Secondary Schizophrenia (13 page)

transform acoustic waves into mechanical vibrations
With respect to tinnitus, exclusion of a structural
and then change fluid pressure in the organ of corti.

lesion in unilateral or pulsatile symptoms is important.

The mammalian chochlea tranduces these changes in
Evidence for use of psychotropic medication
[128]
and
fluid pressure, via stereocilia, into neural activity
[135].

herbal remedies such as ginko biloba
[146]
is limited.

The eighth cranial nerves project bilaterally via the
Education, provision of adequate support, and white-inferior colliculus and medical geniculate nucleus to
noise masking devices can be effective
[147].

the primary auditory cortex in the superior temporal gyrus as well as other areas such as the limbic
system. Although receptor cells can be regenerated
Complex auditory hallucinosis

from the adjacent supporting Deiters’ cells after injury
Changes in pitch or frequency, timbre and harmon-in birds, reptiles, and amphibians, in mammals it is
ics, can make a sound more complex. Further com-believed they can be produced only during embryoge-plexity is introduced by combinations of frequencies
nesis
[136].
Hence damage to the hair cell array is not
and individual sounds and the characteristics of the
reparable and may result in faulty or false input into
sound envelope (attack or beginning, sustain or main
central pathways.

component and decay, or the transition to silence). The
A number of well-replicated observations chal-changes in a sound over time, for example, in a repeat-lenge receptor damage as the sole mechanism
[133].

ing pattern or rhythm can introduce musical quali-First, many sufferers of hearing loss do not describe
ties. Another layer of complexity is the interpretation
chronic tinnitus
[128].
Second, tinnitus usually per-of complex sounds. Difference between input to left
sists after the division of the eighth cranial nerve
[137].

and right cochlea can introduce spatial characteris-Last, reports of distress and disability has not been
tics. Complex sounds may construct words and the
shown to correlate with measures of tinnitus loudness,
tone or context of spoken language may convey emo-implying significant emotional factors
[138].
Hence it
tions and affect. Similarly, music can also convey emo-is more likely that tinnitus involves alteration in the
tion, often linked to memory and previous experience
central auditory pathway and changes in limbic mech-of that piece of music. Perception and comprehension
anisms that link emotions to sensory experiences as
of language involve complex cortical and subcortical
well peripheral receptor injury
[139].

mechanisms which are well described elsewhere
[135].

Evidence for such a model is in evolution. Animal
Hallucinations of complex sounds are experi-

models have demonstrated increased activity in the
enced in a variety of organic states. These tend to
inferior colliculus (after salicylate toxicity)
[140]
and
be transient, associated with disorders of perception

dorsal cochlear nucleus (high intensity injury)
[141].

in other modalities and phenomenologically distinct
Introduction – Section 1

from those that characterize psychiatric illness such as
monitoring
[157].
Functional neuroimaging has sug-schizophrenia. For example, in delirium, auditory hal-gested involvement of Broca’s area and the supple-lucinosis is characterized by sounds or voices which
mentary motor area, primary and higher-order audi-accompany VHs
[148],
such as sounds and speaker
tory and association cortex (particularly on the left),
announcements of a train station the patient feels is
and Wernicke’s area
[157,
158, 159,
160].
Some evi-next to his or her hospital bed. This form of halluci-dence suggests that the experience of external auditory
nosis can occur in alcohol withdrawal
[125],
usually
hallucinations in schizophrenia is due to pathology
within the first 24 hours
[149],
epilepsy, acute renal or
affecting the planum temporale, a temporal cortical
hepatic failure, or other encephalopathies
[150].

region posterior to the primary auditory cortex in Heschl’s gyrus involved in analysis of spatially determined

speech properties
[161]
and this may be at least partially mediated by disrupted dopaminergic transmis-

disorders: schizophrenia

sion in cortical-subcortical circuitry
[162].

In contrast to the relatively sparse descriptions of
the phenomenology of auditory hallucinations in sec-

ondary psychoses, there is a reasonably rich description of the form and content of hallucinations in

schizophrenia. Two medium-sized, fine-grained phenomenological studies – one published
[151]
and
Epilepsy

involving 100 subjects, and one unpublished (Trauer,
All forms of auditory hallucinations have been
Mackinnon, and Copolov, personal communication)
reported in seizure disorders for many years, but are
and involving 199 subjects – have shown that in
usually associated with complex partial seizures. As
schizophrenia and related disorders, auditory halluci-many as 16% of patients with temporal lobe seizures
nations involve a number of voices (the mean being
have been reported as experiencing some form of
three
[151]
) that are frequently but not always neg-auditory hallucination
[163].
In a large retrospective
ative in content (e.g., derogatory, critical, and intru-study of more than 3,000 patients with complex partial
sive), and more often of known identity and of the male
seizures, Mauguiere and colleagues
[164]
reported a
gender. Voices are heard inside the head, outside the
frequency of auditory ictal phenomena in 2.4% This
head, or both inside and outside in roughly equal pro-included hyperacusis (19%), elementary noises (14% )
portions (34%, 28%, and 38%)
[152].
There is mixed
speech (18%), and music (23%).

evidence as to whether externally heard hallucinated
Auditory hallucinations can comprise some of
voices are more likely to be judged to be real,
[151,

the symptoms of a schizophrenia-like psychosis in
152,
153]
but they both appear to evoke similar lev-epilepsy. Most (
∼
70%) of these seizure disorders have
els of negative feelings
[152].
Most hallucinated voices
a temporal focus
[165]
and have the clinical pat-are heard clearly and are either loud or very loud, and
tern of complex partial seizures. The psychoses of
address the hearer in the second or third person
[154].

epilepsy are currently defined as ictal (concurrent with
Approximately 50% of adult psychiatric patients with
seizure), postictal (within 1–2 days of seizure) and
auditory hallucinations experience command hallu-brief (days to weeks post seizure) or chronic interic-cinations, with approximately 50% being associated
tal
[166].
Although ictal psychoses most closely resem-with dangerous behavior
[155].
The majority (66%) of
ble a delirium as described above, often with pre-patients with auditory hallucinations report using cop-served, if delayed insight, the other presentations may
ing strategies to deal with them; such strategies include
include auditory hallucinations, particularly of the
distraction, auditory competition, or trying to relax or
spoken voice, which mimic those of schizophrenia.

sleep, which are often at least partially successful
[4].

A large body of research has explored the neurobiological basis for the high rate of auditory halluci-Traumatic brain injury
nations in schizophrenia. Consensus is emerging that
Auditory hallucinations are also reported in trau-aberrant speech mechanisms underlie these symptoms
matic brain injury. Although psychotic symptoms
in most psychotic patients
[156],
resulting in inner
are described in up to 8% with some form of trau-

speech identified as external due to defective self-matic brain injury, delusions are more common than
Chapter 3 – Secondary hallucinations

hallucinations, of which auditory hallucinations are
back between the perception and recognition modules
the most common, particularly if the psychotic symp-resulting in a percept without a stimulus. This, in turn,
toms are of delayed onset
[167]
. Frontal and temporal
would allow inputs to be misinterpreted or act as trig-lobe abnormalities on neuroimaging are more com-gers for musical hallucinosis.

mon in patients with traumatic brain injury and psy-Some anatomical substrates for this model have
chosis, but there was no association with left or right
been suggested by functional neuroimaging. Although
lesions or the severity of hallucinations. Unfortunately,
perception of simple sounds may involve primary
the precise nature of auditory hallucinations is poorly
auditory cortex (Heschl’s gyrus)
[175]
, perception of
characterized in the literature, although derogatory
complex sounds seems to be more widely distributed.

spoken words are described
[168].
Auditory hallu-The right planum temporale and bilateral frontal areas
cinations and schizophrenia-like psychosis are also
seem to be involved in determination of melody
[176],

described in patients who have undergone temporal
whereas the cerebellum and basal ganglia seem to have
lobectomy, with the hallucinations most often taking
a role in the processing of rhythmic sound
[177].

the form of second person spoken voices
[169].
In this
Lesions in the brainstem
[178, 179],
either hemi-group, bilateral temporal lobe lesions are a risk factor
sphere
[180],
and the occiptal lobe
[181]
have been
for the development of psychotic symptoms.

reported in musical hallucinosis. However, multiple
vascular lesions suggested by white matter hyperinten-sities on neuroimaging are also common associations
Musical hallucinosis

[173, 182].
The presence of central vascular lesions
One of the most interesting forms of isolated audi-may represent the additional risk factor that distin-tory hallucinosis is musical hallucinosis. Musical hal-guishes patients with musical hallucinosis from those
lucinosis can be defined as the perception of music
with deafness without these symptoms. It is possible
without the presence of an external musical stimu-that vascular lesions may disconnect afferent inputs or
lus in which the subject maintains insight. Although
cortical networks increasing the threshold for sponta-these phenomena have been described in psychotic illneous activity. The wide variety nature and location
ness, epilepsy, and a variety of brain lesions including
of lesions in the auditory system that may result in
intracerebral haemorrhage
[170],
they more often are
musical hallucinosis mirrors the heterogeneous lesions
seen in elderly patients with acquired deafness
[171].

associated with complex visual hallucinations
[183].

Some authors have reported patients with musi-Unfortunately, there is little evidence available to
cal hallucinosis later developing auditory hallucina-guide treatment apart from the appropriate treat-tions characteristic of schizophrenia
[172].
However,
ment of the underlying lesion. Pharmacological treat-musical hallucinosis is most commonly seen in per-ments are usually ineffective; most authors recom-sons with hearing loss, advanced age, brain disease,
mend audiological assessment and appropriate ampli-cognitive impairment, female gender, and social isola-fication
[172]
when deafness is the trigger. Progno-tion. Although the relative importance of each of these
sis is usually guarded with musical hallucinosis per-factors is not well understood
[173],
deafness is one of
sisting and worsening as deafness progresses. Evolu-the most common associations.

tion to AHs and paranoid delusions characteristic of
Mechanisms underlying the generation of musilate onset schizophrenia-like illnesses have also been
cal hallucinosis remain poorly understood. The most
reported
[184].

compelling neurobiological model is one of spontaneous activity arising in a deafferented auditory sys-