Recession of sensory loss from the midline following trigeminal sensory root section: collateral sprouting from the normal side?

The extent of transmedian innervation of the lower lip, chin, tongue and teeth has been investigated in 20 patients who had undergone trigeminal sensory root section between 4 months and 9 years previously, and in 20 control patients whose inferior alveolar and lingual nerves had been anesthetized unilaterally. There was significantly greater transmedian cutaneous innervation in the surgical group. This may be explained by collateral sprouting of sensory nerves across the midline into the chronically denervated area.