206 - 6D70 Delirium

6D70 Delirium

Clinical Descriptions and Diagnostic Requirements for ICD-11 Mental, Behavioural or Neurodevelopmental Disorders • Linguistic and cultural proficiency must also be considered when interpreting test results, in terms of both whether the individual understood the instructions and the impact on test performance. • When standardized testing is utilized for determination of neurocognitive impairment, it should be appropriately developed and normed for the population of which the individual being tested is a member. Where appropriately normed and standardized tests are not available, assessment of the essential features of these disorders requires greater reliance on clinical judgement based on appropriate evidence and other quantified clinical assessment. General considerations related to sex and/or gender for neurocognitive disorders • Performance on clinical assessment or standardized neuropsychological/cognitive testing may differ according to sex and/or gender-related factors. When clinical assessment or standardized neuropsychological/cognitive testing is utilized for determination of memory or other neurocognitive impairment, sex and/or gender-related factors should be considered and accounted for when possible. Delirium Delirium includes the following subcategories: 6D70.0 Delirium due to disease classified elsewhere 6D70.1 Delirium due to psychoactive substances, including medications 6D70.2 Delirium due to multiple etiological factors 6D70.Y Delirium, other specified cause 6D70.Z Delirium, unknown or unspecified cause. General diagnostic requirements for delirium Essential (required) features • A disturbance of attention, orientation and awareness developing within a short period of time (e.g. within hours or days), typically presenting as significant confusion or global neurocognitive impairment, with transient symptoms that may fluctuate depending on the underlying causal condition or etiology, is required for diagnosis. • The disturbance represents a change from the individual’s baseline functioning. 6D70 Neurocognitive disorders | Delirium

603 Neurocognitive disorders • Delirium may be caused by the direct physiological effects of a medical condition not classified under mental, behavioural and neurodevelopmental disorders, by the direct physiological effects of a substance or medication – including withdrawal – or by multiple or unknown etiological factors. • The symptoms are not better accounted for by a pre-existing or evolving neurocognitive disorder (e.g. amnestic disorder, mild neurocognitive disorder, dementia) or by another mental disorder (e.g. schizophrenia or another primary psychotic disorder, a mood disorder, post-traumatic stress disorder, a dissociative disorder). • When a substance or medication is present, the symptoms are in excess of those typical of substance intoxication or substance withdrawal for that substance, although delirium can occur as a complication of intoxication or withdrawal states (see 6D70.1 Delirium due to psychoactive substances, including medications, below). Additional clinical features • In delirium, cognition is typically impaired in a global manner, such that multiple areas of neurocognitive functioning are impaired upon assessment. • Delirium may include impaired perception, which can manifest as illusions (i.e. misinterpretations of sensory inputs), delusions or hallucinations. • Delirium often includes disturbance of emotion, including anxiety symptoms, depressed mood, irritability, fear, anger, euphoria or apathy. • Behavioural symptoms may be present (e.g. agitation, restlessness, impulsivity). A disturbance of the sleep-wake cycle, including reduced arousal of acute onset or total sleep loss followed by reversal of the sleep-wake cycle, may also be present. • The presence of a pre-existing neurocognitive disorder can increase the risk of delirium and complicate its course. Boundary with normality (threshold) • Normal ageing is typically associated with some degree of cognitive change. Delirium is differentiated from age-related cognitive changes by the sudden onset of symptoms (e.g. within hours or days), the presence of significant confusion and/or global neurocognitive impairment, and the transient and typically fluctuating symptom presentation. Course features • Onset of symptoms is typically sudden (e.g. within hours or days), with a transient and/or fluctuating course. • Symptoms are generally expected to remit with treatment of the underlying etiology or elimination of the causative substance from the body. Neurocognitive disorders | Delirium

Clinical Descriptions and Diagnostic Requirements for ICD-11 Mental, Behavioural or Neurodevelopmental Disorders Developmental presentations • Susceptibility to delirium in infancy and childhood may be greater than in early and middle adulthood. • In childhood, delirium may be related to febrile illnesses and certain medications (e.g. anticholinergics). • Older individuals are especially susceptible to delirium compared with younger adults. Culture-related features • Performance during clinical assessment may vary according to cultural and/or linguistic factors. When assessing impairment in neurocognitive functioning and activities of daily living, cultural and linguistic factors should be considered and accounted for when possible. • When standardized neuropsychological/cognitive testing is utilized for determination of neurocognitive impairment, performance should be measured with appropriately normed, standardized tests. In situations where appropriately normed and standardized tests are not available, assessment of neurocognitive functioning requires greater reliance on clinical judgement. (See the section on general cultural considerations for neurocognitive disorders above for additional information and examples.) Boundaries with other disorders and conditions (differential diagnosis) Boundary with dementia Delirium is differentiated from other neurocognitive disorders in that the former is characterized by global neurocognitive impairment and confusion that have a precipitous onset, are transient, and fluctuate depending on the underlying causal condition or etiology. Dementia is more typically characterized by impairment in specific neurocognitive abilities, and is often progressive and more gradual in onset. Individuals with dementia are at increased risk of delirium, and those who develop acute disturbances in attention, orientation and awareness should be assigned an additional diagnosis of delirium and evaluated to determine its specific etiology. Boundary with neurocognitive impairment associated with acquired or traumatic brain injuries Delirium is differentiated from an acute confusional or agitated state related to acquired or traumatic brain injuries by the absence of evidence of a preceding neurological injury or event (e.g. traumatic brain injury, cerebral haemorrhage, stroke). Neurocognitive disorders | Delirium

605 Neurocognitive disorders Boundary with transient global amnesia Unlike delirium, transient global amnesia is characterized by the presence of isolated memory impairment alongside intact functioning in other cognitive areas (e.g. naming skills, selfidentification). Although both disorders may present with memory impairment, delirium is frequently characterized by additional symptoms, including significant confusion, global neurocognitive impairment, and behavioural and emotional disturbance (e.g. hallucinations, agitation). Boundary with factitious disorder and malingering In factitious disorder and malingering, the neurocognitive symptoms characteristic of delirium are consciously feigned. Feigned or induced symptoms may be – although they are not necessarily – atypical in pattern, magnitude or course, or may be medically implausible. Individuals with factitious disorder feign neurocognitive symptoms in order to seek attention, especially from health-care providers, and to assume the sick role. Malingering is characterized by intentional feigning of neurocognitive impairment for obvious external incentives (e.g. disability payments). Boundary with schizophrenia and other primary psychotic disorder Delirium accompanied by hallucinations and/or delusions is differentiated from schizophrenia and other primary psychotic disorders by the absence of other characteristics of these disorders, and by symptoms that are transient and fluctuate depending on the underlying causal condition or etiology. Boundary with dissociative amnesia Selective memory deficits are present in dissociative amnesia, and may be accompanied by confusion about identity if dissociative fugue is present. Dissociative amnesia is not characterized by disturbances in attention or awareness, general confusion or global neurocognitive impairment, which are features of delirium. Delirium due to disease classified elsewhere Essential (required) features • All diagnostic requirements for delirium are met. • There is evidence from the history, physical examination or laboratory findings that the neurocognitive disturbance is caused by the direct physiological consequences of a medical condition. This judgement depends on establishing the following. • The medical condition is known to be capable of producing delirium. • The course of the delirium (e.g. onset, trajectory of symptoms, response to treatment) is consistent with causation by the medical condition. Note: when delirium is due to a disease or condition classified elsewhere, the diagnostic code corresponding to that disease or condition should be assigned along with delirium due to disease classified elsewhere. If the delirium is attributed to multiple medical conditions or to a medical condition and a substance or medication, the category 6D70.2 Delirium due to multiple etiological factors should be used instead. This may include medications being used to manage the medical condition. Neurocognitive disorders | Delirium 6D70.0

Clinical Descriptions and Diagnostic Requirements for ICD-11 Mental, Behavioural or Neurodevelopmental Disorders Potentially explanatory medical conditions (examples) • Certain infectious or parasitic diseases (e.g. meningitis, viral hepatitis, sepsis) • Diseases of liver (e.g. chronic hepatic failure, hepatic encephalopathy) • Diseases of the circulatory system (e.g. acute myocardial infarction) • Diseases of the nervous system (e.g. cerebral ischaemic stroke, epilepsy or seizures, hypertensive encephalopathy) • Diseases of the urinary system (e.g. kidney failure, urinary tract infection) • Endocrine disorders (e.g. diabetic ketoacidosis, hyperthyroidism, hypothyroidism) • Metabolic disorders (e.g. acidosis, disorders of urea cycle metabolism, hypoglycaemia, hypomagnesaemia, hypo-osmolality, hyponatraemia) • Neoplasms of the brain or central nervous system • Nutritional disorders (e.g. vitamin B1, B3 or B12 deficiency) Delirium due to psychoactive substances, including medications Essential (required) features • All diagnostic requirements for delirium are met. • There is evidence from history, physical examination or laboratory findings that the neurocognitive disturbance is caused by the direct physiological consequences of use of a substance or medication. This judgement depends on establishing the following. • The substance and the amount and duration of its use or withdrawal from the substance is known to be capable of producing delirium. • The course of the delirium (e.g. onset, trajectory of symptoms, eventual remission with elimination of the substance from the body) is consistent with causation by the substance. • The duration or severity of the symptoms is substantially in excess of the characteristic syndrome of substance intoxication or substance withdrawal due to the specified substance. Note: each specific substance that has been identified as contributing to the delirium should be classified using the appropriate substance-specific category. If one or more of the categories appearing below is diagnosed, a separate diagnosis of delirium due to psychoactive substances, including medications, should not be assigned. 6C40.5 Alcohol-induced delirium (see Table 6.16, p. 484, for a description of delirium associated with alcohol withdrawal) 6C41.5 Cannabis-induced delirium 6C42.5 Synthetic cannabinoid-induced delirium 6C43.5 Opioid-induced delirium 6C44.5 Sedative, hypnotic or anxiolytic-induced delirium (see Table 6.16, p. 484, for a description of delirium associated with sedative, hypnotic or anxiolytic withdrawal) Neurocognitive disorders | Delirium 6D70.1

607 Neurocognitive disorders 6C45.5 Cocaine-induced delirium 6C46.5 Stimulant-induced delirium, including amfetamines, methamfetamine and methcathinone 6C47.5 Synthetic cathinone-induced delirium 6C49.4 Hallucinogen-induced delirium 6C4B.5 Volatile inhalant-induced delirium 6C4C.5 MDMA or related drug-induced delirium, including MDA 6C4D.4 Dissociative drug-induced delirium, including ketamine and PCP 6C4E.5 Delirium induced by other specified psychoactive substance, including medications 6C4F.5 Delirium induced by multiple specified psychoactive substances, including medications 6C4G.5 Delirium induced by unknown or unspecified psychoactive substance A diagnosis corresponding to the pattern of use of the relevant psychoactive substance (e.g. episode of harmful psychoactive substance use, harmful pattern of psychoactive substance use, substance dependence) may also be assigned. If the delirium is attributed to a substance or medication together with one or more medical conditions, the category 6D70.2 Delirium due to multiple etiological factors should be used instead. This may include medications being used to manage the medical condition. Delirium due to multiple etiological factors Essential (required) features • All diagnostic requirements for delirium are met. • There is evidence from the history, physical examination or laboratory findings that the delirium is caused by either: • the direct physiological consequences of multiple diseases classified elsewhere; or • one or more diseases classified elsewhere and the direct effects of a substance or medication on the central nervous system. • This judgement depends on establishing the following. • The medical conditions are known to be capable of producing delirium. • If applicable, the amount and duration of use of the substance or withdrawal from the substance is known to be capable of producing delirium. • If applicable, the duration or severity of the symptoms is substantially in excess of the characteristic syndrome of substance intoxication or substance withdrawal due to the specified substance. • The course of the delirium (e.g. onset, trajectory of symptoms, eventual remission with elimination of the substance from the body) is consistent with causation by the medical conditions and, if applicable, the substance. Note: when delirium is related to one or more diseases or conditions classified elsewhere, the diagnostic code corresponding to those diseases or conditions should be assigned along with delirium due to multiple etiological factors. Neurocognitive disorders | Delirium 6D70.2