A distinct pattern of physical and behavioral characteristics are present in
people with SMS. An individual with SMS may have just a few or many of the features
listed below:
Major Physical
Features (> 75% of affected individuals)
Characteristic facial
appearance; flattened mid-face, down-turned mouth, prominent and often rosy
cheeks; prominent jaw in older children and adults; dark eyebrows that meet
in midline (synophrys). (Note: these facial characteristics can be subtle.)
Low muscle tone
(hypotonia)
Oral-sensory motor
dysfunction (poor suck/swallow, decreased tongue strength & movement,
open mouth posture, frequent drooling, textural aversions)
Middle ear problems
(chronic ear infections) and laryngeal anomalies
Hoarse voice, hypernasal
speech
Short fingers and
toes
Hyporeflexia
Signs of peripheral neuropathy
Markedly flat feet
Distinct, broad-based
gait (walking pattern)
Decreased sensitivity
to pain
Major Developmental & Behavioral Features* (> 75% of affected individuals)
Developmental delay
Variable levels of mental retardation (mild - moderate)
Generalized complacency/lethargy (infancy)
Mouthing objects or hands that persists beyond early childhood
Speech delay and articulation problems
Sensory integration issues
Teeth grinding
Delayed toileting skills (delayed potty training and/or persistence of nighttime
bedwetting (enuresis) for age)
Maladaptive behaviors such as: hyperactivity, impulsivity, attention seeking
(especially from adults); easy excitability or distractibility; sudden mood
shifts; explosive outbursts; prolonged tantrums; and aggressive or destructive
behavior
Sleep disturbance (chronic)
Frequent nighttime awakenings
Increased daytime sleepiness/naps
Early morning awake times (5:30 a.m. - 6:30 a.m.)
Inverted circadian rhythm of melatonin
Stereotypic/repetitive behaviors such
as arm hugging/hand squeezing when excited, “lick and flip” behavior (i.e.,
quick flipping pages of books/magazines with/without licking finger)
Self-injurious behaviors: head banging, hand biting, picking
at skin, sores and nails, pulling off finger- and toenails (older ages), inserting
foreign object into ears, nose or other body orifices.
Positive behavioral features
Endearing/appealing personalities
Excellent long term memory for names, places, events
Great sense of humor
Common Features (50% - 75%
of affected individuals)
Infrequent crying and diminished vocalizations for age
Low muscle tone (hypotonia) persisting into childhood
Feeding problems (poor suck/swallow, transitioning from pureed
to textured foods)
Delayed gross motor and fine motor skills
Less Common Features (25%
- 50% of affected individuals)
Congenital heart
defects / murmurs
Lowered immune function
Seizures
Thyroid function adnormalities
Occasional
Features (<25% of affected individuals)
Renal/urinary trace abnormalities
Forearm abnormalities
Cleft lip/palate
Retinal detachment
* While it is possible
that a person with SMS could never show significant behavioral problems, some
degree of self-injurious behavior and sleep disturbance occurs in most SMS individuals.
Despite their very difficult behaviors, children and adults with SMS are very
affectionate and have engaging personalities and much untapped potential.
* Note: Individuals with SMS are often diagnosed with psychiatric diagnoses based on
DMSIV criteria (dual diagnosis), including: attention deficit/hyperactivity
disorder (ADHD), attention deficit disorder (ADD), obsessive compulsive disorder
(OCD), oppositional defiant disorder (ODD), etc.