Second edition

18.qxd 3/10/08 9:52 AM Page 583
Course
Idiopathic periodic limb movement disorder appears to be
chronic; the course of the secondary form is determined by
the underlying cause. Tricyclic antidepressants may exacerbate
this disorder (Ware et al. 1984).
Etiology
The idiopathic form appears to be inherited and, as indicated
by single photon emission computed tomography
(SPECT) studies, is associated with a deficiency of postsynaptic
dopamine receptors in the striatum (Staedt et al.
1995). Although the mechanism underlying the abnormal
movements is not known, their strong resemblance to a
Babinski response suggests that they result from a lack of
normal supraspinal inhibition (Smith 1985).
Secondary forms have been associated with congestive
heart failure (Hanley and Zuberi-Khokhar 1996), chronic
hemodialysis (Rijsman et al. 2004), alcohol withdrawal
(Gann et al. 2002), and spinal cord lesions (Lee et al. 1996).
Rare cases have also been reported secondary to lacunar
infarctions in the corona radiata (Kang et al. 2004) and in
the pons (Kim et al. 2003).
Differential diagnosis
Isolated jerkings, occurring at a frequency of up to five per
hour, may be an incidental finding on polysomnography
(Mendelson 1996) and are not associated with any
symptoms.
Hypnic jerks (Oswald 1959), also known as ‘sleep starts’,
are a normal accompaniment of the transition into sleep.
They differ from the jerkings seen in periodic limb movements
in that they are very brief, typically involve all four
extremities, and occur only as the individual is falling asleep.
Myoclonus, discussed in Section 3.2, is distinguished
from the jerkings of periodic limb movements by its
‘shock-like’ rapid onset, in contrast to the relatively
leisurely evolution of the jerking movement.
Treatment
Various medications are effective, including levodopa/carbidopa
(Becker et al. 1993; Brodeur et al. 1988; Kaplan et al.
1993), pramipexole (Montplaisir et al. 1999), gabapentin
(Garcia-Borreguero et al. 2002), clonazepam (Mitler et al.
1986b; Ohanna et al. 1985; Peled and Lavie 1987; Saletu
et al. 2001), and oxycodone (Walters et al. 1993). The choice
among these and their method of use are similar to that
noted for restless legs syndrome in Section 18.11; of note,
‘augmentation’, as may be seen with dopaminergic agents
in the restless legs syndrome, has not been reported in periodic
limb movement disorder. Interestingly, in an open
18.13 Painful legs and moving toes 583
study bupropion was also effective (Nofzinger et al. 2000),
as was selegiline (Grewal et al. 2002).
18.13 PAINFUL LEGS AND MOVING TOES
As the name implies, this syndrome is characterized by
pain in the legs (which may be quite severe) and involuntary
movements of the toes, all resulting in insomnia. This
is a rare but potentially devastating condition.
Clinical features
The syndrome (Dressler et al. 1994; Spillane et al. 1971)
generally has an onset in the sixth or seventh decades. In
most cases pain appears first and, although symptoms may
begin unilaterally, bilateral involvement eventually ensues.
As noted by Spillane et al. (1971), the pain varies ‘in intensity
from discomfort to a pain of great severity . . . an ache,
an intense pressure, a tightness, a feeling that the toes were
pulling or being pulled, a throbbing, bursting, crushing . . .
[or] a deep burning’ and the movements consist of a ‘sinuous
clawing and re-straightening, fanning and circular
movements of the toes’. The effect of the toe movements
can be remarkable: one of Spillane et al.’s patients ‘was surprised
to see that the toes were actually moving “as though
they were playing a piano on their own” ’. The symptoms
are not relieved by walking about and insomnia can be
severe (Montagna et al. 1983). When sleep does come, the
abnormal movements cease.
Course
In most case this syndrome appears to be chronic.
Etiology
The syndrome has been noted secondary to lesions of the
cord, posterior lumbar roots, and peripheral nerves, and
with trauma to the back or feet (Dressler et al. 1994; Ikeda
et al. 2004; Montagna et al. 1983; Nathan 1978; Pla et al.
1996; Schott 1981). Interestingly, lesions or trauma need
not be bilateral; unilateral lesions may be followed initially
by an ipsilateral onset, but eventually the contralateral
extremity becomes involved.
Differential diagnosis
The restless legs syndrome is distinguished by an absence of
pain and abnormal movements, and by the characteristic
relief obtained by walking about. Reflex sympathetic dystrophy
is distinguished by the lack of abnormal movements.