Adult-onset primary focal foot dystonia

Clinical neurophysiology in the treatment of movement disorders: IFCN handbook chapter

In this review, different aspects of the use of clinical neurophysiology techniques for the treatment of movement disorders are addressed. First of all, these techniques can be used to guide neuromodulation techniques or to perform therapeutic neuromodulation as such. Neuromodulation includes invasive techniques based on the surgical implantation of electrodes and a pulse generator, such as deep brain stimulation (DBS) or spinal cord stimulation (SCS) on the one hand, and non-invasive techniques aimed at modulating or even lesioning neural structures by transcranial application. Movement disorders are one of the main areas of indication for the various neuromodulation techniques. This review focuses on the following techniques: DBS, repetitive transcranial magnetic stimulation (rTMS), low-intensity transcranial electrical stimulation, including transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS), and focused ultrasound (FUS), including high-intensity magnetic resonance-guided FUS (MRgFUS), and pulsed mode low-intensity transcranial FUS stimulation (TUS). The main clinical conditions in which neuromodulation has proven its efficacy are Parkinson's disease, dystonia, and essential tremor, mainly using DBS or MRgFUS. There is also some evidence for Tourette syndrome (DBS), Huntington's disease (DBS), cerebellar ataxia (tDCS), and axial signs (SCS) and depression (rTMS) in PD. The development of non-invasive transcranial neuromodulation techniques is limited by the short-term clinical impact of these techniques, especially rTMS, in the context of very chronic diseases. However, at-home use (tDCS) or current advances in the design of closed-loop stimulation (tACS) may open new perspectives for the application of these techniques in patients, favored by their easier use and lower rate of adverse effects compared to invasive or lesioning methods. Finally, this review summarizes the evidence for keeping the use of electromyography to optimize the identification of muscles to be treated with botulinum toxin injection, which is indicated and widely performed for the treatment of various movement disorders.

Functional dystonia: A pitfall for the foot and ankle surgeon

Functional dystonia represents a condition where psychological distress is being expressed as involuntary muscle contractions. In the foot and ankle, it most commonly presents as a sudden onset of a painful fixed ankle/hindfoot deformity in a female patient with a history of trivial trauma or surgery. The "fixed deformity" found on clinical examination is usually correctable under general anesthesia. Less commonly, it can present in the toes or may present as paroxysmal muscle movements rather than a fixed deformity. CRPS may occur concurrently with the dystonia. Failure to consider the diagnosis leads to a long delay in appropriate diagnosis, patient distress and unnecessary or even harmful surgery. A better approach to this clinical syndrome is to define it as fixed abnormal posturing that is most commonly psychogenic. Early referral to a movement disorder clinic is recommended. The prognosis is generally poor as less than a quarter of patients report subjective long-term improvement even when managed in a movement disorder clinic. Foot and ankle surgeons should, whenever possible, avoid operating on patients with functional dystonia in order to avoid symptomatic deterioration.

Research Priorities in Limb and Task-Specific Dystonias

Dystonia, which causes intermittent or sustained abnormal postures and movements, can present in a focal or a generalized manner. In the limbs, focal dystonia can occur in either the upper or lower limbs and may be task-specific causing abnormal motor performance for only a specific task, such as in writer’s cramp, runner’s dystonia, or musician’s dystonia. Focal limb dystonia can be non-task-specific and may, in some circumstances, be associated with parkinsonian disorders. The true prevalence of focal limb dystonia is not known and is likely currently underestimated, leaving a knowledge gap and an opportunity for future research. The pathophysiology of focal limb dystonia shares some commonalities with other dystonias with a loss of inhibition in the central nervous system and a loss of the normal regulation of plasticity, called homeostatic plasticity. Functional imaging studies revealed abnormalities in several anatomical networks that involve the cortex, basal ganglia, and cerebellum. Further studies should focus on distinguishing cause from effect in both physiology and imaging studies to permit focus on most relevant biological correlates of dystonia. There is no specific therapy for the treatment of limb dystonia given the variability in presentation, but off-label botulinum toxin therapy is often applied to focal limb and task-specific dystonia. Various rehabilitation techniques have been applied and rehabilitation interventions may improve outcomes, but small sample size and lack of direct comparisons between methods to evaluate comparative efficacy limit conclusions. Finally, non-invasive and invasive therapeutic modalities have been explored in small studies with design limitations that do not yet clearly provide direction for larger clinical trials that could support new clinical therapies. Given these gaps in our clinical, pathophysiologic, and therapeutic knowledge, we have identified priorities for future research including: the development of diagnostic criteria for limb dystonia, more precise phenotypic characterization and innovative clinical trial design that considers clinical heterogeneity, and limited available number of participants.

Adult onset primary focal dystonia of the foot: an orthopaedic intervention

A 54-year-old woman presented to a foot centre with a chief symptom of cramping in her toes, which, she believed, was of a secondary cause originating from a bunion. She was treated conservatively; however, she returned a month later as the symptoms had progressed to painful cramping of toes, toe-curling and instability while walking, due to involuntary movement of her toes. It was believed that the patient presented with a rare case of primary adult onset focal foot dystonia. This case report explains dystonia further in detail and delves into the different treatment and management options available today, including the unique orthopaedic intervention provided for this patient.

Dystonic Pseudo Foot Drop

The most common presentation of foot dystonia in patients with Parkinson's disease (PD) or dystonia is inversion of the foot accompanied by flexion of the toes, with or without extension of the hallux. Less commonly, foot dystonia may mimic foot drop, as occurs with weakness of the dorsiflexors muscles, resulting in a pseudo foot drop. This has rarely been reported in the literature and has been poorly recognized, often leading to misdiagnosis and unnecessary investigations and treatment. We report 5 patients with dystonic pseudo foot drop, one of them diagnosed with early-onset PD, 2 with sporadic PD, and 2 with dystonia. Despite the steppage gait, their physical exam revealed normal strength, and no other explanation for a "foot drop" was found. It is important to recognize this phenomenology, which can be a clue to the diagnosis of early-onset PD, and may be responsive to levodopa in selected patients.

Epidemiology and treatment of 23 musicians with task specific tremor

BACKGROUND

Task specific tremors in musicians have been mainly described as primary bowing tremor in string instrumentalists in relatively small sample sizes. Our aim was to describe epidemiology, risk factors, phenomenology and treatment options of this disorder in 23 musicians of different instruments.

METHODS

We included 23 professional musicians (4 female, 19 male; mean age 51.5 ± 11.4 years) with a TSTM. During anamnesis, clinical examination, by mail or via telephone patients were asked for epidemiological, phenomenological information, risk factors and treatments. We then compared our findings to primary writing tremor, the most common task specific tremor.

RESULTS

Age at onset of the TST was 44.6 ± 13.6 years and tremor appeared 35.1 ± 13.5 years after beginning to play the instrument. The majority of patients were string instrumentalists, followed by woodwind instrumentalists. Other instrumentalists were a guitarist, pianist and percussionist respectively. In contrast to primary writing tremor, we also found proximal muscles of the upper extremity involved in tremor. A positive family history was found in Prior trauma was more common than in primary writing tremor. Treatment with a positive effect on tremor were in order of efficacy: Botulinumtoxin, Primidone, Propranolol, Trihexyphenidyl. No patient had undergone deep brain stimulation.

CONCLUSION

Task specific tremor in musicians is a heterogeneous disorder with a male gender predominance that shares many commonalities with PWT. The onset age as well as the time between starting to play the instrument and tremor onset has a wide range. Because previous trauma and overuse appear to be risk factors, preventive measures against playing related injuries are necessary. There appears to be a genetic predisposition for TST. No single beneficial medication exists and treatment of patients remains highly individual. It should be discussed, whether deep brain stimulation should be offered not only to patients that do not respond to any other medication but early in the course of the disease.

Adult-onset Idiopathic Focal Lower Extremity Dystonia: A Rare Task-Specific Dystonia

Background

Adult-onset focal lower extremity (LE) dystonia is rare, but there have recently been a number of case series that have reported an idiopathic variant triggered during ambulation.

Methods

We describe nine patients with idiopathic, focal task-specific LE dystonia. We conducted a comparative analysis that included our cohort and several recently published case series to further characterize the disorder.

Results

A total of 48 patients (37 female, 11 male) were compared. The average age of onset was 48 years; 36 patients had distal extremity involvement (75%), 5 proximal (10%), and 7 both proximal and distal (15%). Among 33 patients in which the dystonic side was known, 20 were affected on the left (61%). Inversion of the foot with flexion of one or more toes was the most prevalent pattern in those with distal extremity involvement.

Discussion

This is a novel task-specific dystonia triggered during ambulation that is often misdiagnosed as an orthopedic or psychogenic issue.

Current and future medical treatment in primary dystonia

Dystonia is a hyperkinetic movement disorder, characterized by involuntary and sustained contractions of opposing muscles causing twisting movements and abnormal postures. It is often a disabling disorder that has a significant impact on physical and psychosocial wellbeing. The medical therapeutic armamentarium used in practice is quite extensive, but for many of these interventions formal proof of efficacy is lacking. Exceptions are the use of botulinum toxin in patients with cervical dystonia, some forms of cranial dystonia (in particular, blepharospasm) and writer's cramp; deep brain stimulation of the pallidum in generalized and segmental dystonia; and high-dose trihexyphenidyl in young patients with segmental and generalized dystonia. In order to move this field forward, we not only need better trials that examine the effect of current treatment interventions, but also a further understanding of the pathophysiology of dystonia as a first step to design and test new therapies that are targeted at the underlying biologic and neurophysiologic mechanisms.

Focal limb dystonia

Limb dystonia (LD) refers to dystonia affecting one arm or leg. Depending on the site of onset, age at onset, and the etiology, progression and prognosis will be different. Usually young-onset primary dystonia affects the lower limbs and tends to generalize, while in adult-onset, it appears in the arm and remains focal. Lower limb dystonia in adults is rare as a primary cause, and parkinsonism or other neurological diseases must always be ruled out. In the text that follows, we review the main clinical features of the primary and secondary limb dystonias considering the age at onset and etiology.

Lower limb involvement in adult-onset primary dystonia: frequency and clinical features

BACKGROUND AND PURPOSE

Despite the growing number of reports describing adult-onset primary lower limb dystonia (LLD) this entity has never been systematically evaluated in the general population of patients with primary adult-onset dystonia.

METHODS

From outpatients with adult-onset primary dystonia attending nine Italian University centres for movement disorders we consecutively recruited 579 patients to undergo a standardized clinical evaluation.

RESULTS

Of the 579 patients assessed, 11 (1.9%) (8 women, 3 men) had LLD, either alone (n = 4, 0.7%) or as part of a segmental/multifocal dystonia (n = 7, 1.2%). The age at onset of LLD (47.9 +/- 17 years) was significantly lower than the age at onset of cranial dystonias (57.9 +/- 10.7 years for blepharospasm, and 58.9 +/- 11.8 years for oromandibular dystonia) but similar to that of all the other adult-onset primary dystonias. The lower limb was either the site of dystonia onset (36.4%) or the site of dystonia spread (63.6%). In patients in whom LLD was a site of spread, dystonia seemed to spread following a somatotopic distribution. Only one patient reported a recent trauma involving the lower limb whereas 36.4% of the patients reported pain at the site of LLD. Only 64% of our patients needed treatment for LLD, and similarly to previously reported cases, the most frequently tried treatments was botulinum toxin and trihexyphenidyl.

CONCLUSION

The lower limb is an uncommon but possible topographical site of dystonia in adulthood that should be kept in consideration during clinical evaluation.

Therapeutic uses of botulinum toxin: from facial palsy to autonomic disorders

BACKGROUND

The therapeutic uses of botulinum toxin have been expanding due to deeper knowledge of its molecular behaviour and different mechanisms of action.

OBJECTIVE

To present suggested doses of Botox and Dysport for controlling the muscle hyperkinetic activity in facial palsy in the perioral area and to review other uses.

METHODS

An extensive updated literature review on the success and limits of the botulinum neurotoxin (BoNT) therapeutic treatments.

RESULTS/CONCLUSION

BoNT can be considered to be the preferred single method for many disorders; it has substituted for some conventional surgical methods and it can be associated with other therapies to increase overall treatment performance. Depending on the disorder, the lack of permanent effect causes no major inconvenience.

High doses of botulinum toxin effectively treat disabling up-going toe

Involuntary up-going toe can be a disabling consequence of dystonia or spasticity. In this study, we treated eight patients with botulinum toxin (BTx) in the extensor hallucis longus (EHL) and applied objective and subjective outcome measures to determine treatment efficacy. Using 100% higher doses than generally reported, patients noted 62+/-20% mean benefit and scores on a modified Fahn-Marsden Dystonia Scale decreased significantly by 1.8+/-0.6 (p=0.010). High doses (up to 160 BTx A units) into the EHL were safe and dosage correlated highly and significantly with treatment efficacy (rho=0.859, p=0.006).

Neurologic uses of botulinum neurotoxin type A

This article reviews the current and most neurologic uses of botulinum neurotoxin type A (BoNT-A), beginning with relevant historical data, neurochemical mechanism at the neuromuscular junction. Current commercial preparations of BoNT-A are reviewed, as are immunologic issues relating to secondary failure of BoNT-A therapy. Clinical uses are summarized with an emphasis on controlled clinical trials (as appropriate), including facial movement disorders, focal neck and limb dystonias, spasticity, hypersecretory syndromes, and pain.

Botulinum toxin: Clinical use

Since its development for the use of blepharospasm and strabismus more than 2.5 decades ago, botulinum neurotoxin (BoNT) has become a versatile drug in various fields of medicine. It is the standard of care in different disorders such as cervical dystonia, hemifacial spasm, focal spasticity, hyperhidrosis, ophthalmological and otolaryngeal disorders. It has also found widespread use in cosmetic applications. Many other indications are currently under investigation, including gastroenterologic and urologic indications, analgesic management and migraine. This paper is an extensive review of the spectrum of BoNT clinical applications.