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approach to Dystonia and myoclonus movement disorders
This document provides an overview of the clinical approach to diagnosing dystonia and myoclonus. It discusses classifying dystonia based on characteristics like distribution, temporal pattern, age of onset, and etiology. Common causes of dystonia include inherited genetic forms, acquired causes like brain injuries, and idiopathic cases. The document also outlines an 8-step approach to diagnosing myoclonus that involves determining if symptoms are truly myoclonus, identifying anatomical substrates, defining the etiology, checking for medication involvement, running routine labs and imaging, considering mitochondrial or neurodegenerative causes, and potentially using next-generation sequencing.
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approach to Dystonia and myoclonus movement disorders
- 1. DYSTONIA CLINICAL APPROACH OsamaA. Ragab Neurology MD
- 2. DYSTONIA • Dystonia isa movement disorder characterized by sustained or intermittent muscle contractions causing abnormal, often repetitive, movements, postures, or both. Dystonic movements are typically patterned, twisting, and may be tremulous. Dystonia is often initiated or worsened by voluntary action and associated with overflow muscle activation.
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- 4. • Several conditionsresulting in abnormal movements, postures, or spasm, which may mimic dystonia, which are also called “pseudo-dystonias.” DYSTONIA
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- 6. AXIS I. CLINICALCHARACTERISTICS
- 7. Infancy (birthto 2 years); Childhood (3–12 years); Adolescence (13–20 years); Early adulthood (21–40 years); Late adulthood (>40 years). AGE AT ONSET
- 8. • Focal. Onlyone body region is affected. Typical examples of focal forms are blepharospasm, oromandibular dystonia, cervical dystonia, laryngeal dystonia, and writer's cramp. • Segmental. Two or more contiguous body regions are affected. Typical examples of segmental forms are: cranial dystonia (blepharospasm with lower facial and jaw or tongue involvement) or bi-brachial dystonia. • Multifocal. Two noncontiguous or more (contiguous or not) body regions are involved. • Generalized. The trunk and at least 2 other sites are involved. Generalized forms with leg involvement are distinguished from those without leg involvement. • Hemidystonia. More body regions restricted to one body side are involved. BODY DISTRIBUTION
- 9. • Persistent. Dystoniathat persists to approximately the same extent throughout the day. • Action-specific. Dystonia that occurs only during a particular activity or task. • Diurnal fluctuations. Dystonia fluctuates during the day, with recognizable circadian variations in occurrence, severity and phenomenology. • Paroxysmal. Sudden self-limited episodes of dystonia usually induced by a trigger with return to preexisting neurological state. TEMPORAL PATTERN
- 10. Isolated Dystonia orCombined with Another Movement Disorder • Isolated dystonia. Dystonia is the only motor feature, with the exception of tremor. • Combined dystonia. Dystonia is combined with other movement disorders (such as myoclonus, parkinsonism, etc.). ASSOCIATED FEATURES
- 11. The presenceor absence of other neurologic or systemic features is a vital component for characterizing dystonia syndromes. Non-motor features have been recently described in cases of dystonia with different etiologies, cognitive decline is typically observed in degenerative or progressive dystonia syndromes. Wilson disease is a disorder where dystonia is typically combined with other neurological or psychiatric symptoms and liver disease. OCCURRENCE OF OTHER NEUROLOGICAL OR SYSTEMIC MANIFESTATIONS
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- 13. AXIS II. ETIOLOGY Evidenceof degeneration, either at the gross, microscopic, or molecular level, provides a useful means to discriminate subgroups of dystonia into degenerative and nondegenerative forms: • Degeneration (progressive structural abnormality, such as neuronal loss); • Static lesions (non-progressive neurodevelopmental anomalies or acquired lesions); • No evidence of degeneration or structural lesion.
- 14. Inherited (dystoniaforms of proven genetic origin). • Autosomal dominant. Several autosomal dominant forms are listed under this heading, such as DYT1 . • Autosomal recessive. The list of autosomal recessive forms of inherited dystonia is continuously growing. Notable forms encompass Wilson disease and NBIA. • X-linked recessive. Inherited dystonia with X-linked transmission encompass forms such as Lubag, Lesch-Nyhan syndrome • Mitochondrial. Mitochondrial forms, such as Leigh syndrome or Leber optic atrophy and dystonia. INHERITED OR ACQUIRED
- 15. Acquired (dystoniadue to a known specific cause). • Perinatal brain injury: dystonic cerebral palsy. • Infection: viral encephalitis, subacute sclerosing panencephalitis, human immunodeficiency virus. • Drug: levodopa and dopamine agonists, neuroleptics . • Toxic: manganese, cobalt, carbon disulfide, cyanide, methanol. • Vascular: ischemia, hemorrhage. • Neoplastic: brain tumor, and paraneoplastic encephalitis. • Brain injury: head trauma, brain surgery (including stereotactic ablations), and electrical injury. • Psychogenic (functional). INHERITED OR ACQUIRED
- 16. Idiopathic (unknowncause). • Sporadic; • Familial. Many cases of focal or segmental isolated dystonia with onset in adulthood fall in this category. Idiopathic forms may be reclassified as inherited, as new dystonia genes are recognized. INHERITED OR ACQUIRED
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- 21. • Myoclonus isa complex hyperkinetic movement disorder characterized by sudden, brief, involuntary jerks of a single muscle or a group of muscles. MYOCLONUS DIAGNOSTIC APPROACH
- 22. • Three approachesto the classification and diagnosis of myoclonus exist: clinical, aetiological and anatomical. • The clinical classification is based on clinical signs, including the distribution and temporal pattern and relationship to motor activity. • The aetiological classification is divided into four subgroups: physiological myoclonus, essential myoclonus, epileptic myoclonus, and symptomatic myoclonus. • The anatomical classification. Myoclonus can be generated in the cortex, in subcortical areas, in the spinal cord, or in the peripheral nerves. MYOCLONUS DIAGNOSTIC APPROACH
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- 24. • Myoclonus (positivemyoclonus) or (negative myoclonus). • Three types of negative myoclonus have been described: • Asterixis in patients with a toxic–metabolic encephalopathy. • Negative myoclonus involving the axial muscles and lower limbs, which results in a wobbling gait and sudden falls. • Epileptic negative myoclonus. Epileptic negative myoclonus is defined as an interruption of muscle activity time-locked to an epileptic EEG abnormality, without evidence of antecedent positive myoclonus. STEP 1: IS THE SYMPTOM REALLY MYOCLONUS?
- 25. STEP 1: ISTHE SYMPTOM REALLY MYOCLONUS?
- 26. STEP 2: ANATOMICAL SUBSTRATESOF MYOCLONUS
- 27. • Cortical andsubcortical myoclonus have a broad differential diagnosis. In general, acute or subacute onset and/or fast progression of myoclonus are important clues for an acquired cause. • Spinal or peripheral myoclonus. • History and clinical examination can differentiate between spinal and peripheral nerve lesion. • Nerve conduction study and EMG.Spinal cord imaging. STEP 3: DEFINING THE AETIOLOGY
- 28. STEP 4: AREMEDICATIONS OR TOXIC AGENTS INVOLVED?
- 29. Laboratory assessment forAcute or chronic renal failure, acute or chronic hepatic failure, chronic respiratory failure with hypercapnia, disturbances of glucose homeostasis, hyperthyroidism, and metabolic alkalosis or acidosis. Careful evaluation of a potential infectious or immune-mediated cause for myoclonus is warranted. CSF analysis to test for immune-mediated disorders and to identify infectious agents. Immune-mediated disorders, such as (anti-NMDAR) encephalitis, stiff-person syndrome ,progressive encephalomyelitis with rigidity and myoclonus. STEP 5: ROUTINE LABORATORY TESTS
- 30. Abnormalities seen onbrain MRI can also indicate a genetic cause, such as neurodegeneration with brain iron accumulation (NBIA) disorders, leukodystrophy, or mitochondrial disorders. The recommended MRI protocol comprises T1-weighted and T2- weighted imaging, fluid-attenuated inversion recovery, and diffusion- weighted imaging (DWI), with administration of gadolinium contrast. Diagnosticians should also consider susceptibility-weighted imaging to assess iron accumulation. STEP 6: BRAIN MRI
- 31. Mitochondrial disorders one mustbe aware of mitochondrial disorders caused by mutations in mitochondrial DNA (mtDNA), which are associated with myoclonus including MERRF syndrome, Leigh syndrome, and MELAS syndrome. Clinical clues for a mitochondrial disorder are multiorgan involvement, ophthalmoplegia, muscle involvement, neuropathy, ataxia, deafness, specific MRI brain findings, and maternal inheritance. STEP 7: MITOCHONDRIAL OR NEURODEGENERATIVE?
- 32. Late-onset neurodegenerative disorders Late-onsetneurodegenerative disorders that are often accompanied by myoclonus include Alzheimer disease, Parkinson disease (PD), multiple system atrophy (MSA) and less commonly dementia with Lewy bodies, Huntington disease, and corticobasal degeneration. Myoclonus in PD and MSA usually manifests as irregular, small- amplitude, often stimulus-sensitive myoclonic jerks of the fingers during muscle activation (cortical polyminimyoclonus). STEP 7: MITOCHONDRIAL OR NEURODEGENERATIVE?
- 33. If the previousdiagnostic steps have not revealed the cause of the myoclonus, the next step is NGS, which comprises several massively parallel sequencing techniques, including whole-genome sequencing (WGS), whole-exome sequencing (WES), and targeted resequencing (TRS). STEP 8: NEXT-GENERATION SEQUENCING