Inner ear drug delivery through a cochlear implant: Pharmacokinetics in a Macaque experimental model.

OBJECTIVES: The method of drug delivery directly into the cochlea with an implantable pump connected to a CI electrode array ensures long-term delivery and effective dose control, and also provides the possibility to use different drugs. The objective is to develop a model of inner ear pharmacokinetics of an implanted cochlea, with the delivery of FITC-Dextran, in the non-human primate model. DESIGN: A preclinical cochlear electrode array (CI Electrode Array HL14DD, manufactured by Cochlear Ltd.) attached to an implantable peristaltic pump filled with FITC-Dextran was implanted unilaterally in a total of 15 Macaca fascicularis (Mf). Three groups were created (5 Mf in each group), according to three different drug delivery times: 2 hours, 24 hours and 7 days. Perilymph (10 samples, 1µL each) was sampled from the apex of the cochlea and measured immediately after extraction with a spectrofluorometer. After scarifying the specimens, x-Rays and histological analysis were performed. RESULTS: Surgery, sampling and histological analysis were performed successfully in all specimens. FITC-Dextran quantification showed different patterns, depending on the delivery group. In the 2 hours injection experiment, an increase in FITC-Dextran concentrations over the sample collection time was seen, reaching maximum concentration peaks (420-964µM) between samples 5 and 7, decreasing in successive samples, without returning to baseline. The 24-hours and 7-days injection experiments showed even behaviour throughout the 10 samples obtained, reaching a plateau with mean concentrations ranging from 2144 to 2564 µM and from 1409 to 2502µM, respectively. Statistically significant differences between the 2 hours and 24 hours groups (p = 0.001) and between the 2 hours and 7 days groups (p = 0.037) were observed, while between the 24 hours and 7 days groups no statistical differences were found. CONCLUSIONS: This experimental study shows that a model of drug delivery and pharmacokinetics using an active pump connected to an electrode array is feasible in Mf. An infusion time ranging from 2 to 24 hours is required to reach a maximum concentration peak at the apex. It establishes then an even concentration profile from base to apex that is maintained throughout the infusion time in Mf. Flow mechanisms during injection and during sampling that may explain such findings may involve cochlear aqueduct flow as well as the possible existence of substance exchange from scala tympani to extracellular spaces, such as the modiolar space or the endolymphatic sinus, acting as a substance reservoir to maintain a relatively flat concentration profile from base to apex during sampling. Leveraging the learnings achieved by experimentation in rodent models, we can move to experiment in non-human primate with the aim of achieving a useful model that provides transferrable data to human pharmacokinetics. Thus, it may broaden clinical and therapeutic approaches to inner ear diseases.

Cochlear compound action potentials from high-level tone bursts originate from wide cochlear regions that are offset toward the most sensitive cochlear region.

Little is known about the spatial origins of auditory nerve (AN) compound action potentials (CAPs) evoked by moderate to intense sounds. We studied the spatial origins of AN CAPs evoked by 2- to 16-kHz tone bursts at several sound levels by slowly injecting kainic acid solution into the cochlear apex of anesthetized guinea pigs. As the solution flowed from apex to base, it sequentially reduced CAP responses from low- to high-frequency cochlear regions. The times at which CAPs were reduced, combined with the cochlear location traversed by the solution at that time, showed the cochlear origin of the removed CAP component. For low-level tone bursts, the CAP origin along the cochlea was centered at the characteristic frequency (CF). As sound level increased, the CAP center shifted basally for low-frequency tone bursts but apically for high-frequency tone bursts. The apical shift was surprising because it is opposite the shift expected from AN tuning curve and basilar membrane motion asymmetries. For almost all high-level tone bursts, CAP spatial origins extended over 2 octaves along the cochlea. Surprisingly, CAPs evoked by high-level low-frequency (including 2 kHz) tone bursts showed little CAP contribution from CF regions ≤ 2 kHz. Our results can be mostly explained by spectral splatter from the tone-burst rise times, excitation in AN tuning-curve "tails," and asynchronous AN responses to high-level energy ≤ 2 kHz. This is the first time CAP origins have been identified by a spatially specific technique. Our results show the need for revising the interpretation of the cochlear origins of high-level CAPs-ABR wave 1. NEW & NOTEWORTHY Cochlear compound action potentials (CAPs) and auditory brain stem responses (ABRs) are routinely used in laboratories and clinics. They are typically interpreted as arising from the cochlear region tuned to the stimulus frequency. However, as sound level is increased, the cochlear origins of CAPs from tone bursts of all frequencies become very wide and their centers shift toward the most sensitive cochlear region. The standard interpretation of CAPs and ABRs from moderate to intense stimuli needs revision.

Direct administration of 2-Hydroxypropyl-Beta-Cyclodextrin into guinea pig cochleae: Effects on physiological and histological measurements.

2-Hydroxypropyl-Beta-Cyclodextrin (HPßCD) can be used to treat Niemann-Pick type C disease, Alzheimer's disease, and atherosclerosis. But, a consequence is that HPßCD can cause hearing loss. HPßCD was recently found to be toxic to outer hair cells (OHCs) in the organ of Corti. Previous studies on the chronic effects of in vivo HPßCD toxicity did not know the intra-cochlear concentration of HPßCD and attributed variable effects on OHCs to indirect drug delivery to the cochlea. We studied the acute effects of known HPßCD concentrations administered directly into intact guinea pig cochleae. Our novel approach injected solutions through pipette sealed into scala tympani in the cochlear apex. Solutions were driven along the length of the cochlear spiral toward the cochlear aqueduct in the base. This method ensured that therapeutic levels were achieved throughout the cochlea, including those regions tuned to mid to low frequencies and code speech vowels and background noise. A wide variety of measurements were made. Results were compared to measurements from ears treated with the HPßCD analog methyl-ß-cyclodextrin (MßCD), salicylate that is well known to attenuate the gain of the cochlear amplifier, and injection of artificial perilymph alone (controls). Histological data showed that OHCs appeared normal after treatment with a low dose of HPßCD, and physiological data was consistent with attenuation of cochlear amplifier gain and disruption of non-linearity associated with transferring acoustic sound into neural excitation, an origin of distortion products that are commonly used to objectively assess hearing and hearing loss. A high dose of HPßCD caused sporadic OHC losses and markedly affected all physiologic measurements. MßCD caused virulent destruction of OHCs and physiologic responses. Toxicity of HPßCD to OHC along the cochlear length is variable even when a known intra-cochlear concentration is administered, at least for the duration of our acute studies.

Perilymph pharmacokinetics of locally-applied gentamicin in the guinea pig.

Intratympanic gentamicin therapy is widely used clinically to suppress the vestibular symptoms of Meniere's disease. Dosing in humans was empirically established and we still know remarkably little about where gentamicin enters the inner ear, where it reaches in the inner ear and what time course it follows after local applications. In this study, gentamicin was applied to the round window niche as a 20 µL bolus of 40 mg/ml solution. Ten 2 µL samples of perilymph were collected sequentially from the lateral semi-circular canal (LSCC) at times from 1 to 4 h after application. Gentamicin concentration was typically highest in samples originating from the vestibule and was lower in samples originating from scala tympani. To interpret these results, perilymph elimination kinetics for gentamicin was quantified by loading the entire perilymph space by injection at the LSCC with a 500 µg/ml gentamicin solution followed by sequential perilymph sampling from the LSCC after different delay times. This allowed concentration decline in perilymph to be followed with time. Gentamicin was retained well in scala vestibuli and the vestibule but declined rapidly at the base of scala tympani, dominated by interactions of perilymph with CSF, as reported for other substances. Quantitative analysis, taking into account perilymph kinetics for gentamicin, showed that more gentamicin entered at the round window membrane (57%) than at the stapes (35%) but the lower concentrations found in scala tympani were due to greater losses there. The gentamicin levels found in perilymph of the vestibule, which are higher than would be expected from round window entry alone, undoubtedly contribute to the vestibulotoxic effects of the drug. Furthermore, calculations of gentamicin distribution following targeted applications to the RW or stapes are more consistent with cochleotoxicity depending on the gentamicin concentration in scala vestibuli rather than that in scala tympani.

Drug delivery into the cochlear apex: Improved control to sequentially affect finely spaced regions along the entire length of the cochlear spiral.

BACKGROUND: Administering pharmaceuticals to the scala tympani of the inner ear is a common approach to study cochlear physiology and mechanics. We present here a novel method for in vivo drug delivery in a controlled manner to sealed ears. NEW METHOD: Injections of ototoxic solutions were applied from a pipette sealed into a fenestra in the cochlear apex, progressively driving solutions along the length of scala tympani toward the cochlear aqueduct at the base. Drugs can be delivered rapidly or slowly. In this report we focus on slow delivery in which the injection rate is automatically adjusted to account for varying cross sectional area of the scala tympani, therefore driving a solution front at uniform rate. RESULTS: Objective measurements originating from finely spaced, low- to high-characteristic cochlear frequency places were sequentially affected. Comparison with existing methods(s): Controlled administration of pharmaceuticals into the cochlear apex overcomes a number of serious limitations of previously established methods such as cochlear perfusions with an injection pipette in the cochlear base: The drug concentration achieved is more precisely controlled, drug concentrations remain in scala tympani and are not rapidly washed out by cerebrospinal fluid flow, and the entire length of the cochlear spiral can be treated quickly or slowly with time. CONCLUSIONS: Controlled administration of solutions into the cochlear apex can be a powerful approach to sequentially effect objective measurements originating from finely spaced cochlear regions and allows, for the first time, the spatial origin of CAPs to be objectively defined.

Perilymph Kinetics of FITC-Dextran Reveals Homeostasis Dominated by the Cochlear Aqueduct and Cerebrospinal Fluid.

Understanding how drugs are distributed in perilymph following local applications is important as local drug therapies are increasingly used to treat disorders of the inner ear. The potential contribution of cerebrospinal fluid (CSF) entry to perilymph homeostasis has been controversial for over half a century, largely due to artifactual contamination of collected perilymph samples with CSF. Measures of perilymph flow and of drug distribution following round window niche applications have both suggested a slow, apically directed flow occurs along scala tympani (ST) in the normal, sealed cochlea. In the present study, we have used fluorescein isothiocyanate-dextran as a marker to study perilymph kinetics in guinea pigs. Dextran is lost from perilymph more slowly than other substances so far quantified. Dextran solutions were injected from pipettes sealed into the lateral semicircular canal (SCC), the cochlear apex, or the basal turn of ST. After varying delays, sequential perilymph samples were taken from the cochlear apex or lateral SCC, allowing dextran distribution along the perilymphatic spaces to be quantified. Variability was low and findings were consistent with the injection procedure driving volume flow towards the cochlear aqueduct, and with volume flow during perilymph sampling driven by CSF entry at the aqueduct. The decline of dextran with time in the period between injection and sampling was consistent with both a slow volume influx of CSF (~30 nL/min) entering the basal turn of ST at the cochlear aqueduct and a CSF-perilymph exchange driven by pressure-driven fluid oscillation across the cochlear aqueduct. Sample data also allowed contributions of other processes, such as communications with adjacent compartments, to be quantified. The study demonstrates that drug kinetics in the basal turn of ST is complex and is influenced by a considerable number of interacting processes.

The auditory nerve overlapped waveform (ANOW) originates in the cochlear apex.

Measurements of cochlear function with compound action potentials (CAPs), auditory brainstem responses, and otoacoustic emissions work well with high-frequency sounds but are problematic at low frequencies. We have recently shown that the auditory nerve overlapped waveform (ANOW) can objectively quantify low-frequency (<1 kHz) auditory sensitivity, as thresholds for ANOW at low frequencies and for CAP at high frequencies relate similarly to single auditory nerve fiber thresholds. This favorable relationship, however, does not necessarily mean that ANOW originates from auditory nerve fibers innervating low-frequency regions of the cochlear apex. In the present study, we recorded the cochlear response to tone bursts of low frequency (353, 500, and 707 Hz) and high frequency (2 to 16 kHz) during administration of tetrodotoxin (TTX) to block neural function. TTX was injected using a novel method of slow administration from a pipette sealed into the cochlear apex, allowing real-time measurements of systematic neural blocking from apex to base. The amplitude of phase-locked (ANOW) and onset (CAP) neural firing to moderate-level, low-frequency sounds were markedly suppressed before thresholds and responses to moderate-level, high-frequency sounds were affected. These results demonstrate that the ANOW originates from responses of auditory nerve fibers innervating cochlear apex, confirming that ANOW provides a valid physiological measure of low-frequency auditory nerve function.

Water permeability of the mammalian cochlea: functional features of an aquaporin-facilitated water shunt at the perilymph-endolymph barrier.

The cochlear duct epithelium (CDE) constitutes a tight barrier that effectively separates the inner ear fluids, endolymph and perilymph, thereby maintaining distinct ionic and osmotic gradients that are essential for auditory function. However, in vivo experiments have demonstrated that the CDE allows for rapid water exchange between fluid compartments. The molecular mechanism governing water permeation across the CDE remains elusive. We computationally determined the diffusional (PD) and osmotic (Pf) water permeability coefficients for the mammalian CDE based on in silico simulations of cochlear water dynamics integrating previously derived in vivo experimental data on fluid flow with expression sites of molecular water channels (aquaporins, AQPs). The PD of the entire CDE (PD = 8.18 × 10(-5) cm s(-1)) and its individual partitions including Reissner's membrane (PD = 12.06 × 10(-5) cm s(-1)) and the organ of Corti (PD = 10.2 × 10(-5) cm s(-1)) were similar to other epithelia with AQP-facilitated water permeation. The Pf of the CDE (Pf = 6.15 × 10(-4) cm s(-1)) was also in the range of other epithelia while an exceptionally high Pf was determined for an epithelial subdomain of outer sulcus cells in the cochlear apex co-expressing AQP4 and AQP5 (OSCs; Pf = 156.90 × 10(-3) cm s(-1)). The Pf/PD ratios of the CDE (Pf/PD = 7.52) and OSCs (Pf/PD = 242.02) indicate an aqueous pore-facilitated water exchange and reveal a high-transfer region or "water shunt" in the cochlear apex. This "water shunt" explains experimentally determined phenomena of endolymphatic longitudinal flow towards the cochlear apex. The water permeability coefficients of the CDE emphasise the physiological and pathophysiological relevance of water dynamics in the cochlea in particular for endolymphatic hydrops and Ménière's disease.

Influence of cochleostomy and cochlear implant insertion on drug gradients following intratympanic application in Guinea pigs.

Locally applied drugs can protect residual hearing following cochlear implantation. The influence of cochlear implantation on drug levels in the scala tympani (ST) after round window application was investigated in guinea pigs using the marker trimethylphenylammonium (TMPA) measured in real time with TMPA-selective microelectrodes. TMPA concentration in the upper basal turn of the ST rapidly increased during implantation and then declined due to cerebrospinal fluid entering the ST at the cochlear aqueduct and exiting at the cochleostomy. The TMPA increase was found to be caused by the cochleostomy drilling if the burr tip partially entered the ST. TMPA distribution in the second turn was less affected by implantation procedures. These findings show that basal turn drug levels may be changed during implantation and the changes may need to be considered in the interpretation of therapeutic effects of drugs in conjunction with implantation.

Gentamicin administration on the stapes footplate causes greater hearing loss and vestibulotoxicity than round window administration in guinea pigs.

Clinically, gentamicin has been used extensively to treat the debilitating symptoms of Mèniére's disease and is well known for its vestibulotoxic properties. Until recently, it was widely accepted that the round window membrane (RWM) was the primary entry route into the inner ear following intratympanic drug administration. In the current study, gentamicin was delivered to either the RWM or the stapes footplate of guinea pigs (GPs) to assess the associated hearing loss and histopathology associated with each procedure. Vestibulotoxicity of the utricular macula, saccular macula, and crista ampullaris in the posterior semicircular canal were assessed quantitatively with density counts of hair cells, supporting cells, and stereocilia in histological sections. Cochleotoxicity was assessed quantitatively by changes in threshold of auditory brainstem responses (ABR), along with hair cell and spiral ganglion cell counts in the basal and second turns of the cochlea. Animals receiving gentamicin applied to the stapes footplate exhibited markedly higher levels of hearing loss between 8 and 32 kHz, a greater reduction of outer hair cells in the basal turn of the cochlea and fewer normal type I cells in the utricle in the vestibule than those receiving gentamicin on the RWM or saline controls. This suggests that gentamicin more readily enters the ear when applied to the stapes footplate compared with RWM application. These data provide a potential explanation for why gentamicin preferentially ablates vestibular function while preserving hearing following transtympanic administration in humans.

Direct entry of gadolinium into the vestibule following intratympanic applications in Guinea pigs and the influence of cochlear implantation.

Although intratympanic (IT) administration of drugs has gained wide clinical acceptance, the distribution of drugs in the inner ear following IT administration is not well established. Gadolinium (Gd) has been previously used as a marker in conjunction with magnetic resonance imaging (MRI) to visualize distribution in inner ear fluids in a qualitative manner. In the present study, we applied gadolinium chelated with diethylenetriamine penta-acetic acid (Gd-DTPA) to the round window niche of 12 guinea pigs using Seprapack(TM) (carboxlmethylcellulose-hyaluronic acid) pledgets which stabilized the fluid volume in the round window niche. Gd-DTPA distribution was monitored sequentially with time following application. Distribution in normal, unperforated ears was compared with ears that had undergone a cochleostomy in the basal turn of scala tympani and implantation with a silastic electrode. Results were quantified using image analysis software. In all animals, Gd-DTPA was seen in the lower basal scala tympani (ST), scala vestibuli (SV), and throughout the vestibule and semi-circular canals by 1 h after application. Although Gd-DTPA levels in ST were higher than those in the vestibule in a few ears, the majority showed higher Gd-DTPA levels in the vestibule than ST at both early and later time points. Quantitative computer simulations of the experiment, taking into account the larger volume of the vestibule compared to scala tympani, suggest most Gd-DTPA (up to 90%) entered the vestibule directly in the vicinity of the stapes rather than indirectly through the round window membrane and ST. Gd-DTPA levels were minimally affected by the implantation procedure after 1 h. Gd-DTPA levels in the basal turn of scala tympani were lower in implanted animals, but the difference compared to non-implanted ears did not reach statistical significance.

Rest-activity disturbances in children with septo-optic dysplasia characterized by actigraphy and 24-hour plasma melatonin profiles.

INTRODUCTION: A trial of melatonin treatment in children with septo-optic dysplasia (SOD) and sleep disruption is accepted clinical practice in many centers. However, no objective measurements of sleep/activity patterns with 24-h melatonin profiles have been published for these individuals, and the pathophysiological basis underlying sleep disorders in SOD remains largely unknown. METHODS: We studied six children with rest-activity disturbances and SOD. All wore an Actiwatch-Mini (a noninvasive method of detecting and recording movement intensity) for 2 wk and were admitted to hospital for a 24-h period during which hourly measurements of serum melatonin were taken. Sleep data were analyzed in conjunction with a detailed sleep diary. Ethical approval was obtained for these studies. RESULTS: Two children produced virtually no melatonin throughout the 24-h period of measurement and had fragmented sleep patterns with no evidence of a non-24-h sleep-wake disorder or delayed sleep-phase disorder. One child had a normal melatonin profile despite actigraphy showing an arrhythmic sleep pattern. The remaining three children had fragmented sleep, with two having normal melatonin profiles and one having a modest increase in daytime melatonin concentrations, making the timing of dim-light melatonin onset difficult to discern. CONCLUSIONS: There is considerable variation in timing and amount of melatonin secretion in these children. Surprisingly, none of the children had either actigraphic or melatonin profile evidence of a non-24-h sleep-wake disorder or delayed sleep-phase disorder. Understanding the heterogeneous nature of underlying sleep disorders in this group of children is important and has implications for their management.

Has publication of the results of the ORACLE Children Study changed practice in the UK?

OBJECTIVE: To investigate whether publication of the results of the ORACLE Children's Study, a 7-year follow-up of the ORACLE trial, changed practice with regard to the routine prescription of antibiotics to women with preterm rupture of membranes or spontaneous preterm labour (intact membranes). DESIGN: A comparative questionnaire survey of clinical practice in November 2007 (before publication) and March 2009 (after publication). POPULATION: Lead obstetricians for labour wards of all maternity units in the UK. METHODS: Self-administered questionnaires requested information about the routine prescription of antibiotics to women with either preterm rupture of membranes or spontaneous preterm labour (intact membranes). MAIN OUTCOME MEASURES: Change in practice for prescription of antibiotics. RESULTS: The response rate was 166/214 (78%) in 2007 and 158/209 (76%) in 2009. In total, 120 maternity units responded on both occasions. For women with preterm rupture of membranes, 162/214 (98%) in 2007 and 151/158 (96%) in 2009 maternity units reported that they prescribed antibiotics, with the majority using erythromycin (98%). For women with spontaneous preterm labour (intact membranes), 35/166 (21%) in 2007 and 25/158 (16%) in 2009 maternity units reported that they routinely prescribed antibiotics. The findings from units who responded on both occasions are similar. CONCLUSIONS: There has been little change in the reported prescription of antibiotics to women with either preterm rupture of membranes or spontaneous preterm labour following publication of the ORACLE Children's Study. This suggests that current practice may require updated guidance.

Childhood outcomes after prescription of antibiotics to pregnant women with preterm rupture of the membranes: 7-year follow-up of the ORACLE I trial.

BACKGROUND: The ORACLE I trial compared the use of erythromycin and/or amoxicillin-clavulanate (co-amoxiclav) with that of placebo for women with preterm rupture of the membranes without overt signs of clinical infection, by use of a factorial randomised design. The aim of the present study--the ORACLE Children Study I--was to determine the long-term effects on children of these interventions. METHODS: We assessed children at age 7 years born to the 4148 women who had completed the ORACLE I trial and who were eligible for follow-up with a structured parental questionnaire to assess the child's health status. Functional impairment was defined as the presence of any level of functional impairment (severe, moderate, or mild) derived from the mark III Multi-Attribute Health Status classification system. Educational outcomes were assessed with national curriculum test results for children resident in England. FINDINGS: Outcome was determined for 3298 (75%) eligible children. There was no difference in the proportion of children with any functional impairment after prescription of erythromycin, with or without co-amoxiclav, compared with those born to mothers who received no erythromycin (594 [38.3%] of 1551 children vs 655 [40.4%] of 1620; odds ratio 0.91, 95% CI 0.79-1.05) or after prescription of co-amoxiclav, with or without erythromycin, compared with those born to mothers who received no co-amoxiclav (645 [40.6%] of 1587 vs 604 [38.1%] of 1584; 1.11, 0.96-1.28). Neither antibiotic had a significant effect on the overall level of behavioural difficulties experienced, on specific medical conditions, or on the proportions of children achieving each level in reading, writing, or mathematics at key stage one. INTERPRETATION: The prescription of antibiotics for women with preterm rupture of the membranes seems to have little effect on the health of children at 7 years of age. FUNDING: UK Medical Research Council.

Childhood outcomes after prescription of antibiotics to pregnant women with spontaneous preterm labour: 7-year follow-up of the ORACLE II trial.

BACKGROUND: The ORACLE II trial compared the use of erythromycin and/or amoxicillin-clavulanate (co-amoxiclav) with that of placebo for women in spontaneous preterm labour and intact membranes, without overt signs of clinical infection, by use of a factorial randomised design. The aim of the present study--the ORACLE Children Study II--was to determine the long-term effects on children after exposure to antibiotics in this clinical situation. METHODS: We assessed children at age 7 years born to the 4221 women who had completed the ORACLE II study and who were eligible for follow-up with a structured parental questionnaire to assess the child's health status. Functional impairment was defined as the presence of any level of functional impairment (severe, moderate, or mild) derived from the mark III Multi-Attribute Health Status classification system. Educational outcomes were assessed with national curriculum test results for children resident in England. FINDINGS: Outcome was determined for 3196 (71%) eligible children. Overall, a greater proportion of children whose mothers had been prescribed erythromycin, with or without co-amoxiclav, had any functional impairment than did those whose mothers had received no erythromycin (658 [42.3%] of 1554 children vs 574 [38.3%] of 1498; odds ratio 1.18, 95% CI 1.02-1.37). Co-amoxiclav (with or without erythromycin) had no effect on the proportion of children with any functional impairment, compared with receipt of no co-amoxiclav (624 [40.7%] of 1523 vs 608 [40.0%] of 1520; 1.03, 0.89-1.19). No effects were seen with either antibiotic on the number of deaths, other medical conditions, behavioural patterns, or educational attainment. However, more children whose mothers had received erythromycin or co-amoxiclav developed cerebral palsy than did those born to mothers who received no erythromycin or no co-amoxiclav, respectively (erythromycin: 53 [3.3%] of 1611 vs 27 [1.7%] of 1562, 1.93, 1.21-3.09; co-amoxiclav: 50 [3.2%] of 1587 vs 30 [1.9%] of 1586, 1.69, 1.07-2.67). The number needed to harm with erythromycin was 64 (95% CI 37-209) and with co-amoxiclav 79 (42-591). INTERPRETATION: The prescription of erythromycin for women in spontaneous preterm labour with intact membranes was associated with an increase in functional impairment among their children at 7 years of age. The risk of cerebral palsy was increased by either antibiotic, although the overall risk of this condition was low. FUNDING: UK Medical Research Council.

Early support developmental journal for children with visual impairment: the case for a new developmental framework for early intervention.

BACKGROUND: Congenital visual impairment has serious consequences for early development, particularly in those with the most profound impairment. Although there is individual variation, developmental delays and risks, including 'developmental setback', are widespread. There is no scientifically robust developmental framework grounded in contemporary theory and scientific knowledge to guide early intervention which may prevent or minimize the risk factors and developmental difficulties. The UK governmental initiative, Early Support, gave the impetus for developing a new developmental framework for babies and young children with visual impairment. METHODS: This paper reports on the scientific literature that underpins the new framework and the limitations of existing intervention materials. The case for focusing on particular vulnerable areas and developing a new developmental framework, the Early Support Developmental Journal for babies and children with severe visual impairment, is presented. CONCLUSIONS: The future direction for service delivery and evaluation is briefly described.

SOX2 anophthalmia syndrome: 12 new cases demonstrating broader phenotype and high frequency of large gene deletions.

BACKGROUND: Developmental eye anomalies, which include anophthalmia (absent eye) or microphthalmia (small eye) are an important cause of severe visual impairment in infants and young children. Heterozygous mutations in SOX2, a SOX1B-HMG box transcription factor, have been found in up to 10% of individuals with severe microphthalmia or anophthalmia and such mutations could also be associated with a range of non-ocular abnormalities. METHODS: We performed mutation analysis on a new cohort of 120 patients with congenital eye abnormalities, mainly anophthalmia, microphthalmia and coloboma. Multiplex ligation-dependent probe amplification (MLPA) and fluorescence in situ hybridisation (FISH) were used to detect whole gene deletion. RESULTS: We identified four novel intragenic SOX2 mutations (one single base deletion, one single base duplication and two point mutations generating premature translational termination codons) and two further cases with the previously reported c.70del20 mutation. Of 52 patients with severe microphthalmia or anophthalmia analysed by MLPA, 5 were found to be deleted for the whole SOX2 gene and 1 had a partial deletion. In two of these, FISH studies identified sub-microscopic deletions involving a minimum of 328 Kb and 550 Kb. The SOX2 phenotypes include a patient with anophthalmia, oesophageal abnormalities and horseshoe kidney, and a patient with a retinal dystrophy implicating SOX2 in retinal development. CONCLUSION: Our results provide further evidence that SOX2 haploinsufficiency is a common cause of severe developmental ocular malformations and that background genetic variation determines the varying phenotypes. Given the high incidence of whole gene deletion we recommend that all patients with severe microphthalmia or anophthalmia, including unilateral cases be screened by MLPA and FISH for SOX2 deletions.

Data collection from very low birthweight infants in a geographical region: methods, costs, and trends in mortality, admission rates, and resource utilisation over a five-year period.

AIMS: 1. To determine the survival and morbidity of infants at discharge with a birthweight of less than 1500 g in the geographically defined population of East Anglia. 2. To demonstrate a cost-effective method of regional data collection. 3. To determine whether there were any changes in the demand for neonatal care. STUDY DESIGN AND SUBJECTS: A prospective cohort analysis using a single database to collect data on 1244 very low birthweight infants from eight neonatal units in one Region from 1993 to 1997. RESULTS: Estimated ascertainment of VLBW infants to the study was 96%. Over the 5 years survival rates were stable (75-79%). 52% of deaths in infants admitted for neonatal care occurred on day 1, with just 15% of deaths occurring after 28 days of life. Mortality risk significantly decreased with increasing gestational age at birth. Compared to 22-25-week old infants, the mortality risk decreased by 65% for 26-27-week old infants (OR 0.35 95% CI (0.21, 0.59)) and by 92% for 32-39-week old infants (OR 0.08 95% CI (0.03, 0.21)) with intermediate odds ratios of 0.22 (0.12, 0.42) and 0.13 (0.06, 0.28) for the 28-29 and 30-39 weeks gestation, respectively. Higher birthweight, after adjusting for gestation also decreased the mortality risk (OR 0.78 per 100 g difference, 95% CI (0.71, 0.86)). No change was seen in the number of extremely preterm infants admitted for intensive care or resource utilisation, although a significant increase was seen in the number of infants dying in delivery rooms. There was a reduction in the reported incidence of pulmonary interstitial emphysema (10-4%) but no change in the number of ventilation days or the rate of chronic lung disease. The mean maternal age increased from 27.7 years to 28.9 years during the study. Maternal steroid administration increased (30% to 59%) and was associated with a decreased risk of mortality (OR 0.44, 95% CI: 0.31-0.62). CONCLUSIONS: It is possible to collect useful data from the neonatal period at a reasonable cost from a geographically defined population. This information was used for informing clinicians, counselling parents and in the era of managed clinical networks will be useful in guiding the provision of effective health care resources.

Outcome at 2 years for very low birthweight infants in a geographical population: risk factors, cost, and impact of congenital anomalies.

AIM: To determine the type and rate of disability at 2 years of age in infants born in the geographically defined population of East Anglia with a birthweight less than 1500 g and to assess the risk factors for disability. STUDY DESIGN: A prospective cohort analysis from all eight neonatal units in East Anglia from 1993-1997 using a single database. METHODS: Local paediatricians assessed children at 2 years using the Health Status Questionnaire and data collection was centrally coordinated. RESULTS: Outcomes for 947 children, 99% of survivors, were available, 74 (7.8%) had severe disability and this was significantly associated with gestational age (p<0.0005), birthweight (p<0.0005) and sex (p=0.046). Major congenital abnormality contributed 27% of all severe disability. The overall cerebral palsy rate was 6.2%, nine children were blind and five had sensorineural hearing loss requiring aids. These children had a high level of use of community services with 19% of the cohort being referred to one or more community service. ELBW infants or those born <30 weeks gestation were 1.5 times and twice as likely to have moderate or severe disability and 2.3 and 5.4 times as likely to have cerebral palsy as those weighing 1000 to 1500 g or >30 weeks gestation. Boys were at higher risk of adverse outcome. CONCLUSIONS: The study was able to define the increased risk associated with being born at lower gestational age or lower birthweight and demonstrates successful ascertainment of outcomes for large local populations at a reasonable cost.