Located at Hennepin County Medical Center in Minneapolis, our lab runs under the supervision of Dr. Uzma Samadani and centers on creating a multimodal classification scheme to assess patients with brain injury. Without accurate diagnostics, it is impossible to know the incidence of concussion or assess its societal impact. Though numerous studies have investigated neurologic deficits, and factors ranging from executive functioning, completion of daily activities, return to work/school, language, reading and other specific impacts of concussion, there is still no broadly accepted definition for concussion and no objective diagnostic. The lack of appropriate classification schemes and objective outcome measures for patients entering clinical trials for concussion and other forms of traumatic brain injury (TBI) contributes to the failure of such trials for therapeutics and prophylactics at great expense to the research and development community and those it hopes to serve, including athletes, students and hapless victims of trauma.
After nearly 30 failed clinical trials with this same goal, our lab uses a novel patent-pending eye tracking technology as a physiological measure of brain injury along with blood-based biomarkers as a chemical measure and radiographic imaging as a structural measure.. We envision a scheme inclusive of these three measures that will become standard of care across hospitals to aid medical professionals in detecting brain injury, categorizing its severity and tracking its long term recovery. Participants voluntarily watch a three minute animated video while a camera and sensor tracks their eye movements. The data we glean from these tracking sessions allows us to recognize patterns and trends indicative of various brain injuries or even no injury. Traumatic brain injury, concussion and elevated intracranial pressure are the main focus of our work but our lab is keen to study many other neurological and ophthalmological conditions as well as normal healthy people with no such medical histories.
Mild brain injury or concussion affects about four million Americans each year. Some people recover completely while others, especially those with multiple concussions, develop chronic headaches, neurodegenerative diseases and psychiatric disorders. Concussions are by definition radiographically silent because no structural injury is incurred that can be seen on CT scan. Some MRI sequences may be useful adjuncts in the diagnosis of concussion but even these are not consistently present in all symptomatic patients. This inability to detect concussion accurately and consistently by means of CT or MRI scans makes it difficult to treat and monitor.
Clinical tests for concussion often require baseline studies, and thus are generally reserved for athletes and others at highest risk for concussion. In contrast, our eye tracking method is rapid, non-invasive and objective. It does not require a baseline test. We are currently developing an eye tracking based biomarker to enable better definition of concussion severity at the time of diagnosis and during long term recovery.
Hydrocephalus and Elevated Intracranial Pressure
Congenital hydrocephalus has an incidence of 3 cases per 1000 births. It is treated with shunting of cerebrospinal fluid, which, in conjunction with shunt revision, is the most common pediatric neurosurgical operation in the United States. If untreated, acute elevations in intracranial pressure due to hydrocephalus can result in permanent neurologic impairment or death. Current methods for rapid diagnosis of hydrocephalus include a specialist's physical examination, brain imaging studies that may require sedation or risk radiation, and direct and invasive measurement of pressures in cavities contiguous with the subarachnoid space via needle or catheter puncture.
Double vision and other ocular disturbances associated with hydrocephalus were first described by Hippocrates in approximately 400 B.C. Papilledema, and its association with elevated intracranial pressure (ICP) was described by Albrecht von Graefe in 1860. In the post-radiographic era, acute and chronic pathology of the optic nerve and disc, and of ocular motility are well characterized in hydrocephalic children and may precede CT findings. We have demonstrated that eye movement tracking technology can assess the function of the three cranial nerves responsible for moving the eye. It may also reveal problems with cranial nerve II, the optic nerve, which mediates vision. The literature suggests hydrocephalus impairs function of these cranial nerves by delaying axoplasmic transport. We are testing whether eye tracking can detect hydrocephalus or shunt malfunction in research funded by the Thrasher Research Fund.
Since children with chronic or treated hydrocephalus may have baseline problems with eye movements, our first aim is to compare the eye movements of shunted asymptomatic children to non-shunted normal children. We expect that some asymptomatic shunted children will have eye movements that are quantifiably the same as non-shunted normal children, while others will not. Our second aim looks at whether the eye movements of children with shunt malfunction causing elevated ICP are impaired, and to see if this impairment improves with treatment of the shunt malfunction. We anticipate replicable changes in the eye movements with elevated ICP.