FETAL / NEONATAL Hypotonia is a common diagnostic problem. It may occur with or without weakness. Decreased fetal movements in utero, persistant hypotonia and difficulty feeding are more consistant with congenital rather than an acquired hypotonia. Common treatable conditions such as hypothyroidism, electrolyte abnormalities and metabolic problems can often be ruled in or out relatively quickly. Supportive treatment while the evaluation progresses is important. The differential diagnosis can be long but often can be identified with an anatomical location:
Central Nervous System
Perinatal hypoxia, birth trauma
Metabolic disorders – mucopolysaccaridosis, lipidoses
Chromosomal disorders – Down Syndrome
Spinal cord injury
Spinal muscle atrophy – Werdnig-Hoffmann
Congenital muscular dystrophy
Congenital myotonic dystrophy
Metabolic myopathies – glycogenoses, mitochondrial
Structural congenital myopathies – nemaline, central core, myotubular
Benign Congenital Hypotonia
Metabolic – hypocalcemia, hypermagnesemia
Endocrine – hypothyroidism
Maternal drugs – narcotics near or at time of birth
J Med Genet. 2011 Dec;48(12):793-801. doi: 10.1136/jmedgenet-2011-100211. Epub 2011 Oct 7.
ΠΡΟΣΟΧΗ ΟΤΑΝ ΣΤΟ ΤΡΙΤΟ ΤΡΙΜΗΝΟ ΕΧΟΥΜΕ ΥΠΟΤΟΝΙΑ ΕΜΒΡΥΟΥ ΠΟΥ ΔΕΝ ΔΙΚΑΙΟΛΟΓΕΙΤΑΙ ΑΠΟ IUGR ΕΜΒΡΥΟ ΚΑΙ ΣΥΝΟΔΕΥΕΤΑΙ ΑΠΟ ΥΔΡΑΜΝΙΟ ΥΠΑΡΧΕΙ ΚΙΝΔΥΝΟΣ ΓΕΝΕΤΙΚΟΥ ΣΥΝΔΡΟΜΟΥ TRI21/ NOONAN SYNDROME/ PRADER WILLY/ ZELLWEGER SYNDROME/ SLOS /FETAL AKINESIA SPECTRUM DISORDERS κτλ
Fetal akinesia: review of the genetics of the neuromuscular causes.
Ravenscroft G, Sollis E, Charles AK, North KN, Baynam G, Laing NG.
Zellweger syndrome is a lethal autosomal recessive disorder
characterized by an absence or marked decrease in peroxisomes,
resulting in profound muscular hypotonia and death
in the neonatal period. Other features include abnormal
facies, redundant nuchal skin fold, neonatal seizures, renal
cysts, cataracts, stippled epiphyses, structural brain and
cardiac abnormalities and severe liver dysfunction. Zellweger
syndrome is genetically heterogeneous and to date, seven
PEX genes have been found associated with this condition
(PEX 1, 2, 5, 7, 10, 12 and 16)7,8. Prenatal diagnosis is available
by assessment of peroxisomal beta-oxidation activity or
by mutation analysis when the mutation is known9.
Clinically, ZSS is characterized by craniofacial
dysmorphic features, severe encephalopathy due to brain
dysgenesis/cerebral lissencephaly , cholestatic liver disease, and renal dysfunction with
cystic kidney disease.1 Most patients present in the neonatal
period with severe hypotonia and major central nervous system
dysfunction including seizures and lack of neurodevelopmental
progress, leading to death in the neonatal period or early infancy.
Craniofacial features include flattened face, large fontanelle, split
sutures, prominent forehead, upslanting palpebral fissures, broad
nasal bridge, and epicanthal folds. Ocular anomalies including
cataract, glaucoma, and pigmentary retinopathy may be present,
as well as sensorineural hearing loss. ZSS is genetically
heterogeneous and can be caused by mutations in at least 13
genes implicated in peroxisomal biogenesis.2 Fetal cerebral imaging performed at 32 weeks of gestation: T2-weighted magnetic resonance imaging showing severe
ventriculomegaly and a strongly simplified pattern of gyration and sulcal development; (B) Dysmorphic craniofacial features including
prominent and high forehead (turicephaly), broad nasal bridge, thickened lips, and micrognathia
Prader-Willi (PWS) syndrome is characterized by severe hypotonia and feeding difficulties in early infancy, followed in later infancy or early childhood by excessive eating and gradual development of morbid obesity (unless eating is externally controlled). Motor milestones and language development are delayed. All individuals have some degree of cognitive impairment. A distinctive behavioral phenotype (with temper tantrums, stubbornness, manipulative behavior, and obsessive-compulsive characteristics) is common. Hypogonadism is present in both males and females and manifests as genital hypoplasia, incomplete pubertal development, and, in most, infertility. Short stature is common; characteristic facial features, strabismus, and scoliosis are often present, and non-insulin-dependent diabetes mellitus often occurs in obese individuals.
Prader-Willi syndrome: is there a recognizable fetal phenotype?
Bigi N, Faure JM, Coubes C, Puechberty J, Lefort G, Sarda P, Blanchet P.
diminished fetal movement, polyhydramnios and oddly positioned hands and feet suggested PWS
Minerva Ginecol. 1997 Jan-Feb;49(1-2):49-52.