Evaluation of Hypertonia in Children

History

  • Medical: The medical history should include questions about reactive airway disease, pulmonary function, scoliosis, feeding difficulties (reflux), and urological difficulties that suggest urinary retention. A history of reactive airway disease or gastroesophageal reflux can warn of possible dangers during anesthesia (21).
  • Surgical: A complete surgical history will add to the picture of the evolving functional disorder and also alert one to possible conflicting therapies that could adversely impact any benefits from a planned surgery.
  • Gestational, birth, developmental: Each type of CP is associated with a typical gestational and birth history as well as a stereotypic pattern of clinical evolution. If a patient’s history does not match what would be expected for the presumed diagnosis of CP, then the diagnosis should be questioned and an underlying degenerative disorder should be ruled out before proceeding with planned surgery to correct spasticity.

Examination

Tone

  • Spasticity: Spasticity is described as a velocity-dependent increase in muscle tone (23). Clinically, spasticity is observed as the reduction in passive range of motion obtained with rapid, repetitive stretching of a muscle in comparison to the passive range of motion obtained with a slow stretching of the same muscle. Spasticity is commonly graded with a modified Ashworth Scale.

Modified Ashworth Scale for Grading Spasticity

Score   Description
0  

No increase in tone

1   Slight increase in tone, manifested by a catch and release or by minimal resistance at the end of the range of motion when the affected part(s) is moved in flexion or extension
2   More marked increase in muscle tone through most of the ROM, but affected part(s) easily moved
3   Considerable increase in muscle tone, passive movement difficult
4   Affected part(s) rigid in flexion or extension

From Bohannon and Smith (22).


  • Dystonia: Dystonia is a movement disorder characterized by involuntary writhing movement, either sustained or intermittent (e.g., twitching), that causes a twisting, repetitive movement and/or posture in a limb (1). It is often triggered by a voluntary movement (1). The movements may involve the extremities or axial skeleton.
  • Rigidity: Rigidity is a resistance to movement that is present even at low speeds of passive stretching of a muscle, and its force is not velocity dependent (1). It has a quality of a lead pipe being bent, and it is present in both agonist and antagonists muscles (co-contraction). There is no associated posturing, nor is any movement triggered by voluntary movement of distal musculature (1).

Contracture

  • Goniometry: Goniometric measurements of the passive range of motion should be recorded so the development of muscle contracture can be appreciated. It can be recorded either as the range obtained when a given muscle is slowly stretched or as the number of degrees of movement or motion that is missing.
Muscle Group   Movment

Normal Range

(deg from neutral)

Shoulder      
    Forward Flexion 180
    Extension 45-60
    Internal Rotation 70
    External Rotation 90
    Abduction 170-180
Elbow      
    Flexion 150
    Extension 0
    Pronation 80-90
    Supination 80-90
Wrist      
    Extension > 60
    Flexion 60-80
Hip      
    Flexion 120-135
    Extension 30
    Abduction 30-50
    Adduction 30
    Medial Rotation 30-40
    Lateral Rotation 40-60
Knee    
    Flexion 135-160
    Extension 0
Ankle      
    Dorsiflexion 15-30
    Plantar Flexion 45-50

 

Limb deformities

  • Femoral anteversion: The difference between the vertical and the axis of the tibia when the patient is prone and the trochanter is positioned so its lateral projection is maximal This is an approximate measure of the degree of abnormal relationship between the angle of the femoral neck and the posterior surface of the distal condyles.
  • Tibial torsion: Most use a thigh-foot angle measurement to assess tibial torsion. This is the angle between the axis of the femur and the axis of the foot with the patient lying prone and the knee and ankle joints held at 90 degrees each.
  • Patella alta: Normally, the top of the patella is one finger width proximal to the adductor tubercle of the femur.
  • Varus and valgus deformities of the foot: Varus (inversion) deformities of the rear foot or forefoot may be present. More rarely, there may be a valgus (eversion) deformity of the rear foot. These should be documented.

Gait

  • Description: The patient should be observed walking, if possible, both with braces and any assistive device (crutches, walkers, etc.) that the patient commonly uses and without braces (and without assistive device, if the patient is able). Any fixed or dynamic deformity at a joint is described, as is limitation in mobility in the joint. The stride length and pattern of foot plant is also described.
  • Formal gait analysis: Formalized study of a child’s pattern of gait can also be obtained. Typically this includes the measurement of the pattern of muscle contraction during the gait cycle, range of joint movements during the gait cycle, and body alignment during the gait cycle. It can also include measurement of forces generated by the legs against force plates that the patient walks over during the testing.

Laboratory Tests

Cerebral palsy

  • No standard testing: No standard tests that will diagnose CP. Tests may be indicated if a metabolic or genetic abnormality is suspected.

Familial spastic paraparesis

  • Genetic screening
  • Metabolic screening

Radiologic Tests

Ultrasound

  • Perinatal injury: Ultrasonography is a useful tool during the perinatal period when the anterior fontanelle is still open. It can be used to identify parenchymal and intraventricular hemorrhage and cystic changes resulting from previous parenchymal injuries.
  • Perinatal hydrocephalus: Ultrasonography can be used to identify causes for accelerated head growth such as hydrocephalus.

CT scans

  • Emergencies: The main use of CT scans in infants and children is for emergent assessment of the brain, but CT scans are being rapidly replaced by quick rapid sequence MRI scans. CT scans are generally not preferred for routine diagnostic evaluations given the associated radiation exposure.
  • Documentation of calcified lesions: There are special situations where calcification is a diagnostic clue, and it is important to determine whether or not it is present. In these situations CT imaging is superior to MRI. An example would be suspected toxoplasmosis or craniopharyngioma.

MRI

  • Preferred imaging technique: MRI is preferred over other imaging techniques due to its resolution.
  • Resolution improves with myelination: The sensitivity of MRI improves in children after 18–24 months of age as myelination of the white matter matures.
  • Brain malformations occur during first and second trimesters: Malformations of proliferation and cellular lineage (microcephaly, hemimegalencephaly, and focal cortical dysplasia with balloon cells) occur earliest, followed by malformations due to disordered neuroblast migration (heterotopias, lissencephaly), and finally malformations of neocortical organization (polymicrogyri, schizencephaly) (25).
  • Early third trimester lesion periventricular: Injuries occurring early in the third trimester will be seen in the periventricular regions on MRI. These include PVL and IVH (24, 25).
  • Late third trimester lesions in gray matter: Injuries occurring late in the third trimester will be located in the gray matter of the basil ganglia, thalamus, central region, and hippocampus (24, 25).

Nuclear Medicine Tests

  • Not indicated

Electrodiagnostic Tests

  • Urodynamics: There is a 15% incidence of urological dysfunction in children with CP, and baseline urological assessment is recommended prior to any surgery (21, 26).

Neuropsychological Tests

  • Not typically done

Correlation of Tests

  • Physical examination and therapist: Any intended surgery must match the problematic tone that is preventing functional improvement from physical therapy.