The descending corticospinal tracts and ascending dorsal columns decussate in the medulla while the ascending lateral spinothalamic tracts decussate within one or two levels of the entrance of the dorsal roots
. As a result, injury to the hemicord results in contralateral loss of pain and temperature below the level of the insult, ipsilateral hemiparesis/hemiplegia as well as ipsilateral loss of proprioception and vibration sense.
The paired PSA originate from the vertebral arteries or PICAs and then descend medial to the dorsal roots
forming an anastomotic network dorsally that supplies the posterior third of the cord [2, 4].
Conservative treatment was initiated with neuroleptic drugs and blocks of the L1/L2 dorsal roots
with local anaesthetics and pulsed radiofrequency lesioning.
After stimulation and control CMGs, spinal dorsal roots
from L5 to S3 were transected sequentially.
Some authors consider that PDLs coincide with the axial lines of Sherrington, which are virtual lines that separate dermatomes arising from nonconsecutive dorsal roots
Comment: Persistent mechanical irritation of the nerve root (as seen with degenerated or herniated discs) sets up a series of events that lead to chronic pain, mediated by sensitization of the dorsal roots
and dorsal horns in the spinal cord.
The dorsal roots
of L2 and L3 have lesser branches, which make up the lateral cutaneous nerve of the thigh, and greater branches, that along with the dorsal root
of L4 are the origins of the femoral nerve.
Randiac, "Excitatory amino acid-mediated components of synaptically evoked input from dorsal roots
to deep dorsal horn neurons in the rat spinal cord slice," Neuroscience Letters, vol.
Effect of Lissauer tract stimulation on activity in dorsal roots
and in ventral roots.
(The ventral and dorsal roots
contain nerves that leave and enter the spinal cord, respectively.) After the axons within this surgically connected nerve have time to regenerate to the target site, the patient can initiate voiding by scratching or gently squeezing their legs or buttocks--i.e., the skin associated with the L5 dermatome--for about ten seconds.
A similar preparation was used for identifying afferent mechanosensory activity in the dorsal roots
. Here the muscles were stimulated mechanically with a fine rod driven either manually or with a loudspeaker activated by pulse generator (Master-8, AMPI).
The dorsal root
entry zone (DREZ) forms the junction between the dorsal roots
of the PNS and the spinal cord (CNS).