260 LETTERS TO THE EDITORS 6. Deuschl G, Bain P, Brin M. Consensus statement of the Movement Disorder Society on Tremor. Ad Hoc Scientific Committee. Mov Disord 1998;13(Suppl.):2–23. 7. Holmes G. On certain tremors in organic cerebral lesions. Brain 1904;27:327–375. 8. Krack P, Deuschl G, Kaps M, Warnke P, Schneider S, Traupe H. Delayed onset of “rubral tremor” 23 years after brainstem trauma. Mov Disord 1994;9:240 –242. 9. Miwa H, Hatori K, Kondo T, Imai H, Mizuno Y. Thalamic tremor: case reports and implications of the tremor-generating mechanism. Neurology 1996;46:75–79. 10. Vidailhet M, Jedynak CP, Pollak P, Agid Y. Pathology of symptomatic tremors. Mov Disord 1998;13(Suppl.):49 –54. 11. Remy P, de Recondo A, Defer G, Loc’h C, Amarenco P, PlanteBordeneuve V, Dao-Castellana MH, Bendriem B, Crouzel C, Clanet M. Peduncular “rubral” tremor and dopaminergic denervation: a PET study. Neurology 1995;45:472– 477. 12. Becker G, Berg D. Neuroimaging in basal ganglia disorders: perspectives for transcranial ultrasound. Mov Disord 2001;16:23–32. 13. Berg D, Siefker C, Becker G. Echogenicity of the substantia nigra in Parkinson’s disease and its relation to clinical findings. J Neurol 2001;248:684 – 689. 14. Behnke S, Berg D, Becker G. Does ultrasound disclose a vulnerability factor for Parkinson’s disease? J Neurol 2003;250(Suppl.): 24 –27. Periodic Limb Movements in Sleep After a Small Deep Subcortical Infarct Periodic limb movements in sleep (PLMS) are characterized by episodes of repetitive, stereotyped, involuntary movements during sleep that typically recur at 5- to 90-second intervals.1 There is no consensus on the pathogenesis of PLMS; however, their excellent response to dopaminergic drugs and worsening with dopamine receptor blockers2 suggest that the dopamine system plays a key role in the pathogenesis of PLMS. We describe a patient who showed PLMS after a small deep subcortical infarction involving the pallidum. A 58-year-old, right-handed man was admitted to our hospital with a 12-hour history of right hemiparesis. He had a 5-year history of hypertension but there was no other personal or family history of medical or neurological diseases. He and his wife denied any history of sleep problems or involuntary movements. On neurological examination, he was alert, attentive, and communicative, and had intact higher cortical functions. There was hemiparesis of the right extremity (Grade III of V by manual muscle testing) with decreased sensation of pain, temperature, and vibration. Increased deep tendon reflexes and Babinski’s sign were observed in the right extremities. Two days after admission, his caregiver reported abnormal movements of the right leg during sleep. Initially, these involuntary movements occurred intermittently, even in a daytime sleep. As time passed, they appeared only in the night, leading to severe sleep disturbance. These involuntary movements consisted of a mixture of repetitive dorsiflexion of the ankle and great toe, with subsequent flexion of the knee, which were con- Published online 30 November 2004 in Wiley InterScience (www. interscience.wiley.com). DOI: 10.1002/mds.20327 Movement Disorders, Vol. 20, No. 2, 2005 fined mostly to the right leg. He said that unpleasant sensation in the right foot sometimes preceded the involuntary movements. Motor power of the leg as well as the arm improved gradually (Grade ⱕIII) 5 days after admission). Brain magnetic resonance images taken the day after admission demonstrated acute discrete infarction in the posterior limb of the left internal capsule and the adjacent pallidum (Fig. 1). Brain single photon emission computed tomography (SPECT) using 99mTc-ethyl cysteinate dimer showed a markedly decreased perfusion in the left basal ganglia. Nocturnal video monitoring with surface electromyography demonstrated typical periodic involuntary movements of the right leg, consisting of flexion of the toe and the knee. These involuntary movements appeared every 14 to 60 seconds and showed periodic bursts of compound muscle action potentials lasting 1 to 2 seconds. The consecutive contraction of the left leg rarely appeared with very small compound muscle action potentials. Polysomnography revealed a total sleep time of 413.5 minutes, a sleep efficiency of 86.8% and a PLMS index of 40.3 per hour. Immediately with the introduction of levodopa (L-dopa; 100 mg/day) with carbidopa at night, the patient and his family reported a marked improvement of the involuntary leg movements during sleep. Discontinuation of L-dopa aggravated the involuntary leg movements again. Three months after L-dopa medication, the patient and his family reported that the movements were controlled well with medication. Our patient had no history of sleep disturbance and the temporal relationship between the infarction and PLMS was obvious. The involuntary leg movements in the patient (ⱕ our patients) met the diagnostic criteria for PLMS1,3 but did not fulfill the essential criteria for restless legs syndrome (RLS).4 To the best of our knowledge, this is the first report of a structural lesion of the basal ganglia associated with PLMS. As well as pharmacologic studies of dopaminergic drugs, the dopamine hypothesis in the pathogenesis of PLMS has been supported by dopamine receptor studies using SPECT or positron emission tomography (PET) images. Ruottinen and colleagues5 reported mild nigrostriatal presynaptic dopamine hypofunction, and Michaud and associates6 and Staedt and coworkers7 demonstrated decreased the striatal dopamine D2 receptor binding in patients with PLMS with RLS. In addition, neurophysiological studies of flexor reflexes, which resemble PLMS clinically and are known to share common mechanisms with PLMS, demonstrate that dopaminergic substances suppress the exaggerated flexor response,8 further strengthening the role of dopaminergic system in the pathogenesis of PLMS. The dopamine abnormality responsible for the PLMS may be mediated by dysfunction of the nigrostriatal dopaminergic pathway (either presynaptic or postsynaptic) or other descending diencephalo–spinal pathways.9 It has been suggested that PLMS may be the result of pyramidal tract involvement. However, motor improvement in our patient was not correlated with improvement of PLMS. A similar discrepancy between pyramidal tract dysfunction and the severity of PLMS has been found in studies of PLMS in spinal cord lesions.10 Pyramidal tract involvement may therefore give a minor contribution to the pathogenesis of PLMS. The generator of PLMS has not been elucidated but their occurrence in patients with various spinal cord lesions indicates that spinal mechanisms are involved. Combined with previous dopamine receptor studies, it seems reasonable to hypothesize LETTERS TO THE EDITORS 261 FIG. 1. Brain magnetic resonance imaging taken the day after admission reveals a small, discrete infarction involving the posterior limb of the left internal capsule and adjacent pallidum on diffusion-weighted (A) and T2-weighted imaging (B). that PLMS result from the loss of supraspinal inhibitory influences secondary to dysfunction of the basal ganglia dopaminergic system. From a clinical viewpoint, the PLMS in our patient with basal ganglia lesion that responded to dopaminergic medication provide the additional evidence for the role of the dopaminergic system in pathogenesis of PLMS. Jin Soo Lee, MD Phil Hyu Lee, MD* Kyoon Huh, MD Department of Neurology Ajou University School of Medicine Suwon, South Korea *E-mail: phisland@chol.net References 1. American Sleep Disorders Association (ASDA). Periodic limb movement disorder and restless legs syndrome. In: International classification of sleep disorders: diagnostic and coding manual. Rochester, MN: Diagnostic Classification Steering Committee; 1990. p 65–71. 2. Hening W, Allen R, Earley C, Kushida C, Picchietti D, Silber M. The treatment of restless legs syndrome and periodic limb movement disorder. An American Academy of Sleep Medicine Review. Sleep 1999;22:970 –999. 3. The Atlas Task Force. Recording and scoring leg movements. Sleep 1993;16:748 –759. 4. Allen RP, Picchietti D, Hening WA, Trenkwalder C, Walters AS, Montplaisi J; Restless Legs Syndrome Diagnosis and Epidemiology workshop at the National Institutes of Health; International Restless Legs Syndrome Study Group. Restless legs syndrome: diagnostic criteria, special considerations, and epidemiology. A report from the restless legs syndrome diagnosis and epidemiology workshop at the National Institutes of Health. Sleep Med 2003;4: 101–119. 5. Ruottinen HM, Partinen M, Hublin C, Bergman J, Haaparanta M, Solin O, Rinne JO. An FDOPA PET study in patients with periodic limb movement disorder and restless legs syndrome. Neurology 2000;54:502–504. 6. Michaud M, Soucy JP, Chabli A, Lavigne G, Montplaisir J. SPECT imaging of striatal pre- and postsynaptic dopaminergic status in restless legs syndrome with periodic leg movements in sleep. J Neurol 2002;249:164 –170. 7. Staedt J, Stoppe G, Kogler A, Riemann H, Hajak G, Munz DL, Emrich D, Ruther E. Single photon emission tomography (SPET) imaging of dopamine D2 receptors in the course of dopamine replacement therapy in patients with nocturnal myoclonus syndrome (NMS). J Neural Transm Gen Sect 1995;99:187–193. 8. Paradiso G, Khan F, Chen R. Effects of apomorphine on flexor reflex and periodic limb movement. Mov Disord 2002;17:594 – 597. 9. Lindvall O, Bjorklund A, Skagerberg G. Dopamine-containing neurons in the spinal cord: anatomy and some functional aspects. Ann Neurol 1983;14:255–260. 10. Nogues M, Cammarota A, Leiguarda R, Rivero A, Pardal A, Encabo H. Periodic limb movements in syringomyelia and syringobulbia. Mov Disord 2000;15:113–119. Dietary Herb Extract Dai-Kenchu-To Ameliorates Constipation in Parkinsonian Patients (Parkinson’s Disease and Multiple System Atrophy) Dai-Kenchu-To (DKT) (50% ginger, 30% “Nin-jin” [ginseng], and 20% “Sansho” [Japanese pepper, Zanthoxylum]) is a dietary herb extract used for relieving abdominal distension in Eastern countries. Because the extract is composed of food additives generally considered safe and timetested, we performed an open trial of DKT’s effects on constipation in parkinsonian patients, using objective measures derived from lower-gastrointestinal tract (GIT) motility tests. We recruited 10 male patients (mean age, 72 years; range, 66 –77 years, mean duration of disease 4 years; range, 3– 8 years). None was taking anticholinergic agents. Six patients had Parkinson’s disease (PD; median Hoehn–Yahr grade 3; range, 2–3) and were all independent in walking, taking a mean daily levodopa dose 200 mg (range, 100 – 400 mg). The other 4 patients had multiple system atrophy (MSA); only 1 was independent in walking. Two MSA subjects received L-dopa treat- Published online 13 December 2004 in Wiley InterScience (www. interscience.wiley.com). DOI: 10.1002/mds.20352 Movement Disorders, Vol. 20, No. 2, 2005