Restless leg syndrome was excluded because after receiving gabapentin, both Mr. W and his wife reported improvement in his leg movements.
Although patients with mood disorders such as depression have normal MSLT results, Mr. W reported no excessive time lying in bed awake, which patients with depression often describe as fatigue and sleepiness. In addition, Mr. W’s score on the Clinically Useful Depression Outcome Scale indicated he was not depressed.
Mr. W’s clinician prescribed off-label sodium oxybate to address his EDS. Its potential benefit in this case may be related to its activity on gamma-aminobutyric acid (GABAB) receptors and its effects in prolonging slow-wave sleep, which has restorative properties. This treatment’s effectiveness in this patient was surprising and without precedent. Because the causes of IH often are not precisely defined, we do not recommend administering a trial of this medication without stepwise exclusion of other causes of sleepiness as demonstrated in Pagel’s algorithm “Diagnosis and Management of Conditions That Cause Excessive Daytime Sleepiness,”6 available at www.aafp.org/afp/2009/0301/p391.html.