localization,myopathy,introduction,.pptx

Its about myopathy

1. Localization in Neurologic Diagnosis Dr Elahe Taghvaei Neurologist

2. Localization in neurologic diagnosis Localization is a process that is must be done to determine the site of the pathologic process involving the nervous system. The nervous system spans from cerebral cortex to nerves and muscles in the toes and we can’t just throw a person in the MRI scanner and scan the whole body each time they have a neurologic complaint. Instead we must deduce the site of the lesion from clues in the neurologic history and examination to guide further studies. Examination plays an important role in understanding the disease even in this age of high tech imaging.

3. Nervous system Central nervous system(CNS) Peripheral nervous system(PNS)

4.   Levels of the nervous system Central Nervous System Cerebrum / cortex Basal ganglia Brainstem Cerebellum Spinal Cord Peripheral Nervous System Roots Plexus Peripheral nerves Neuromuscular junction Muscle The purpose of this lecture is to review the anatomy, neurologic symptoms and examination findings that allow one to localize to one of these levels accurately. first differentiation is between central and peripheral nervous system levels.

5. Central nervous system The CNS (upper motor neuron) includes the brain and spinal cord. Upper motor neuron lesions result in cognitive disorders , spasticity , hyperreflexia , sensory alterations , and pathologic reflexes . Cerebral hemispheres White matter tracts Cerebellum Basal ganglia Spinal cord In general, cerebral lesions involving grey matter (cortex) are associated with defects in higher cortical function (e.g.. dementia, aphasia ) and seizures , whereas those involving white matter ( subcortex ) are associated with paresis and hemisensory defects .

6. Peripheral nervous system The PNS includes lower motor neurons and the nervous outside the CNS. Lower motor neuron lesions result in weakness , flaccidity , sensory alterations , and loss of deep tendon reflexes but absence of pathologic reflexes Lower motor neurons including: anterior horn cells nerve roots plexuses peripheral nerves neuromuscular junctions skeletal muscles

7. Neurologic localization first differentiation is between central and peripheral nervous system levels. Correlate neurologic signs and clinical features to the appropriate level of the neuroaxis for the following neurologic localizations : Focal cortical disease , including a gross classification of aphasias ; Cerebellar disease ; Brainstem lesions ; Spinal cord disease ; Root and peripheral nerve disease ; Neuromuscular junction dysfunction ; Myopathy

8. Neurologic localization As one approaches a patient with neurologic complaints or findings, one should ask several questions . 1)What does the history and examination show ? 2)Can the symptoms and/or neurologic findings be explained by One single lesion ? Multiple discrete lesions? (like Multiple sclerosis)A diffuse process (like a metabolic or toxic condition such as hypoglycemia, hyponatremia, a toxin) 3 ) What level or levels of the nervous system are affected ? 4 ) Always keep in mind false localizing signs – such as a 6th nerve palsy from increased intracranial pressure rather than a lesion directly on the abducens nucleus or CN VI. Also keep vigilant about psychogenic findings such as functional weakness, sensory complaints – findings that don’t seem to obey neurologic rule.

9. Cerebrum

10. Frontal lobe FUNCTIONS : cognition , personality, speech, reasoning ability. COMMON LESIONS : Strokes, tumours, and trauma,… LESION RESULT IN: cognitive disorder (e.g. dementia ), aboulia (slowness of response), nonfluent aphasia( Broca,s aphasia), hemiparesis, partial seizers.

11. Temporal lobe FUNCTIONS : Processing auditory information and with the encoding of memory and Memory and emotions . The dominant temporal lobe, which is the left side in most people, is involved in understanding language and learning and remembering verbal information. The non-dominant lobe, which is typically the right temporal lobe, is involved in learning and remembering non-verbal information (e.g. visuo -spatial material and music). COMMON LESIONS :Stroke , Tumours and trauma. LESIONS RESULT IN : Difficulty in understanding spoken words (Receptive Aphasia) Difficulty in recognising faces (Prosopagnosia) Emotional disturbance (e.g. Aggressive behaviour ) Memory impairment, homonymous hemianopi , aphasia (if dominant hemisphere), complex partial seizures.

12. Parietal lobe FUNCTIONS : The parietal lobe is vital for sensory perception and integration, including the management of taste, hearing, sight, touch, and smell. Sensation , praxis (ability to carry out desired acts). COMMON LESIONS : Strokes, tumours, and trauma. LESIONS RESULT IN : Difficulty with drawing objects Difficulty in distinguishing left from right Spatial disorientation and navigation difficulties Problems with reading (Alexia) Inability to locate the words for writing (Agraphia) Difficulty with doing mathematics (Dyscalculia) Lack of awareness of certain body parts and/or surrounding space (Neglect) difficulty performing previously learned tasks), partial seizures. ( Apraxia ) partial seizures.

13. Occipital lobe FUNCTION: visuospatial processing, distance and depth perception, color determination, object and face recognition( Vision) . COMMON LESIONS : Strokes, tumours, and trauma. LESIONS RESULT IN : Homonymous hemianopasia or blindness

14. Thalamus Localization : Thalamus lies above brainstem  in the middle of brain . Thalamus allows nerve fibers connections to reach all areas of cerebral cortex (the outer layer of your brain). Thalamus is part of an area of brain called the diencephalon. FUNCTIONS : T halamus is  body's information relay station. All information from body's senses (except smell) must be processed through thalamus before being sent to brain's cerebral cortex for interpretation. Integration of sensory functions . COMMON LESIONS : Strokes, haemorrhage,…. LESIONS RESULT IN : Altered sensation and pain on opposite side, gaze deviation.

15. Basal ganglia The parts of the basal ganglia include: Caudate nucleus Globus pallidus Putamen Functios :The basal ganglia are  a group of structures near the center of brain that form important connections . These connections allow different areas of your brain to work together. The basal ganglia manage the signals brain sends that help you move your muscles. Clues to BG localization include:Some types of tremor,Rigidity,Hypokinesia or hyperkinesia,Postural disturbances. Many movement disorders caused by dysfunction in this system are not associated with dramatic abnormalities on routine imaging – so the clinician must recognize typical syndromes by clinical features on history and exam. Parkinson disease,Hungtington disease,…

16. Internal Capsule Localization : The internal capsule is a white matter structure situated in the  inferomedial  part of each cerebral hemisphere of the brain. It carries information past the basal ganglia, separating the caudate nucleus and the thalamus from the putamen and the  globus pallidus . The internal capsule contains both ascending and descending axons, going to and coming from the cerebral cortex .. The corticospinal tract constitutes a large part of the internal capsule, carrying motor information from the primary motor cortex to the lower motor neurons in the spinal cord. FUNCTIONS : Pathway for motor and sensory systems. COMMON LESIONS : Strokes, haemorrhage,…. LESIONS RESULT IN : Contralateral hemiparesis and hemisensory deficits.

17. Cerebellum FUNCTION : Balance and coordination. COMMON LESIONS : Strokes, haemorrhage,tumors ,…. LESIONS RESULT IN: Ataxia, dysmetria , incoordination.

18. Brain stem

19. Midbrain FUNCTIONS : Integration of vertical eye movement, sensory and motor function, Nuclei present in the Midbrain Trochlear nucleus (IV) - motor,Oculomotor nucleus(III ) – motor,Edinger-Westphal nucleus (III) – visceromotor . COMMON LESIONS : Stroke,haemorrhage,tumor ,…. LESION RESULT IN : Papillary dilatation , paralysis, oculomotor weakness frequently accompanied by contralateral hemiparesis , paresis of upgaze .

20. Pons FUNCTION : Vital function (e.g.., breathing, consciousness, cardiac function), motor and sensory functions, lateral eye movement, Nuclei present in the  Pons Cochlear nuclei(VIII ) – sensory ,Vestibular nuclei(VIII ) – sensory,Salivary nuclei - visceromotor   (IX ),(VII ), Facial nucleus(VII ) – motor,Abducens nucleus(VI ) – motor, Trigeminal motor nucleus (V ) – motor,Main trigeminal nucleus(V ) - sensory (fine touch and vibration) COMMON LESIONS : Stroke, Multiple sclerosis,tumor ,…. LESIONS RESULT IN: Hemi- or quadriplegia, pinpoint pupils , horizontal gaze palsy , internuclear opthalmoplegia , coma or “locked-in” state; upbeat nyastagmus is common .

21. Medulla Oblontaga FUNCTION: Swallowing, cardiac function , lingual movements, motor and sensory function, Nuclei present in the  medulla Hypoglossal nucleus  ( XII) – motor,Dorsal motor nucleus of vagus nerve  (X) – visceromotor,Nucleus ambiguus ( IX, X, XI ) – motor,Solitary nucleus (VII, IX, X ) COMMON LESIONS : Strokes, syrinx , tumor ,…. LESIONS RESULT IN : Lateral medullary or Wallenberg's syndrome ( crossed sensory syndrome- numbness on one side of the face and the opposite side of the body, hoarseness, dysphagia, Horner's syndrome, and ipsilateral ataxia); medial medullary syndrome ( ipsilateral tongue deviation and contralateral hemiparesis ).

22. Cervical spinal cord FUNCTIONS : sensory and motor function of the arms and legs . COMMON LESIONS : usually spondylosis (cervical degenerative joint disease), MS, trauma,tumor ,…. LESIONS RESULT IN: Quadra- or paraparesis , spasticity in arms and legs with Babinski’s sign , sensory level in cervical area, urinary retention, loss of position sense

23. Thoracic spinal cord FUNCTION: Motor and sensory functions of the arms and legs, bladder function. COMMON LESIONS : usually tumours metastatic to bone or intradural tumours (e.g. meningioma, neurofibromas ); strokes and herniated disks are rare. LESIONS RESULT IN: spastic paraparesis or paraplegia with bilateral Babinski’s sign; sensory level in thoracic area; urinary retention; loss of position sense in feet ( unless anterior spinal artery syndrome, in which posterior column function spared ).

24. Conus medullaris Localization : The lowermost tapering extremity of the spinal cord is called the conus medullaris , which is around the first or second lumbar vertebra and can sometimes be lower. FUNCTION : bladder and bowel function. COMMON LESIONS : usually tumours in region of L1. LESIONS RESULT IN: Saddle anaesthesia , bladder and bowel dysfunction, pain in legs may occur late in course.

25. Cauda equina Localization : The individual nerve roots at the end of the spinal cord that provide motor and sensory function to the legs and the bladder continue along in the spinal canal. The cauda equina is the continuation of these nerve roots in the lumbar and sacral region . These nerves send and receive messages to and from the lower limbs and pelvic organs. FUNCTIONS : Sensory and motor function in legs, bladder and bowel function. COMMON LESIONS :Herniated lumbar disks or meningeal cancer,…. LESIONS RESULT IN: Scattered pain and weakness in legs , loss of knee and/or ankle reflexes, bladder and bowel dysfunction.

26. Anterior horn cells Location : one of the divisions of the  gray matter of the spinal cord , the anterior horn contains cell bodies of  motor neurons, which innervate skeletal muscle to cause movement FUNCTIONS : Motor function to individual muscles. COMMON LESIONS : Usually motor neuron disease (e.g.., ALS) LESIONS RESULT IN: Weakness, flaccidity, fasciculation, and atrophy in the distribution of the motor unit , loss of reflexes.

27. Nerve root FUNCTIONS : Sensory and motor function to individual muscles. COMMON LESIONS : Disk herniation. LESIONS RESULT IN: Usually causes pain and parasthesias in the dermatomal distribution and weakness in myotomal distribution.

28. Peripheral nerve FUNCTIONS : Sensory and motor function to individual muscles. COMMON LESIONS : Usually peripheral neuropathies, solitary nerve or plexus lesions, mononeuritis multiplex. LESIONS RESULT IN: Numbness, paresthesias , weakness, flaccidity, loss of reflexes, and loss of vibratory and position sense in the nerve distribution.

29. Neuromuscular junction Localization : NMJ is a highly specialized synapse between a motor neuron nerve terminal and its muscle fiber that are responsible for converting electrical impulses generated by the motor neuron into electrical activity in the muscle fibers FUNCTION : Motor function to individual muscles. COMMON LESIONS : myasthenia gravis,botulism ,…. LESIONS RESULT IN: Variable weakness with fatigability; absence of sensory findings and normal reflexes.

30. Skeletal Muscle FUNCTION : Movement of joints and strength. COMMON LESIONS : Usually muscular dystrophies,polymyositis,dermatomyositis ,…. LESIONS RESULT IN: Proximal muscle weakness with intact reflexes and absence of sensory symptoms or findings .

31. Upper motor neuron(UMN) vs Lower motor neuron(LMN)signs UMN signs: Increased tone spasticity,Hyperreflexia,Extensor plantar response. LMN signs :Decreased tone,Hyporeflexia,Flexor plantar response,Muscle atrophy, fasciculations . The spinal cord is where the UMN completes its journey and the LMN takes over as we head down the neuroaxis . The spinal cord has both upper motor neurons (descending corticospinal tracts) and lower motor neurons (ventral horn motor cell bodies) in it . Sometimes there can be a mix of UMN and LMN signs in a spinal cord disorder although the UMN signs usually predominate You must get clear the neurologic examination findings that differentiate between UMN and LMN lesions – reflexes, tone, toes and muscle bulk.

32. Neuroimaging Common neuroimaging modalities include: X-ray Computerized tomography (CT) scans Magnetic Resonance imaging (MRI ) Magnetic resonance angiography (MRA ) CT angiography (CTA) Magnetic resonance venogram (MRV ) Carotid duplex US Transcranial Doppler Catheter angiography

33. Approach to the patient with muscle weakness

34. DEFINITION Weakness is the inabilitiy to perform a desired movement with normal force because of reduction in muscle strength MYOPATHY :Disorders in which there is a primary functional or structural impairment of skeletal muscle.

35. Approach to myopathy The evaluation of the patient presenting with a complaint of “weakness” involves the following steps: Distinguishing true muscle weakness from asthenia or motor impairment not due to loss of muscle power. Localizing , within the neuromuscular system, the site of the lesion that is producing weakness. Determining the cause of the lesion Distinguishing between myopathy and non myopathic pain or weakness is the first step in evaluating patients with muscle-related complaints. Joint pain, fatigue, poor exercise tolerance or paresthesia, rather than a true muscle weakness .

36. Clinical evaluation History Examination Investigations

37. History Which negative and/or positive symptoms and signs does the patient demonstrate ? What is the temporal evolution ? Are there Precipitating factors that trigger episodic weakness or myotonia ? Are associated systemic symptoms or signs present ? Family history What is the distribution of weakness?

38. Which negative and/or positive symptoms and signs does the patient demonstrate? Negative Weakness Fatigue Exercise intolerance Muscle atrophy Positive Myalgia Cramps Contractures myotonia myoglobinuria

39. Weakness Weakness is a cardinal symptom. The distribution of weakness is variable and may change over time. Complaints such as difficulty arising from a chair or low toilet, difficulty climbing stairs, a waddling gait, difficulty lifting objects over the head, combing hair or brushing teeth( proximal weakness ). Distal weakness is less common.

40. Gower’s Sign Patients with proximal leg weakness may rise from sitting on the floor by climbing up their legs with their hands.

41. Weakness Onset Course Limbs involved Muscle involved Progression Presence of sensory/ autonomic symptoms

42. Weakness: Proximal lower extremities: difficulty climbing stairs, arising from a low chair or toilet, or getting up from a squatted position. Proximal upper extremities: trouble lifting objects over their head and brushing their hair. Distal upper extremities: difficulty opening jars, inability to turn a key in the ignition. Distal lower extremities: tripping due to foot drop . Cranial muscle weakness, dysarthria, dysphagia, or ptosis.

43. Fatigue less useful negative symptom Nonspecific abnormal fatigability after exercise can result from certain metabolic and mitochondrial myopathies, and it is important to define the duration and intensity of exercise that provokes the fatigue.

44. Exercise intolerance A less reliable negative symptom. Often reflects the general level of conditioning and health. In patients without any objective weakness, depression should be considered. Exclude certain metabolic myopathies or mitochondrial cytopathies . Ask if it is elicited by brief or long term exercise (carbohydrates or lipid metabolism).

45. Myalgia Infrequent symptom. Orthopedic or rheumatologic conditions are more frequent causes. Constant proximal muscle pain often accompanies inflammatory myopathies. Episodic myalgias after exercise point to metabloic myopathies . In patients with waxing and waning diffuse myalgias , anexity should be ruled out.

46. Muscle cramp Involuntary contractions of muscle that last for seconds to minutes . They are typically benign and occur predominantly in calves , occurring frequently in normal individuals, and are seldom a feature of a primary myopathy. Cramps can occur with: old age, dehydration, prolonged sitting, use of diuretics , hyponatremia,azotemia , hypothyrodism and DM. They are most common in motor neuron disease (especially amyotrophic lateral sclerosis) and chronic neuropathies rather than myopathies. Cramps are only common in metabolic myopathies .

47. Muscle contractures uncommon They are typically provoked by exercise in patients with glycolytic enzyme defects. Contractures differ from cramps in that they usually last longer and are electrically silent with needle EMG.

48. Myotonia Impaired relaxation after sustained voluntary contractions. A painless phenomenon. Commonly involves intrinisic hand muscles and eyelids. It is due to repetitive depolarization of the muscle fibers. It improves with repeated exercise Clinically myotonia can be seen by tapping the muscle ( percussion myotonia ) or by forceful voluntary contractions of muscle groups ( action myotonia ). Typical tests are squeezing the hand of the examiner or forceful closure of the eye .

49. Myotonia

50. paramyotonia congenita paradoxical myotonia in that symptoms are typically worsened by exercise or repeated muscle contractions. Exposure to cold results in worsening of both myotonia and paramyotonia .

51. Myoglobinuria Excess myoglobin in urine resulting in a cola colored urine . It is an uncommon finding. Severe and relatively acute muscle fiber damage . Severe myoglobinuria can result in renal failure due to acute tubular necrosis . If patients complain of exercise-induced weakness and myalgias , they should be asked if their urine has ever turned cola-colored or red during or after these episodes. Recurrent myoglobinuria is usually due to an underlying metabolic myopathy isolated episodes, particularly occurring after unaccustomed strenuous exercise, are frequently idiopathic. Causes : Idiopathic. strenuous exercise. Drugs or toxin intake. Infections. Heat stroke. In case of recurrent myoglobinuria , glycogenoses , lipid storage myopathies or central core disease with malignant hyperthermia should be ruled out.

52. What is the temporal evolution? onset duration evolution of the patient’s symptoms

53. onset Myopathies Presenting at Birth Congenital myotonic dystrophy, Congenital muscular dystrophy Lipid storage diseases (carnitine deficiency) Glycogen storage diseases (acid maltase and phosphorylase deficiencies ) Myopathies Presenting in Childhood Muscular dystrophies, Inflammatory myopathies, Inflammatory myopathies, Lipid storage disease (carnitine deficiency) Glycogen storage disease (acid maltase deficiency) Mitochondrial myopathies Endocrine-metabolic disorders Hypokalemia Hypocalcemia Hypercalcemia Myopathies Presenting in adulthood Muscular dystrophies Inflammatory myopathies, Metabolic myopathies, Endocrine myopathies Thyroid Parathyroid Adrenal Pituitary disorders Toxic myopathies , Myotonic dystrophy , Distal myopathies Nemaline myopathy Centronuclear myopathy

54. Evolution and duration episodic periods of weakness with normal strength interictally ( periodic paralysis, metabolic myopathies due to certain glycolytic pathway disorders). constant weakness: acute or subacute progression inflammatory myopathies ( dermatomyositis and polymyositis ); chronic slow progression over years most muscular dystrophies IBM nonprogressive weakness with little change over decades congenital myopathies

55. Monophasic or relapsing polymyositis can occasionally have an acute monophasic course with complete resolution of strength within weeks or months. Patients with periodic paralysis or metabolic myopathies can have recurrent attacks of weakness over many years, a patient with acute rhabdomyolysis due to cocaine may have a single episode.

56. Pattern of weakness Pattern 1: Proximal Limb-Girdle Weakness Pattern 2: Distal Weakness Pattern 3: Proximal Arm/Distal Leg Weakness ( scapuloperoneal distribution) Pattern 4: Distal Arm/ ProximalLeg Weakness: distal forearm muscles (wrist and finger flexors) and proximal leg weakness knee extensors (quadriceps). Pattern 5: Ptosis With or Without Ophthalmoplegia oculopharyngeal dystrophy, mitochondrial myopathies, myotonic dystrophy Pattern 6: Prominent Neck Extensor Weakness ‘‘dropped head syndrome” amyotrophic lateral sclerosis and myasthenia gravis.

57. Precipitating factors illegal drug or prescription medication use that might produce a myopathy. weakness , pain, and/or myoglobinuria provoked by exercise a glycolytic pathway defect. Episodes of weakness with a fever carnitine palmityl transferase deficiency. Periodic paralysis is characteristically provoked by exercise or ingestion of a carbohydrate meal followed by a period of rest. Patients with paramyotonia congenita frequently report that cold exposure may precipitate their symptoms of muscle stiffness.

58. Are associated systemic symptoms or signs present? Cardiac disease Arrhythmias Kearns-Sayre syndrome Andersen’s syndrome Polymyositis Muscular dystrophies Myotonic Limb-girdle 1B, 2C-2F, 2G Emery- Dreifuss " Congestive Heart Failure Muscular dystrophies Duchenne Becker Emery- Dreifuss Myotonic Limb-girdle 1B, 2C-2F, 2G Nemaline myopathy Acid maltase deficiency Carnitine deficiency Polymyositis

59. Respiratory Insufficiency Muscular Dystrophies Duchenne Becker Emery- Dreifuss Limb-girdle Myotonic Congenital Metabolic Myopathies Acid maltase deficiency Carnitine deficiency Mitochondrial Myopathies Congenital Myopathies Nemaline Centronuclear Inflammatory Myopathies Polymyositis

60. Hepatomegaly may be seen in myopathies associated with deficiencies in acid maltase, debranching enzyme infectious disease. mitochondrial disorder.

61. Family history A thorough family history is clearly of great importance in making a correct diagnosis. Questions regarding family members’ use of canes or wheelchairs , skeletal deformities , or functional limitations are usually more informative than questions such as, ‘‘Does any member of your family have a muscle disease?’’

62. Diagnosis of Myopathy Based on Pattern of Inheritance X-Linked Duchenne Becker Emery- Dreifuss Autosomal Dominant Facioscapulohumeral Limb-girdle Oculopharyngeal muscular dystrophy Myotonic dystrophy Periodic paralysis Paramyotonia congenita Thomsen disease Central core myopathy" Autosomal Recessive Limb-girdle Metabolic myopathies Becker myotonia Maternal Transmission Mitochondrial myopathies

63. What is the distribution of weakness? It is important to know which muscles to test and how to grade their power

64. Inspection Atrophy selective atrophy of the quadriceps and forearm flexor muscles is highly suggestive of inclusion body myositis. Distal myopathies may have profound atrophy of the anterior or posterior lower extremity compartments. (LGMD 2G in 50% of pt ) Hypertrophy LGMD2C–2F, LGMD2I, (LGMD 2G in 50% of pt ) myotonia congenita amyloidosis, sarcoidosis, and hypothyroid myopath Pseudohypertrophy Duchenne and Becker dystrophy Fasciculation-  MND or neuropathy Scapular wining FSHD. LGMD1B ( laminopathy ), LGMD2A ( calpainopathy ), LGMD2C–2F ( sarcoglycanopathies ).

65. Investigations Muscle enzymes : Creatine Kinase ( CK) Aldolase. LDH. Aminotransferase. The CK is elevated in the majority of myopathies but may be normal in slowly progressive myopathies. Genetic testing . Electrophysiological Studies MRI (inflammation , edema with active myosotis, fibrosis, and calcification,…). Muscle biopsy

66. Electrophysiological Studies Electrodiagnostic technique for evaluating and recording the electrical activity produced by skeletal muscles, the signals can be analyzed to detect abnormalities. Confirm localization . can be a guide as to which muscle to biopsy. R/O neuropathy, NMG disease, MND. NCS are typically normal in patients with myopathy. Needle EMG examination: motor units Brief duration, small-amplitude Early recruitment

67. Nerve Conduction Study(NCS)

68. Electromyography (EMG)

69. Classification Congenital myopathies. Muscular dystrophies. Channelopathies . Metabolic myopathies. Mitochondrial myopathies. Inflammatory myopathies. Toxic, metabolic and infectious.

70. Congenital myopathies Clinical characteristics present from birth or prenatally . Prenatal: decreased fetal movement. Postnatal: hypotonia , poor respiratory effort, difficulty feeding, reduced muscle bulk, weakness. First year and beyond: hypotonia , weakness, delayed milestones, failure to thrive, recurrent respiratory infections, flaccid speech. Slow or non progressive course. Central core disease,Multicore ( minicore ) disease,Nemalin myopathy,Myotubular ( centronuclear ) myopathy,Myofibrillar myopathy,Congenital fiber type disproportion.

71. Muscular dystrophies Inherited myopathies. Variable age at onset. Progressive degeneration of the muscles with connective tissue replacing muscle fibers. Systemic involvement Dystrophinopathies ( Duchenne and Beker ). Emery- Dreifuss muscular dystrophy. Autosomal dominant dystrophies: * fascioscapulohumeral MD. * Oculopharyngeal MD. * Congenital and proximal myotonic dystrophy. Limb girdle MD .

72. Inflammatory myopathies Polymyositis Dermatomyositis Inclusion body myositis

73. PM and DM Multi-system disorders. Sub-acute progressive proximal skeletal muscle weakness. Mild myalgias and muscle tenderness. Neck flexors are comonly involved. Facial muscles are usually spared Dysphagia due to pharyngeal and upper esophageal muscles involvement. In advanced cases muscle wasting and hyporeflexia . Respiratory muscles weakness. Interstitial lung disease (anti- tRNA synthetase or Jo-1). Cardiac arrhythmias, bundle branch block and ST changes. Polyarteritis . Raynaud phenomenon. Cutaneous manifestations ( Gottron’s papules and the helitrope eruption)are the hallmark featuresin DM that precedes or accompany weakness. Malignancy .

74. Gottron’s papules

75. IBM Proximal lower extremity weakness is usually the first sign. Chronic slowly progressive symmetic myopathy. Asymmetric weakness could occur. Myalgia. Wrist and finger flexors weakness, hip flexors and quadriceps muscles. Mild facial weakness. Esophageal dysmotility and dysphagia.

76. Toxic myopathies Alcohol, cocaine Lipid lowering agents Steroids Antimalarials , antiretroviral Antipsychotic Chemotherapy

77. Statin induced myopathy The mechanism is not well understood. Myalgia 2-11% Myopathic weakness 2-11% Myositis. Myonecrosis 0.5% Rhabdomyolysis 0.1% Patients should be alerted to report the new onset of myalgia and weakness. Caution in patients with renal failure, hypothyroidism and liver failure.

78. History and physical examination are of great important for differentiation of weakness due to myopathy from the other causes. Myopathy could be inherited or acquired. There is a wide variation in the age of onset of different types of myopathies but in all the cardinal symptom is weakness. Screening for systemic involvement ( cardiac, pulmonary) early on diagnosis affect long term prognosis.