By Dr. Lawrence Earl, MD; National Academy of DOT Medical Examiners
Medical examiners often grapple with waiting periods, navigating rules from the Federal Motor Carrier Safety Administration (FMCSA) versus discretionary guidelines. The relevant rules for subdural hematoma are 49CFR391.41(b)7, regarding neuromuscular and vascular disease, and (b)8, seizure disorders. Neither of these, or any of the rules, say anything about waiting periods. Everything other than what is written in the rule is guidelines.
Considering subdural hematoma following head injuries prompts criteria discussions about seizures and traumatic brain injury. Occlusive cerebrovascular insults, leading to bleeding or stroke, carry a significant 16% seizure rate over the next five years, justifying a five-year waiting period similar to stroke cases.
Recommendations for traumatic brain injury involve a one-year waiting period without seizures or a stroke risk in specific brain areas. A moderate brain insult, whether vascular or traumatic, warrants a recommended two-year waiting period, extending to five years with early seizures or seizure risk. Bleeds or clots in cortical or subcortical brain areas justify a recommended five-year waiting period for anticonvulsants, compared to a one- or two-year waiting period in other situations without stroke or early seizures.
Making a certification decision involves assuming a normal exam, comprehensive neuro evaluations, neuro-ophthalmological evaluation, (something that’s probably not used enough) the neuro psych or the neurocognitive testing, and the clearance letter is from the neurologist who understands the job of commercial driving.
In a driver who has had a single unprovoked seizure, there’s a 36% recurrence within five years and only 2-3% recurrence after five years. After having a single unprovoked seizure, it’s advised to wait five years of anti-seizure medication to certify. When an underlying condition is the reason for the seizure, like a medication, diabetic problem, or some other metabolic issue that caused the seizure, that is removed, and it’s not thought to be recurrent, then there’s no specific waiting period.Usually with subdural hematoma, we’re talking about traumatic brain injury, and the criteria would be whether it’s a severe injury, penetration of the dura, and loss of consciousness for over 24 hours. They have a high seizure risk forever in these cases, so they’re disqualified. A moderate traumatic brain injury is where it does not penetrate the dura. Loss of consciousness is generally less, (more than 30 minutes, but less than 24 hours). These carry a two-year waiting period without seizure. A five-year waiting period would be necessary if they did have a seizure, and these are all maximum one-year certification.
If there was a mild brain injury with no dural penetration or loss of consciousness or loss of consciousness was brief (less than 30 minutes), then again, it would be a two-year wait if there was a seizure, and there’s no specified waiting period if there was not a seizure. Certification can be for up to two years if there was no seizure.
Why did this individual have a subdural hematoma? They’re not usually just incidental findings. There usually has been some trauma. Was this person an alcoholic and falls a lot? Do they have uncontrolled diabetes? Do they have an unrecognized bleeding problem and should that be evaluated? Are there falls for some other reason? You may also want to consider, again, neurocognitive testing. This is something most neurologists probably have availability of performing, and it’s probably underutilized and should be used more in safety-sensitive positions.
