Case 9:
The second case reported by Vitte et al (2002) was a
52-year-old right-handed man was seen 2 days after
an embolization of a diencephalic arterio venous
malformation that had induced a venous infarction of
the two inferior colliculi. He had a mild bilateral
sensorineural hearing loss of 53 dB for the right side
and 30 dB for the left side. Impedance-audiometry
revealed normal middle ear pressure and mobility
bilaterally. The crossed and uncrossed stapedial
reflexes were normal (acoustic reflex threshold: 100
dB for all the frequencies tested); the brainstem
auditory evoked potentials (BAEPs) were also normal.
However, no responses were recorded during the
speech audiometry.
MRI showed two well-limited hyperintense lesions
involving the two inferior colliculi and suggesting an
infarction. The patient was treated with a protocol
including perfusions of steroids and an agonist of
dopamine (Piribedil; Eutherupie, Nevilly, France) for 1
week, followed by oral treatment for 2 months. Three
months later, the speech discrimination was 100%
bilaterally.
Cases 8:
Vitte et al (2002) reported two cases of deafness
associated with midbrain injury. The first patient was
a 57-year-old right-handed woman seen 15 days
after a head injury. She was disoriented, but could
speak, read, and write; however, she was unable to
hear. She had lost consciousness in a motor vehicle
accident.
Standard pure tone audiometry demonstrated a mild
bilateral sensorineural hearing loss of 38 dB for the
right side and 56 dB for the left side.
Impedance-audiometry revealed normal middle ear
pressure and mobility bilaterally. The crossed and
uncrossed stapedial reflexes were well preserved
bilaterally. The acoustic reflex thresholds indicated
that the middle and inner ear and the auditory nerve
were intact. Brainstem auditory evoked potentials
(BAEPs) also appeared normal.
Speech audiometry failed to reveal any response.
Thus because objective audiometry was normal and
subjective audiometry was abnormal, her deafness
was considered to be psychological.
An MRI scan, however, revealed a lesion localized to
the tectum of the mesencephalon and involving the
two inferior colliculi. The lesion was hyperintense on
T1- and T2-weighted sequences, suggesting a
hemorrhage. She was treated with bolus of steroids
(1 g in a 1-hour perfusion of isotonic glucose) 3
times for the first week and once a month for 6
months. After 18 months, there was a recovery of
the speech discrimination, which allowed the patient
to wear hearing aids.
Case 7:
Masuda et al (2000) described the case of a
48-year-old right-handed woman whose native
language was Portuguese. She had moved to Japan
8 years before the onset of her illness and spoke
Japanese well. She developed headaches and
visual disturbances in the spring of 1996, and was
found to have a pineal body tumor. In June 1996,
she underwent surgery for resection of the tumor.
Histologic examination revealed an astrocytoma, but
its removal resulted in injury of the inferior colliculi;
the cerebral cortex and subcortex were not injured.
Immediately after surgery, the patient noted bilateral
hearing loss and was referred to the
otorhinolaryngology clinic. She had bilateral tinnitus
without dizziness or vertigo, but had a mild visual
disturbance when looking upward. Otherwise she
showed no other neurologic abnormalities or mental
status change.
The patient could not understand verbal
communications in either Japanese or Portuguese,
whether presented as monosyllables, words, or
sentences. She could speak, read, and write in both
languages without difficulty and with the same
competence as before her surgery. She could
identify nonverbal sounds such as the ring of
telephone and a baby's cry, and she was able to
distinguish some new sounds during the first year
after surgery. She also correctly identified pieces of
music familiar to her before the surgery, but she
could not understand the lyrics.
A postoperative MRI scan disclosed remaining tumor
that was compressing and partially destroying the
region, including both inferior colliculi and the medial
geniculate bodies (MGBs). Destruction of the
inferior colliculi was more severe on the left side than
on the right. The cerebral cortex and subcortex
appeared normal.
Case 6:
Johkura et al (1998) reported the case of a
46-year-old right handed man who lost
consciousness in a skiing accident. On admission to
the hospital a brain CT scan revealed a small
contusion in the left frontal lobe base. When he
regained consciousness five days after the accident,
he complained that he was uaable to recognize any
sounds. Otherwise he showed no focal neurologic
signs.
Six months after the skiing accident the patient was
referred for further evaluation of his persistent
hearing disorder. He was alert and cooperative,
although he was unable to understand verbal and
many nonverbal sounds. His cognitive functions were
normal; he was able to speak, read, write and sing.
His neurologic examination was otherwise normal.
Brain CT showed the old small contusion in the left
frontal lobe base. MRI revealed a small punctuate
hematoma in the inferior colliculi as an area of
decreased signal intensity on both T1- and
T2-weighted images. Johkura et al suggested the
lesions may have resulted from contact of the
midbrain with the free edge of the tentorium during
the skiing accident.
Johkura et al referred to their patient as a case of
verbal auditory agnosia, and pointed out that this had
long been recognized to result from lesions deep in
the left temporal lobe believed to disrupt auditory
input from the medial geniculate bodies. They
conclude that their patient's injury indicates that loss
of brainstem processing should be considered as
causes of auditory agnosia.
Case 5:
Hu et al (1997) reported a case quite similar to that
of Jani et al (1991), in which a 48-year old
right-handed woman lost consciousness in a motor
vehicle accident and suffered multiple abrasions of
the scalp. In the emergency room she awakened
and became combative and disoriented. A CT of her
head revealed high density in the basal cisterns
compatible with subarachnoid hemorrhage (SAH).
Her recovery was uneventful, she had no headache
or focal neurologic signs, but she complained of total
deafness. A repeated CT on the fourth hospital day
revealed resolution of the SAH. She was able to
speak, read, and write; her cognitive functions were
normal, but she was unable to hear. There was no
evidence of a thought disorder. She did not hear a
tuning fork, but did feel the vibration.
She did not respond to either pure tone or speech
stimuli presented in behavioral auditory tests.
Impedance audiometry revealed normal middle ear
pressure and mobility bilaterally. The crossed and
uncrossed stapedial reflexes were well preserved
bilaterally. Brainstem auditory evoked potentials
(BAEPs) on the fourteenth hospital day were normal
including even the "late waves;" wave V was well
preserved but with prolongation of latency both with
increased frequency or decreased intensity.
Because the objective tests of hearing were normal,
and only the behavioral audiometry tests abnormal,
her deafness was considered to be psychological.
On the 17th hospital day, MRI revealed abnormal
signal changes in the lateral caudal inferior colliculi.
They were isointense in the plain T1-weighted study
without gadolinium, but hyperintense lesions
appeared in the T2-weighted study. The lesions
were enhanced after Gd-DTPA. The patient
received short term corticosteroid therapy, but her
hearing impairment persisted. Follow-up MRI on day
25 showed resolution of the lesions.
Hu et al noted that the MRI examination was very
helpful in detecting, localizing, and characterizing the
lesions of the inferior colliculi; the abnormality seen
on MRI provided objective anatomical evidence for
the organicity of her deafness. Like Jani et al
(1991), contusion resulting from impact with the free
edge of the tentorium may have caused the injury.
Case 4:
Meyer et al (1996) reported the case of a 36-year
old patient who developed progressive signs of
raised intracranial pressure at the age of 28,
diagnosed as having obstructive hydrocephalus, and
was shunted. One year before admission a pineal
region mass was described to the first time. This
showed pronounced enhancement on MRI and
occupied the dorsal midbrain with exophytic growth.
His neurological examination was normal apart from a
reduced visual acuity. Speech and pure tone
audiograms were normal as were brainstem auditory
evoked potentials (BAEPs).
The growth was excised via an
infratentorial-supracerebellar approach. The inferior
colliculi could not be identified during surgery.
Complete removal was documented on postoperative
MRI as well as destruction of both inferior collculi.
Histology disclosed a pilocytiuc astrocytoma grade 1.
After surgery the patient was unable to understand
verbal communication, but nonverbal hearing,
reading, writing, and dpeaking abilities were
unimpaired. He could still identify and localize all
sources of non-verbal sounds. Furthermore, he also
identified correctly pieces of music that he had known
before. Pure tone audiogram and BAEPs were
normal and identical to those vefore operation.
Speech audiogram performance, however, had
dramatically deteriorated to discrimination scores of
10 and 20.
Meyer et al claimed there were 62 cases in the
medical literature of hearing impairment associated
with pineal area tumors, and that pure word deafness
with lesions restricted to the inferior colliculus was
reported in three of these cases; citations to the
reports were not provided.
Meyer et al suggested that the inferior colliculus may
provide a "gating process" that blocks "irrelevant"
sensory input, which would be essential for linguistic
comprehension.
Case 2:
Jani et al (1991) described a 46-year-old left-handed
woman not wearing a seat belt when she was involved
in a motor vehicle accident. When paramedics
arrived, she was awake but combative and
disoriented. She had a palpable carotid pulse but no
peripheral blood pressure. Her systolic blood
pressure increased to 80 mm Hg with fluid
resuscitation. In the emergency room the patient
remained combative; she moved all extremities and
seemed to follow commands. There were no signs of
head injury, but pelvic and rib fractures, as well as
bilateral pulmonary edema, were revealed by x-rays.
No abnormalities were seen in a computed
tomographic (CT) scan of the head. She required
endotracheal intubation and therapeutic embolization
of a bleeding inferior gluteal artery. Pancuronium
bromide was given for agitation.
At 48 and 72 hours after admission, she continued to
follow simple commands. Another CT scan showed
no abnormalities. On the fourth day she was able to
move all extremities, but not on command. On the
fifth day she wrote "help" on a piece of paper.
It was learned on day 6 that she had a history of
major mood disorder, and she was started on
fluoxetine (Prozac, Dista Products Co., Indianapolis
IN) on day 7.
It became clear on day 7 that the patient was not
following commands, although she was alert. On day
11 she whispered that she had been unable to hear
for several days. She was examined on day 12 by a
psychiatrist, who suggested a diagnosis of conversion
disorder and prescribed amoxapine (Ascendin,
Lederle Labs, Pearl River NY), 150 mg at bedtime.
On day 12 she was seen by a neurologist who found
her in distress; she spoke only in a whisper and
indicated that she was unable to hear. She followed
some verbal cues but used signs to communicate; she
was able to read and whisper sentences written for
her, and followed written commands. She wrote well
except for some spelling errors. She did not hear a
tuning fork but did feel the vibration. She appeared
not to hear and did not respond to provocative
statements made from a location in which she could
not read lips. Her mood and affect were depressed,
but there was no evidence of thought disorder, and
cognitive functions appeared normal. The
neurological exam was otherwise within normal limits.
On day 17 an MRI scan of the head was performed.
The axial T2-weighted images demonstrated foci of
markedly decreased intensity in the superior
cerebellar peduncles and the inferior colliculi. After
administration of gadolinium
diethylene-riamine-pentaacetic acid (Gd-DTPA) there
was enhancement of the inferior colliculi; on the right,
the lesion extended into the dorsal pons. Sagital
T1-weighted images before Gd-DTPA did not show
the abnormality. Another MRI scan on Day 35 also
showed findings consistent with bilateral hemorrhagic
contusion in both inferior colliculi and in the right
superior cerebellar peduncle. It was noted that the
patient had not received anticoagulant therapy.
Several attempts were made to determine hearing
sensitivity using behavioral audiometric tests. The
patient occasionally described hearing "static" for
both pure tones and speech stimuli between 50 and
90 dB HL bilaterally. Hearing thresholds could not be
reliably obtained because the patient became
fatigued and irritable during test sessions, and her
responses were inconsistent. Impedance audiometry
revealed normal middle ear pressure and mobility
bilaterally. The uncrossed acoutic stapedial reflex was
present for both ears; but pontine abnormality was
indicated by absence of the crossed stapedial reflex.
Auditory brainstem responses (ABRs) were recorded
using broad-band clicks. Waves I to IV were present
with left ear stimulation and I to III with right ear
stimulation. Wave V was absent bilaterally. Detection
thresholds for waves I and II were at 50 dB nHL for
both ears. Thus both the ABR and acoustic
thresholds ruled out severe peripheral hearing loss
bilaterally and provided evidence of brain stem
dysfunction.
After 44 days, the patient was discharged to a
rehabilitation hospital. One year after her accident,
her hearing impairment was persistent.
The authors noted that this was a case of isolated
midbrain contusion after severe closed head trauma,
and that such mesencephalic injury has often been
attributed to contusion of the dorsal midbrain by the
tentorium as a result of acceleration-deceleration
forces. Extensive hemorrhage causing coma and
corticospinal tract signs usually occur with such
injuries. The authors comment that the case they
describe in this report is remarkable in that the injury
was limited to the inferior colliculi and upper pons, and
manifested only by auditory impairment.
The authors commented further that most traumatic
hearing impairment is caused by abnormality of the
peripheral auditory system, and that deafness by
rostral brainstem disease is uncommon and only
occurs when the injury is bilateral and discrete. They
cite a case of unilateral damage that did not cause
significant hearing loss, and they note that unless the
injury is discrete it will affect the reticular activation
system with resulting coma that will mask any hearing
loss.
The MRI scan provided unequivocal evidence of an
organic cause, which was not evident on the CT scan.
The authors note that Gd-DTPA is the first enhancing
agent approved for MRI imaging, and that it
accumulates in areas of disruption of the blood-brain
barrier caused by infections, neoplasms, or trauma.
The authors commented that reliance on CT scanning
and behavioral hearing tests could have resulted in a
misdiagnosis. The initial diagnosis of conversion
disorder had been based on the patient's pre-existing
mood disorder and apparent absence of brain or
inner ear injury.
Case:
Case 1:
Howe and Miller (1975) provided clinical and
neuropathological reports of deafness associated with
abnormalities of the inferior colliculi before the era of
magnetic resonance imaging (MRI). Their patient was
a 59-year-old woman who was the driver of an
automobile involved in a single vehicle accident. She
sustained an apparent head injury. According to her
husband, she was diabetic, she had a history of
alcoholism, and she had been drinking before the
accident.
Initial examination disclosed a right parietal scalp
abrasion. The patient was initially lethargic but readily
arousable. Subsequently she became combative and
commenced shouting obscenities. Her ocular fundi
were normal. A complete right oculomotor palsy was
present, and bilateral Babinski signs were elicited.
She would neither answer questions nor follow
commands, and it was felt she was probably deaf,
although malingering was an early consideration.
Inspection of the external auditory canals revealed no
abnormality. She did not respond to tuning fork, and
she was not startled by loud noises. Ice water caloric
testing gave normal responses bilaterally.
X-rays of her skull and and cervical spine were normal.
Pancerebral angiography was performed within 24
hours of admission and revealed ventricular dilation
but no evidence of a mass lesion.
Further investigation of her deafness was undertaken.
No response was obtained during audiometric testing.
Cortical evoked responses were investigated, and
auditory stimuli to both ears simultaneously and to
each ear separately produced no clearly defined
cortical evoked responses with computer averaging.
During subsequent weeks the patient's level of
consciousness fluctuated, although there were
intervals when she would follow written commands.
Her condition gradually deteriorated. Since her
deafness and ventricular dilation had remained
unexplained, ventriculography was performed shortly
before her death. The ventricular pressure was 80
mm of cerebrospinal fluid, and the radiographic picture
was compatible with central cerebral atrophy. A lateral
laminagram selected from this examination showed a
normal cerebral aqueduct and a normal fourth
ventricle. There is no evidence of an intrinsic or
extrinsic mass lesion of the brainstem or midbrain, and
the quadrigeminal plate is normal. Several days after
this study the patient died of disseminated intra
vascular coagulation.
On pathologic examination, the brain appeared slightly
atrophic, weighing 1,250 gm. The external
appearance of the cerebral cortex was normal. When
the brain was sectioned, punctuate hemorrhages were
identified in the caudal midbrain and pons. There also
appeared to be hemorrhagic lesions in the inferior
colliculi and the lateral lemnisci. The temporal lobes
and acoustic nerves were normal. The temporal
bones were not removed, but there were no fractures
anywhere in the base of the skull when viewed in situ.
Microscopic examination revealed lesions in both
lateral lemnisci. These lesions were at least 3 weeks
old. The medial longitudinal fasciculi were intact, as
would be expected from the patient's normal response
to caloric testing. Degeneration within the inferior
colliculi, the termination of many of the lateral
lemniscal fibers, was seen in a section taken through
the midbrain. Sections taken at appropriate levels
revealed no evidence of degeneration in the cochlear
nuclei.
Howe and Miller commented that the histologic
evidence in their patient indicates nearly complete
obliteration of the auditory pathway at upper pontine
and midbrain levels, and they go on to suggest that
contusion of the brainstem against the tentorial
incisura is a plausible but unproved mechanism of this
type of injury.
Case 13:
Kimiskidis et al (2005) described the case of a
48-year-old woman admitted to the hospital because
of a severe headache of sudden onset, followed
rapidly by a comatose state. An emergency
computed tomographic scan showed a
mesencephalic hemorrhage. The patient was
intubated and admitted to the intensive care unit.
During the next 5 days, she developed a mild
hydrocephalus, which was treated conservatively and
which gradually subsided.
Three weeks later, the patient fully regained
consciousness and was transferred to the increased
care unit. She was unable to perceive speech but
could speak, read, and write. She was cooperative
and fully orientated. On neurologic examination,
there was bilateral trochlear nerve palsy, a limitation
of upward gaze, retraction nystagmus, and
hemihypesthesia on the right.
Magnetic resonance imaging of the brain, performed
2 months after admission, revealed a residual brain
hemorrhage localized to the quadrigeminal plate,
involving the inferior colliculi. There was no evidence
of a cryptic malformation, which Kimiskidis et al noted
is a usual cause of mesencephalic hematomas.
Because deafness was the patient's main complaint,
she was subjected to detailed audiologic testing 4
weeks after admission and at a follow-up visit 5
months later. Pure tone audiometry showed a
bilateral severe sensorineural hearing loss that had
partially improved 5 months later. In speech
audiometry, the patient was totally unable to perceive
any of the words presented at suprathreshold levels,
and at the follow-up evaluation her speech
discrimination score remained at zero percent. The
stapedius reflexes were elicited with normal
thresholds, bilaterally.
Brainstem auditory evoked potentials (BAEPs) were
recorded, and waveforms I through V were of normal
amplitude and latencies, bilaterally. Transient
evoked otoacoustic emission (TEOAE) recording was
performed to evaluate the integrity of the cochlear
function. TEOAEs were recorded with normal
amplitude and reproducibility 4 weeks after admission
and 5 months later.
The results of audiological testing indicated
sensorineural hearing loss with disproportionate poor
speech discrimination. The authors noted that
because stapedius reflexes were normal, the lesion
was localized above the level of the superior olive
nucleus.
Case 12:
Pan et al (2004) described the case of the 14-year-
old boy who developed progressive hearing
impairment and occasional severe headache. The
patient had normal development and school
performance before the onset of hearing
disturbances. Detailed history revealed no evidence
of congenital or developmental hearing disorders. For
the past 3 months, his mother had to face him and
talk slowly for him to understand. During
conversations, he usually interpreted others’ speech
by reading the speakers’ lips. He had difficulty
understanding when listening to telephone calls. On
neurologic examination, the patient was alert and
cooperative with profound hearing disturbance. There
were bilateral papilledema, ptosis, and Parinaud
syndrome (upward gaze palsy, retraction nystagmus,
and impaired convergence). Motor and sensory
examination was normal, and the plantar response
was flexor bilaterally. There was dysmetria and
dysdiadochokinesia, more severe on the left side.
Head MRI revealed a tectal tumor infiltrating the
inferior colliculi with obstructive hydrocephalus and
extension into right posterior thalamus. Another mass
was noted on the right frontal ventricular wall with
heterogenous enhancement by gadolinium. Excision
of the frontal tumor revealed germinoma with
lymphocytic infiltration and reactive astrocytosis.
Endoscopic third ventriculostomy relieved the
hydrocephalus. Immunostaining for neuron-specific
enolase and glial fibrillary acid protein was negative.
Serum levels of alpha-fetoprotein and beta-human
chorionic gonadotropin were within normal limits.
The patient was treated with fractionated
radiotherapy at 5,000 cGy. The headache and
papilledema subsided, and there was radiologic
evidence of complete remission. Follow-up MRI up to
3 years after treatment did not disclose recurrence.
Before and after treatment, audiologic and
neuropsychological testing was done. At first auditory
comprehension was severely impaired and improved
a little only when the examiner faced the patient and
spoke slowly. Writing, naming, and reading
comprehension were normal. The patient performed
poorly on dictation, with a 20% correction rate. There
were a few phonemic errors in his spontaneous
speech; otherwise the speech was fluent and
intelligible.
On testing nonverbal environmental sounds
(including a ringing bell, a telephone, and a clicking
watch) recorded on a tape, he could only recognize 7
of the 16 test sounds. He had difficulty differentiating
between voices of different genders (50% correct).
On testing of musical ability, he could not tell whether
it was piano, flute, or violin. In two-tone discrimination
test, he could not differentiate between two tones
whether the intervals were half, two, four, or eight
steps, either in ascending or descending sequences.
He had difficulty recognizing different melodies, and
he could not sing as he used to.
Linguistic testing was performed in a quiet room, with
the examiner speaking behind the patient so that the
patient could not read the examiner’s lips. He had a
90% correct rate in identifying the common vowels in
Mandarin (a, e, i, o, u). The stop consonant-vowel
discrimination was performed in two steps, and each
test set was repeated 100 times.
Four different test sets were given in both stages. In
the first stage, the patient was asked to discriminate
between two stop consonant-vowel sets that differed
in the articulation place of the stop consonants (e.g.,
/pa/ vs /ta/ or /ga/ vs /da/). There was only one
discriminating feature between these two test sets. He
achieved a correct rate of 53% on average.
In the second stage, test sets with two discriminating
features were given, different in the articulation place
of the stop consonants and the nature of whether
they were voiced or voiceless. For example, he was
asked to discriminate between /ga/ and /ta/ or /da/
and /ka/. He achieved an average correct rate of 85%.
The result of pure tone audiometry on admission was
normal, with detection threshold of 10 dB over a
frequency range from 125 to 8,000 Hz binaurally. The
tympanogram and stapedial acoustic reflex were
normal. Brainstem auditory evoked potentials
(BAEPs) were performed, and all components of
BAEPs were evoked with normal latencies. However,
the amplitudes of wave V were attenuated bilaterally.
During the follow-up period, the patient showed a
steady but limited improvement of hearing ability.
Auditory and neuropsychological tests were
performed 6 months and 2.5 years later, with similar
results. Dictation improved with a correct rate of
60%. Follow-up audiometry showed a mild hearing
loss with a detection threshold of 20 to 30 dB (see
figure 2). Wave V of BAEP was absent bilaterally.
Pan et al. cited the reports of Meyer et al (1996), Hu
et al (1997), Johkura et al (1998), Masuda et al
(2000), and Vitte et al (2002), and concluded that
restricted damage to inferior colliculi may result in
impaired sound recognition with a normal detection
threshold, the audiologic and neuropsychological
findings of which may be indistinguishable from that
caused by lesions of the auditory cortex.
Case 11:
Musiek et al (2004) reported the case of a
21-year-old college student hospitalized because of
severe headaches and vomiting. He became
unresponsive and was transferred to a tertiary care
hospital, where he became somewhat responsive,
but also combative, and nonverbal. His pupils were
at this time unequal and minimally responsive; he
made purposeful movements to noxious stimuli, but
did not follow commands and was totally
unresponsive to verbal stimuli. A computerized
tomography (CT) scan showed a subarachnoid
bleed. Soon after admission a diagnosis of Neisseria
meningitis was made; this is a rare type of meningitis
that can result in vascular lesions.
During the next two weeks, the patient began to
improve. He started vocalizing and saying a few
words, which were used appropriately most of the
time. He was able to move all extremities
appropriately and purposefully, and his mental status
was improving. He communicated by writing on a
pad, which he did reasonably well' however, he
remained unresponsive to all sounds. He was
transferred to a rehabilitation hospital then shortly
thereafter became an outpatient. During the next
five months he was seen for audiological follow-up
and auditory therapy, as his main problem was
hearing loss.
An MRI was performed after three weeks in the
hospital. The MRI showed infarcts at the superior left
cerebellum/occipital lobe and the left inferior
temporal lobe, neither of which was thought to
contribute to the patient's auditory problems.
However, in the midbrain, both inferior colliculi were
almost totally infracted with some spread of the
compromise into the inferior aspect of the superior
colliculi; there was less involvement in the anterior or
ventral aspects than in the posterior aspect of the
colliculi.
During most of the patient's first week of
hospitalization, personnel working with him noted no
response to any sound. Toward the end of the
week, and for several weeks thereafter, the patient
claimed he heard a certain sound, yet other people
in the room with him did not hear the sound.
Beginning in his second week, the patient
acknowledged hearing some sounds in his
environment that were actually present, but he could
not identify the exact nature and/or the source of
these sounds. It appeared that the sounds that he
heard were relatively loud and of a broad spectrum.
By the third week of his hospital stay, definite
improvements in hearing were noted. The patient
could hear voices, but he could not understand
anything that was being said to him. He stated,
"Voices don't sound like voices." He spoke often, but
in a monotone voice. Listening was a strain, and
fatigued him to the point where he often complained
about it. He continued to hear environmental
sounds, such as a dish being dropped and water
running from a faucet, and was able to discern loud
sounds from soft, but was inconsistent in
identification of the sources of environmental
sounds. The patient complained of extreme difficulty
listening to people speak whenever background
noises were present. At this point in his recovery, he
was able to read slowly, and this skill has continued
to improve over time.
During the fourth week, the patient reported that he
felt his hearing was improving. He could hear voices
on TV but could not understand what was being said.
In general, the patient knew when people were
speaking but could not follow speech on a consistent
basis. He stated that riding in a car was difficult
because everything was too loud.
There remained some disassociation between what
the patient believed he heard and what sounds were
actually present in his environment. He claimed to
be able to hear women's voices better than men's,
and he reported that he could hear parts of his
girlfriend's voice on the phone. During this time
period, the patient began to experience bilateral
tinnitus (ringing type sound), which he reported was
worse in the morning than later in the day.
From about 5 to 12 weeks, the patient's hearing
continued to show steady improvement. He could
understand several words, and this gradually
improved over time but was highly dependent on the
patient's being located in a quiet environment.
Background noise, even of low intensity (e.g. noise
from a small fan), caused considerable problems in
his understanding of speech. He noted that he
heard better when he was actively participating in a
conversation compared to when he was listening
passively. He reported that speech seemed muffled
and described his listening experiences as if he were
listening to speech over a two-way radio transmitter.
He could hear birds chirp but described the chirping
as having a "robotic" quality.
During the next 10 months, the patient's ability to
understand speech in quiet continued to improve,
and he was able to follow most conversations.
Complex and similar sounding words remained
difficult for him to correctly interpret and discriminate,
and background noise continued to be a major
detriment to his accurate understanding of speech.
The patient's confidence in communication improved
considerably over this period of time, and at this
point in his recovery he had gone back to college
and appeared to be doing satisfactorily with some
accommodations such a preferential seating. His
auditory behavior 10 months after his illness was
similar to that of an individual with a moderately
severe high=frequency loss. However, background
noise continued to be a major problem, more so than
would be expected for a person with only a
moderately severe high-frequency sensorineural
hearing loss.
The patient underwent extensive audiological testing.
In the beginning, one difficulty determining
thresholds for pure tones was that the patient noted
little or no tonality in the stimuli; hence the sounds
were not distinctive. This was particularly true for low
frequencies. The patient at first also had difficulty
maintaining attention. Speech audiometry could not
be obtained during early evaluations although
measures such as tympanograms and acoustic reflex
thresholds were grossly within the normal range.
Detailed accounts are given in this paper of testing
during the patient's recovery that indicated gradual
improvement. Background noise remained as a
difficult impediment for the patient, especially in
speech understanding. Auditory brainstem response
(ABR) testing throughout the recovery period
showed normal waves 1, II, and III bilaterally, but the
IV-V complex was compromised for both ears. The
ABR test results remained the same over the next 10
months.
In their discussion of this patient their findings during
recovery, Musiek et al made special note of the
patient's thinking that he heard sounds that really did
not exist, and they note that this has been seen in
centrally deaf patients before. The authors were not
sure if this phenomenon occurs because the sounds
are imagined in some manner, such as an auditory
illusion or hallucination, or whether they are the
result of some other psychophysiological
phenomenon.
Case 10:
Hoistad and Hain (2003) presented the case of a
43-year-old male who had been diagnosed HIV
positive 12 years earlier, and who developed
non-Hodgkin's lymphoma with CNS involvement one
year before experiencing hearing difficulties and
intermittent tinnitis. The patient's lymphoma was in
remission when he sought help for his hearing
problems.
An audiogram demonstrated modest low- and
high-frequency losses but normal bilateral pure-tone
thresholds. Word recognition scores were 44 percent
in the right ear and 20 percent in the left ear. These
scores were considered far worse than would be
explained by the patient's pure-tone thresholds.
Magnetic resonance imaging of the brain/head with
gadolinium demonstrated enhancement of the right
and left inferior colliculi (ICs). Small lesions of the
corpus callosum, septum pellucidum, and the medial
aspect of the left temporal lobe were also discovered.
Hoistad and Hain cited the case reports of Sloane et
al (1943), Dix and Hood (1973), Howe and Miller
(1975), Hart et al (1989), Jani et al (1991), Bognar et
al (1994), Meyer et al (1996), and Vitte et al (2002)
as describing hearing impairment associated with
lesions in the vicinity of the inferior colliculus (IC).
They cited five cases in which a lesion was restricted
to the IC; the patients of Jani et al (1997) and Hu et al
(1997) were completely deaf and audiometric data
not obtainable. The patient of Meyer et al (1996) had
the ICs resected on removal of a tectal plate glioma,
with dramatic deterioration of speech comprehension
but with pure-tone audiometry and brainstem auditory
evoked potentials (BAEPs) remaining normal. Vitte et
al (2002) described two cases with bilateral and
symmetrical lesions of the ICs, and mild sensorineural
hearing loss combined with complete word deafness
in both. Hoistad and Hain noted that their case
resembled the last three, in which pure-tone audition
was retained but with very poor word discrimination
scores.
Hoistad and Hain concluded that the case they
described provides additional evidence for the
existence of an extralemniscal pathway for audition of
pure tones, but that the IC plays a critical role in the
processing of speech.
Case 3:
Nageo et al (1992) reported the case of a
39-year-old woman with sudden onset of headache,
drowsiness, and diplopia. On admission she had a
right fourth nerve palsy and paraesthesiae of the
right ear lobe, nose, limbs and trunk. Deep tendon
reflexes were slightly brisker on the left side. CT
showed a dense area in the left inferior colliculus.
Two weeks later she had transient hearing
disturbance in the right ear. One month after the
ictus her neurological abnormalities were less
pronounced, except for the paraesthsiae in the right
limbs. After 15 months, MRI showed a low signal
area in the left inferior colliculus on both T2- and
T1-wighted sequences.
Nageo et al cite an earlier report by Cocito et al
(1990) which they believed was the only other case
of hemorrhage in the inferior colliculus. Hearing
disturbance, fourth nerve palsy and paraesthesiae
on the opposite side were common in that case also,
except that the fourth nerve palsy was ipsilateral in
the case reported by Cocito et al, and their case was
not drowsy. Nageo et al concluded that hemorrhage
in the anteromedial portion of the inferior colliculus
causes drowsiness and contralateral fourth nerve
palsy because the dorsolateral tegmental nucleus
and its central projection are located near the
trochlear nucleus; while on the other hand,
hemorrhage in the dorsolateral portion of the inferior
colliculus causes an ipsilateral fourth nerve palsy
without dowsiness as in the case of Cocito et al.
Jani NN et al. (1991) Deafness
after bilateral midbrain contusion:
a correlation of magnetic
resonance imaging with auditory
brain stem evoked responses.
Hu C-J, et al. (1997) Traumatic
brainstem deafness with normal
brainstem auditory evoked
potentials.
Meyer B et al (1996) Pure word
deafness after resection of a
tectal plate glioma with
preservation of wave V of brain
stem auditory evoked potentials.
Johkura K et al (1998) Defective
auditory recognition after small
hemorrhage in the inferior
colliculi.
Masuda S et al (2000) Word
deafness after resection of a
pineal body tumor in the
presence of normal wave
latencies of the auditory brain
stem response.
Vitte E et al (2002) Midbrain
deafness with normal brainstem
auditory evoked potentials. (Two
cases)
Hoistad DL et al (2003) Central
hearing loss with a bilateral
inferior colliculus lesion.
Kimiskidis VK et al (2004)
Sensorineural hearing loss and
word deafness caused by a
mesencephalic lesion:
clinicoelectrophysiologic
correlations.
Pan CL et al (2004) Auditory
agnosia caused by a tectal
germinoma.
Nagao M et al. (1992)
Haemorrhage in the inferior
colliculus.
Musiek FE et al (2004) Central
deafness associated with a
midbrain lesion.
Case: 1
Case:
Case:
Case:
Case:
Case:
Case:
Case:
Case:
Case:
Case:
Case:
Case:
Case:
Vitte E et al (2002) Midbrain
deafness with normal brainstem
auditory evoked potentials. (Two
cases)
Howe JR, Miller CA. Midbrain
deafness following head injury.
Neurology. 1975
Mar;25(3):286-9.
Case 1 - Notes:
Head injury, auto accident
Patient was Diabetic
History of alcoholism
Combative
Malingering considered
Jani NN, Laureno R, Mark AS,
Brewer CC. Deafness after
bilateral midbrain contusion: a
correlation of magnetic
resonance imaging with
auditory brain stem evoked
responses.
Neurosurgery. 1991
Jul;29(1):106-8; discussion
108-9.
Case 2 - Notes:
Motor vehicle accident
Combative & disoriented
History of mood disorder
Psychiatric disorder considered
Nagao M, Kita Y, Kamo H.
Haemorrhage in the inferior
colliculus. Neuroradiology.
1992;34(4):347.
Case 3 - Notes:
Sudden hemorrhage
Meyer B, Kral T, Zentner J.
(1996) Pure word deafness
after resection of a tectal plate
glioma with preservation of
wave V of brain stem auditory
evoked potentials. Journal of
Neurology, Neurosurgery and
Psychiatry. 61:423-4.
Case 4 - Notes:
Pineal mass
surgical damage of the IC
Hu CJ, Chan KY, Lin TJ, Hsiao
SH, Chang YM, Sung SM.
Traumatic brainstem deafness
with normal brainstem auditory
evoked potentials. Neurology
1997;48:1448–1451.
Case 5 - Notes:
Motor vehicle accident
Combative & disoriented
Psych cause considered
Johkura K, Matsumoto S,
Hasegawa O, Kuroiwa Y. (1998)
Defective auditory recognition
after small hemorrhage in the
inferior colliculi. Journal of the
Neurological Sciences.
161:91-6.
Case 6 - Notes:
Traumatic injury/ ski accident
Masuda S, Takeuchi K,
Tsuruoka H, Ukai K, Sakakura
Y. (2000) Word deafness after
resection of a pineal body tumor
in the presence of normal wave
latencies of the auditory brain
stem response. The Annals of
otology, rhinology, and
laryngology. 2000 Dec;109(12
Pt 1):1107-12.
Case 7 - Notes:
Pineal tumor
surgical injury of inferior colliculi
Vitte E, Tankéré F, Bernat I,
Zouaoui A, Lamas G, Soudant J.
Midbrain deafness with normal
brainstem auditory evoked
potentials. Neurology 2002;58:
970–973. (Case 1 of 2)
Case 8 - Notes:
Motor vehicle accident
Psychological considered
Vitte E et al (2002) Midbrain
deafness with normal
brainstem auditory evoked
potentials. (Case 2)
Case 9 - Notes:
Hemorrhage
Hoistad DL, Hain TC (2003)
Central hearing loss with a
bilateral inferior colliculus
lesion. Audiol Neurootol 2003
Mar-Apr; 8(2):111-223
Case 10 - Notes:
HIV lymphoma
Musiek FE, Charette L, Morse D,
Baran JA. (2004) Central
deafness associated with a
midbrain lesion. J Am Acad
Audiol 2004 feb; 15(2):133-151.
Case 11 - Notes:
Meningitis
Vascular lesions
Pan CL, Kuo MF, Hsieh ST.
Auditory agnosia caused by a
tectal germinoma. Neurology.
2004 Dec 28;63(12):2387-9.
Case 12 - Notes:
Tectal germinoma
Kimiskidis VK, Lalaki P,
Papagiannopoulos S,
Tsitouridis I, Tolika T, Serasli E,
Kazis D, Tsara V,
Tsalighopoulos MG, Kazis A.
Sensorineural hearing loss and
word deafness caused by a
mesencephalic lesion:
clinicoelectrophysiologic
correlations. Otol Neurotol. 2004
Mar;25(2):178-82.
Case 13 - Notes:
Hemorrhage
Links to cases 2-13: