Eur J Trauma Emerg Surg (2012) 38:75–77 DOI 10.1007/s00068-011-0093-6
SHORT COMMUNICATION
Optic nerve sheath measurement and raised intracranial pressure in paediatric traumatic brain injury S. Agrawal • J. Brierley
Received: 9 December 2010 / Accepted: 1 March 2011 / Published online: 22 March 2011 Ó Springer-Verlag 2011
Abstract Introduction The optimal management of children ventilated for more than 4 h with traumatic brain injury (TBI) necessitates invasive intracranial pressure (ICP) monitoring, though some patients never have raised ICP. If noninvasive screening can reliably rule out elevated ICP, invasive devices can be limited to those in whom neurointensive care measures are indicated. Materials and methods We measured the optic nerve sheath diameter (ONSD) with a 10-MHz ultrasound probe in 11 children (age range 2–15 years, median 9.2 years) with severe TBI admitted to a regional neuro-surgical paediatric intensive care unit (PICU) requiring ICP monitoring and neuro-protection. Simultaneous invasive ICP was recorded and more than 15 mmHg was considered to be abnormal. ONSD [4.5 mm in children over 1 year of age was considered to be abnormal. Results and conclusions All children with clinically significantly raised ICP had abnormal ONSD, whereas those with normal ICP did not. Despite the small numbers, this study suggests that the ONSD may be useful in identifying children with TBI and normal ICP and, so, help avoid the insertion of unnecessary ICP monitors. Keywords Optic nerve sheath Paediatric Traumatic brain injury Intracranial pressure
S. Agrawal J. Brierley Paediatric and Neonatal Intensive Care Unit, Institute of Child Health and Great Ormond Street Hospital for Children, London WC1N 3JH, UK S. Agrawal (&) PICU, St. Mary’s Hospital, London W2 1NY, UK e-mail: [email protected]
Background The management of traumatic brain injury (TBI) in children who are critically ill is conventionally based on the optimal management of cerebral perfusion pressure (CPP), which necessitates invasive intracranial pressure (ICP) monitoring in those with severe head injury or those who require mechanical ventilation for more than 4 h for the management of associated injuries [1]. Manipulation of the CPP using invasively measured ICP remains the basis of neuro-intensive care, the gold standard for managing TBI patients, with a goal of achieving adequate cerebral perfusion and limiting secondary brain injury [1]. The decision to insert an invasive ICP monitor is based upon the clinical history of the injury, as well as computed tomography (CT) scan findings, as it is sometimes difficult to identify patients who should have invasive ICP monitoring based upon CT findings alone. As some TBI patients never have raised ICP and, furthermore, invasive ICP monitoring can be difficult in other circumstances, such as the lack of technical expertise or associated coagulopathy, it would be helpful if an accurate non-invasive screening tool for raised ICP could avoid device insertion in those in which it will prove unnecessary. The quest for a non-invasive surrogate marker for ICP has led to the investigation of several techniques, including Doppler measurements of middle cerebral artery pulsations, impedance audiometry to measure the pressure changes at the base of the ear ossicles and ultrasound measurements of the optic nerve sheath diameter (ONSD) [2]. The perineural space of the intra-orbital portion of the optic nerve is in direct communication with the subarachnoid space and, consequently, this portion of the nerve is directly affected by changes in the ICP; when the ICP rises above a certain point, displacing cerebrospinal fluid (CSF)
123
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S. Agrawal, J. Brierley
Results
ONSD plotted against simultaneous intracranial pressure 6
ONSD (mm)
5 4 0
10
20
30
40
50
3 2 1
Series1 0
Intracranial pressure (mmHg)
Fig. 1 Optic nerve sheath diameter (ONSD) versus invasive intracranial pressure (ICP)
into the perineural space, the diameter of the nerve sheath increases [3, 4]. The ONSD (Fig. 1) can be measured by ultrasound and can represent a dynamic change in the ICP [5]. If non-invasive screening can reliably predict elevated ICP, invasive devices can potentially be limited to those in whom standard neuro-intensive care measures are indicated. We aimed to demonstrate whether the ONSD could detect raised ICP in children admitted with TBI to the paediatric intensive care unit (PICU).
Methods After seeking parental permission, the ONSD was measured in 11 children with severe TBI admitted to a regional neuro-surgical PICU requiring ICP monitoring and neuroprotection over an 8-month period in 2008. The ONSD was measured by one of the two authors, who are paediatric intensivists trained in the use of ultrasound on the PICU. Patients were excluded if they had any signs of orbital injury and if the authors were not available (to reduce the inter-observer bias). The person measuring the ONSD was blinded to the ICP reading at the time of measurement. The ONSD was measured with a SonoSite MicroMaxx ultrasound machine (SonoSite Ltd., Hitchin, UK) using a 10-MHz ultrasound probe, 3 mm behind the optic disc in both eyes (mean of three readings per eye, averaged for the ONSD). The ONSD was measured after admission to the PICU, when there were no major fluctuations in the ICP. Simultaneous measurements of invasive ICP were recorded. ICP more than 15 mmHg and ONSD [4.5 mm in children over 1 year of age was considered to be abnormal, suggesting increased ICP [5, 6].
123
Eleven children between 2 and 15 years of age (median 9.2 years) were included in the study. Adequate ageappropriate CPP [1] was achieved in 10/11 patients (one patient had an ICP of 42 mmHg, hence, could not achieve the target CPP). Seven of the 11 patients required inotropes to achieve the required CPP and seven patients had raised ICP. The median ONSD for children with raised ICP was 5.2 mm (range 4.7–5.4 mm) (right eye) and 5.1 mm (range 4.6–5.5 mm) (left eye), whereas it was 4.0 mm (range 3.5–4.2 mm) (right eye) and 3.9 mm (range 3.4–4.6 mm) (left eye) in patients with normal ICP. All children with clinically significantly raised ICP had increased ONSD, which was statistically significant (p = 0.025), whereas those with normal ICP did not. No increase in the ICP was observed in any patient while performing the orbital ultrasound.
Discussion Ultrasonography is a useful, portable and reproducible tool to diagnose various different conditions in emergencies, allowing appropriate and timely intervention. Over the last two decades, its utility to assess raised ICP has been explored [7]. Various studies have described a good correlation of the ONSD with the ICP detected by CT imaging of the brain. Most of the adult studies have tried to find a correlation of the ONSD with other non-invasively predicted ICP values, either by CT scan findings or transcranial Doppler (TCD) sonography, and have found a significant correlation between the ONSD and severe brain injury [8, 9]. Geeraerts et al. [10] and Soldatos et al. [11] carried out a simultaneous measurement of the ONSD and the invasive ICP in adult trauma patients with ICP bolt and found a significant correlation between the two measurements. There are no studies in children correlating the ONSD with a simultaneously measured ICP by invasive means. A recently published study by Le et al. [12] indicated a significant correlation between the ONSD and raised ICP in children; however, they have used the CT scan findings as a marker for raised ICP and the limitations of CT scanning when assessing raised ICP are well known to paediatric intensivists [13]. That the ONSD increases with an increase in the ICP has been suggested in various paediatric illnesses, such as hydrocephalous and head injury [14, 15]. This study is the first pilot study in children correlating raised ONSD with a simultaneously measured invasive ICP in TBI and suggests that the ONSD might reflect a realtime change in the ICP [16].
Optic nerve sheath measurement and raised ICP in paediatric TBI
As our aim was to assess the ONSD as a screening tool, we have not investigated ONSD and ICP variations within the same patient, and, furthermore, the exact prediction of the ICP from the ONSD is difficult, as any single value of ONSD can represent an ICP range of more than 10 mmHg. Therefore, before the widespread use of the ONSD for assessing raised ICP in children, further paediatric studies are needed in order to substantiate our results. However, we suggest that the ONSD may be a useful screening tool to predict which children with TBI warrant invasive ICP measuring devices for diagnostic and therapeutic interventions.
Conclusions Despite the small numbers, this study suggests the optic nervesheath diameter (ONSD) may be useful in identifying children with traumatic braininjury (TBI) and normal intracranial pressure (ICP), and, therefore, help to avoid the unnecessary insertion of ICP monitors, with exposure of the child to the risks of bleeding and infection, however small. Larger trials are required to substantiate these results. Conflict of interest
None.
References 1. Adelson PD, Bratton SL, Carney NA, Chesnut RM, du Coudray HE, Goldstein B, Kochanek PM, Miller HC, Partington MD, Selden NR, Warden CR, Wright DW; American Association for Surgery of Trauma; Child Neurology Society; International Society for Pediatric Neurosurgery; International Trauma Anesthesia and Critical Care Society; Society of Critical Care Medicine; World Federation of Pediatric Intensive and Critical Care Societies. Guidelines for the acute medical management of severe traumatic brain injury in infants, children, and adolescents. Chapter 5. Indications for intracranial pressure monitoring in pediatric patients with severe traumatic brain injury. Pediatr Crit Care Med. 2003;4:S19–24. 2. Stocchetti N. Could intracranial pressure in traumatic brain injury be measured or predicted noninvasively? Almost. Intensive Care Med. 2007;33:1682–3.
77 3. Helmke K, Hansen HC. Fundamentals of transorbital sonographic evaluation of optic nerve sheath expansion under intracranial hypertension. I. Experimental study. Pediatr Radiol. 1996;26: 701–5. 4. Helmke K, Hansen HC. Fundamentals of transorbital sonographic evaluation of optic nerve sheath expansion under intracranial hypertension. II. Patient study. Pediatr Radiol. 1996;26:706–10. 5. Ballantyne J, Hollman AS, Hamilton R, Bradnam MS, Carachi R, Young DG, Dutton GN. Transorbital optic nerve sheath ultrasonography in normal children. Clin Radiol. 1999;54:740–2. 6. Ko¨rber F, Scharf M, Moritz J, Dralle D, Alzen G. Sonography of the optical nerve—experience in 483 children. Rofo. 2005;177: 229–35. 7. Soldatos T, Chatzimichail K, Papathanasiou M, Gouliamos A. Optic nerve sonography: a new window for the non-invasive evaluation of intracranial pressure in brain injury. Emerg Med J. 2009;26:630–4. 8. Geeraerts T, Launey Y, Martin L, Pottecher J, Vigue´ B, Duranteau J, Benhamou D. Ultrasonography of the optic nerve sheath may be useful for detecting raised intracranial pressure after severe brain injury. Intensive Care Med. 2007;33:1704–11. 9. Tayal VS, Neulander M, Norton HJ, Foster T, Saunders T, Blaivas M. Emergency department sonographic measurement of optic nerve sheath diameter to detect findings of increased intracranial pressure in adult head injury patients. Ann Emerg Med. 2007;49:508–14. 10. Geeraerts T, Merceron S, Benhamou D, Vigue´ B, Duranteau J. Non-invasive assessment of intracranial pressure using ocular sonography in neurocritical care patients. Intensive Care Med. 2008;34:2062–7. 11. Soldatos T, Karakitsos D, Chatzimichail K, Papathanasiou M, Gouliamos A, Karabinis A. Optic nerve sonography in the diagnostic evaluation of adult brain injury. Crit Care. 2008;12: R67. 12. Le A, Hoehn ME, Smith ME, Spentzas T, Schlappy D, Pershad J. Bedside sonographic measurement of optic nerve sheath diameter as a predictor of increased intracranial pressure in children. Ann Emerg Med. 2009;53:785–91. 13. Rennick G, Shann F, de Campo J. Cerebral herniation during bacterial meningitis in children. BMJ. 1993;306:953–5. 14. Newman WD, Hollman AS, Dutton GN, Carachi R. Measurement of optic nerve sheath diameter by ultrasound: a means of detecting acute raised intracranial pressure in hydrocephalus. Br J Ophthalmol. 2002;86:1109–13. 15. Tsung JW, Blaivas M, Cooper A, Levick NR. A rapid noninvasive method of detecting elevated intracranial pressure using bedside ocular ultrasound: application to 3 cases of head trauma in the pediatric emergency department. Pediatr Emerg Care. 2005;21:94–8. 16. Malayeri AA, Bavarian S, Mehdizadeh M. Sonographic evaluation of optic nerve diameter in children with raised intracranial pressure. J Ultrasound Med. 2005;24:143–7.
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SHORT COMMUNICATION
Optic nerve sheath measurement and raised intracranial pressure in paediatric traumatic brain injury S. Agrawal • J. Brierley
Received: 9 December 2010 / Accepted: 1 March 2011 / Published online: 22 March 2011 Ó Springer-Verlag 2011
Abstract Introduction The optimal management of children ventilated for more than 4 h with traumatic brain injury (TBI) necessitates invasive intracranial pressure (ICP) monitoring, though some patients never have raised ICP. If noninvasive screening can reliably rule out elevated ICP, invasive devices can be limited to those in whom neurointensive care measures are indicated. Materials and methods We measured the optic nerve sheath diameter (ONSD) with a 10-MHz ultrasound probe in 11 children (age range 2–15 years, median 9.2 years) with severe TBI admitted to a regional neuro-surgical paediatric intensive care unit (PICU) requiring ICP monitoring and neuro-protection. Simultaneous invasive ICP was recorded and more than 15 mmHg was considered to be abnormal. ONSD [4.5 mm in children over 1 year of age was considered to be abnormal. Results and conclusions All children with clinically significantly raised ICP had abnormal ONSD, whereas those with normal ICP did not. Despite the small numbers, this study suggests that the ONSD may be useful in identifying children with TBI and normal ICP and, so, help avoid the insertion of unnecessary ICP monitors. Keywords Optic nerve sheath Paediatric Traumatic brain injury Intracranial pressure
S. Agrawal J. Brierley Paediatric and Neonatal Intensive Care Unit, Institute of Child Health and Great Ormond Street Hospital for Children, London WC1N 3JH, UK S. Agrawal (&) PICU, St. Mary’s Hospital, London W2 1NY, UK e-mail: [email protected]
Background The management of traumatic brain injury (TBI) in children who are critically ill is conventionally based on the optimal management of cerebral perfusion pressure (CPP), which necessitates invasive intracranial pressure (ICP) monitoring in those with severe head injury or those who require mechanical ventilation for more than 4 h for the management of associated injuries [1]. Manipulation of the CPP using invasively measured ICP remains the basis of neuro-intensive care, the gold standard for managing TBI patients, with a goal of achieving adequate cerebral perfusion and limiting secondary brain injury [1]. The decision to insert an invasive ICP monitor is based upon the clinical history of the injury, as well as computed tomography (CT) scan findings, as it is sometimes difficult to identify patients who should have invasive ICP monitoring based upon CT findings alone. As some TBI patients never have raised ICP and, furthermore, invasive ICP monitoring can be difficult in other circumstances, such as the lack of technical expertise or associated coagulopathy, it would be helpful if an accurate non-invasive screening tool for raised ICP could avoid device insertion in those in which it will prove unnecessary. The quest for a non-invasive surrogate marker for ICP has led to the investigation of several techniques, including Doppler measurements of middle cerebral artery pulsations, impedance audiometry to measure the pressure changes at the base of the ear ossicles and ultrasound measurements of the optic nerve sheath diameter (ONSD) [2]. The perineural space of the intra-orbital portion of the optic nerve is in direct communication with the subarachnoid space and, consequently, this portion of the nerve is directly affected by changes in the ICP; when the ICP rises above a certain point, displacing cerebrospinal fluid (CSF)
123
76
S. Agrawal, J. Brierley
Results
ONSD plotted against simultaneous intracranial pressure 6
ONSD (mm)
5 4 0
10
20
30
40
50
3 2 1
Series1 0
Intracranial pressure (mmHg)
Fig. 1 Optic nerve sheath diameter (ONSD) versus invasive intracranial pressure (ICP)
into the perineural space, the diameter of the nerve sheath increases [3, 4]. The ONSD (Fig. 1) can be measured by ultrasound and can represent a dynamic change in the ICP [5]. If non-invasive screening can reliably predict elevated ICP, invasive devices can potentially be limited to those in whom standard neuro-intensive care measures are indicated. We aimed to demonstrate whether the ONSD could detect raised ICP in children admitted with TBI to the paediatric intensive care unit (PICU).
Methods After seeking parental permission, the ONSD was measured in 11 children with severe TBI admitted to a regional neuro-surgical PICU requiring ICP monitoring and neuroprotection over an 8-month period in 2008. The ONSD was measured by one of the two authors, who are paediatric intensivists trained in the use of ultrasound on the PICU. Patients were excluded if they had any signs of orbital injury and if the authors were not available (to reduce the inter-observer bias). The person measuring the ONSD was blinded to the ICP reading at the time of measurement. The ONSD was measured with a SonoSite MicroMaxx ultrasound machine (SonoSite Ltd., Hitchin, UK) using a 10-MHz ultrasound probe, 3 mm behind the optic disc in both eyes (mean of three readings per eye, averaged for the ONSD). The ONSD was measured after admission to the PICU, when there were no major fluctuations in the ICP. Simultaneous measurements of invasive ICP were recorded. ICP more than 15 mmHg and ONSD [4.5 mm in children over 1 year of age was considered to be abnormal, suggesting increased ICP [5, 6].
123
Eleven children between 2 and 15 years of age (median 9.2 years) were included in the study. Adequate ageappropriate CPP [1] was achieved in 10/11 patients (one patient had an ICP of 42 mmHg, hence, could not achieve the target CPP). Seven of the 11 patients required inotropes to achieve the required CPP and seven patients had raised ICP. The median ONSD for children with raised ICP was 5.2 mm (range 4.7–5.4 mm) (right eye) and 5.1 mm (range 4.6–5.5 mm) (left eye), whereas it was 4.0 mm (range 3.5–4.2 mm) (right eye) and 3.9 mm (range 3.4–4.6 mm) (left eye) in patients with normal ICP. All children with clinically significantly raised ICP had increased ONSD, which was statistically significant (p = 0.025), whereas those with normal ICP did not. No increase in the ICP was observed in any patient while performing the orbital ultrasound.
Discussion Ultrasonography is a useful, portable and reproducible tool to diagnose various different conditions in emergencies, allowing appropriate and timely intervention. Over the last two decades, its utility to assess raised ICP has been explored [7]. Various studies have described a good correlation of the ONSD with the ICP detected by CT imaging of the brain. Most of the adult studies have tried to find a correlation of the ONSD with other non-invasively predicted ICP values, either by CT scan findings or transcranial Doppler (TCD) sonography, and have found a significant correlation between the ONSD and severe brain injury [8, 9]. Geeraerts et al. [10] and Soldatos et al. [11] carried out a simultaneous measurement of the ONSD and the invasive ICP in adult trauma patients with ICP bolt and found a significant correlation between the two measurements. There are no studies in children correlating the ONSD with a simultaneously measured ICP by invasive means. A recently published study by Le et al. [12] indicated a significant correlation between the ONSD and raised ICP in children; however, they have used the CT scan findings as a marker for raised ICP and the limitations of CT scanning when assessing raised ICP are well known to paediatric intensivists [13]. That the ONSD increases with an increase in the ICP has been suggested in various paediatric illnesses, such as hydrocephalous and head injury [14, 15]. This study is the first pilot study in children correlating raised ONSD with a simultaneously measured invasive ICP in TBI and suggests that the ONSD might reflect a realtime change in the ICP [16].
Optic nerve sheath measurement and raised ICP in paediatric TBI
As our aim was to assess the ONSD as a screening tool, we have not investigated ONSD and ICP variations within the same patient, and, furthermore, the exact prediction of the ICP from the ONSD is difficult, as any single value of ONSD can represent an ICP range of more than 10 mmHg. Therefore, before the widespread use of the ONSD for assessing raised ICP in children, further paediatric studies are needed in order to substantiate our results. However, we suggest that the ONSD may be a useful screening tool to predict which children with TBI warrant invasive ICP measuring devices for diagnostic and therapeutic interventions.
Conclusions Despite the small numbers, this study suggests the optic nervesheath diameter (ONSD) may be useful in identifying children with traumatic braininjury (TBI) and normal intracranial pressure (ICP), and, therefore, help to avoid the unnecessary insertion of ICP monitors, with exposure of the child to the risks of bleeding and infection, however small. Larger trials are required to substantiate these results. Conflict of interest
None.
References 1. Adelson PD, Bratton SL, Carney NA, Chesnut RM, du Coudray HE, Goldstein B, Kochanek PM, Miller HC, Partington MD, Selden NR, Warden CR, Wright DW; American Association for Surgery of Trauma; Child Neurology Society; International Society for Pediatric Neurosurgery; International Trauma Anesthesia and Critical Care Society; Society of Critical Care Medicine; World Federation of Pediatric Intensive and Critical Care Societies. Guidelines for the acute medical management of severe traumatic brain injury in infants, children, and adolescents. Chapter 5. Indications for intracranial pressure monitoring in pediatric patients with severe traumatic brain injury. Pediatr Crit Care Med. 2003;4:S19–24. 2. Stocchetti N. Could intracranial pressure in traumatic brain injury be measured or predicted noninvasively? Almost. Intensive Care Med. 2007;33:1682–3.
77 3. Helmke K, Hansen HC. Fundamentals of transorbital sonographic evaluation of optic nerve sheath expansion under intracranial hypertension. I. Experimental study. Pediatr Radiol. 1996;26: 701–5. 4. Helmke K, Hansen HC. Fundamentals of transorbital sonographic evaluation of optic nerve sheath expansion under intracranial hypertension. II. Patient study. Pediatr Radiol. 1996;26:706–10. 5. Ballantyne J, Hollman AS, Hamilton R, Bradnam MS, Carachi R, Young DG, Dutton GN. Transorbital optic nerve sheath ultrasonography in normal children. Clin Radiol. 1999;54:740–2. 6. Ko¨rber F, Scharf M, Moritz J, Dralle D, Alzen G. Sonography of the optical nerve—experience in 483 children. Rofo. 2005;177: 229–35. 7. Soldatos T, Chatzimichail K, Papathanasiou M, Gouliamos A. Optic nerve sonography: a new window for the non-invasive evaluation of intracranial pressure in brain injury. Emerg Med J. 2009;26:630–4. 8. Geeraerts T, Launey Y, Martin L, Pottecher J, Vigue´ B, Duranteau J, Benhamou D. Ultrasonography of the optic nerve sheath may be useful for detecting raised intracranial pressure after severe brain injury. Intensive Care Med. 2007;33:1704–11. 9. Tayal VS, Neulander M, Norton HJ, Foster T, Saunders T, Blaivas M. Emergency department sonographic measurement of optic nerve sheath diameter to detect findings of increased intracranial pressure in adult head injury patients. Ann Emerg Med. 2007;49:508–14. 10. Geeraerts T, Merceron S, Benhamou D, Vigue´ B, Duranteau J. Non-invasive assessment of intracranial pressure using ocular sonography in neurocritical care patients. Intensive Care Med. 2008;34:2062–7. 11. Soldatos T, Karakitsos D, Chatzimichail K, Papathanasiou M, Gouliamos A, Karabinis A. Optic nerve sonography in the diagnostic evaluation of adult brain injury. Crit Care. 2008;12: R67. 12. Le A, Hoehn ME, Smith ME, Spentzas T, Schlappy D, Pershad J. Bedside sonographic measurement of optic nerve sheath diameter as a predictor of increased intracranial pressure in children. Ann Emerg Med. 2009;53:785–91. 13. Rennick G, Shann F, de Campo J. Cerebral herniation during bacterial meningitis in children. BMJ. 1993;306:953–5. 14. Newman WD, Hollman AS, Dutton GN, Carachi R. Measurement of optic nerve sheath diameter by ultrasound: a means of detecting acute raised intracranial pressure in hydrocephalus. Br J Ophthalmol. 2002;86:1109–13. 15. Tsung JW, Blaivas M, Cooper A, Levick NR. A rapid noninvasive method of detecting elevated intracranial pressure using bedside ocular ultrasound: application to 3 cases of head trauma in the pediatric emergency department. Pediatr Emerg Care. 2005;21:94–8. 16. Malayeri AA, Bavarian S, Mehdizadeh M. Sonographic evaluation of optic nerve diameter in children with raised intracranial pressure. J Ultrasound Med. 2005;24:143–7.
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