Hendrik J. Stam

The epidemiology of cerebral palsy: Incidence, impairments and risk factors

Purpose. Describing the epidemiology of cerebral palsy (CP), its impairments and risk factors. Method. Literature review 1965 – 2004. Search terms: Cerebral palsy, incidence, prevalence, impairments, risk factors. Results. In the last 40 years the prevalence of CP has risen to well above 2.0 per 1000 life births. In this time span the proportion of low-birthweight infants rose, the proportion of diplegia decreased, while the proportion of hemiplegia increased. CP is more prevalent in more deprived socio-economic populations. The majority of people with CP have the spastic syndrome of which the diplegic group is the smallest. Dependent on the subgroup of CP, 25 – 80% have additional impairments. A large proportion has some kind of cognitive impairment; the prevalence varies with the type of CP and especially increases when epilepsy is present. Epilepsy is present in 20 – 40%; it is most common among the hemi- and tetraplegics. Sensibility of the hands is impaired in about half. Chronic pain is reported by more than a quarter of the adults. Up to 80% have at least some impairment of speech. Low visual acuity is reported in almost three-quarters of all children. Half of all children have gastrointestinal and feeding problems. Stunted growth occurs in a quarter, while under- or overweight problems are present in half of the children. Almost 70% of people with spastic CP have abnormal brain CT findings; abnormal cranial ultrasounds is most strongly associated with hemiplegia, normal cranial ultrasounds with diplegia. The most important risk factors for CP are low birthweight, intrauterine infections and multiple gestation.

Pelvic pain during pregnancy is associated with asymmetric laxity of the sacroiliac joints

Objective. The aim of this study was to investigate the association between pregnancy‐related pelvic pain (PRPP) and sacroiliac joint (SIJ) laxity.

Determinants of locomotor disability in people aged 55 years and over: The Rotterdam study

Locomotor disability, as defined by difficulties in activities of daily living related to lower limb function, can be the consequence of diseases and impairments of the cardiovascular, pulmonary, nervous, sensory and musculoskeletal system. We estimated the associations between specific diseases and impairments and locomotor disability, and the proportion of disability attributable to each condition, controlling for age and comorbidity. The Rotterdam Study is a prospective follow-up study among people aged 55 years and over in the general population. Locomotor disability in 1219 men and 1856 women was assessed with the Stanford Health Assessment Questionnaire. Diseases and impairments were radiological osteoarthritis, pain of the hips and knees, morning stiffness, fractures, hypertension, vascular disease, ischemic heart disease, stroke, heart failure, chronic obstructive pulmonary disease (COPD), depression, Parkinsons disease, osteoporosis, diabetes mellitus, overweight, and low vision. Adjusted odds ratios, etiologic and attributable fractions were calculated for locomotor disability. The occurrence of locomotor disability can partly be ascribed to joint pain, COPD, morning stiffness, diabetes and heart failure in both men and women. In addition in women osteoarthritis, osteoporosis, low vision, fractures, stroke and Parkinsons disease are significant etiologic fractions. In men with morning stiffness, joint pain, heart failure, diabetes mellitus, and COPD a significant proportion of their disability is attributable to this impairment. In women this was the case for Parkinsons disease, morning stiffness, low vision, heart failure, joint pain, diabetes, radiological osteoarthritis, stroke, COPD, osteoporosis, and fractures of the lower limbs, in that order. We conclude that locomotor complaints, heart failure, COPD and diabetes mellitus contribute considerably to locomotor disability in non-institutionalized elderly people.

Measurement of sacroiliac joint stiffness in peripartum pelvic pain patients with Doppler imaging of vibrations (DIV)

OBJECTIVES The research question of the present study was: are sacroiliac joint stiffness levels of peripartum pelvic pain patients different from those of healthy subjects? STUDY DESIGN A cross-sectional comparative sacroiliac joint stiffness analysis of peripartum pelvic pain patients with healthy subjects. In previous studies we introduced a new technique, Doppler imaging of vibrations (DIV), to assess sacroiliac joint stiffness using colour Doppler imaging and vibrations. The measurements were performed on a group of peripartum pelvic pain patients (n=56) and on a control group (n=52). The differences in sacroiliac joint stiffness between the patient group and the control group were tested statistically by means of the Wilcoxons two sample test, the chi-square test and Students t-tests. RESULTS Both patients and controls displayed stiff as well as unstiff joints with no significant difference. There was a significant difference between the groups with regard to the relative difference of sacroiliac joint stiffness between left and right. CONCLUSIONS A diagnostic tool which can possibly be developed in the future could demonstrate an objective finding among women with peripartum pelvic pain. DIV is easy to apply and non-invasive. Asymmetric stiffness of the sacroiliac joints seems to be more directly related to low back pain and pelvic pain, not the stiffness level of a single sacroiliac joint.

The measurements of sacroiliac joint stiffness with colour Doppler imaging: a study on healthy subjects

RATIONALE AND OBJECTIVES Primary peripartum pelvic and low back pain is a common complaint of females. The etiologic relation between pain and pelvic stability has been shown in previous studies, but at present there is no objective clinical testing method to evaluate pelvic stability. METHODS In this study, a dynamic measurement method using sonoelasticity to assess the sacroiliac joint (SI) stiffness was tested in vivo in 14 healthy female volunteers. With the subjects in supine position vibrations were unilaterally applied to the anterior iliac spine. The vibrations were registered by a Colour Doppler Imaging (CDI) transducer over the ipsilateral SI joint. Since the threshold level of the apparatus has a direct relation with the power of the vibrations, the intensity of the vibrations (sonoelasticity) on the sacrum and ilium was measured indirectly in threshold units. The differences between the threshold values were accepted as the power loss of vibrations through the SI joint. One-way analysis of variance-test and T-test for paired samples were applied on the measurement results (P < 0.05). RESULTS Statistically, the results showed a satisfactory intraindividual reproducibility and inter-individual variability. There was no significant difference between the data derived from the left SI joint and right SI joint. CONCLUSIONS Based on the promising results on healthy female volunteers, this method will be specifically used in future studies on patients with peripartum pelvic pain.

THE USE OF COLOR DOPPLER IMAGING FOR THE ASSESSMENT OF SACROILIAC JOINT STIFFNESS: A STUDY ON EMBALMED HUMAN PELVISES

PURPOSE The validity and reproducibility of an instrumented dynamic examination method to measure sacroiliac (SI) joint stiffness was tested in vitro. METHODS Four embalmed human female pelvises were excitated by a pelvic vibrator. A color Doppler imaging (CDI) scanner was used to image the amplitude of vibrations at different sites of the pelvis. Vibrations were applied to the anterior superior iliac spines unilaterally and were received by CDI all over the ipsilateral SI region. Three different stability conditions were created in the SI joints: no intervention, screwed and ligaments cut. Test results were quantified by taking the minimum threshold levels of the bones. The relative difference of vibration intensity between ipsilateral ilium and sacrum at each stability condition is accepted as the stiffness level for the SI joint. RESULTS Statistics showed high reproducibility and significant differences between the stability conditions. Dynamic testing based on the use of vibrations provides visible and quantifiable intra- and inter-individual differences between SI joint stiffnesses. CONCLUSIONS This new method is objective and reproducible. Future in vivo application is promising since there are no technical and safety restrictions.

Measurement of tendon excursion velocity with colour Doppler imaging: a preliminary study on flexor pollicis longus muscle

PURPOSE To study the use of colour Doppler imaging (CDI) for the measurement of maximum and mean tendon velocity. Recent studies showed that CDI, normally used for blood flow examinations, can be used for the imaging of tendons at the hand and wrist region. Although other modalities are available for imaging of the muscle-skeletal system, in vivo measurements of the velocity of tendon excursion are not possible. METHODS The flexor pollicis longus (FPL) tendon of 16 healthy volunteers was measured bilaterally at two levels (wrist and thenar). A splint from the fingers along the proximal lower arm was applied. The thumb was fixed to the splint from the the first phalanx to allow flexion of the interphalangeal (IP) joint only. Pulsed CDI was used for the measurements. The maximum and mean velocities of the FPL tendon were measured at spectrum display mode during continuous voluntary contractions. At least 10 sequential Doppler peaks (cm/s) were recorded at every trial. The measurements were repeated three times. Paired t-test and correlation coefficients were calculated between levels on the same side and the opposite side. RESULTS No significant differences were found between two levels of the same hand and of the opposite hand. As expected, the data revealed variations in the inter-individual tendon velocities. CONCLUSIONS The velocity of the excursion of the FPL tendon can be measured with CDI with good reproducibility. It is expected that velocity measurements can be used in the future for the assessment of other tendons affected by various disorders.

Reliability of sacroiliac joint laxity measurement with Doppler imaging of vibrations

We developed a noninvasive technique, referred to as Doppler imaging of vibrations (DIV), to measure laxity of the sacroiliac joint (SIJ). The purpose of this study was to examine the reliability of SIJ laxity measurements. A total of 10 healthy women (mean 29.6 +/- 6 years old) participated in the study. At both sides, SIJ laxity was measured with DIV in threshold units (TU). Reliability and measurement error were assessed from repeated measurements by five testers on two occasions as well as by one experienced tester. Intraclass correlation coefficients ranged from 0.53 to 0.80 for all five testers, and from 0.75 to 0.89 for the one experienced tester. Only changes larger than 1.94 to 3.60 TU (any tester) or 1.45 to 2.38 TU (experienced tester) could be confidently detected. DIV is a reliable technique for SIJ laxity measurements in healthy subjects, when performed by an experienced tester.