life and lead to
inappropriate treatment decisions.9

JT Giacino’s contribution
to this work was supported
in part by the National
Institute on Disability and
Rehabilitation Research
(award #H133A070030). We
thank the patient’s treating
physician for facilitating
the patient’s participation
in the study and assisting
with coordination of
study-related activities.
We are also indebted to
the rehabilitation team for
assisting with development
and implementation
of the augmentative
communication system and,
most of all, to the patient’s
family members for their
untiring dedication and
support. Charles P Vega,
University of California,
Irvine, CA, is the author of
and is solely responsible for
the content of the learning
objectives, questions and
answers of the Medscapeaccredited continuing
medical education activity
associated with this article.

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Competing interests
The authors declared no
competing interests.

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