Introduction The term "locked-in
syndrome" was proposed in 1966 by Plum and
Posner. Nevertheless, this condition was first
described by Alexandre Dumas with the figure of
the totally paralysed M. Noirtier de Villefort
in his book "Le comte de Monte-Cristo", edited
1844-1845, over 100 years before. M. Noirtier de
Villefort was alert and oriented, but he could
communicate only with his eyes. In this novel,
Noirtier de Villefort dictates his last will to
an advocate by using eye movements, blinking and
a letter list. The clinical criteria of complete
locked-in syndrome are tetraplegia and paralysis
of cranial nerves except vertical eye movements
and preserved consciousness.
We describe a patient with a locked-in
syndrome due to a vascular malformation of the
basilar artery-megadolichobasilar artery
(fusiform aneurysm, vertebrobasilar
dolichoectasia) with bilateral masticatory
spasms and persistent trismus. Yawning with
complete opening of the mouth despite to trismus
as a voluntaryÐinvoluntary dissociation was
present.
Case report A 62-year-old woman
presented with sudden onset of weakness of right
side limbs. On admission, the patient was alert
and orientated. She had deviation of both eyes
to the right side with gaze palsy to the left
side. Other cranial nerves were spared. The
patient had a moderate right hemiparesis
involving equally the arm and the leg with
minimal flaccidity in the paretic limbs. The
deep tendon reflexes were absent. She had a
right Babinski response. No cerebellar ataxia
was observed and no sensory deficits could be
detected.
CT performed on the first hospital day
demonstrated an extremely dilatated basilar
artery with small thrombus in the tip of the
basilar artery (Fig. 1), and MRI demonstrated
left pontine infarction, and a
megadolichobasilaris (Fig. 2). The patient was
treated with 20 000 units heparin intravenously
daily and all the symptoms except right leg
paresis were transient. One week after the
ictus, the right hemiparesis occurred again and
it was progressive to tetraplegia for several
hours. However, she was still alert and
oriented. Contact by using of vertical eye
movements and blinking was preserved. The
patient had bilateral paresis of abducens nerve.
She had a prominent hypomimia, but no
lagophthalmus. She had bilateral masticatory
spasms with trismus, but a frequent yawning
(ca. every 5 min) with a complete opening of
the mouth was possible. There were anarthria and
severe dysphagia. She had soft palate paresis,
and brisk gag reflexes. Masseter reflex was also
very brisk. It was flaccid tetraplegia with
bilateral Babinski signs and extremely brisk
deep tendon reflexes. No sensory deficitscould
be detected. MRI demonstrated massive and
bilateral pontine infarction (Fig. 3).
Discussion The clinical picture in
our patient was corresponding to classical
locked-in syndrome due to bilateral affection of
pontine cranial nerves nuclei, lateral
corticospinal tract and supranuclear affection
of bulbar nuclei (pseudobulbar syndrome). The
most common lesion underlying the locked-in
syndrome is an occlusion of the basilar artery
with destruction of the pontine base
[3].
Other causes are bilateral midbrain stroke
[4], bilateral capsula interna stroke
[5], pontine
gliomas [6], tentorial herniation
[7], trauma [8], encephalitis
[9], and peripheral causes as the
GuillainÐBarre syndrome [10].
Locked-in syndrome is often caused by pontine
infarction, and pontine infarction is often
associated with megadolichobasilaris
[3,11,12]. However, the classical
locked-in syndrome caused by the thrombosed
megadolichobasilar artery is unusual
[13].
Trismus due to irritation of the motor
trigeminal area has been observed in patients
with brainstem lesions as tumours [15],
vascular lesions with pseudobulbar syndrome
[16], multiple sclerosis [17],
progressive supranuclear palsy [18],
cerebral deep venous thrombosis [19],
and motoneuron disease [20]. Unilateral
trismus caused by vertebrobasilar dolichoectasia
with truncal irritation of the motor root of the
trigeminal nerve is a rare disease that has been
described only once [14]. In contrast to
an irritation of the trigeminal nerve in this
patient, we presume that rather an irritation of
the trigeminal nuclear area was the cause of
trismus in our patient, because MRI could not
demonstrate a contact of the
magadolichobasilaris to both trigeminal
roots.
Yawning is also a very unusual sign
in patients with locked-in syndrome. A single
description of yawning in locked-in syndrome
was published in 1977
[21]. This patient with pontine glioma
and locked-in syndrome could not open or close
the mouth, but he was able to yawn. The author
concluded that the motivation of yawning stems
from the sleep inducting system in the region of
the raphe-nuclei and is projected directly to
the nuclei of the caudal brainstem nerves
[21]. Nevertheless, the brainstem
mechanisms of yawning are not completely
understood, but it seemed that the question of
Wimalaratna and Capildeo "Is
yawning a brainstem phenomenon?"
[22] can be answered partially.
Respiratory neurons, motor nuclei of the 5,
7, 10 and 12th cranial nerve, phrenic nerve and
accessory respiratory muscles, parasympathetic
terminals of the lacrimal glands and the frontal
cortex must be involved in yawning
[23].
Anatomic centre of this complex neuronal network
can be presumed in the lower brain stem nearby
the brainstem reticular formation. The impetus
of physiological yawning is not really clear.
Abnormal frequent yawning can be caused by
intoxication, by drug side effects,
postencephalitic state, apallic syndrome, CNS
tumours and some other conditions [24].
There must be a functional anatomic way to
initiate and execute yawning as an involuntary
motor phenomenon despite destruction of
voluntary movements of facial and trigeminal
motor functions like our patient shows.
To our knowledge, our publication is the
first description of combined
megadolichobasilaris, locked-in syndrome,
trismus and frequent yawning in the same
patient.
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