Tuesday, 27 December 2011

MUS and Neuropsychology

What Can Neuropsychology Contribute to the Identification and Treatment of Medically Unexplained Neurological Symptoms?

Medically Unexplained Symptoms (MUS) is an umbrella term for a broad collection of symptoms and syndromes that physical processes alone fails to explain. It has been criticised as type of 'non diagnosis' as it essentailly diagnoses what it is not rather than what it is. However, the term has gained popularity over other terms, such as cogniform disorder or somatisation because patients tend to view it as non-threatening, and because positive relationships to professionals (usually the GP) are a key correlate to positive outcome. Examples of MUS phenomena arguably include: inexplicable pain, inexplicable headache, fibromyalgia, chronic fatigue, and non epileptic attack disorder. 

Up to one in five GP appointments is MUS related. It is important to statistically contextualise prevalency as sometimes medical experts are wrong and up to 5% of those diagnosed with MUS subsequently turn out to be medically explainable cases following long term follow-up. However, a mixture of factors including: a growth in civil prosecution, an increase in 'blame culture' and the advent of patient internet derived knowledge, has meant medics have approaches MUS with relentlessly fruitless further medical investigations. The costs and harms both physically, psychologically and financially of this trend is worrying and has attracted attention from psychologists and neuropsychologists alike.

The contribution clinical psychology and neuropsychology can make to MUS sufferers is at two levels: identification and treatment. Where complaints are made of a neurological nature symptom validity tests (SVTs) are routinely used in neuropsychological assessment to identify MUS. They are particular useful in questions over whether a patient has infact sustained a mild head injury or whether they are:
1 Completely malingering
2 or either consciousely or unconsciousely exaggerating symptoms

The BPS now advise routine use of SVTs even in clear cases of organic pathology, primarily to substantiate the reliability of test results and clinical interpretations. Each SVT has it's strengths and weaknesses. Each test aims to strike an appropriate balance between the likelihood of making type 1 versus type 2 error. Each test essentially aims to identify those who are making less than maximum effort. Similarly, 'forced choice' tests, tests that even when completed by random chance stand a 50% correct level, specifically aim to identify those who deliberately aim to mislead testers.  Psychological assessments of personality and psychopathology can also be used as an adjunct in correctly identifying MUS. Subscales indicating anxiety, depression, somatisation, neuroticism and exaggeration of symptoms are often used as indicators of potential MUS. Unusual symptoms, symptoms out of context, long histories of attendance at A&E/GP are other indicators of increased MUS likelihood (see previous blog on DSM-IV indicators).

Most often psychological factors play a central explanatory role. It is believed approximately 70% of MUS patients share comorbidity with psychiatric symptoms, most often anxiety and depression, although the extrapolation of cause and effect complicate this simplistic statistic. At the level of treatment psychologists offer evidence based 'talking interventions' such as CBT and associated approaches. Such approaches focus upon: treating anxiety and depression symptoms, encouraging patients to acceptance their scenario and their symptoms, symptom management and dissemination of psychological formulation as an explanation of symptoms. 

Psychologists  have become increasingly interested in being involved at the primary care level. In Devon, Plymouth began a pilot project in 2008 focussing upon scripting GP messages on initial MUS diagnosis, specific risk assessment for MUS patients and approaches aimed at minimising unneccessary and potentially harmful medical investigations. Psychological approaches have identified the importance in 'getting in early'. Clinicians and researchers have identified a 6 month critical period for intervening (Bass/Stone/Halligan). Beyond this outcomes become  increasingly pessimistic. MUS unsurprisingly fall into three crude groups, of which research is in process: 1. Those who are treatable; 2. Those who may become treatable; and 3. Those who will be highly resistant. Psychologists with considerable MUS experience will usually know which group a patient fits into following the first or second session.

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