Introduction
As the name suggests, nocturnal paroxysmal dystonia is dystonic attacks that occur during the night in events or episodes. This is a rare type of various dystonic attack and a clinical form of epilepsy. Nocturnal paroxysmal dystonia does not occur with any age or sexual preferences and no family predispositions. But the attacks are stereotyped, unique, and recurrent.
What Is Dystonia?
Dystonia is a neurological movement disorder of repetitive muscular contractions leading to recurrent and twisting involuntary movements and abnormal postures. Dystonia can be hereditary or acquired due to an irritative lesion in the basal ganglia located deep within the brain's cerebral hemispheres, which is responsible for muscular contraction. Those include brain injury, tumor, stress, lead or carbon monoxide poisoning, or a response to neuroleptic drugs. This disorder is rare; also, about 1 % of the world population has been affected. Women are more likely than men to have.
How Is Dystonia Being Classified?
Dystonia has many subtypes that are classified on the basis of etiology, onset, muscle involvement, and pattern of attacks. The following are the types of dystonia.
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Based on the age of onset.
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Based on the topographic distribution, that is, the number of muscles involved- the five subtypes are focal, segmental, multifocal, hemidystonia, and generalized.
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Based on the temporal aspects.
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Based on the clinical features.
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Based on the etiology or causes - four subtypes of the nervous system are pathology, inherited, acquired, and idiopathic.
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Based on the pattern or theme of dystonic attacks.
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Cervical or torticollis is the most common type affecting the neck muscles.
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Cranial affecting the head and facial muscles.
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Oromandibular dystonia results in distorted speech as the oral and jaw muscles are affected.
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Blepharospasm affects the functioning of eyelids from involuntary blinking to functionally blind.
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Spasmodic dystonia affects speech by causing spasms in throat muscles.
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Paroxysmal dystonia is a recurrent episodic attack.
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Tardive is due to the discrete response of a drug.
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Torsion is the rare and serious one that results in disability.
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Writer’s dystonia - as the name suggests, attacks only during writing with the involvement of upper arm muscles.
What Is Nocturnal Paroxysmal Dystonia?
Nocturnal paroxysmal dystonia (NPD) is a rare neurological disorder characterized by repetitive dystonic postures, choreoathetosis (involuntary twitching), or ballistic movements involving one or all extremities with the neck. Nocturnal and paroxysmal in the name indicates that this dystonia occurs in episodes during NREM sleep. NREM (non-rapid eye movement) is one of the phases of sleep where the eyeball remains still under the closed eyelids.
A person encountering NPD often shows normal brain functioning and neuroimaging without any neurological abnormalities. The movements tend to occur in a stereotyped fashion in each person.
What Are the Types of NPD?
This disorder of sleep-related motor attacks comprises the following two variants based on the duration of dystonic attacks.
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Short-lasting NPD.
The short-lasting attacks develop for a duration of seconds to one minute with a frequency of two to twenty times per night recurrently. Dystonic postural attacks are often limited to one limb or all four limbs.
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Long-lasting NPD.
Prolonged attacks of motor agitation lasting for 2 to 50 minutes recur many times during sleep, seldom followed by anxiety. Here, the dystonic posture most commonly involves all four limbs and the trunk. However, long-lasting attacks can slowly worsen cognitive impairment.
How Nocturnal Dystonia Occurs?
There is no exact cause of this disorder. However, the common causes of dystonia can be related to NPD. Nocturnal paroxysmal dystonia is also a form of nocturnal frontal lobe epilepsy that occurs due to a tumor, injury, or infection in the brain's frontal lobes.
What Are the Features of Nocturnal Paroxysmal Dystonia?
Dystonic posture and tonic muscular movements are the prominent features of NPD. The attacks awaken the person abruptly from sleep, frequently accompanied by the following characters.
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Temor, muscular pain.
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Involuntary movements of extremities and neck.
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Unconscious or automatic imitation of expressions.
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Involuntary blinking or closing of eyelids.
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A 'dragging leg' theme.
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Altered speech and vocalization.
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Dyskinetic movements.
At the end of each dystonic attack, the person appears clear-minded, well-oriented, and even gets back to sleep. Some show diurnal attacks or occasional fits of epileptic origin with NPD that remain sporadic and exceptional.
How Is Nocturnal Paroxysmal Dystonia Diagnosed?
Though an evident tool to identify NPD is still unknown, the diagnosis can be made by several examinations and investigations. In addition to NPD, other various types of dystonic attack should be taken into concern.
The common investigations to identify a person with NPD are mentioned below.
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A brief medical history.
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Neurological examination, laboratory test.
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CT (computed tomography) scan in case of any underlying pathology.
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Electroencephalogram (EEG) recordings during the day and sleep show the evidence and depth of epilepsy or any frontal lobe seizure.
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Polysomnographic investigations: Polysomnographic monitoring under audiovisual control enhances the paroxysmal abnormal movements during sleep. Also used to differentiate epileptic seizures from other disorders.
How to Treat Nocturnal Paroxysmal Dystonia?
NPD is efficiently manageable with the right intervention and care. Pharmacological intervention, along with physical therapies for the consequences of attacks could pave the way for the betterment of the disorder.
Physical Intervention -
Physical intervention for dystonia is ineffectual. Physical therapy for the consequences of involuntary motor attacks is performed to bring out the changes in balance, motion, and functions of the muscles. The interventions include therapeutic exercises, splinting, mobilization of joints, postural priming, manual stretching of limbs, gait (way of walking) alteration, and environmental modification. As the disorder is uncommon, the researchers identified the physiotherapy treatment as less effective.
Therapeutic -
Pharmacological drugs such as Benzodiazepines, Lithium, Phenytoin, and Sodium valproate remain ineffective in nocturnal paroxysmal dystonia.
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Carbamazepine, an anticonvulsant drug, is the choice of drug for short-lasting dystonia. Carbamazepine from 100 mg to 400 mg suppresses and abolishes the nocturnal attacks. Follow-up and observations every six months are needed. Withdrawal of this medication could lead to a subsequent relapse.
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Other drugs, such as anticholinergics, dopamine-depleting drugs, and muscle relaxants, are known to help with dystonia.
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Baclofen, a skeletal muscle relaxant, is used to treat muscle spasticity with dystonia in the form of a baclofen pump.
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Botulinum toxin injections provide short-term relief to the affected muscles. But it may lead to weakness or paralysis.
Surgery -
Denervation of particular muscles could provide some relief but is performed only in extreme cases as the procedure is irreversible. Deep brain stimulation has been achieved recently in severe cases of generalized dystonia.
Conclusion
Though there is no such specific treatment for NPD, further examination is needed to clarify the issue and to delineate a reliable therapy for nocturnal motor attacks. In addition, the remission of dystonic episodes requires the right pharmacological intervention, therapeutic exercises, and beneficent caring.
