Saturday, February 16, 2008

28 - kuntz nerve or nerve of kuntz

Over the last few years many questions about the Kuntz Nerve have been asked. "What do you know about the Kuntz Nerve? What do you do with the Kuntz Nerve?" It is somewhat difficult to explain the controversy surrounding the name Kuntz nerve which is causing a lot of confusion among laymen and physicians alike.

An understanding of the origin of the sympathetic enervation of the upper limb is important in surgical sympathectomy procedures (ETS). During the 1920's sympathectomy was done for a variety of reasons such as elevated blood pressure, circulation problems within the hands, cardiac pain, etc. Most of the above mentioned reasons were found not to be helped by the sympathectomy. When the sympathectomy was done for circulation problems in the hand there was an initial improvement with warming of the hands and better blood flow but most of those failed after 6 months to a year. This high failure rate prompt Doctor Kuntz to look for a reason for the failure. Since one could not perform post mortem examinations on patients, he performed anatomical studies on cats. While doing this anatomical dissection on cats he found some nerve fibers connecting the sympathectic nerve to other nerves within the chest cavity. Since then the name Kuntz nerve came about. These particular anatomical findings were not found in humans. The reasons for the failures when sympathectomy was done for vascular problems is known now to be unrelated to sympathectomy. The reason for the failure is due to post denervation hypersensitivity (meaning extra sensitivity to circulating chemicals within the blood causing the blood vessels to constrict). Somehow this term Kuntz nerve found its way into the modern sympathectomy literature.

Over the last few years there were two anatomical studies done on cadavers trying to solve this issue. In both studies they found a nerve segment that goes in between the first intercostal nerve and the brachial plexus. The exact function of this nerve segment is unknown. The intercostal nerves are made of bundles of sensory and motoric and sympathetic fibers that run in between the ribs. The brachial plexus is a motoric nerve bundles that inervate the upper extremities and the shoulders. The exact function of that particular nerve is not known. Moreso the space between the first rib and the intercostal nerve is generally speaking an area not touched by ETS surgeons doing the ETS procedure. The fact that this area is generally not touched by ETS sugeons makes it less significant in regards to true nature of this elusive nerve.

The mere fact that an anatomical nerve was found does not mean that it has any physiological role in the sympathetic function. Surgeons who claim to see and cut the Kuntz nerve do not even do the disection in those above mentioned areas. The eponym, nerve of Kuntz, should be restricted to descriptions of the intra thoracic branch of the first intercostal nerve. Practically those surgeons who are performing the ETS on a daily basis do not even get to that site. Bleeding problems as well as severe collateral injuries restrict the approach to those sites. In order to expose this elusive nerve one must perform a very delicate dissection with two or three instruments to enable this step. Most of the ETS surgeons who perform this operation do it with one single instrument that does not allow this type of dissection.

Recently Dr. Reisfeld went back to the anatomy laboratory and performed 6 cadaver studies. This means that 12 separate disections were done in the upper part of the chest cavity trying to even further clear the issue of the "Kuntz nerve". Those disections were done with the help of 2 experienced Anatomists (University Medical Doctors who teach anatomy in medical school). In none of those disections no significant nerve connections were found between the second ganglia to the first ganglia. Between the first ganglia and the brachial plexus some very fine fibres were found but there exact psyiological function is not known. This particular area is not being touched by any ETS surgeon because of the proximity to a variety of other important structures and because of the fact that it is not as accessible.

Doctor Reisfeld believes that the clinical and anatomical data do not support the Kuntz nerve as a significant reason in recurrence after a successful ETS. The most likely reason for late recurrence is the creation of alternate pathways within the Spinal cord. The possibility of a re-growth of the sympathetic chain is a practical possibility since the sympathetic chain has the canny ability for regrowth. The regrowth can happen if the operation is being done with the cutting method, excision, or ultrasound desication. Dr. Reisfeld found that with the clamping method the recurrence rate is even lower than with the cutting method.

The above outlined views about the Kuntz nerve was supported also in the last meeting held in finland in 2001. In the international meeting held in 2001 in Finland this view was supported by other leading ETS surgeons.

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