Hypotonia, or low muscle tone, can have central or peripheral causes. Central hypotonia accounts for 60-80% of cases and is due to problems in the brain or spinal cord, while peripheral hypotonia accounts for 15-30% of cases and results from issues with nerves or muscles. A hypotonic infant may not display weakness. The document outlines how to classify hypotonia based on its location, potential causes, how to take a history and examine a hypotonic child, important lab investigations, and general management approaches.

1. Dr Nehal Shah
PGR peads ii
Services hospital
lahore

2. Hypotonia means low tone
Muscle tone is resistance to passive movement
 Central hypotonia accounts for 60 to 80 %
 Peripheral hypotonia accounts for 15 to 30 %

4. Hypotonia vs weakness
Hypotonia: decrease resistance to passive movement
around a joint
Weakness :decrease in maximum power that can be
generated.
Hypotonic infants may not have weakness
Central origin hypotonia may or may not be associated
with weakness
Hypotonia with profound weakness suggest LMN cause

5.  The maintenance of normal tone requires intact
central and peripheral nervous systems.
 Hypotonia is a common symptom of neurological
dysfunction and occurs in diseases of the brain, spinal
cord, nerves, and muscles .

6. Classification(location)
 Brain
 Spinal cord
 Peripheral nerves
 Neuromuscular Transmission
 Muscles
 Systemic disorders

7. Brain
 Hypoxic ischemic Encephalopathy
 Hypotonic Cerebral Palsy
 Benign Congenital Hypotonia
 Excessive Subarachnoid space
 Cerebellar disorders
 Cortical Dysgenesis

8. SPINAL CORD
 Spinal Cord Injury – Broken Neck
 Spinal Muscular Atrophy
INFECTIONS
 Enterovirus - POLIO
 Transverse Myelitis
MASS LESIONS

9. Anterior horn cell disorders
 Infantile spinal muscular atrophy
 Traumatic myelopathy ( esp. following breech delivery
)
 Hypoxic ischemic myelopathy
 Infantile neuronal degeneration

10. Neuromuscular junction disorders
 Myasthenia gravis ( Transient acquired neonatal
myasthenia ,congenital myasthenia)
 Infantile botulism

11. Myopathies
 Congenital myopathy
 Nemaline myopathy
 Central core disease
 Myotubular myopathy
 Congenital fiber type disproportion myopathy
 Multicore myopathy

12. Metabolic causes
 MITOCHONDRIAL
 Congenital Lactic ACIDOSIS
 Hyperammonemia
 AMINOACIDURIAS
 NON-KETOTIC Hyperglycemia

14. Genetic disorders
 PRADER-WILLI
 ANGELMAN’S SYNDROME
 CRI DU CHAT
 CEREBRO-HEPATO-RENAL SYDROME
 WILLIAM’S SYNDROME
 TRISOMY 21
 TRISOMY 13

15.  The most common central cause of hypotonia is hypoxic
encephalopathy / cerebral palsy in the young infant.
 The most common neuromuscular causes, although still rare,
are congenital myopathies, congenital myotonic dystrophy,
and spinal muscular atrophy.
 Disorders with both central and peripheral manifestations is
acid maltase deficiency (Poompe disease).

17. Approach to hypotonic child
 History
 Examination
 Investigation

18. History
Obstetric history
Pre,peri and postnatal hx
Maternal exposures to toxins or infections suggest a
central cause
Information on fetal movement in utero, fetal
presentation, and the amount of amniotic fluid.
Low Apgar scores may suggest floppiness from birth
Breech delivery or cervical position – cervical spinal cord
trauma

19. Course of illness
 A term infant who is born healthy but develops
floppiness after 12 to 24 hours >> suspect inborn error
of metabolism
 Infants suffering central injury usually develop
increased tone and deep tendon reflexes.

20. Developmental hx
 Motor delay with normal social and language
development decreases the likelihood of brain
pathology.
 Loss of milestones increases the index of suspicion for
neurodegenerative disorders.

21. Dietary hx
A dietary/feeding history may point to diseases of the
neuromuscular junction, which may present with
sucking and swallowing difficulties that ‘fatigue’ or ‘get
worse’ with repetition.

22. Family hx
 Developmental delay (a chromosomal abnormality)
 Delayed motor milestones (a congenital myopathy)
 Premature death (metabolic or muscle disease).

23. Quality of cry
 High-pitched or unusual-sounding cry - suggests CNS
pathology
 A weak cry - diaphragmatic weakness
 Fatigable cry - congenital myasthenic syndrome.

24. Age of onset
 SMA 1 : <6m
 SMA 2: 2M to 15m
 SMA 3 : at or after 12 month
 Neonatal mysthenia : soon after birth
 Juvenile mysthenia : > 6m

25. Sudden onset :IVH in premature infants
Proximal weakness (unable to stand): myopathy
Distal ( unable to hold things) : neuropathy
Muscle pain:
Acute polyneuropathies
Myositis
Ischemic myopathies
Metabolic disease

26. Hx of fatigue on continuous sucking : Mysthenia
Hx of constipation : Botulism
Hx of easy bruising,poor wound healing : Ehler danlos

27. Examination

28. Detection of hypotonia
Bizzare or unusual posture
Decrease resistance of joints to passsive movement
Increase in range of movement at joints
Decrease spontaneous movement

29. Anthropometry
Obesity > parder willi syndrome
Microcephaly > cerebral palsy
Macrocephaly
 myelomeningocele
 Congenital toxoplasma

32. Clinical signs in floppy infant
 In supine,, Frog position
 Their heads lag when are held up
 They slip through at the shoulders
 Do not stand upright on their legs
 Form inverted U shape in ventral suspension
 Lie flat when in prone position.

34.  Venteral suspension
 Inverted U position
The back hangs over the examiner''s hand,, and the
limbs and head hang loosely
Passiive extension off the legs
 Pull to sit
Head lag

36. Clues to anterior horn cell disorder
 Hypotonia
 Generalized weakness
 Absent reflexes
 Feeding difficulties
Classic infantile form of spinal muscular atrophy
Fasciculations of the tongue as well as an intention
tremor.
Affected infants are alert and have profound distal
weakness.

37. Clues to central hypotonia
 Dysmorphic features
 Depressed level of consciousness or lethargy
 Abnormal eye movements or inability to track visually
 Early onset seizures
 Apnea
 Exaggerated irregular breathing patterns.
 Predominant axial weakness
 scissoring on vertical suspension
 Fisting of the hands
 Hyperactive or normal reflexes
 Malformations of other organs

38. Clues to peripheral hypotonia
 Alert infant and appropriate response to surroundings
 Normal sleep-wake patterns
 Associated with profound weakness Hypotonia and
hyporeflexia / areflexia
 muscle atrophy, lack of abnormalities of other organs,
 the presence of respiratory and feeding impairment,
and impairments of ocular or facial movement

39. Clues to specific diagnosis
 Hepatosplenomegaly – storage disorders, congenital
infections
 Renal cysts, high forehead, wide fontanelles –
Zellweger’s syndrome
 Hepatomegaly, retinitis pigmentosa – neonatal
adrenoleukodystrophy
 Congenital cataracts, glaucoma – oculocerebrorenal
(Lowe) syndrome
 Abnormal odour – metabolic disorders
 Hypopigmentation, undesceded testes – Prader Willi

40. Features of weakness
 Poor ability to cough and clear airway secretions.
 Poor swallowing ability
 Crying character [weak,, low pitched]
 Paradoxical breathing pattern.. Intercostal muscles
paralyzed with intact diaphragm..

44. Distinct pattern of weakness
Axial weakness (central hypotonia)
Bulbar and ocular muscle involvement (myasthenia
syndrome)
Progressive proximal symmetrical weakness(
distrophinopathy)
Distal muscle group involvement(peripheral
neuropathy)

45. Lab investigations

46. If central hypotonia is suspected

47. If peripheral hypotonia is
suspected

48. Management
 Most have no cure,
 Progressive course
AIM IS
 Life support : intubation, mechanical ventilation,
feeding support
 Prevent and relief contracture:
physiotherapy,cast,surgical correction
 Prevent and treat infections
 Genetic counseling
 Psychological support