Oct. 13, 2017
Jordan W. Swanson, M.D., and others from the University of Pennsylvania published research evaluating the use of optical coherence tomography (OCT) to detect elevated intracranial pressure in children in the April 2017 issue of JAMA Ophthalmology.
In the same issue, Michael C. Brodsky, M.D., Ophthalmology, John J. Chen, M.D., Ph.D., Ophthalmology, and Nicholas M. Wetjen, M.D., a pediatric neurosurgeon at Mayo Clinic's campus in Rochester, Minnesota, discussed the study findings.
"Lumbar puncture is the usual confirmatory procedure for the diagnosis of intracranial hypertension, but lumbar cerebrospinal fluid pressure does not always reflect the intracranial pressure (ICP), especially in children," says Dr. Brodsky. "As a result, direct monitoring is the current gold standard for ascertainment of ICP. Direct monitoring is more invasive than lumbar puncture and requires general anesthesia and hospital admission to monitor ICP over a period of days. It also carries a low risk of central nervous system infection or injury.
"The OCT evaluation of the 3-D disk parameters to detect intracranial hypertension proposed by Dr. Swanson and others is novel. Prior OCT studies have typically reported the peripapillary retinal nerve fiber layer (RNFL) thickness. In contrast, these investigators manually measured various parameters of the disk itself, including the maximum RNFL, maximal retinal thickness and maximal anterior retinal projection of the disk.
"OCT has shown high sensitivity for identifying subtle neuroanatomical changes within and around the optic disk that correlate with the presence of papilledema. It is noninvasive and can often be performed without sedation or hospital admission."
Children with craniosynostosis
Dr. Chen comments: "The 3-D OCT disk parameters in this study yielded a sensitivity of 89 percent and specificity of 62 percent in detecting elevated ICP in children with craniosynostosis. In contrast, the standard automated optic nerve head parameters, including the average peripapillary RNFL thickness, did not differentiate patients with elevated ICP and those without elevated ICP, which suggests the 3-D parameters of the disk may be more sensitive than the standard peripapillary RNFL thickness measurements in detecting raised ICP.
"Pending clarification of the neurocognitive effects of intracranial hypertension and the true physiological threshold for ICP elevation, it remains unclear how this sensitive technology will affect the decision to proceed with cranial vault decompression for craniosynostosis or shunting for hydrocephalus.
"It is important to note that direct intracranial pressure monitoring is not routine in children with uncomplicated craniosynostosis or hydrocephalus. Here at Mayo Clinic, we do not typically monitor children with single suture craniosynostosis less than 2 years of age unless there is a clinical suspicion that they have developmental delays, irritability or headaches related to decreased intracranial volume. Without visible papilledema, there is no threat to the vision in these children.
"However, we tend to monitor children with syndromic craniosynostosis because they have a higher risk of decreased intracranial volume, hydrocephalus and poor venous outflow, which puts them at higher risk of intracranial hypertension. This complex form of craniosynostosis can be independently associated with hydrocephalus (ventriculomegaly), and may portend a different clinical outcome than in those without hydrocephalus. Three-dimensional OCT disk measurements could play a large role in these patients."
Study raises new questions
Dr. Chen notes: "The complexity of OCT data analysis may limit the general applicability of this study. These OCT measurements require the ability to accurately calibrate, demarcate, quantitate and interpret subtle neuroanatomic aberrations, which is a diagnostic skill set likely to be inaccessible to many practicing ophthalmologists.
"In addition, 3-D OCT disk parameters may have less specificity than the standard OCT peripapillary RNFL thicknesses because congenital anatomic variations in the disk will likely have a larger effect on the variability of the disk parameters. Ultimately, we will need automated ways of measuring the 3-D OCT disk parameters and prospective evaluations of these parameters to see how they vary with treatment of intracranial hypertension."
Dr. Brodsky concludes: "This study represents an important step forward in providing sensitive noninvasive detection of elevated ICP in children who are symptomatic. OCT could change current neurosurgical practice by sparing these children the stress and risks of invasive ICP monitoring, and perhaps positioning the ophthalmologist to play a more determinative role in ascertaining the need for neurosurgical intervention."
For more information
Swanson JW, et al. Evaluation of optical coherence tomography to detect elevated intracranial pressure in children. JAMA Ophthalmology. 2017;135:320.
Brodsky MC, et al. Optical coherence tomography for the noninvasive detection of elevated intracranial pressure: A new role for the ophthalmologist? JAMA Ophthalmology. 2017;135:329.