MRI offers new marker for raised intracranial pressure
MRI measurements of the thickness of the optic nerve sheath are a good marker for raised intracranial pressure (ICP), according to research published Thursday in BioMed Central’s open-access journal Critical Care.
The dural sheath surrounding the optic nerve communicates with the subarachnoid space and distends when ICP is elevated, according to Thomas Geeraerts, from Addenbrooke's Hospital in Cambridge, England. He led a team that investigated whether MRI can be used to precisely measure the diameter of the optic nerve and its sheath.
The authors carried out a retrospective blinded analysis of brain MR images in a cohort of 38 patients requiring ICP monitoring after traumatic brain injury and 36 healthy controls.
According to the study results, a retro-bulbar optic nerve sheath diameter (ONSD) above 5.82 mm predicts raised ICP in 90 percent of cases.
"Raised ICP is frequent in conditions such as stroke, liver failure and meningitis. It is associated with increased mortality and poor neurological outcomes. As a result, the early detection and treatment of raised ICP is critical, but often challenging. Our MRI-based technique provides a useful, non-invasive solution,” Geeraerts said.
The early detection of raised ICP can be very difficult when invasive devices are not available. "Clinical signs of raised ICP such as headache, vomiting and drowsiness are not specific and are often difficult to interpret. In sedated patients, clinical signs frequently appear well after the internal damage has been done. Optic nerve sheath distension could be an early, reactive and sensitive sign of raised ICP,” the authors wrote.
"We found that ONSD measurement was able to provide a quantitative estimate of the likelihood of significant cranial hypertension,” Geeraerts concluded.
The dural sheath surrounding the optic nerve communicates with the subarachnoid space and distends when ICP is elevated, according to Thomas Geeraerts, from Addenbrooke's Hospital in Cambridge, England. He led a team that investigated whether MRI can be used to precisely measure the diameter of the optic nerve and its sheath.
The authors carried out a retrospective blinded analysis of brain MR images in a cohort of 38 patients requiring ICP monitoring after traumatic brain injury and 36 healthy controls.
According to the study results, a retro-bulbar optic nerve sheath diameter (ONSD) above 5.82 mm predicts raised ICP in 90 percent of cases.
"Raised ICP is frequent in conditions such as stroke, liver failure and meningitis. It is associated with increased mortality and poor neurological outcomes. As a result, the early detection and treatment of raised ICP is critical, but often challenging. Our MRI-based technique provides a useful, non-invasive solution,” Geeraerts said.
The early detection of raised ICP can be very difficult when invasive devices are not available. "Clinical signs of raised ICP such as headache, vomiting and drowsiness are not specific and are often difficult to interpret. In sedated patients, clinical signs frequently appear well after the internal damage has been done. Optic nerve sheath distension could be an early, reactive and sensitive sign of raised ICP,” the authors wrote.
"We found that ONSD measurement was able to provide a quantitative estimate of the likelihood of significant cranial hypertension,” Geeraerts concluded.