Repetitive sleep starts: An important differential diagnosis of infantile spasms

OBJECTIVE

Repetitive sleep starts (RSS) are clusters of nonepileptic, spasm-like movements occurring during sleep onset. However, their characteristics have yet to be defined. We conducted a clinicoelectroencephalographic study of children with RSS to clarify their detailed characteristics.

METHODS

To differentiate starts from epileptic spasms, we recruited children with brief "crescendo-decrescendo" muscle contractions that simultaneously involved the limbs and trunk without electroencephalogram changes, and that fulfilled the following criteria: (1) repeated occurrence (five or more) and (2) manifestation during sleep stage N1-N2. A total of nine children met these criteria. Their clinical information and video-electroencephalogram data were analyzed retrospectively.

RESULTS

The background conditions observed at onset of RSS were perinatal hypoxic-ischemic encephalopathy (n = 4), West syndrome of unknown etiology (n = 1), and traumatic brain injury (n = 1). The age at onset of RSS, the number of starts in a given RSS cluster, the interval between starts, and the duration of surface electromyogram activity were between 3 and 46 months, 5 and 547, <1 and 60 s, and 0.3 and 5.4 s, respectively. None of the median value of these parameters differed between children with and without corticospinal tract injury. During the median follow-up period of 33 months, RSS disappeared spontaneously in five.

CONCLUSION

This is the largest case series of RSS clarifying their clinicoelectroencephalographic characteristics reported to date. To avoid unnecessary antiepileptic therapies, clinicians should be aware of RSS and distinguish it from other disorders involving involuntary movements or seizures, especially epileptic spasms.

Propriospinal Myoclonus

Propriospinal myoclonus (PSM) consists of paroxysmal and sudden jerks involving axial flexion trunk and hip muscles, conditioning sudden myoclonias of the trunk and arms/limbs, both spontaneous and triggered by sensory stimulations, emerging in relaxed wakefulness typically during the transition between wake and sleep. Generally, PSM originates from a thoracic myelomere and spreads caudally and rostrally, provoking flexion and/or extension movements, leading to jumps or trunk jerks. They appear triggered by the lying-down position and disappear when the subject stands up. The main consequences are the difficulties in sleep start and the reappearance during the period of wakefulness after sleep onset.

Myoclonus: Pathophysiology and Treatment Options

OPINION STATEMENT

Treatment of myoclonus requires an understanding of the physiopathology of the condition. The first step in treatment is to determine if there is an epileptic component to the myoclonus and treat accordingly. Secondly, a review of medications (e.g., opiates) and comorbidities (e.g., hepatic or renal failure) is required to establish the possibility of iatrogenic and reversible conditions. Once those are eliminated, delineation between cortical, cortico-subcortical, subcortical, brainstem, and spinal generators can determine the first-line treatment. Cortical myoclonus can be treated with levetiracetam, valproic acid, and clonazepam as first-line agents. Phenytoin and carbamazepine may paradoxically worsen myoclonus. Subcortical and brainstem myoclonus can be treated with clonazepam as a first-line agent, but levetiracetam and valproic acid can be tried as well. L-5-Hydroxytryptophan and sodium oxybate are agents used for refractory cases. Spinal myoclonus does not respond to anti-epileptic drugs, and clonazepam is a first-line agent. Botulinum toxin treatment can be useful for focal cases of spinal myoclonus. The etiology of propriospinal myoclonus is controversial, and a functional etiology is suspected in most cases. Treatment can include clonazepam, levetiracetam, baclofen, valproate, carbamazepine, and zonisamide. Functional myoclonus requires multimodal and multidisciplinary treatment that may include psychotropic drugs and physical and occupational therapy. Close collaboration between neurologists and psychiatrists is required for effective treatment. Finally, deep brain stimulation targeting the globus pallidus pars-interna bilaterally has been used in myoclonus-dystonia when pharmacological treatments have been exhausted.

Propriospinal myoclonus: The spectrum of clinical and neurophysiological phenotypes

Propriospinal myoclonus (PSM) is a rare type of spinal myoclonus characterized by muscle jerks that usually start in the midthoracic segments and then slowly propagate up and down into the spinal cord, resulting in repetitive and irregular jerky flexion, or extension of the trunk, neck, knees and hips. PSM can be symptomatic, but up to 80% of reported cases appear idiopathic. PSM tends to occur especially while the subject is lying down. PSM at sleep onset was first described by experts in sleep medicine. The original electrophysiological features included fixed pattern of muscle activations, slow spinal cord conduction (5-15 m/s), electromyographic burst duration less than 1000 ms, synchronous activation of agonist and antagonist muscles and no involvement of facial muscles. PSM has been reported to be a functional (psychogenic) movement disorder in a number of cohorts. The differential diagnosis between idiopathic PSM and the functional forms is not always straightforward. A consistent polymyographically documented muscle activation pattern may be supportive but by no means sufficient and additional neurophysiological investigations are required. PSM should be differentiated from other movement disorders involving the abdomen and trunk, or occurring at sleep-wake transition. This article offers a comprehensive overview of the spectrum of PSM phenotypes.

Four cases with peripheral trauma induced involuntary movements

Background and Purpose

Although peripheral trauma induced movement disorders have been rarely reported, diagnostic criteria for peripherally induced movement disorders (PIMD) have been established. Because preexisting subclinical movement disorders, or secondary gain for compensation and legal purposes are difficult to confirm, differential diagnosis for physicians still remains difficult.

Case Reports

We present four patients developed movement disorders after relatively various intervals after traffic accident. Three patients of them showed tremor and one patient presented propriospinal myoclonus. In this report, we investigate whether peripheral trauma can lead to movement disorders and describe the relationship between peripheral injury and movement disorders in four cases.

Conclusions

Injury was serious enough to develop involuntary abnormal movements with pain and the latency between injury and the onset of movements in all of cases was less than 1 year. Thus, our cases showed temporal and anatomical correlation between injury and the onset of movement disorder, strongly supporting the cause-and-effect relationship by previous diagnostic criteria for peripherally induced movement disorders.