| Prediction of neurosensory disability in very low birth weight preterm infants. Structural and functional brain imaging and hearing screening at term age and follow-up of infants to a corrected age of 18 months | ||
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Fourteen of the preterm infants (27%) had at least one neurosensory disability, including 12 with CP, four of whom, together with two infants without CP, had permanent hearing loss. In terms of intrauterine growth, two of the 16 SGA infants had CP and two others permanent hearing loss. The mean (SD) birth weights of the infants with and without neurosensory disability were 942 (211) g and 1232 (274) g, respectively (p=0.01, independent samples t test), and their mean (SD) gestational ages at birth were 27.5 (1.5) weeks and 30.0 (2.0) weeks (p<0.01, independent samples t test).
The findings in the MRI and SPET examinations were compared to findings in US examinations for predicting CP. Numbers of the cases in examinations are summarised in table 11.
Table 11. Numbers (n) of preterm infants with normal and abnormal findings in brain magnetic resonance imaging (MRI) and single photon emission tomography (SPET) examinations at term age in relation to findings in ultrasound (US) examinations in preterm infants with and without cerebral palsy (CP and non-CP) as an outcome at a corrected age of 18 months.
| Groups of infants with examinations | US (n=51) | MRI (n=50) | SPET (n=34) | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| CP | Non-CP | Normal (n=34) | Abnormal (n=16) | Normal (n=18) | Abnormal (n=16) | |||||||
| CP | Non-CP | CP | Non-CP | CP | Non-CP | CP | Non-CP | |||||
| Normal US without SPET | 1 | 14 | 0 | 14 | 1 | 0 | – | – | – | – | ||
| Normal US with SPET | 3 | 17 | 1 | 14 | 1 | 3 | 1 | 12 | 2 | 5 | ||
| Total (n) | 4 | 31 | 1 | 28 | 2 | 3 | 1 | 12 | 2 | 5 | ||
| Abnormal US without SPET | 0 | 2 | 0 | 1 | 0 | 1 | – | – | – | – | ||
| Abnormal US with SPET | 8 | 6 | 0 | 4 | 8 | 2 | 1 | 4 | 7 | 2 | ||
| Total (n) | 8 | 8 | 0 | 5 | 8 | 3 | 1 | 4 | 7 | 2 | ||
| All (n) | 12 | 39 | 1 | 33 | 10 | 6 | 2 | 16 | 9 | 7 | ||
| – = not done | ||||||||||||
Prediction of CP was most sensitive in the case of parenchymal lesion visible in MRI. Out of the ventricular-brain ratios, only an abnormal trigone index predicted CP in both US and MRI examinations. Wide extracerebral spaces or delayed myelination as seen in MRI did not predict CP. Brain perfusion SPET attained a sensitivity and specificity of the same magnitude as US for predicting all forms of CP, but its sensitivity in predicting moderate or severe CP was better (100% vs. 71%, but with a specificity of 67% vs. 74%, p=0.002 vs. 0.070). The predictive values of the different imaging methods for CP as recorded in the present series are summarised in Table 12.
Table 12. Performance of brain magnetic resonance imaging (MRI) and brain perfusion single photon emission tomography (SPET) at term age for the prediction of cerebral palsy as an outcome at a corrected age of 18 months in very low birth weight preterm infants with reference values for ultrasounds (US).
| Imaging method and defects to be predicted | Number of infants | Sensitivity (%) | Specificity (%) | Odds ratio | 95 % confidence interval | p-value |
|---|---|---|---|---|---|---|
| MRI | 50 | |||||
| Parenchymal lesion | 19 | 100 | 79 | <0.001 | ||
| Parenchymal lesion, excluding subependymal haemorrhages | 10 | 82 | 97 | 171.0 | 13.9–2100.0 | <0.001 |
| Abnormal trigone index | 4 | 27 | 97 | 14.2 | 1.3–155.2 | 0.029 |
| Reference US | 51 | |||||
| Parenchymal lesion | 14 | 67 | 85 | 11.0 | 2.5–48.4 | 0.001 |
| Parenchymal lesion, excluding subependymal haemorrhages | 7 | 58 | 100 | <0.001 | ||
| Abnormal trigone index | 16 | 58 | 76 | 4.5 | 1.1–17.7 | 0.031 |
| MRI and/or US | 51 | |||||
| Parenchymal lesion in both | 11 | 67 | 92 | 24.0 | 4.5–129.0 | <0.001 |
| Parenchymal lesion in one | 21 | 83 | 72 | 12.7 | 2.4–67.6 | 0.002 |
| SPET | 34 | |||||
| Perfusion defect | 16 | 82 | 70 | 10.3 | 1.8–60.4 | 0.010 |
| Cranio-caudal defect | 13 | 73 | 78 | 9.6 | 1.8–50.3 | 0.007 |
| Cranio-caudal sensomotor or thalamic hypoperfusion | 11 | 64 | 83 | 8.3 | 1.6–42.6 | 0.011 |
| Reference US | 34 | |||||
| Parenchymal lesion | 12 | 73 | 83 | 12.7 | 2.3–70.0 | 0.005 |
Prediction of neurosensory disability was based on abnormal brainstem dimensions in MRI and unilateral or bilateral failures in components of BAEP. Brainstem dimensions in MRI gave poor sensitivity values of 23–31%, but their specificities reached 100%. BAEP components gained more significant predictive values, with sensitivities of 79–93% and specificities of 49–91%. The significant predictive values of brainstem dimensions and BAEP for neurosensory disability are summarised in Table 13.
Table 13. Brainstem dimensions in magnetic resonance imaging (MRI) and absence or abnormal peak and inter-peak latencies and the amplitude ratio V/I in brainstem auditory evoked potentials (BAEPs) at term age for the prediction of neurosensory disability in very low birth weight preterm infants at a corrected age of 18 months.
| Imaging method and abnormal parameters | Number of infants | Sensitivity (%) | Specificity (%) | Odds ratio | 95 % confidence interval | p-value |
|---|---|---|---|---|---|---|
| Brainstem MRI | 50 | |||||
| Sagittal dimensions | ||||||
| Mesencephalon | 23 | 97 | 10.8 | 1.0–115.4 | 0.049 | |
| Pons | 31 | 100 | 0.003 | |||
| Axial dimensions | ||||||
| Mesencephalon | 31 | 100 | 0.003 | |||
| Pons | 23 | 100 | 0.015 | |||
| BAEP | 51 | |||||
| Peak latency I | 93 | 59 | 19.1 | 2.3–161.6 | 0.001 | |
| Peak latency III | 79 | 68 | 7.6 | 1.8–32.6 | 0.005 | |
| Peak latency V | 86 | 49 | 5.7 | 1.1–29.0 | 0.029 | |
| Inter-peak latency I–V | 79 | 68 | 7.6 | 1.8–32.6 | 0.005 | |
| Inter-peak latency III–V | 93 | 57 | 17.1 | 2.0–144.4 | 0.001 | |
| Amplitude ratio V/I | 79 | 89 | 30.3 | 5.8–156.7 | <0.001 | |
| Inter-peak latency III–Vand amplitude ratio V/I | 79 | 91 | 41.6 | 7.3–236.5 | <0.001 | |
| Inter-peak latency III–Vor amplitude ratio V/I | 93 | 57 | 17.1 | 2.0–144.4 | 0.001 |
Prediction of permanent hearing loss succeeded best with ABR, which had a sensitivity of 100%, whereas the TEOAE and FF auditory examinations achieved only a half of this figure. The predictive values of the various hearing assessments for permanent hearing loss in the series are summarised in Table 14.
Table 14. Auditory brainstem responses (ABR), transient evoked otoacoustic emissions (TEOAEs), and free-field auditory examination (FF) at term age for the prediction of permanent hearing loss in very low birth weight preterm infants at a corrected age of 18 months.
| Screening method | Number of infants | Sensitivity (%) | Specificity (%) | Odds ratio | 95 % confidence interval | p-value |
|---|---|---|---|---|---|---|
| ABR | 51 | |||||
| Bilateral fail | 7 | 100 | 98 | <0.001 | ||
| TEOAE | 44 | |||||
| Bilateral fail | 9 | 50 | 84 | 5.3 | 0.9–33.0 | 0.089 |
| FF | 51 | |||||
| Fail | 4 | 50 | 98 | 42.0 | 3.3–536.8 | 0.004 |