Approach to floppy child/ LMN Flashcards
What are fasciculations?
Spontaneous and involuntary contractions
What is hypotonia?
Decreased tone separated into central and peripheral causes of hypotonia
What are the central causes of hypotonia?
- Disorder of the CNS
- birth asphyxia, mental retardation - Down’s syndrome
- Metabolic disorders
- rickets
- hypothyroidism - Connective tissue disorders
- marfans syndrome
- osteogenesis imperfecta
What are the peripheral causes of hypotonia?
- Anterior horn cell
- infantile spinal muscle atrophy
- poliomyelitis - Neuropathies(nerve roots)
- Giullian Barre syndrome - Myasthenia gravis (NMJ)
- Muscular dystrophies
- Duchenne’s
- X-linked disorder
How do we clinically asses a child’s tone?
180 degree maneuvre
- Supine(froglike posture usually)
- Head lag
- Pull to sit(a normal baby at 6 months has a rounded back)
- Vertical suspension (the head, arms and legs will usually just dangle like a raggedy doll in these patients)
What must we think is the region of Cayuse if there is developmental delay?
Central lesion
What should we think of if a child has brisk deep tenons and truncal hypotonia?
- Immediately think of hypotonic CP
If the child presents with rickets and acidosis what should we think of?
Endocrine or metabolic cause for the hypotonia
What other clinical signs can children with hypotonia present with?
- Facial muscle movement
- Ocular muscle movement
- Stiff joints-which is common in congenital muscular dystrophy and congenital myotonic dystrophy
- Contractures
- Sucking and swallowing difficulties
What are the anterior horn cell causes?
- Infantile spine muscular atrophy
2. Poliomyelitis
What is infantile spinal muscular atrophy?
- the most common neuro muscular disorder of childhood
- affects the legs more than the arms
- they present with facial weakness 50% of the time and fasciciulations of the tongue
What are the different types of SMA?
- Type 1-most severe and occurs in the first couple of weeks from birth. Mom notices that baby is becoming progressively weaker. They never get to sit
- Type 2-moderate(they never stand)
- Type 3-mild(they can stand alone)
What is SMA Type 1 and how does it present?
—presents in first weeks of life
- presents with generalised weakness,wasting and poor head control
- poor sucking and swallowing because of bulbar weakness
- sweating palms and soles of feet
What in the chest is affected by the child with Type 1 SMA?
- they present with recurrent respiratory infections
- intercostal muscles are affected causing breathing difficulties
- Chest is bell-shaped
What is type 2 SMA?
This type of SMA is moderately severe and occurs in the first months of life
- it commonly involves the respiratory system
- the children present with reduced but not absent reflexes
What is type 3 SMA?
The mildest form of SMA
- the child usually has normal milestones
- the proximal muscle weakness usually presents similarly to Duchenne’s muscle dystrophy
- they usually walk flat footed and the foot is exerted
- they usually have fasciculations of the fingers(micromyoclonus)
- the prognosis is usually good and the tendon reflexes are initially normal
What special investigations do we do in children with spinal muscle atrophy?
- Ultrasound of the muscles shows muscle atrophy and echo
- Muscle enzymes(CPK) are usually normal
- Electromyography- there is neurogenic atrophy and fibrillation potentials and large polyphasic potentials at rest
- Muscle biopsy- there are strophic type 1 and 2 muscle fibres
Is SMA usually autosomal dominant or recessive?
- usually autosomal recessive
- gene SMN is usually translocated to chromosome 5
What management do we do for these patients?
We give them supportive treatment to treat the resp infections and physio
What is poliomyelitis?
- it a condition caused by enterovirus affecting the anterior horn cells
- it is usually preceded by mild GIT symptoms like nausea and vomiting and then develops into fever, headache, pain in the neck, back and limbs and muscle spasms
When do the muscle spasms present in patients with poliomyelitis?
Usually a week or two after the virus enters the gastro-intestinal tract
What are the associated clinical manifestations of poliomyelitis?
- Respiratory depression
- Bulbar involvement affecting swallowing and feeding
- There is often total flaccid quadriplegia (floppy baby syndrome)
What special investigations do we usually do in these patients?
- Electromyography- evidence of denervation
- CSF-usually protein is elevated and there are increased leucocytes
- Culture of the blood or CSF usually confirms diagnosis
How do we manage polio?
- We can prevent it by immunizations
2. Supportive treatment-oxygen etc.
What are examples of other enteroviruses?
- Coxsackie
2. Echovirus
What affects the nerve roots?
Guillain Barre syndrome
What is guillain barre syndrome?
It is a demyelinating neuropathy of the anterior and posterior nerve roots caused by the body’s immune response
What are the clinical signs of guillain barre syndrome?
- A upper respiratory tract infection occurs (cocksackie, echo, herpes simplex) a week or two before official motor signs
- Paraesthesia in the fingers and toes
- Reduced reflexes
- Paralysis of the legs, ascending to the trunk, upper limbs, respiratory, bulbar and facial muscles
- They often present with sensory loss in the glove and stocking distribution
What special investigations do we do in guillain barre syndrome?
- CSF which usually has elevated protein
What is the management of guillain barre syndrome?
- supportive
- Physiotherapist
- IV gammaglobulin-400mg/kg/day for 4/5 days
What is the prognosis of guillain barre syndrome?
Good prognosis
Above 80% will recover even if it takes months to a year
What are the disorders we can expect at the NMJ?
- Myasthenia gravis
- Botulinum toxicity
- Organophosphate poisoning
What is myasthenia gravis?
-it is a disorder that causes the inhibition of Ach due to the antibodies attaching themselves on the nicotine causes receptors preventing an action potential from occurring
What are the clinical features of myasthenia gravis?
- Weakness
- Weakness affecting the extra-ocular muscles causing drooping and ptosis
- Abnormal fatigue after repetitive movements or stimulation and this improves after rest
How do we diagnose myasthenia gravis?
- Serum anti-AchR antibodies can be detected in 65-75% of patients with generalised myasthenia gravis
- They often present in conditions like diabetes, thyroid disease and arthritis
- We can also give intram-muscular neostigmine and observe how power returns after 10-15 minutes
How do we treat myasthenia gravis?
- We can do a thymectomy (the earlier it is done the better)
- Immunosuppressive therapy (steroids but not for long periods of time)
- Pyridostigmine ( 15-60 mg 4 hourly)
What can we use in myasthenia crises?
IV gammaglobulin or plasma exchange
What are the types of myasthenia?
- Neonatal form -this is when maternal IgG antibodies cross the placenta and the mom has myasthenia gravis
- the baby is born with hypotonia, apneao and bulbar weakness and seizures
- they make a full recovery within 3-5 weeks
What is botulinusm?
-it is toxicity of botulinim toxin after it is ingested (eg. honey)
How does botulinism present in children?
- Generalised weakness
- Bulbar weakness
- Ophthalmoplegia
What is organophosphate poisoning?
-it is a toxin that can be ingested or goes through the skin and causes ACh inhibition preventing action potentials from going through
How does organophosphate present?
- Salivation
- Lacrimation
- Bronchospasm
- Muscle weakness and fasciculations
- Decreased respiratory effort
- Anxiety, confusion, headache, generalised seizures
What is the management of organophosphate poisoning?
- Atropine and pralidoxinela which is a cholinesterase activator
What are the muscle disorders?
- Congenital myopathies
- Muscular dystrophies
- Myotonic disorders
- Metabolic/inflammatory myopathies
What are congenital myopathies?
-These present at birth and are relatively non-progressive or have slow progression
How many congenital myopathies are there?
6 types
- Central core disease
- Mini core disease
- Normalize myopathy
- Myotubular myopathy
- Congenital fiber type disproportion
- Congenital myopathy
What is central core disease?
- it usually occurs in infancy or later in childhood
- associated with malignant hyperthermia
- core has a predilection for type 1 fibres
What does central core disease present with?
- muscle weak, muscle cramps particularly after exercise
- mild facial weakness
What is minicore disease?
- mild, non-progressive
- associated with nocturnal hypoventialtion causing disturbed sleep and morning headaches
- this is treated with nasal oxygen
What are muscular dystrophies?
This is genetically determined muscle disorders with progressive generation of skeletal muscle but has no structural abnormality in the central and the peripheral nervous system
What is Duchenne’s dystrophy?
-it is a X-linked genetic disorder that is caused by a deficiency in the protein DYSTROPHIN
When does Duchenne’s present?
After 5 years
What are the clinical symptoms of Duchenne’s muscular dystrophy?
- Waddle gait with frequent falls and difficulty walking up stairs
- Proximal muscle weakness -causes toe walking, waddle gait, lordotic posture
- Gower’s sign
- Pain and pseudohypertrophy of the muscles(calves, triceps, deltoids and massater muscles)
- Scoliosis and contractures
- Reduced or absent reflexes
- Respiratory infection
What usually causes the child’s death in Duchenne’s muscle dystrophy?
- Respiratory infection
What special investigations do we do in children with Duchenne’s muscle dystrophy?
- Biopsy-usually can test whether dystrophin is present or not
- Serum muscle enzyme-CPK is usually elevated
- EMG- typical myopathic pattern
- DNA testing is now also available
How do we mange patients with Duchenne’s muscle Dystrophy?
Keep child mobile
-physio is important , splints, surgical intervention for the complications and contractures
What are the myotonic syndromes?
Muscle poorly nourished and contracted and cannot relax
-so basically the muscle cannot relax and has sustained contraction due to instability of the muscle cell membrane
What is myotonic dystrophy?
- occurs on chromosome 19
- usually adolescents and adults
- in babies presents with hydroamnios and the baby is hypotonic,, small for gestational age and have stiff joints
What are the two types of myotonic conditions?
- Myotonic dystrophy
2. Myotonic congenital
What are the examples of metabolic/inflammatory muscle disorders?
Glucogenesis
Mitochondrial myopathy
Lipid stirring myopathy
Periodic paralysis
What are the signs of a LMN lesion?
- Hypotonia (decreased tone)
- Muscle weakness(paralysis)
- Decreased or absent reflexes
- Muscle wasting(don’t use it you lose it)
- Fasciculations
