Exhaustive analysis of BH4 and dopamine biosynthesis genes in patients with Dopa-responsive dystonia

Dopa-responsive dystonia is a childhood-onset dystonic disorder, characterized by a dramatic response to low dose of L-Dopa. Dopa-responsive dystonia is mostly caused by autosomal dominant mutations in the GCH1 gene (GTP cyclohydrolase1) and more rarely by autosomal recessive mutations in the TH (tyrosine hydroxylase) or SPR (sepiapterin reductase) genes. In addition, mutations in the PARK2 gene (parkin) which causes autosomal recessive juvenile parkinsonism may present as Dopa-responsive dystonia. In order to evaluate the relative frequency of the mutations in these genes, but also in the genes involved in the biosynthesis and recycling of BH4, and to evaluate the associated clinical spectrum, we have studied a large series of index patients (n = 64) with Dopa-responsive dystonia, in whom dystonia improved by at least 50% after L-Dopa treatment. Fifty seven of these patients were classified as pure Dopa-responsive dystonia and seven as Dopa-responsive dystonia-plus syndromes. All patients were screened for point mutations and large rearrangements in the GCH1 gene, followed by sequencing of the TH and SPR genes, then PTS (pyruvoyl tetrahydropterin synthase), PCBD (pterin-4a-carbinolamine dehydratase), QDPR (dihydropteridin reductase) and PARK2 (parkin) genes. We identified 34 different heterozygous point mutations in 40 patients, and six different large deletions in seven patients in the GCH1 gene. Except for one patient with mental retardation and a large deletion of 2.3 Mb encompassing 10 genes, all patients had stereotyped clinical features, characterized by pure Dopa-responsive dystonia with onset in the lower limbs and an excellent response to low doses of L-Dopa. Dystonia started in the first decade of life in 40 patients (85%) and before the age of 1 year in one patient (2.2%). Three of the 17 negative GCH1 patients had mutations in the TH gene, two in the SPR gene and one in the PARK2 gene. No mutations in the three genes involved in the biosynthesis and recycling of BH4 were identified. The clinical presentations of patients with mutations in TH and SPR genes were strikingly more complex, characterized by mental retardation, oculogyric crises and parkinsonism and they were all classified as Dopa-responsive dystonia-plus syndromes. Patient with mutation in the PARK2 gene had Dopa-responsive dystonia with a good improvement with L-Dopa, similar to Dopa-responsive dystonia secondary to GCH1 mutations. Although the yield of mutations exceeds 80% in pure Dopa-responsive dystonia and Dopa-responsive dystonia-plus syndromes groups, the genes involved are clearly different: GCH1 in the former and TH and SPR in the later.

Segawa disease with a novel heterozygous mutation in exon 5 of the GCH-1 gene (E183K)

We report a novel missense mutation in the GCH-1 gene resulting in Segawa disease. The patient, a 6-year-old girl, presented with dystonia. Her CSF biopterin and neopterin levels were reduced, suggesting Segawa disease. L-dopa administration led to clinical improvement. Genetic analysis revealed a missense mutation in exon 5 of the GCH-1 gene (E183K). Although dystonia or other movement disorders were not identified in her family, this may be explained by the low penetrance of Segawa disease.

[Efficacy and side-effects of the botulinum toxin A treatment in patients with focal dystonia]

An aim of the study was to determine side-effects of disport, the botulinum toxin A (BTA), in the treatment of patients with spasmodic torticollis (ST) and blepharospasm (BS). More than 800 injections of BTA to patients with ST and 110 - to patients with BS have been performed for 6-years period. Side-effects are specified as follows: 1) autonomic reactions observed in women with increased anxiety and signs of autonomic dysfunction (47,5%) patients with ST), with most marked symptoms in the first injection and their further decreasing; 2) local side-effects related with errors in dose adjustment, injection technique (37,3% patients with ST and 59,5% patients with BS); 3) the smallest group of side-effects not related to the doctor's experience and adequate psychological preparation of the patient for manipulation (myasthenia-myopathia syndrome after the BTA therapy).

[Bent spine straightens up--a case of camptocormia]

Bent spine, i.e. camptocormia appears in several disease. Segmental dystonia is one of these. A few cases benefiting from botulinum toxin therapy have been described in the literature. We describe a case, in which segmental dystonia is associated with camptocormia, causing the patient to use a wheelchair. The condition fulfilled the criteria of both clinical and electromyographic dystonia. Administration of botulinum toxin into rectus abdominus muscles was started. The response was good: the patient was able to walk in a fairly erect posture assisted by a rolling walker.

Dystonia

INTRODUCTION

Dystonia is usually a lifelong condition with persistent pain and disability. Focal dystonia affects a single part of the body; generalised dystonia can affect most or all of the body. It is more common in women, and some types of dystonia are more common in people of European Ashkenazi Jewish descent.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of drug treatments, surgical treatments, and physical treatments for focal, and for generalised dystonia? We searched: Medline, Embase, The Cochrane Library, and other important databases up to July 2007 (BMJ Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 13 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS

In this systematic review we present information relating to the effectiveness and safety of the following interventions: acetylcholine receptor inhibitors, acupuncture, anticholinergic drugs, anticonvulsants, atypical antipsychotic drugs, benzodiazepines, biofeedback, botulinum toxin, chiropractic manipulation, deep brain stimulation of thalamus and globus pallidus, dopaminergic agonists and antagonists, gamma-aminobutyric acid (GABA) inhibitors, microvascular decompression, myectomy, occupational therapy, osteopathy, pallidotomy, physiotherapy, selective peripheral denervation, serotonergic agonists and antagonists, speech therapy, and thalamotomy.

Treatment of generalized tardive dystonia with clozapine

Tardive dystonia is a syndrome of sustained muscle contractions, frequently causing twisting and repetitive movements or abnormal postures, associated with prolonged exposure to antipsychotics. We report a case of a 35-year-old patient with schizophrenia who developed a generalized form of tardive dystonia after switching of clozapine to risperidone treatment that persisted after switch to olanzapine and during the period while treatment with an antipsychotic was discontinued. It was successfully managed with reintroduction of clozapine. The case may represent the first report of generalized tardive dystonia while taking risperidone. The possible pathophysiological bases of the disorder are discussed. The goal of our report is to emphasize that an adequate trial of clozapine is a worthwhile option in the cases of tardive dystonia, even where discontinuation of antipsychotics was unsuccesful.

Segawa's disease: dopa-responsive dystonia

The genetics and symptoms of Segawa's disease are described. The latter can show considerable variation, especially if the onset of the condition is delayed. It is usually of autosomal dominant inheritance, but a recessive form can occur. The dominant and recessive forms are caused by a gene mapped to chromosome 14. The fluctuating dystonia is typical, but is not essential for the diagnosis. Affected children can suffer from sleep disorders, such as excessive sleepiness and nightmares. In some children with this condition mutations in the GCH-1 gene coding for guanosine triphosphate cyclohydrolase 1 have been found. The enzyme catalyses the first step in the biosynthesis of tetrahydrobiopterin. A point mutation in the tyrosine hydrolase gene has been found in some of the recessive forms, and the gene mapped to chromosome 11, but this cannot be called Segawa's disease. The deficiency of guanosine triphosphate cyclohydrolase 1 causes a defect in serotonin metabolism and in the biosynthesis of tetrabiopterin and a disturbance of dopamine metabolism. This leads to a deficiency of dopamine in the striatum, and to the motor dysfunction of the syndrome. The diagnosis can be established by cerebrospinal fluid examination, and confirmed in some patients by genetic studies. Treatment is with levodopa, and the results are dramatic.

Assessment: Botulinum neurotoxin for the treatment of movement disorders (an evidence-based review): report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology

OBJECTIVE

To perform an evidence-based review of the safety and efficacy of botulinum neurotoxin (BoNT) in the treatment of movement disorders.

METHODS

A literature search was performed including MEDLINE and Current Contents for therapeutic articles relevant to BoNT and selected movement disorders. Authors reviewed, abstracted, and classified articles based on American Academy of Neurology criteria (Class I-IV).

RESULTS

The highest quality literature available for the respective indications was as follows: blepharospasm (two Class II studies); hemifacial spasm (one Class II and one Class III study); cervical dystonia (seven Class I studies); focal upper extremity dystonia (one Class I and three Class II studies); focal lower extremity dystonia (one Class II study); laryngeal dystonia (one Class I study); motor tics (one Class II study); and upper extremity essential tremor (two Class II studies).

RECOMMENDATIONS

Botulinum neurotoxin should be offered as a treatment option for the treatment of cervical dystonia (Level A), may be offered for blepharospasm, focal upper extremity dystonia, adductor laryngeal dystonia, and upper extremity essential tremor (Level B), and may be considered for hemifacial spasm, focal lower limb dystonia, and motor tics (Level C). While clinicians' practice may suggest stronger recommendations in some of these indications, evidence-based conclusions are limited by the availability of data.

Evidence for the effectiveness of botulinum toxin for writer's cramp

We performed a comprehensive literature search of clinical studies published between 1989 and 2007 concerning the use of botulinum neurotoxin (BoNT) in the treatment of writer's cramp (WC). Publications were categorized as Classes I-IV using the scale developed by the Therapeutics and Technology Assessment (TTA) subcommittee of the American Academy of Neurology. Our search resulted in 17 clinical publications discussing the treatment of WC with BoNT. The literature search results were: one publication being Class I, two being Class II, 11 being Class III, and three being Class IV.

Frequency of GCH1 deletions in Dopa-responsive dystonia

We performed a systematic study on the frequency of point mutations and deletions of the gene GCH1 in dopa-responsive dystonia (DRD). A total of 136 dystonia patients were studied. Fifty of these had a sustained response to oral L-Dopa therapy (group 1: definite diagnosis of DRD), whereas the response to L-Dopa was incomplete or not tested in 86 patients (group 2: possible diagnosis of DRD). We found a GCH1 point mutation in 27 patients of group 1 (54%) and in four patients of group 2 (5%). Of these, nine single and one double mutation have not been described before. GCH1 deletions were detected in four patients of group 1 (8%) and in one patient of group 2 (1%). Among GCH1 point-mutation-negative patients with a definite diagnosis of DRD (group 1), the frequency of GCH1 deletions was 17% (4/23). We conclude that GCH1 deletion analysis should be incorporated into the routine molecular diagnosis of all patients with DRD with a sustained response to L-Dopa.

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).

[Adult-onset primary focal foot dystonia]

INTRODUCTION

Adult-onset primary focal foot dystonia is a rare event. Up to now, only 7 cases have been reported in the literature. Since the idiopathic-type food dystonia is uncommon in adults, secondary types must be ruled out.

CLINICAL REPORT

We present the case of a 51 year woman with a 3 year history of focal food dystonia. She had abnormal posture of the foot with plantar flexion and inversion, which worsened with action. Complementary studies aimed at ruling out secondary causes were all negative. The dystonia remained limited to her food and she did not develop any other neurological symptoms. She benefited from botulinum toxin treatment.

CONCLUSIONS

Primary focal foot dystonia is uncommon in adults. The most common pattern is plantar and five toes flexion. Associated pain is common. Its pathogenesis is only partially understood, the neurophysiologic studies and functional resonance showing a loss of inhibitory control at spine and brainstem levels, abnormal cortical plasticity and altered sensorimotor integration. The response of this disorder to drugs is poor, however, the patients may benefit from botulinum toxin infiltrations of the muscles involved.

A progressive, fatal dystonia-Parkinsonism syndrome in a patient with primary immunodeficiency receiving chronic IVIG therapy

X-linked agammaglobulinemia (XLA) is a primary immunodeficiency disorder caused by a mutation in the Bruton agammaglobulinemia tyrosine kinase gene that results in severe B-cell deficiency. So far, neurological complications of XLA have been primarily related to acute and/or chronic central nervous system enteroviral infections. In the last few years a progressive neurodegenerative syndrome of unknown etiology has been described in XLA patients. We describe and present a video of an XLA patient who developed a fatal dementing, dystonia-Parkinsonism syndrome 14 years into his immune disorder. Physician awareness of this rare syndrome may lead to its better characterization and management.

Oromandibular dystonia

Oromandibular dystonia (OMD) is a rare neuromuscular disorder characterized by involuntary repetitive muscular contraction affecting different parts of the oromandibular region. Its various physical manifestations can be extremely debilitating and socially disabling to affected patients. To date, there is no commonly accepted set of diagnostic criteria nor well-defined management pathways. This paper aims to discuss some aspects of clinical manifestations, diagnostic criteria, neurological mechanisms, and treatment options for OMD, with illustrations from 6 clinical cases.

Morphometric changes of sensorimotor structures in focal dystonia

Idiopathic cervical dystonia (CD) and benign essential blepharospasm (BEB) are the most common forms of focal dystonia. Previous autopsy and imaging studies suggested that these disorders are not accompanied by structural brain abnormalities. However, recent brain voxel-based morphometry (VBM) studies of these conditions suggest that there actually may be changes in gray matter. The objective of this stdy was to detect possible gray matter abnormalities in patients with CD and BEB using VBM and to compare the results between the two conditions and with age- and gender-matched controls. High-resolution MRI was employed to evaluate healthy controls and individuals with BEB and CD. Eleven BEB, 9 CD, and 14 healthy control subjects were imaged. VBM revealed alterations of gray matter structures involved in sensorimotor processing in the individuals with focal dystonia. In CD subjects there was increased gray matter in the thalamus, caudate head bilaterally, superior temporal lobe, and left cerebellum, while gray matter was decreased in the putamen bilaterally. BEB subjects had increased gray matter in the caudate head and cerebellum bilaterally as well as decrease in the putamen and thalamus bilaterally. These findings strongly underline the recent notion that idiopathic focal dystonias might have a detectable structural correlate. They also demonstrate structural similarities of the investigated focal dystonias, possibly reflecting a shared common pathophysiological origin.

Dystonia during feeding as an early sign of dopa-responsive dystonia

A 21/2-month-old girl presented with feeding difficulties of 8 weeks' duration. She cried, vomited, arched, and became rigid during every feeding. She was suspected of having gastroesophageal reflux disease. Dystonia and developmental delay became apparent at age 8 months. Nasogastric tube feeding and gastrostomy with Nissen's fundoplication were performed at age 7 and 12 months, respectively. She was treated with baclofen, trihexyphenidyl, and antireflux therapy, without benefit. She became severely developmentally delayed with marked head lag, dystonia, and rigidity. Levodopa therapy was initiated at age 21 months. She manifested dramatic improvement over the next year. Dystonia, rigidity, and retching disappeared soon after treatment. She experienced good catch-up in development. She exhibited poor head control and an inability to reach out at age 21 months, but bottom shuffling was observed at age 26 months, and walking and speaking three-word sentences at age 2 years and 10 months. Pertinent issues relating to signs, pathophysiology, genetics, and biochemical defects are discussed briefly.

What is new in the era of focal dystonia treatment? Botulinum injections and more

PURPOSE OF REVIEW

The treatment options for the management of dystonias continue to evolve and improve. Clinical outcomes, however, are not predictably consistent using a single treatment regimen in all patients.

RECENT FINDINGS

Botulinum toxin is still considered the best treatment option for the treatment of focal dystonias: blepharospasm, hemifacial spasm, and apraxia of eyelid opening. New findings indicate that physicians may be a little more aggressive with the dosage when the disease progresses. A new formulation of botulinum toxin has been produced that includes no proteins and may address the immunoresistance that can occur with prolonged use. Additional systemic medications may be helpful as adjuncts only in selected cases. Improved surgical techniques are now more successful and cause fewer complications. Therefore, many refractory cases are now offered a surgical approach alone or in combination with botulinum toxin.

SUMMARY

There have been recent therapeutic developments in the treatment of ocular dystonias.

Sensory integration in writer's cramp: comparison with controls and evaluation of botulinum toxin effect

OBJECTIVE

Abnormal temporal and spatial sensory integration have been described in mixed groups of dystonic patients. We tested somatosensory integration and the effect of botulinum toxin (BoNT) in patients with writer's cramp (WC).

METHODS

Median and ulnar SEPs were recorded in 29 WC patients and in 10 controls. We performed: individual and simultaneous stimulation of median and ulnar nerves (MU) and paired stimulation of median nerve at interstimulus-interval (ISI) of 40 and 100 ms. All the trials were repeated after blinded randomized treatment with placebo or BoNT-A.

RESULTS

We found no differences between patients and controls in standard SEPs. Spatial (except for N9) and temporal suppression after ISI 40 were present in both groups for all the waves; after ISI 100, suppression was present only for N70. There were no differences between patients and controls. After BoNT-A treatment, no changes were observed.

CONCLUSIONS

In contrast with previous findings in heterogeneous dystonic groups, and although some studies suggest impairment of spatial and temporal sensory discrimination in patients with focal dystonia, in our large cohort of patients with WC we found no evidence of abnormal somatosensory integration investigated by means of SEPs and no changes in somatosensory variables after BoNT-A treatment.

SIGNIFICANCE

Our findings may suggest pathophysiological differences between focal and generalized dystonia, and may also point to an inferior sensitivity of SEPs in detecting abnormalities in sensory discrimination as compared to methods based on subjective discrimination.