Spastic Squint Neck
1.Definition.
Spastic squint: is a syndrome in which the head and neck are twisted and turned as a result of primary involuntary contraction of neck muscles, and is most common in adults with limited type of dystonia episodes, and is more accurately called idiopathic cervical dystonia. It is defined as: the abnormal involuntary muscle contraction caused by the neck of the arbitrary twisting and turning.
2.Prevalence.
The prevalence of spastic dystonia is about 9/100,000, and the incidence in women is usually 1.5 to 1.9 times higher than that in men. The peak age of onset is 50～60 years old, and 70%～90% of patients have onset between 40～70 years old.
3.Etiology
The exact cause of spastic squint is not yet clear, but may be related to the following aspects.
(1) Genetic factors: Some adults with dystonia limited seizures are genetically determined.
2) Trauma: The literature reports that 9% to 16% of patients have a history of prior head or neck trauma, usually occurring weeks to months before onset.
3) Vestibular abnormalities: Increased or asymmetrical vestibulo-ocular reflex responsiveness has been reported in patients with spastic squint, which cannot be corrected after treatment with botulinum toxin.
(4) Other: The central control of compensatory head and neck torsion mediation is involved due to altered peripheral proprioceptive stimuli, and the central integration of afferent nerve impulses is impaired.
4, Clinical manifestations
The disease is mostly adult-onset, with a slightly higher incidence in women than in men. The onset of the disease is slow, with gradual exacerbation, and rarely subsides or remits on its own. The abnormal movement of the head and neck muscles is not controlled, and the muscle groups are often involved bilaterally, but the degree of involvement is often asymmetrical, resulting in a twisting movement of the head to one side. The disease is aggravated by activity or work stress, and the symptoms decrease or disappear during sleep. Symptoms often appear suddenly as a “pulling or dragging of the neck” or as an involuntary rotation or sharp turn of the head. Atypical symptoms can lead to misdiagnosis as “arthritis, cervical radiculopathy, psychiatric disorders, Parkinson’s or TMJ syndrome”.
Cervicoclavicular tilt tends to worsen within 3-5 years, with a duration that varies widely from 1 month to 18 years. And then there is a tendency for the symptoms to stabilize. After stabilization there may be a slight remission process. However, remission is not obvious and is often incomplete or non-persistent. However, almost all patients relapse within 5 years, and there is an alternation between remission and relapse. Functional impairment is common in patients with spastic strabismus, and also, many patients present with depressive manifestations. In addition, pain is more prevalent in spastic strabismus.
5 .Typing
1）Typing according to the extent of spastic muscles involved The spastic muscles are confined to the neck and only cause the symptoms of cervical squint, which is called simple ST. The spastic muscles involve the face, throat, limbs or trunk, and the symptoms of this type of ST are only part of the systemic symptoms, which is called symptomatic ST.
(2) According to the posture of the slanting neck, it is classified as rotational type, among which there are horizontal rotational type, backward rotational type and forward flexion rotational type; lateral flexion type; forward flexion type, backward flexion type and mixed type.
(3) Classification according to the degree of disease: heavy and light.
(4) According to the mode of muscle spasm, there are tonic type, clonic type, and mixed type of tonic and clonic.
6.Diagnosis
The diagnosis is still based on clinical diagnosis, combined with palpation, electromyography, local block and neck muscle performance, etc. The diagnosis and clinical typing will be made and treatment plan will be formulated.
7.Surgical treatment
The aim of treatment is to relieve symptoms, improve quality of life and prevent complications. Surgical treatment is required for those patients whose dystonia is persistent, ineffective to a large number of drugs and botulinum toxin injections and accompanied by significant functional impairment.
Professor Xiu Bo performs a case-by-case analysis of spastic dystonia and takes a personalized and optimized approach to treatment. Depending on the patient’s condition, a combination of microvascular decompression, neurectomy and/or myotomy is chosen, i.e., to allow for as much unrestricted neck movement as possible while relieving the spastic squint. For example, depending on the extent of muscle involvement in the neck, paraneoplastic microvascular decompression and anterior cervical root amputation of nerves 1 to 3 may be performed. Clinical practice has shown that most patients with spastic squint can recover from this procedure.