R. Hayashi et al., Relation between changes in long-latency stretch reflexes and muscle stiffness in Parkinson's disease - comparison before and after unilateral pallidotomy, CLIN NEU, 112(10), 2001, pp. 1814-1821
Objective: To study the effects of posteroventral pallidotomy on both the s
ize of long-latency stretch reflex (LLR) and the muscle stiffness in the wr
ist flexor muscles.
Patients and methods: Eleven consecutive patients (right-handed, 6 men and
5 women) underwent left-side microelectrode-guided pallidotomy. The LLR of
the contralesional forearm was studied at baseline and 2-3 months after sur
gery while patients continued to take their optimal medical regimens ('on'
period). Patients were instructed not to respond to the perturbation (passi
ve mode) or to oppose the mechanical extensor perturbation (active mode).
Results: The stretch reflex evoked by extension perturbations of the wrist
consisted of a short-latency reflex, (M1) and an LLR (M2). Pallidotomy had
no effects on the size of M1 components in both passive and active mode and
on that of M2 component in the passive mode, however, it significantly red
uced M2 component in the active mode (P < 0.05). The inherent muscle stiffn
ess over 60 ms period of mechanical stretch was not influenced by pallidoto
my in any experimental condition (preoperative vs. postoperative or passive
mode vs. active mode). The hand displacement following M2 component increa
sed significantly after pallidotomy in both passive (P < 0.005) and active
mode (P < 0.05). The inverted value of the displacement following M2 compon
ent correlated with the size of M2 component (r = 0.60, P < 0.001).
Conclusions: Pallidotomy decreased the transcortical reflex gain, probably
at cortical level, and consequently reduced muscle stiffness. (C) 2001 Publ
ished by Elsevier Science Ireland Ltd.