むずむず足症候群 (ＲＬＳ) の６０〜８０％に合併する（逆は真ならず）が、ＲＬＳが下肢の
不快な感覚であるのに対し、ＰＬＭＤは親指、足関節の背屈運動であり、周期的 (規則的) に
おこる不随意運動である。（R/O "睡眠てんかん" では周期性はみられない）

RLSはbefore sleep (入眠前) の疾患であり、

PLMDはafter(=during) sleep(入眠後=既に睡眠に入っている時に起こる)の疾患である。

浅いノンレム睡眠で起りやすく、深いノンレム睡眠やREM睡眠では殆どみられない。

                                                                   

                           PLMS                 RLS                

        SLEEP               after sleep                before sleep

        DIAGNOSIS        polysomnographic       clinical        

periodic (rhythmic) leg (arm) movements, such as dorsiflexion (extension) of the big toe with fanning of

the small toes, accompanied by flexion of the ancles, knees and hip that may or may not be associated with arousal.

 

・Only a small fraction (30%) of all patients with PLMD have RLS. Thus, the abscence of a history of RLS

does not diminish the possibility of the presence of PLM. In contrast, if a patient has RLS, he or she

also has PLM (70-90%).

＜PLMS scoring (1993 ASDA American Sleep Disorders Association)＞

During sleep (scored only on those epochs which the patients are asleep) ;

1) 0.5 to 5 second duration (lasting) of burst of anterior tibialis activity

2) an amplitude of at least 25% of the bursts recorded during biocalibration(=voluntary toe dorsiflexion)(覚醒時の随意収縮)

                                                       ↓

             1)and2)の条件がそろえば is scorred "leg movement(LM)"

            leg movement(LM)が更に下記3)のperiodicの条件を満たせばis scored "PLM"

                                                       ↓

3) a series of 4 events (burst) separated by intervals of 5(4) to 90 seconds

                                               (occuring every 5 to 90 seconds)

                                       (measured from leg movement onset to leg movement onset)

                                                        ↓

                              PLM during sleepを"PLMS"と言う

4) limb movements preceeded by spontaneous arousal(=following arousal), or resulting from arousals

   associated with the termination of a respiratory event(=apnea termination) are not scored as PLMs.

     (無呼吸終結時の覚醒反応に一致して起こる)

    ・hypnic jerks睡眠時筋攣縮＝sleep starts睡眠時ひきつけ（びくつき）＝hypnagogic jerks入眠時筋攣縮＝stage1

      に至る前のうとうとと眠る状態で出現し、入眠すると起こらない。これもbefore sleep故not scored

5) simultaneous movements in both legs are counted one movement(=in the two- channel method of

　　　　↓                                                                                                            display).

　　unless the second leg movement is more than 5 seconds after the onset of the first

    (some use 5 seconds after the offset of the first leg movement)

・PLMS index(/hour)＝number of PLMS per hour of sleep＝total number of PLMs / (TST(min)/60min) ;

   greater than 5 is considered pathologic; 5 to 24 mild, 25 to 49 moderete, ≧ 50 severe

・PLMS-arousal index(/hour)＝total number of PLMs associated with arousal / (TST(min)/60min) ;

   ＞25/hr in severe insomnia or EDS.　　　　                  ↓

          to be scored as PLM with arousal , an arousal must occur simultaneously with a LM or

          following the LM by less than(＜) 3 seconds

 

          Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｃｌａssification of Sleep Disorders Criteria for PLMS Severity 

                  SEVERITY           PLM  INDEX(/HR)            PLM  AROUSAL INDEX(/HR)            

                  Mild                    5-24                              Not specified

                  Moderate            25-49                             Not specified

                  Severe               ≧50　　　　　　　　　　　　　　＞25/ｈｒ　　　　　　　　　　　　　　　　　 

 

・monitoring of both legs(=dual monitoring) is suggested., because PLM may occur in one or both legs.

・PLMs are restricted to NREM sleep in many patients(stage1に入るとすぐ出現しstage2で頻回となり、

  stage3〜4では減少する),(通常REM睡眠では出現しない) but PLMs in REM sleep can occur (重症例).

・Patients usually do not remember PLMs, but bedmates may report movement.

・K-alpha complex (K-complex と其れに続く α波の群発) がみられる。

 

・PLMS and Microarousal : rule to score MA (ASDA : The American Sleep Disorders Association)

 in NREM sleep, MA are defined as a return to alpha or theta activity lasting between 3 and 15

                     seconds.

 in REM sleep, criteria include, in addition to EEG changes, an increase in chin EMG amplitude.

 

・ＲＬＳの入眠障害や再入眠障害に対し、ＰＬＭＤは中途覚醒（一晩に２回以上目が覚める）の

原因となるが、中途覚醒が少なければEDS(日中傾眠)の原因にはならない。

sleep continuity (=sleep-maintenance) is desrupted by frequent awakenings (e.g., OSAS)

・Functional Significance of PLMS :

  Most authors have concluded that PLMS have little impact on nocturnal sleep or daytime vigilance.

  Some have questioned whether PLMD is a real clinical entity. �ｧ PLMS occur in many asymptomatic individuals.

 

・ＲＬＳ同様夜間後半から早朝にかけて軽減ないし消失する。カフェインや疲れで増悪する。

・nasal CPAPによるOSASの治療開始後、無呼吸が減少したにも関らず、不眠や過眠が改善

しない時には、 PLMs の出現や増悪が原因かもしれない。この時はPLMDの治療をする。

・                  Causes and Associations of PLMS                  

             �ｨ any cause of RLS

             �ｨ withdrawal of anticonvulsants, barbiturates, hypnotics

             �ｨ associated with narcolepsy, OSA, RBD, CPAP titration 

　　　　　　�ｧ in many asymptomatic individuals                             

治療；RLSと同じ（∵RLSとPLMDは病態が共通）

 ・ traditionalにはリボトリールKLONOPIN（benzodiazepin clonazepam）0.5〜1.0mg-->

�@ decrease in the arousals associated with the leg movements, but no decrease in the number

of leg movements.�A pottential to worsen sleep apnea, �B absolutely contraindicated in hypoventilation; should be used with caution in patients with OSA.

 ・ alternative to the benzodiazepin はDA agents ;

�@SINEMET(carbidopa/levodopa (25/100 mg) combination)=Dopamine precursors

-->decrease the amount of leg movements

OR

�A MIRAPEX(Pramipexole)=Dopamine agonists

（注意）DA agents may exert a stimulant (or an alerting) effect that might further disrupt

nocturnal sleep or EDS.