Hereditary geniospasm: linkage to chromosome 9q13-q21 and evidence for genetic heterogeneity

Geniospasm: A systematic review on natural history, prognosis, and treatment

BACKGROUND

Geniospasm is a rare and generally benign movement disorder of the chin yet with potentially debilitating complications. Due to its rarity, previous literature was limited to only case reports or series with critical knowledge gap on its natural history, prognosis, and management. We aimed to establish the natural history, prognosis, and treatment for geniospasm.

METHODS

A systematic review on case reports or series was performed with literature search on PubMed and Google Scholar, from inception through December 2021. The quality of the reports was assessed with low-quality articles excluded for analyses other than demographics.

RESULTS

Forty-one articles were included for demographic analysis (n = 489) while forty articles for other analyses (n = 451). There was only slight male preponderance of this disease in our cohort (Male:Female = 1.2:1) with 98.6% having family history of geniospasm, 68.1% having onset below 1 year of age, 91.4% having emotional triggers of the symptoms, 25.7% having geniospasm in sleep, 100% involving mentalis muscles, 4.9% involving muscles adjacent to mentalis, 55.2% having regular paroxysms (≥1/week, but brief in 56.3% of the cases) and only 11.1% having complications. The paroxysms reduced with age, but complete remission only happened in 9.9%. Females (p = 0.010) and those without geniospasm in sleep (p = 0.048) were associated with good outcome of the disease. Geniospasm was usually refractory to treatment except for regular botulinum toxin injections.

CONCLUSION

Generally, geniospasm improved with age but complete remission was rare. Considering our review limitations, our findings should be interpreted with caution. Future studies of higher evidence level are crucial.

Tremor Syndromes: An Updated Review

Tremor is the most commonly encountered movement disorder in clinical practice. A wide range of pathologies may manifest with tremor either as a presenting or predominant symptom. Considering the marked etiological and phenomenological heterogeneity, it would be desirable to develop a classification of tremors that reflects their underlying pathophysiology. The tremor task force of the International Parkinson Disease and Movement Disorders Society has worked toward this goal and proposed a new classification system. This system has remained a prime topic of scientific communications on tremor in recent times. The new classification is based on two axes: 1. based on the clinical features, history, and tremor characteristics and 2. based on the etiology of tremor. In this article, we discuss the key aspects of the new classification, review various tremor syndromes, highlight some of the controversies in the field of tremor, and share the potential future perspectives.

Hereditary geniospasm in a mother and son treated with botulinum toxin injection: A case report

Hereditary geniospasm is a rare and benign disorder that can cause distress and social embarrassment to patients. There are only a handful of possible treatment options available. Due to the rarity of the condition, practices differ across the world and the results are varied. These include beta-blockers, benzodiazepines and anti-epileptics. These treatments can have significant side-effects when used long term. However, botulinum toxin injections have been successfully used in a handful of cases. We report a successful botulinum treatment of hereditary geniospasm in a mother and son, with the injection protocols.

Effective Treatment of Geniospasm: Case Series and Review of the Literature

Background:

Geniospasm is a rare genetic disorder characterized by paroxysmal rhythmic or irregular movements of the chin and lower lip due to repetitive contractions of the mentalis muscle. Pathophysiology is poorly understood, and optimal treatment has not been established.

Methods:

Geniospasm was characterized in a series of patients after evaluation in our clinics, and a comprehensive review of all cases in the medical literature was performed.

Results:

We evaluated four patients (1 female) in four families with geniospasm, aged 4 months to 9 years. Bothersome symptoms were present in one patient, who was treated with regular injections of onabotulinumtoxinA, with complete resolution of symptoms and no adverse effects. 9 patients in the literature have had similar outcomes.

Conclusions:

Limited data exist with regard to the effective treatment of geniospasm. Several treatments have been used historically, with variable outcomes. Our results, together with those of prior reported cases, demonstrate benefit of the use of botulinum toxin injections for management of this condition.

Isolated and combined genetic tremor syndromes: a critical appraisal based on the 2018 MDS criteria

The 2018 consensus statement on the classification of tremors proposes a two-axis categorization scheme based on clinical features and etiology. It also defines "isolated" and "combined" tremor syndromes depending on whether tremor is the sole clinical manifestation or is associated with other neurological or systemic signs. This syndromic approach provides a guide to investigate the underlying etiology of tremors, either genetic or acquired. Several genetic defects have been proven to cause tremor disorders, including autosomal dominant and recessive, X-linked, and mitochondrial diseases, as well as chromosomal abnormalities. Furthermore, some tremor syndromes are recognized in individuals with a positive family history, but their genetic confirmation is pending. Although most genetic tremor disorders show a combined clinical picture, there are some distinctive conditions in which tremor may precede the appearance of other neurological signs by years or remain the prominent manifestation throughout the disease course, previously leading to misdiagnosis as essential tremor (ET). Advances in the knowledge of genetically determined tremors may have been hampered by the inclusion of heterogeneous entities in previous studies on ET. The recent classification of tremors therefore aims to provide more consistent clinical data for deconstructing the genetic basis of tremor syndromes in the next-generation and long-read sequencing era. This review outlines the wide spectrum of tremor disorders with defined or presumed genetic etiology, both isolated and combined, unraveling diagnostic clues of these conditions and focusing mainly on ET-like phenotypes. Furthermore, we suggest a phenotype-to-genotype algorithm to support clinicians in identifying tremor syndromes and guiding genetic investigations.

Expert recommendations for diagnosing cervical, oromandibular, and limb dystonia

BACKGROUND

Diagnosis of focal dystonia is based on clinical grounds and is therefore open to bias. To date, diagnostic guidelines have been only proposed for blepharospasm and laryngeal dystonia. To provide practical guidance for clinicians with less expertise in dystonia, a group of Italian Movement Disorder experts formulated clinical diagnostic recommendations for cervical, oromandibular, and limb dystonia.

METHODS

A panel of four neurologists generated a list of clinical items related to the motor phenomenology of the examined focal dystonias and a list of clinical features characterizing neurological/non-neurological conditions mimicking dystonia. Thereafter, ten additional expert neurologists assessed the diagnostic relevance of the selected features and the content validity ratio was calculated. The clinical features reaching a content validity ratio > 0.5 contributed to the final recommendations.

RESULTS

The recommendations retained patterned and repetitive movements/postures as the core feature of dystonia in different body parts. If present, a sensory trick confirmed diagnosis of dystonia. In the patients who did not manifest sensory trick, active exclusion of clinical features related to conditions mimicking dystonia (features that would be expected to be absent in dystonia) would be necessary for dystonia to be diagnosed.

DISCUSSION

Although reliability, sensitivity, and specificity of the recommendations are yet to be demonstrated, information from the present study would hopefully facilitate diagnostic approach to focal dystonias in the clinical practice and would be the basis for future validated diagnostic guidelines.

Unusual tremor syndromes: know in order to recognise

Tremor is a common neurological condition in clinical practice; yet, few syndromes are widely recognised and discussed in the literature. As a result, there is an overdiagnosis of well-known causes, such as essential tremor. Many important unusual syndromes should be considered in the differential diagnosis of patients with tremor. The objective of this review is to provide broad clinical information to aid in the recognition and treatment of various unusual tremor syndromes in the adult and paediatric populations. The review comprised of a comprehensive online search using PubMed, Ovid database and Google Scholar to identify the available literature for each unusual tremor syndrome. The review includes fragile X-associated tremor/ataxia syndrome, spinocerebellar ataxia type 12, tremors caused by autosomal recessive cerebellar ataxias, myorhythmia, isolated tongue tremor, Wilson's disease, slow orthostatic tremor, peripheral trauma-induced tremor, tardive tremor and rabbit syndrome, paroxysmal tremors (hereditary chin tremor, bilateral high-frequency synchronous discharges, head tremor, limb-shaking transient ischaemic attack), bobble-head doll syndrome, spasmus nutans and shuddering attacks. Rare tremors generally present with an action tremor and a variable combination of postural and kinetic components with resting tremors less frequently seen. The phenomenology of myorhythmia is still vague and a clinical definition is proposed. The recognition of these entities should facilitate the correct diagnosis and guide the physician to a prompt intervention.

Tongue biting: a case of sporadic geniospasm during sleep

ABSTRACT

We report a healthy teenager with involuntary nocturnal tongue biting resulting in recurrent tongue injury. Causes for tongue biting during sleep in children include seizures, bruxism, faciomandibular myoclonia, hypnic myoclonia, and rarely geniospasm, which has been described as a rare inherited movement disorder accompanied with chin quivering. In the absence of family history, we diagnosed our patient with sporadic geniospasm based on polysomnographic findings with good response to clonazepam. Geniospasm should be considered in the differential diagnosis of cases with unexplained tongue injury in sleep.

Abnormalities of Masseteric Inhibitory Reflex in Hereditary Geniospasm: Evidence for a Brainstem Myoclonus

We studied two unrelated families with several members suffering from geniospasm. Here, we aim to clarify the pathophysiology underlying the hereditary geniospasm through testing of brainstem excitability by the recovery cycles of the blink reflex (BR) and the masseteric inhibitory reflex (MIR). The R2 component of the BR and the SP2 component of the MIR and their recovery cycle were analyzed in 3 patients and 8 healthy, age-matched subjects as the control group. Patients with geniospasm exhibited a different excitability of the BR, compared to the control, group, as shown by the larger R2 component area of BR in controls than patients. Notably, the mean recovery index was 0.61 ± 0.19 in geniospasm patients and 0.40 ± 0.15 in controls (P ≤ 0.05). Interestingly, the recovery cycle of the MIR showed a loss of inhibition in both patients studied, as indicated by the behavior of the SP2 component. Our cases showed a partial impairment of the activity of brainstem inhibitory interneurons, indicated by the abnormal recovery cycle of MIR. These results would implicate a mechanism akin to brainstem myoclonus for the generation of geniospasm.

Tremor syndromes

PURPOSE OF REVIEW

The purpose of this review is to explain a practical clinical approach to the diagnosis and management of tremor.

RECENT FINDINGS

A number of rare but important causes of tremor have been delineated, which means that attention to detail in clinical assessment of patients with tremor is even more important.

SUMMARY

Tremors are best divided into those occurring mainly at rest, mainly on posture, and mainly during action. This basic division leads directly to differential diagnosis and effective treatment.

Chin tremor in full-term neonate after hypoxia

CONTEXT

Newborns may present a range of motor phenomena that are not epileptic in nature. Chin tremor is an unusual movement disorder that typically starts in early childhood and may be precipitated by stress and emotion. Its pathophysiology has not been fully elucidated.

CASE REPORT

We describe a full-term newborn that, immediately after neonatal anoxia, presented body and chin tremors that were unresponsive to anti-epileptic drugs. Subsequent neurological evaluation revealed signs of pyramidal tract damage and chin tremor triggered by percussion and crying. We discuss the hypothesis that the anatomopathological abnormality may lie at the level of the higher cortical centers or midbrain.

CONCLUSIONS

Further studies are needed in order to gain greater comprehension of neonatal tremors. Recognition of the various etiological possibilities and consequent management of treatable causes is essential for care optimization.

Unusual focal dyskinesias

This chapter reviews focal dyskinesias that affect a restricted region of the body in isolation. Focal dyskinesias often affect body parts not commonly involved in isolation by movement disorders and are not readily classified into one of the major categories of movement disorders or peripheral nerve excitability syndromes. The clinical features and phenomenology of these "unusual focal dyskinesias" are discussed according to the region affected (ear, lip, chin, jaw, tongue, abdomen, and diaphragm (belly dancer's dyskinesias), back, scapula, and limbs). The phenomenology and origin of the unusual focal dyskinesias remain the subject of debate. Most are characterized by slow semirhythmic jerky movements at variable (usually slow) frequencies superimposed on sustained postures, consistent with dystonic movements. However, the body parts affected and pattern of occurrence (in repose rather than during action) are different to those usually seen in primary dystonia. Many of the unusual focal dyskinesias are associated with trauma and pain to the affected region, prompting the suggestion that the movements follow central sensorimotor reorganization occurring spontaneously or secondary to changes in the peripheral nervous system. In other cases, inconsistent signs and spontaneous recovery suggest a psychogenic origin.

Hereditary chin tremor in Parkinson's disease

Hereditary chin tremor (HCT) is characterized by rhythmical, involuntary movements of the chin muscles usually inherited in an autosomal dominant pattern. We describe a 74-year old man with familial, childhood-onset chin tremor, and a 3-year history of progressive hand tremor, gait difficulty, and other parkinsonian features. Since chin tremor often occurs in Parkinson's disease (PD), a coexistent HCT may not be recognized unless past and family history of tremor is carefully explored.

Recurrent nocturnal tongue biting in a child with hereditary chin trembling

A 13-month-old boy presented with repeated episodes of tongue biting during sleep. On evaluation, he was found to have hereditary chin trembling, a rare autosomal dominant condition characterized by continuous or intermittent tremulous activity of the mentalis muscle. This is the first report of this kind from India. The tongue biting appeared to be the result of parasomnia. Treatment with clonazepam was very effective; it completely ameliorated the symptom of tongue biting but had no effect on chin trembling.

Increased tremor severity in bilineal essential tremor: A report of two families

Up to 6% of the general population have essential tremor (ET). In a number of couples both partners may have ET. The clinical profile of ET in children and the parents where both parents and the child have ET remains to be established. We report on two families where both parents and one child have ET. The severity of ET was greater in the children than in either parent. Such families could provide special opportunity to determine relation between genotype and phenotypic expression of ET.

[Movement disorders in childhood: classification and genetic update]

Abnormal movements are not unusual in childhood. Recent genetic progresses provide a new approach of childhood movement disorders. Several loci have been identified in paroxysmal dyskinesia, or in Gilles de la Tourette syndrome. A gene has been cloned in Hallervorden-Spatz syndrome, and a gene has recently been implicated in benign hereditary chorea. Considerable advances concern the genetic of dystonic syndromes: several chromosomal localizations have been identified, and several genes have been cloned. Genetic advances allow nosographic reclassification of some entities and offer new molecular tools for a more appropriate diagnosis. The increasing wealth of genetic knowledge will provide further insight in the understanding of abnormal movement disorders in childhood.

Hereditary ataxias and paediatric neurology: new movers and shakers enter the field

Over 25 autosomal dominant and autosomal recessive spinocerebellar ataxias have been isolated over the last decade. The recognition of paediatric ataxia phenotypes and, in addition, other movement disorders including hereditary choreiform and parkinsonian syndromes, has improved our knowledge of these diseases. Advances in molecular genetics has allowed fuller delineation and better recognition of these diseases.

Hereditary chin trembling: a new family with exclusion of the chromosome 9q13-q21 Locus

Hereditary chin trembling is a rare autosomal dominant condition that has been linked to chromosome 9q13-21 in one kindred. We describe a four-generation family with this condition and, using linkage analysis, have excluded the 9q13-21 region as causing the chin trembling in this family.

The genetics of primary dystonias and related disorders

Dystonias are a heterogeneous group of disorders which are known to have a strong inherited basis. This review details recent advances in our understanding of the genetic basis of dystonias, including the primary dystonias, the 'dystonia-plus' syndromes and heredodegenerative disorders. The review focuses particularly on clinical and genetic features and molecular mechanisms. Conditions discussed in detail include idiopathic torsion dystonia (DYT1), focal dystonias (DYT7) and mixed dystonias (DYT6 and DYT13), dopa-responsive dystonia, myoclonus dystonia, rapid-onset dystonia parkinsonism, Fahr disease, Aicardi-Goutieres syndrome, Hallervorden-Spatz syndrome, X-linked dystonia parkinsonism, deafness-dystonia syndrome, mitochondrial dystonias, neuroacanthocytosis and the paroxysmal dystonias/dyskinesias.

Nonparkinsonian tremors

Tremors other than those associated with Parkinson's disease are commonly encountered in clinical practice. The differentiation of tremor subtypes depends primarily on the presence of distinct clinical characteristics and is facilitated by the use of consistent nomenclature. Such differentiation can be helpful in determining the etiology of the tremor and assist in its management. In this review, the authors outline recently proposed changes to classification and review the clinical features, differential diagnosis, and current therapy for nonparkinsonian tremors.

Linkage of familial hemophagocytic lymphohistiocytosis to 10q21-22 and evidence for heterogeneity

Familial hemophagocytic lymphohistiocytosis (FHL) is an autosomal recessive disorder characterized by the early onset of overwhelming activation of T lymphocytes and macrophages, invariably leading to death, in the absence of allogeneic bone marrow transplantation. Using genomewide genetic linkage analysis, we analyzed a group of 17 families with FHL and mapped a locus for FHL to the proximal region of the long arm of chromosome 10. Ten families showed no recombination with three tightly linked markers, D10S1650 (LOD score [Z]=6.99), D10S556 (Z=5.40), and D10S206 (Z=3.24), with a maximum multipoint LOD score of 11.22 at the D10S1650 locus. Haplotype analysis of these 10 families allowed us to establish D10S206 and D10S1665 as the telomeric and the centromeric flanking markers, respectively. Heterogeneity analysis and haplotype inspection of the remaining families confirmed that in seven families FHL was not linked to the 10q21-22 region, thus providing evidence for genetic heterogeneity of this condition.

Epidemiology and genetics of essential tremor

Essential tremor (ET) is one of the most common movement disorders. However, the etiology and pathogenesis are as yet unknown. Continued research will give us clues to understanding the impact on society, identifying genetic and environmental contributors to the disease, understanding the significance of a sporadic case, the phenotypic spectrum and timing of presentation, and the relationship with other neurologic disorders. Because the condition is both clinically and genetically heterogeneous and there is overlap with these other disorders, such as dystonia, parkinsonism, peripheral neuropathy, and migraine, the definition of phenotype plagues research in this area. Advances in understanding the genetic and molecular underpinnings of tremor should provide additional tools to unravel the clinical phenotype (including physiology), genotype-phenotype relationships, and the epidemiology of tremor.