Neurosurgery notes/Paediatrics/Paediatric Syndrome/Down syndrome

Down syndrome

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Paediatric Syndrome

General

  • Most common genetic cause of intellectual disability overall
  • Affects 1 in every 700 infants born in the United States

Life expectancy

  • 47 yrs

Pathophysiology

  • Presence trisomy of chromosome 21 accounts for excessive production of specifc proteins, resulting in comorbidities such as
    • Acute lymphocytic leukaemia (ALL)
    • Alzheimer’s disease (AD)

Clinical features

System
Features
CNS
Mental retardation, early dementia, hearing impairment
Cardiac
Endocardial cushion defect: ASD, VSD, PDA, tetralogy of Fallot
Facial
Round face, occipital/nasal flattening, Brushfield spots (speckled iris), open mouth and protruding tongue, upslanting palpebral fissure, epicanthal folds
Hands and feet
Single transverse palmar (Simian) crease, short fingers, curved little finger (clinodactyly), sandal gap between big toe and adjacent toe
Spine/MSK
Hypotonia, atlanto-axial instability
GI
Duodenal atresia/stenosis, annular pancreas, omphalocele, Hirschsprung's disease, imperforate anus, tracheoesophageal fistula
Immune
Impaired cellular immunity (more infections), autoimmune disorders, increased childhood risk of AML-M7 and ALL
Endocrine
Hypo/hyperthyroidism, type 1 diabetes mellitus, infertility in males
Brushfield spots are visible between the inner and outer circle of the iris.
Brushfield spots are visible between the inner and outer circle of the iris.

Neurological sequalae

Hypotonia

  • Defined as low resting muscle tone
  • 80% of newborns with DS
  • Chief cause of
    • Gross motor delay,
    • Failure-to-thrive
      • Feeding difficulties
      • Tend to improve by age 3 months and resolve by 8 months of age [
    • Various musculoskeletal abnormalities

Intellectual disability

  • Most common genetic cause of intellectual disability,
  • Can be seen in nearly all Down
  • Nonverbal skills appear to develop normally, whereas language skills become deficient and never fully recover

Hearing impairment

  • 47.4 and 85% of PwDS are reported to have some form of hearing impairment,
  • Due to
    • Middle ear effusion or other types of conductive hearing loss as the most common aetiology
    • Sensorineural hearing loss accounting for 2.7–4.5%
    • Prevalence increases with age and higher frequencies are the most affected

Visual impairment

  • 43.3% of moderate-to-severe impairment
  • Refractive errors, strabismus, epiphora, and nystagmus are the most common ocular findings

Atlantoaxial instability

  • Excessive movement/ligamentous laxity between the C1 and C2 vertebrae.
  • Prevalence 9.5 and 14.6%, with 1.5–3.8% of these cases becoming symptomatic, typically in the pre-teen and teen years
  • Present as compressive myelopathy, which can present as a decrease in muscle strength and tone, hyperrefexia, and gait instability
    • Bowel and bladder symptoms are only present in severe cases
  • Don’t do radiological screening now as not all patients have it
    • Instead get full hx and examine before radiological investigation

Autism spectrum disorder (ASD)

  • A disorder of social communication and, in many situations, intellectual disability

Epilepsy

  • Higher prevalence of epilepsy than the general population,
  • Rates ranging from 1 to 13% according
  • Bimodal distribution:
    • The onset is prior to age one in 40%
      • Infantile spasms
    • Over age 30 in another 40%
      • Myoclonic seizures

Moyamoya syndrome

  • Prevalence of MMS is 3.8% in PwDS and as high as 9.5% in PwDS under 15 years of age
  • Patients present with a bilateral infarction at onset, with 87% presenting with strokes and with a minority classified as transient ischemic attacks (TIAs). The majority of strokes were ischaemic (77% in one study) with hemorrhagic strokes being rare

Cerebral amyloid angiopathy

  • Accumulation of amyloid proteins in the cerebral vessels
  • Signs of microbleeds possibly associated with CAA have been reported in PwDS as young as 30
  • Additional chromosome 21 which contains the gene responsible for the production of amyloid precursor protein (APP)
  • Spectrum of bleeds: intraparenchymal and subarachnoid hemorrhage to cortical microbleeds and grey matter infammation
  • a Convexal subarachnoid atraumatic hemorrhage in a FLAIR sequence. 
  • b Microinfarcts in diffusion weighted imaging. 
  • c Cortical superficial siderosis in T2*gradient echo sequence. 
  • d Lobar intracerebral hemorrhage in a CT. 
  • e Inflammatory reaction in FLAIR sequence. 
  • f Dilated perivascular spaces in T2-weighted sequence. 
  • g White matter hyperintensities in FLAIR sequence. 
  • h Cortico-subcortical microbleeds in susceptibility weighted imaging. 
Schematic representation of the neuroimaging spectrum of manifestations of cerebral amyloid angiopathy. 
Schematic representation of the neuroimaging spectrum of manifestations of cerebral amyloid angiopathy.