Friday, May 8, 2009

Lumbar pathologies & muscle sympathetic activity in lower extremity

Both disc & vertebral abnormalities commonly presents with clinical symptoms affecting the lower extremities. Patients commonly present with pain, numbness and sensory disturbance in lower extremities. Some times these symptoms are suggested to be related to sympathetic nerve disturbance.

Akihiko N & colleagues examined whether these patients experience a difference in sympathetic nerve flow in terms of muscle sympathetic nerve activity (MSA) compared to healthy subjects. Salient points from the study are as follows:

1. Basic MSAs (muscle sympathetic activities) for IDH (inter-vertebral disc Hernia) and SCS (spinal canal stenosis) patients that were introduced from a common peroneal nerve.
2. MSA behavior and muscle blood flow introduced from the tibialis anterior muscle over 30 seconds while performing the Valsalva maneuver are examined.

NB:
1. Valsalva Maneuver is a well known technique that artificially facilitate MSA
2. Sympathetic activity in muscle has a vaso-constrictive response.

The findings are as follows:

1. Muscle sympathetic activities are statistically higher than those of the healthy subjects in basic MSAs via common peroneal nerve.
2. Muscle blood flow was inversely proportional to MSA for the normal subjects, and this relationship was observed for IDH patients as well as SCS patients.
3. But, MSA behavior and muscle blood flow introduced from the tibialis anterior muscle via Valsalva technique, showed slower changes than healthy subjects.

Hence maintained but delayed vaso-constrictive response is observed in cases affected by lumbar pathologies. According to the authors these findings suggest that the systemic physiological response to the maneuver is maintained, but that, some local modification mechanisms exist.

Reference:
Journal of Nippon Medical School; Vol. 72 (2005) , No. 2 pp.96-104

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