Descriptive Psychopathology: The Signs and Symptoms of ...

168 Section 3: Examination domainswith schizophrenia. 59 Associated poor executive functioning and frontal circuitryabnormalities are noted. 60 Patients with OCD have subtle oculomotor perturbations,and these are associated with poor executive functioning. 61Jerky and chaotic eye movements (opsoclonus and ocular flutter) occurringwhen the eyes are at rest are associated with cerebellar disease. Horizontal andvertical gaze nystagmus are also cerebellar signs. Nystagmus and abducen’s nerve(sixth cranial nerve) palsy (the patient cannot look up and laterally) are seenin Wernicke’s encephalopathy (an acute delirium most often seen in patients withchronic alcoholism and associated low thiamine levels).Apraxia of gaze is the inability to move the eyes to the examiner’s requests whilespontaneous eyes movement is preserved (an aspect of Bailint syndrome). 62 Abnormalgaze is also reported in thalamic, pontine, and brainstem lesions that can bestbe identified by positron emission tomography (PET), not standard MRI. 63Rare syndromes with disturbance in gaze that can elicit the diagnosis of hysteriaare the Miller–Fisher syndrome from brainstem involvement (progressive upward,lateral, and downward gaze paralysis with ataxia and areflexia), 64 Parinaud’s syndromefrom midbrain involvement (intermittent tonic gaze upward or downwarddeviations), 65 and Claude’s syndrome involving the dorsal midbrain (ipsilateralthird nerve palsy with horizontal gaze problems and contralateral ataxia). 66Movements associated with seizure disorderSeizure disorder is common, and about 10% of epileptics are hospitalized forpsychiatric reasons, while another 20% are regularly treated in psychiatric outpatientsettings. 67 Most movement features of seizure disorder are sudden in onset,repetitive, and of short duration (Table 7.3). None is pathognomonic. Myoclonus,for example, is also seen in toxic states, early in the course of Creutzfeldt–Jakobdisease, and late in Alzheimer’s disease, in several genetic storage disorders,following cerebral anoxia, disease in the central tegmental tract (e.g. infarction,neoplasm, inflammatory), and in disorders of voluntary movement (e.g. RamseyHunt syndrome with associated intension tremor, dysarthria, and ataxia). Asterixisdiffers from myoclonus, and represents a flapping movement of the outstretchedarms due to lapse in postural tone, and is seen in toxic states. 68Sleep-related abnormal movementsAbout a third of the general population at any given time suffers from sleepdifficulties, and sleep disturbance is a common feature of neuro-psychiatric illness. 69Melancholic patients have prolonged sleep onset and shortened REM latency. 70Some seizure disorders typically emerge at night, while some sleep disorders are