What Really Happens When We Decompress A Nerve?

Sitting in the center of the third row in the Wiener Staatsoper (Vienna State Opera House), I was awestruck by how the opera company had so effortlessly put on one of my favorite operas, The Barber of Seville. Dr. Gointu Amabala, the famous neuroscientist from Mumbai, brought me to this magnificent venue. He loved the opera and would make the long trek to Vienna from India just to attend one performance. “So what did you think?” he asked in his clipped accent. “Well, I always wanted to attend an opera here and nonetheless one of my favorite ones at that. Frankly, I may be more fascinated by how much must go on behind the scenes in order to pull off such a grand event than how grand the event was. Does that make sense?” “Perfectly, perfectly.” He almost always repeated himself and then confirmed my linguistic assumption by adding, “I understand, I understand.” Amabala was known and highly respected throughout the world of neuroscience for his work on the blood nerve barrier. “I am not heading to the airport until 5 p.m. tomorrow afternoon so meet me here at noon. I have something very special to show you.” The streets of Vienna were alive after leaving the Staatsoper and patrons were filling the little bistros for late night delights and pouring into the Hotel Sacher for a small slice of perhaps the most world famous chocolate cake, the Sachertorte. Tradition has it that the folks who run the hotel have locked the secret recipe down since its introduction to the world in 1832. Like the opera I just attended, this little chocolate delight had a whole lot going on behind the scenes. The next day at noon, I met Professor Amabala back at the opera house. I still had no idea on why he wanted to meet me here again. Unlike 12 hours earlier, there was virtually no one on the Ringstrasse. “I have arranged for a tour of the opera house for us,” he informed me. “Excellent,” I said, somewhat mentally relieved now that the mystery had been solved. “I presume we will get to see behind the scenes and see what really makes the opera work.” “For sure, for sure.” He then proceeded to give me a quick didactic on how surgeons fail to recognize the intricacies and beauty of neurophysiology, and that there is almost always so much more to the story or event than meets the eye. While the opera house tour guide escorted us through the maze of wires, hoists, movable platforms and multitudes of backdrops, Dr. Amabala asked me what seemed to be a very easy question. “What happens when you decompress an entrapped nerve?” Before I quickly shot back with the obvious answer that decompression relieves the ischemia and nerve regeneration starts to occur, I knew he was not asking that simple of a question. I hesitated to give an answer, knowing that he was looking for something much deeper. “Well,” I said, “like this opera house and that delicious Sachertorte we had last night, I am sure that there is a whole plethora of neurophysiology occurring that only a world famous neuroscientist like yourself could raise the curtain.” We climbed stairs to the top of the backstage and peered down on the first few rows of the theatre, when I had to point out that there was where we sat last night. “What a different perspective,” he said without repeating it. Maybe he was disproving my theory of linguistics. “We are only 30 meters from where we sat last night and what you see now is not even close to how it appeared last night.” I was now very curious to hear his answer to his own question. What was really happening when we decompressed a nerve? Is it just some local, focal phenomenon or is there perhaps something systemic going on with the peripheral nerves? “Dr. Amabala,” I asked, “what is really happening from a neurophysiology standpoint?” He stopped his climb and turned to look down and back at me. “First, call me by my first name, Gointu. We are friends and colleagues so it’s Gointu. Second, wait until we can sit down for a minute and I will answer the rest of the question.” He was a little out of breath. A few minutes later, he whispered something to the tour guide and the rest of the group moved on ahead. We sat down on one of the catwalks. After a few minutes and him catching his breath, he started telling me about some things he had discovered in the mouse regarding the neurophysiology of the blood nerve barrier. He explained to me that even though surgeons think of just the apparent or mechanical aspect of what they are doing, there is much more going on. “When you do a neurolysis, you are doing things on the microscopic level.” Before I could come back with the fact that we used microscopes, he corrected himself. “Molecular, not microscopic.” Gointu then gave me a fascinating explanation of neuroscience. He inundated me with one mental discovery after another, such as the fact that the endoneurial space is a privileged one with a different composition of electrolytes than surrounding tissue or the bloodstream. Wow, that is some cool stuff. Also consider the fact that this space can easily build up pressure and become edematous because there is no method of lymphatic drainage. Once the endoneurial space becomes edematous, neurovascular changes occur allowing permeability and ultimate extravasation of nociceptive molecules and immune cells. This process emanating from a focal nerve injury such as an entrapment can then lead to a hematogenous dissemination for induction of chronic pain at sites distant to the site of entrapment. Now that is a double wow. Yeah, folks, Gointu maybe just gave me the reason for why some patients who undergo an isolated nerve decompression feel better in other areas distant from the site of where we worked. I always thought they were “crazy.” Maybe not. He went on to talk about vascular endothelial growth factors and fibrinogen, and that maybe we would have some cool drugs in the near future that could selectively address the injured site of the nerve without affecting normal neural tissue. This interesting little man from Mumbai, Professor Gointu Amabala, then stood up on the undulating catwalk and declared, “Maybe you decompressors are actually doing something systemic?” Now was that a question or a statement? Maybe, just like with the opera, and the Sachertorte, there is a whole lot going on with what we are doing with nerve decompression? Suggested Reading 1. Lim TK, Shi XQ, Martin HC, et al. Blood-nerve barrier dysfunction contributes to the generation of neuropathic pain and allows targeting of injured nerves for pain relief. Pain. 2014; 155(5):954-967.