4. ORGANIC MENTAL DISORDERS
4. 1 ORGANIC HALLUCINOSIS
ICD – 10 describes organic hallucinosis as a disorder
of persistent or recurrent hallucinations; usually visual or auditory;
that occur in clear consciousness; in the absence of significant
intellectual decline, predominant disturbance of mood and predominance of
delusions. Hallucinations have been reported in various neurological and
systemic medical disorders.
Visual hallucinations
Visual hallucinations occur in various
non-psychiatric conditions including cerebral lesions, sensory
deprivation, the administration of psychedelics (e.g. LSD and mescaline)
and migraine. Elementary visual hallucinations and negative hallucinations
of visual loss occur in occipital lobe epilepsy (Kuzniecky et al., 1997;
Aykut-Bingol et al., 1998). Visual phenomena may also occur in temporal
lobe seizures. Besides complex visual hallucinations (Penfield and Jasper,
1954; Gloor et al., 1982), some authors have mentioned simple,
occipital-like visual experiences in temporal lobe seizures (French et
al., 1993; Bien et al., 2000). Well-formed visual hallucinations have been
reported in Parkinson’s disease (PD) (Fénelon et al., 2000). Hallucinations and delusions in patients with PD were reported
before the introduction of dopaminergic therapy but are usually considered
to represent behavioral complications of drug treatment (Cummings, 1991);
and olanzapine (Wolters et al., 1996) and clozapine (Musser and Akil, 1996) have
been shown to be effective on treating these phenomena. Visual
hallucinations are also reported in Lewy Body Disease and are related to
Lewy Bodies in the temporal lobe (Harding et al., 2002). “Charles Bonnet
syndrome” describes patients with complex visual hallucinations and eye
disease; some authors also use the eponym to describe all patients with
complex visual hallucinations with preserved insight regardless of whether
the experiences are the result of cerebral lesions, metabolic disturbance
or eye disease (Santhouse et al., 2000). The hallucinations are usually
vivid images of animals or human beings, and the patient is aware of their
unreality (Ovsiew, 2002). Risperidone was found effective in controlling
visual hallucinations in a child with the syndrome (Maeda et al., 2003).
Vivid, elaborate, and well-formed visual hallucinations may occur with
diseases in the upper brainstem or thalamus and are called peduncular
hallucinosis. Palinopsia, the persistence or recurrence of visual stimulus
after the disappearance of the stimulus, have been associated with drugs
(cannabis, trazodone, nefazodone, etc.), seizures (temporal and
occipital), focal cerebral lesions, and Creutzfeldt–Jakob disease. (Howard
et al., 2000).
Auditory hallucinations
Auditory hallucinations have been reported in
patients with pontine lesions (Cascino and Adams, 1986; Douen and Bourque,
1997).
Gustatory hallucinations
Gustatory hallucinations are usually associated with
temporal lobe lesions and uncinate gyrus fits (Kolb and Brodie, 1982), and
are usually unpleasant (Haussen-Hauv and Bancaud, 1987).
Olfactory hallucinations
Olfactory hallucinations are reported in temporal
lobe epilepsy, and are distinguished from those occurring in psychiatric
disorders by absence of associated delusions and recognition of the
symptom as a part of the illness (Pryse-Phillips, 1971). Olfactory
hallucinations are also found in patients with migraine (Walburg and
Zeigler, 1982).
Somatosensory hallucinations
Somatosensory hallucinations are reported most
frequently in association with seizure disorders. Kinesthetic
hallucinations, perceptions that unmoving body parts are moving, may
involve amputated body parts (Kolb and Brodie, 1982).
Management
The treatment is directed at the underlying organic
cause. However, symptomatic treatment with antipsychotics is often
effective in controlling the hallucinations. Exceptions to this include
seizures in which the seizure-threshold lowering effects of the
antipsychotics may exacerbate the condition. It should also be kept in
mind that anticholinergic effects of low potency antipsychotics may
exacerbate the hallucinations in patients with drug-induced delirium. |
