Abstract
During rehabilitation after whiplash injuries or whiplash-associated disorders (WAD), patients often suffer from mental fatigue, specifically having difficulty with attention, concentration, and learning. Glutamate, the most extensively studied excitatory neurotransmitter in the nervous system, is indispensable for information intake and processing within the brain. After glutamate has elicited its effects on the postsynaptic and adjacent glial membrane receptors, the astroglial cells, one of the supporting cells in the brain, remove excess glutamate from the extracellular space. The extracellular concentration of glutamate must be low in order for glutamatergic neurotransmission to be effective. We hypothesize that one underlying mechanism at the cellular level for this mental fatigue could be a reduced capacity of the astrocytes to clearthe extracellular space of glutamate. In support of our hypothesis, substances are produced as a consequence of theWADthat result in an inhibition of the astroglial transport capacity of glutamate. Disturbed neck muscle function due to muscle stretching, neck pain or stretching of nerve cell processes and blood vessels within the brain, as well as anxiety secondary to the symptoms, could lead to a production of substances and altered conditions that, in turn, keep the symptoms active for long time periods. Our hypothesis could serve as one biological basis for understanding and recognizing the symptoms, which are regarded by many clinicians as unspecific, and are probably underestimated. Furthermore, strategies for treatment could be formulated and explored.