Medical Student The George Washington University School of Medicine and Health Sciences Staten Island, New York
Abstract Text:
Introduction: For each of the 1.5 million patients in the U.S. diagnosed per year, with traumatic brain injury (TBI), there are an equal number sustaining brain injury that is unrecognized and undiagnosed, from sports, motor vehicle collisions, and among survivors of domestic/intimate partner violence and child abuse. Signs of oculomotor dysfunction are present on the neurologic examination of 33-66% of TBI patients whose symptoms may include: double vision, problems with depth perception, vestibular and balance problems and occipitocervical headaches.
Background: Near Point of Convergence (NPC) is relatively simple to assess by asking a patient to track an object, such as a pen or the examiner’s index finger, moving toward their nasion to determine the distance at which they report the single image splitting to a double image. It is normal for the image to split at 5 cm from the nasion, and it is abnormal if the split occurs at greater than 10 cm from the nasion. This literature review was performed to determine if the simple 2-3 minute NPC assessment at point of care may be a reliable biomarker to screen for brain injuries and/or track patients’ recovery.
Methods: A PubMed literature search was performed for English language primary research articles published between September 2014, when the neurosurgery concussion guidelines were published, and December 2022 using keywords - near point of convergence or convergence insufficiency and TBI or brain injury.
Results: Of the 74 articles meeting inclusion criteria, 47/74 (63.5%) considered NPC as a possible biomarker for TBI, citing that measuring NPC adds to the sensitivity of concussion screening. While several studies described that abnormal NPC improves over time as a patient recovers, of the articles which followed NPC measurements over serial examinations, 9/74 (12.2%), there was no consensus regarding efficacy for tracking recovery or its use for prognostication.
Conclusion: For patients with both known TBI and undiagnosed TBI, assessment of near point of convergence may be a sensitive screening biomarker for brain injury. There is not enough data currently available to determine whether NPC is useful for tracking TBI recovery. Further research is needed to determine if this low cost and readily available TBI biomarker should be used routinely as part of initial screening for those at risk for TBI, and whether following the NPC over subsequent evaluations aids in the tracking of and thus prognosis for recovery.
Keywords: Near Point of Convergence, Convergence Insufficiency, Screening, Recovery