Follow up and continuation from an earlier post.

Commercial drivers with hearing disorders or trauma, who have symptoms that may interfere with driving, such as balance problems and dizziness need further evaluation by a specialist before they can be certified.  The Conference on Neurological Disorders and Commercial Drivers convened the summer of 1988.  They reviewed and proposed modifications of the neurological recommendations for the Federal Highway Administration-Office of Motor Carriers, to update Department of Transportation (DOT) standards adopted in the 1970s.   The Conference was composed of four task forces who prepared reports on the Static, Progressive and Episodic (I & II) Neurological Conditions.  They reviewed and gave recommendations for evaluating commercial drivers who suffered from a variety of conditions such as TIAs, cerebrovascular accidents, traumatic brain injury, spinal cord injury, neuromuscular disorders, neuropathies, dementia, headaches, epilepsy, CNS tumors, sleep disorders (sleep apnea/narcolepsy), vertigo and dizziness. They also reviewed medications used in treatment and possible disqualifying side effects.  As discussed in an earlier post on seizure exemption, recall that it was this Conference that the FMCSA chose to disregard and instead used the more recent 2007 MEP Recommendations of The Seizure Disorder (G. Krauss M.D.) in granting exemptions to commercial drivers who did not meet the epilepsy standard in 2013.

With regards to neurological hearing disorders, the 1988 Conference on Neurological Disorders recommended disqualification when there is a diagnosis of Meniere’s Disease, labyrinthine fistula, or non-functioning labyrinth due to the potential for sudden incapacitation from uncontrolled vertigo and dizziness impairing balance, equilibrium and orientation.   Should a driver have a diagnosis of vertigo, he must not have uncontrolled vertigo and must be symptom free for at least 2 months with a diagnosis of either Benign Positional Vertigo or Vestibulopathy (acute or chronic).

For background information on Meniere’s Disease  and the labyrinthine disorders please see the links and references listed.

Medications commonly used to treat vertigo include those from the antihistamine, benzodiazepine, and phenothiazine groups:

• Meclizine (antivert) and promethazine (phenergan).  1st generation non-selective antihistamines that antagonize both central and peripheral histamine (H1) receptors as well as cholinergic receptors. They are used to treat vertigo and motion sickness and have anti-emetic (anti-nausea and vomiting) effects.   Meclizine has a 6 hour half life and promethazine (7-14 hr).  Adverse effects that can potentially affect safe driving include drowsiness, dizziness, confusion, sedation, blurred vision and impaired coordination.  Additionally, promethazine is a neuroleptic medication with weak anti-psychotic effects (not really used for that purpose any longer), but is used for sedation pre-op and to treat allergic conditions.
• Diazepam (valium) is a long acting benzodiazepine (half life 30-60 hours) that binds to benzodiazepine receptors and is used in many different other medical situations such as for sedation (pre-op or prior to medical procedures), to treat muscle spasms,  seizure disorders and in status epilepticus, anxiety, and in drug and alcohol withdrawal.

Given the potential for significant side effects with benzodiazepines, (especially those with longer half lives like valium), and the general warnings they carry regarding impairment while driving vehicles or operating machinery, the following recommendation from the Neurological  Conference was not at all surprising.  Also note that they also recommend caution with antihistamines, as should be taken with any medication (prescribed or over the counter) with adverse effects that may interfere with safe driving.

• In the 1988 Neurological Conference it was recommended that:

The requirement for either benzodiazepine or phenothiazines for the treatment of vertigo would render the individual unqualified for driving a commercial vehicle.  Special consideration should be given to the possible sedative side effects of antihistamines; the physician must determine if these drugs are producing sedation in an individual driver.

 

References:

1.  Conference on Neurological Disorders and Commercial Drivers, July 1988.   Harold E. Booker M.D. et al
2.  FMCSA Reports on Medical Conditions
3.  National Institute on Deafness and Other Communication Disorders (NIDCD)
4.  Vestibular Disorders Association.  Perilymph Fistula (PLF).
5.  John Hopkins Medicine Neurology and Neurosurgery.  Bilateral Loss of Labyrinthine Function.
6.  Wikepedia