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Floppy (Hypotonic) Infant. M. Mohammadi MD Professor, Pediatric Neurology (TUMS) Children Medical Center Hospital www.profmohammadi.net January 2013. Types of Tone. Phasic → rapid contraction in response to a high-intensity stretch (Deep Tendon Reflexes)
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Floppy (Hypotonic) Infant M. Mohammadi MD Professor, Pediatric Neurology (TUMS) Children Medical Center Hospital www.profmohammadi.net January 2013
Types of Tone Phasic→ rapid contraction in response to a high-intensity stretch (Deep Tendon Reflexes) Postural→ the prolonged contraction of antigravity muscles in response to the low-intensity stretch of gravity
Postural Tone www.profmohammadi.net
Postural Tone www.profmohammadi.net
Hypotonia • Hypotonia is a common symptom of neurological dysfunction and occurs in diseases of the brain, spinal cord, nerves, and muscles. • One anterior horn cell and all the muscle fibers that it innervates make up a motor unit. The motor unit is the unit of force. www.profmohammadi.net
Some Terms • A primary disorder of the anterior horn cell body is a “neuronopathy”. • A primary disorder of the axon or its myelin covering is a “neuropathy”. • A primary disorder of the muscle fiber is a “myopathy”. • In infancy and childhood, cerebral disorders are far more common than motor unit disorders (cerebral hypotonia). www.profmohammadi.net
Appearance of Hypotonia • Frog leg • Hand position • Pectusexcavatum • Flattening & loss of hair on occiput • Head lag & shoulder droop in sitting position • Arthrogryposis (hypotonia in uterus) • CDH • Traction & Suspension responses (vertical,Horizontal) www.profmohammadi.net
Traction Response www.profmohammadi.net
Vertical Suspension www.profmohammadi.net
Horizontal Suspension www.profmohammadi.net
Clues to Cerebral Hypotonia • Abnormalities of other brain functions • Dysmorphic features • Fisting of the hands • Malformations of other organs • Movement through postural reflexes • Normal or brisk tendon reflexes • Scissoring on vertical suspension www.profmohammadi.net
Approach to Diagnosis • The first step, determining the disease location is in the brain, spine, or motor u • More than one site may be involved. • The brain and the peripheral nerves are concomitantly involved in some lysosomal & mitochondrial disorders. • Both brain and skeletal muscles are abnormal in infants with acid maltase deficiency & congenital myotonic dystrophy. www.profmohammadi.net
Combined Cerebral and MotorUnit Hypotonia • Acid maltase deficiency • Familial dysautonomia • Giant axonal neuropathy • Hypoxic-ischemic encephalomyopathy • Infantile neuronal degeneration • Lipid storage diseases • Mitochondrial (respiratory chain) disorders • Neonatal myotonic dystrophy • Perinatal asphyxia secondary to motor unit disease www.profmohammadi.net
Motor Unit Disorders withPerinatal Respiratory Distress www.profmohammadi.net • Acute infantile spinal muscular atrophy • Congenital hypomyelinating neuropathy • Congenital myotonic dystrophy • Familial infantile myasthenia • Neurogenic arthrogryposis • X-linked myotubular myopathy
Clues to Motor Unit Disorders • Absent or depressed tendon reflexes • Failure of movement on postural reflexes • Fasciculations • Muscle atrophy • No abnormalities of other organs www.profmohammadi.net
Fasciculations www.profmohammadi.net
Muscle Atrophy www.profmohammadi.net
Differential Dx of Hypotonia www.profmohammadi.net
Evaluation of Motor UnitDisorders • DNA-based testing • Edrophonium chloride (Tensilon test) • Electrodiagnosis • Electromyography • Nerve conduction studies • Repetitive stimulation • Muscle biopsy • Nerve biopsy • Serum creatine kinase www.profmohammadi.net
Gower Sign www.profmohammadi.net
Waddling Gait www.profmohammadi.net
Myotonia www.profmohammadi.net
Myotonia www.profmohammadi.net
Myotonia www.profmohammadi.net
Phenotypic Characteristics www.profmohammadi.net
Phenotypic Characteristics www.profmohammadi.net
Some Words About EDX • Electrodiagnostic Studies • EMG • NCS • RST • F Wave • H Reflex • ….. • Useful mean to screen hypotonia • Trained, expert hands • Highly Sensitive, but non-specific www.profmohammadi.net
Surface electrodes used in pediatric EMG Child recording electrode Infant Recording electrode Disposable self adhesive electrodes Stimulating electrode mohamadi@sina.tums.ac.ir
Needle electrodes used in pediatric EMG mohamadi@sina.tums.ac.ir
Needle electrodes used in pediatric EMG mohamadi@sina.tums.ac.ir
Motor NCS & Sensory NCS Posterior Tibialis Motor NCS Medial Plantar Sensory NCS mohamadi@sina.tums.ac.ir
Motor studies mohamadi@sina.tums.ac.ir
Algorhitmic Approach www.profmohammadi.net
THANKS FOR YOUR ATTENTION www.profmohammadi.net