Thursday, February 26, 2004

More on Sleep Disorders

No Medical Condition is Simple
Flexible Thinking in Medical Treatment

[left brain stuff:] A while back (February 4, 2004) I blogged about a report on a study of obstructive sleep apnea.  The study showed that there are abnormalities in brain waves of patients with sleep apnea who are asleep -- even when they are not actually having apnea.  The study is important because it illustrates that obstructive sleep apnea is more complex than originally thought.  Now we see a report that shows a link between a different sleep disorder -- restless legs syndrome -- and mood and anxiety symptoms. 

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(from Medscape; free registration required)

NEW YORK (Reuters Health) Feb 25 - Patients with restless legs syndrome exhibit relatively high levels of anxiety and depression, according to a report in the February issue of the Journal of Neurology, Neurosurgery, and Psychiatry.

"Restless legs syndrome (RLS) is an important and common cause of insomnia, and previous studies indicate that psychiatric well-being may be impaired among RLS patients," Dr. Serhan Sevim and colleagues from Mersin University, in Turkey, write. In a population-based survey, they examined the association between anxiety/depression and RLS.

The researchers obtained data on 3234 subjects enrolled in the Mersin University Neuro-Epidemiology Project. A total of 103 subjects had RLS, and were assessed for symptoms of anxiety and depression using the Hamilton Anxiety and Depression Scales. These patients were compared with 103 contemporaneous controls.

Compared with controls, RLS patients had significantly greater anxiety and depression symptoms. The mean Hamilton anxiety score was 8.03 in the RLS patients compared with 5.91 in the controls; the mean depression scores were 9.27 vs 5.88, respectively.

A correlation was observed between the severity of RLS and of anxiety and depression symptoms, researchers report.

"We conclude that assessment of psychiatric status of RLS patients can be helpful and sometimes necessary to determine additional features and treatment strategies of this troublesome condition," Dr. Sevim and colleagues note.

They add that a longitudinal assessment would be necessary to establish temporality; ie, to determine whether anxiety or depression are a consequence of RLS.

J Neurol Neurosurg Psychiatry 2004;75:226-230.

[right brain stuff:] In my view, the key phrase in this report is: "We conclude that assessment of psychiatric status of RLS patients can be helpful and sometimes necessary to determine additional features and treatment strategies of this troublesome condition," Dr. Sevim and colleagues note.  In a way, this is a cautionary tale.  It is very easy for a physician to assess and treat the main complaint of the patient, and ignore everything else.  The take-home message here is that is is essential to assess the overall level of function of the patient after the treatment has been instituted.  If a patient has depression and RLS, and you treat the RLS only, you may think you have done a great service; but in actuality, the patient still is not going to do well. 

In the case of comorbid RLS and depression, there is another risk.  If the patient presents with a chief complaint of depression, and you treat the depression but not the RLS, you actually could make the patient worse.  The reason is that most antidepressants can increase the severity of RLS.  This may be due to the fact that serotonergic drugs can decrease dopamine synthesis (Baldessarini RJ, Marsh E (1990), Fluoxetine and side effects. Arch Gen Psychiatry 47(2):191-192 [letter]).  See this  Psychiatric Times article for an overview of the relationship between antidepressants and movement disorders. 

On a more abstract level, this illustrates the problems that can arise when a strictly linear problem-solving approach is employed in medical practice.  The usual heuristic  of symptoms --> diagnosis --> treatment  is overly simplistic.  It is more appropriate to uses a looping strategy in which the treatment is followed by reassessment, then revision of diagnosis and/or treatment if the results are not satisfactory.  The reassessment step sometimes requires flexible thinking, as it is essential to avoid the trap of reassessing only the original chief complaint. 

Sometimes, the symptoms --> diagnosis --> treatment  process is complicated by the fact that there is more that one possible diagnosis. In that case, it is important to consider the diagnostic possibilities and see if there are two (or more) possible diagnoses can be treated in the same way.  When that turns out to be the case, it may be appropriate to institute treatment that will cover the set of possible diagnoses that all have a common treatment

For example, on the surface it appears that it should be easy to distinguish a patient with RLS from one with depression, but for various reasons, this is not always the case.  If you cannot tell whether the patient has depression, RLS, or both, it could be that the most reasonable course of action would be to give the patient a dopaminergic antidepressant.  This could result in significant clinical improvement regardless of the diagnosis.  Such a strategy could be viewed as shortcut, a way to institute treatment without going through all the steps that would be required to establish a firm diagnosis.  If a shortcut is used, though, it is even more important to examine carefully the outcome of the treatment and revise your interventions if necessary. 

For an good brief review of RLS, see this  Journal of Postgraduate Medicine article.  A more thorough review can be found here, at eMedicine.