J. Keith Brown

Abnormalities in cardiac and respiratory function observed during seizures in childhood.

The aim of this study was to observe any changes in cardiac and respiratory function that occur during seizures. Thirty‐seven children (20 males, 17 females; median age 7y 6mo, range 1y 6mo to 15y 6mo) were studied. We recorded electroencephalograms, respiratory rate, heart rate, electrocardiograms, blood pressure, oxygen saturation, heart rate variability (time domain analysis), and cardiac vagal tone. A respiratory pause was defined as an interruption in respiration lasting more than 3s but less than 15s. Apnoea was defined as absence of respiration for more than 15s. Tachypnoea was defined as a 10% increase in respiratory rate from the pre‐ictal baseline. Bradypnoea was defined as a 10% decrease in respiratory rate from the pre‐ictal baseline. Significant hypoxia was defined as a saturation of less than 85%. A significant change in heart rate was taken as a 10% increase or decrease below the baseline rate. Data were obtained from 101 seizures: 40 focal seizures, 21 generalized seizures, and 40 absences. Focal seizures were frequently associated with significant respiratory abnormalities, tachypnoea in 56%, apnoea in 30%, frequent respiratory pauses in 70%, and significant hypoxaemia in 40%. The changes seen in respiratory rate were statistically significant. Changes in cardiac parameters, an increase or decrease in heart rate, were observed in only 26% of focal seizures and 48% of generalized seizures. We conclude that seizure activity can disrupt normal physiological regulation and control of respiratory and cardiac activity.

ASSESSMENT OF SPASTICITY IN HEMIPLEGIC CEREBRAL PALSY I: PROXIMAL LOWER-LIMB REFLEX EXCITABILITY

The quadriceps and hamstring muscles of 13 children with hemiplegic cerebral palsy were studied using ramp and sinusoidal stretches at three different muscle lengths. Overall, the hamstring muscles showed greater velocity sensitivity than the quadriceps, with the hamstrings having the lowest reflex velocity and frequency thresholds close to maximum knee extension. At this position, the hemiparetic hamstrings alone showed a weakly significant reduced reflex frequency threshold compared with non‐paretic muscles. For all other muscle lengths, non‐paretic and hemiparetic muscles displayed similar reflex thresholds when subjected to sudden, discontinuous or repetitive rhythmical, sinusoidal stretches. The number of muscles for which a reflex threshold could be established declined progressively as the angle at the knee joint approached 90o of flexion. Muscles for which no reflex threshold could be demonstrated had similar velocities and frequencies of stretch as those in which a reflex was obtained.

ASSESSMENT OF SPASTICITY IN HEMIPLEGIC CEREBRAL PALSY. II: DISTAL LOWER-LIMB REFLEX EXCITABILITY AND FUNCTION

A clinical method for measuring the stretch reflex theshold and gain of muscles acting across the ankle joint in children with congenital hemiplegia is described. The stretch reflexes of all limbs were velocity‐dependent. Hemiparetic limbs were not necessarily spastic compared with non‐paretic limbs, suggesting that the term ‘spastic hemiplegia’ should be used more selectively and emphasis be placed on the heterogeneity of the hemisyndromes of childhood. Abnormal motor control, planning and dexterity, the hemipostures and plastic (non‐electrical) muscle changes may be more important measures of impairment than reflex excitability. A general scheme for assessing reflex excitability and available treatments applicable to all types of cerebral palsy is proposed.

Somatosensory evoked potentials as a means of assessing neurological abnormality in congenital talipes equinovarus.

Somatosensory evoked potentials (SSEPs) are a very sensitive measure of the functional integrity of the neuroaxis, including peripheral and central structures. When used in diagnostic mode they can provide additional information regarding the probable areas of dysfunction. SSEPs were recorded from 44 children (64 feet with congenital talipes equinovarus, CTEV), between the ages of 2 to 15 years, who had structural CTEV deformity previously treated by surgery, with no clinical evidence of neurological deficit. SSEPs were elicited after sequential and bilateral stimulation (0.1 ms/5 Hz/10 to 20 mA) of the posterior tibial nerve and the common peroneal nerve and were recorded cortically (P40). In half the children, additional recordings were conducted at the knee (N5), the first lumbar spinous process (N14), and the seventh cervical spinous process (N20). Eighteen children had abnormal responses, four children had non-reproducible responses, and 22 children had normal responses. Analysis of the data at different levels of the nervous system showed that eight children had abnormality at the spinal level. The surgical outcome was influenced by the neurological abnormality, with an excellent or good outcome in 34 of 36 feet with normal neurology and 19 of 28 feet where a deficit was present (p<0.05). These findings support the neurological theory as an etiological factor in CTEV deformity.Somatosensory evoked potentials (SSEPs) are a very sensitive measure of the functional integrity of the neuroaxis, including peripheral and central structures. When used in diagnostic mode they can provide additional information regarding the probable areas of dysfunction. SSEPs were recorded from 44 children (64 feet with congenital talipes equinovarus, CTEV), between the ages of 2 to 15 years, who had structural CTEV deformity previously treated by surgery, with no clinical evidence of neurological deficit. SSEPs were elicited after sequential and bilateral stimulation (0.1 ms/5 Hz/10 to 20 mA) of the posterior tibial nerve and the common peroneal nerve and were recorded cortically (P40). In half the children, additional recordings were conducted at the knee (N5), the first lumbar spinous process (N14), and the seventh cervical spinous process (N20). Eighteen children had abnormal responses, four children had non-reproducible responses, and 22 children had normal responses. Analysis of the data at different levels of the nervous system showed that eight children had abnormality at the spinal level. The surgical outcome was influenced by the neurological abnormality, with an excellent or good outcome in 34 of 36 feet with normal neurology and 19 of 28 feet where a deficit was present (p<0.05). These findings support the neurological theory as an etiological factor in CTEV deformity.Somatosensory evoked potentials (SSEPs) are a very sensitive measure of the functional integrity of the neuroaxis, including peripheral and central structures. When used in diagnostic mode they can provide additional information regarding the probable areas of dysfunction. SSEPs were recorded from 44 children (64 feet with congenital talipes equinovarus, CTEV), between the ages of 2 to 15 years, who had structural CTEV deformity previously treated by surgery, with no clinical evidence of neurological deficit. SSEPs were elicited after sequential and bilateral stimulation (0.1 ms/5 Hz/10 to 20 mA) of the posterior tibial nerve and the common peroneal nerve and were recorded cortically (P40). In half the children, additional recordings were conducted at the knee (N5), the first lumbar spinous process (N14), and the seventh cervical spinous process (N20). Eighteen children had abnormal responses, four children had non‐reproducible responses, and 22 children had normal responses. Analysis of the data at different levels of the nervous system showed that eight children had abnormality at the spinal level. The surgical outcome was influenced by the neurological abnormality, with an excellent or good outcome in 34 of 36 feet with normal neurology and 19 of 28 feet where a deficit was present (p<0.05). These findings support the neurological theory as an etiological factor in CTEV deformity.

Continuum of reflex excitability in hemiplegia: influence of muscle length and muscular transformation after heel‐cord lengthening and immobilization on the pathophysiology of spasticity and clonus

The electromyographic (EMG) responses to tendon taps at the ankle and ensuing muscular twitch forces and temporal parameters were studied at varying angles across the joint range in 18 children, aged 3 to 14.9 years, with congenital hemiparetic cerebral palsy and 22 healthy (control) children, aged 3 to 13.6 years. Those subjects with hemiparesis were community ambulators without assistance. In all subjects, passive muscle stretch caused a waxing of the reflex EMG and twitch force near neutral (with the sole of the foot at right angles to the tibia) and a diminution of these with further dorsiflexion. Twitch times increased with each dorsiflexing increment, being slowest at maximum dorsiflexion and fastest at the resting plantarflexion angle. Heterogeneity of the hemiparetic‐limb data is evident when compared with data of non‐paretic and unaffected limbs, with clear differences in the clonic (fast twitch) as opposed to non‐clonic (slow twitch) muscles. In four cases with clinical clonus, clonus frequency was reduced by passive dorsiflexion. Plaster immobilization for 1 month produced clonus which was previously absent in one subject, and caused a fast‐twitch phenotype to emerge in two subjects. Follow‐up after heel‐ cord lengthening in one subject showed that clonus frequency diminished from 9 to 3 Hz with slowing and strengthening of muscle‐twitch phenotype. Short‐ and long‐term peripheral manipulations appear to regulate neuromuscular excitability according to whether muscles are loaded or unloaded. Although damage to the nervous system provides the setting for reflex excitability, the data suggest that the muscle length (which specifies the joint angle) and the muscle‐twitch phenotype of any given limb for any given case appear to dictate the actual speed and strength of reflex muscle‐twitch and clonus profiles. This study illustrates how peripheral manipulations of muscles and tendons may alter the expression of what have hitherto been considered as exclusively central phenomena.

Heterogeneity of neurological syndromes in survivors of grade 3 and 4 periventricular haemorrhage

To evaluate the topographical neurological distribution, patterns of abnormal tone and related functional neuromotor impairment after grade 3 and grade 4 intraventricular/periventricular haemorrhage (IPVH), 33 children with previous grade 3 or 4IPVH of mean gestational age 30.9 weeks (range 25–40 weeks) and mean birth weight 1743 g (range 866–3600 g) were examined neurologically at 4.7 years (range 0.75–10.8 years). Neurological signs were absent in 10/33 cases which were equally distributed between the grade 3 and grade 4 IPVH groups. The largest single topographical neurological distribution was hemiparesis in 8/23, followed jointly by diplegia (cerebral paraplegia) in 6/23 and triplegia in 6/23 cases and finally quadriplegia in 3/23 cases. Grade 4 IPVH tended to result in asymmetrical syndromes, accounting for 7/8 cases of hemiparesis and 5/6 cases of triplegia, whereas all 3/3 cases of quadriplegia followed grade 3 IPVH. The 6/23 cases of diplegia were shared between the grade 3 and grade 4 IPVH groups. Tone was normal in 7/8 of the hemiparetic subjects. Dystonia was the commonest tone abnormality, affecting 8/23 children with neurological disturbance, followed by ataxia/hypotonia in 4/23 and mixed dystonia/ hypotonia in 3/23. Only 1/23 cases had signs of spasticity. Spasticity is rare following severe IPVH. Diplegic children had a better functional neuromotor grade than hemiparetic children, who in turn did better than triplegic children. Ataxia hypotonia resulted in better functional outcome than dystronia, which in turn was more favourable than mixed tone patterns. Cranial imaging by ultrasound (US) or computed tomographic (CT) scanning proved an unreliable prognostic indicator except in the case of hemiparesis, for which US scans correctly predicted the affected side in 5/7 cases. The neurological syndromes following severe IPVH differ from the classical encephalopathy of prematurity, and this should lead to a re-appraisal of the trends in the prevalence of cerebral palsy. Caution should be exercised in the interpretation of cranial imaging with regard to pessimistic prognoses in the presence of changes or undue optimism in their absence.