INTRODUCTION The brain is a world consisting of a number of unexplored continents and great stretches of unknown territory. --Santiago Ramón y Cajal (1852-1934), pathologist and neuroanatomist There were three doctors working at the clinic with over fifty patients to be seen. I was the most junior doctor. John, the senior registrar, was in a room next to mine. He was a few years ahead of me in training. Experience counts for a great deal as a doctor so his knowledge was far greater than mine. The third doctor was the consultant for whom we both worked. As usual there were far too many people to be seen in the time allotted.

We all had to work more quickly than we were comfortable with. I was required to discuss any difficult problem with John or the consultant. It was a time in my career when I thought that a good doctor was one who worked quickly and wasn''t a nuisance to their senior colleagues. I avoided asking for help if at all possible. The patients'' notes were piled high on a trolley outside the consultant''s room. They were visible to all the anxiously waiting people. Everybody turned to look as I took a set off the top of the pile and brought them into my office to read. They contained only a few pages.

I was relieved. A thick file meant years of history to understand and a chronic problem that might not be solvable. So many neurological conditions are incurable and very challenging to treat. A thin file could indicate a minor issue that had disappeared since the patient was last seen. When I opened the notes, though, I sighed. The man had only been to the clinic once before and I was the doctor who had seen him that time too. The tests I had ordered then came back as normal, which meant I hadn''t found the source of the problem. I would have preferred one of the other doctors to see him this time.

Maybe they would notice what I had missed. My letter recording our conversation said that he had odd sensations in his right arm. I had examined him and found nothing amiss. I had wondered if the problem might be a trapped nerve in his neck. I ordered electrical tests to examine the integrity of the nerves traveling into the arm. Those tests found that the nerves seemed to be working as they should. I knew that if the man was no better since that first meeting I wouldn''t really know what to do next. My only hope was that he had recovered without my help.

I called him into the room. "How have you been?" I asked. "The same," he told me, and my heart sank. "Okay. Well . can you explain the problem to me again?" "I get goosebumps running down my right forearm. Very noticeable goosebumps. That''s all of it.

" He made it sound so simple but the symptoms just didn''t speak to me. "Is there any numbness?" I asked. "No." "In between the goosebumps, does your arm feel otherwise normal?" "Mostly, except when the goosebumps arrive." He opened and closed his fist and stared at the offending arm. I was trying to feel my way through the problem. Trying to understand. I was not succeeding.

"Is your hand or arm weak?" "No . maybe . no. When I have the goosebumps it feels weird enough that I think, if I was holding something, I would drop it." "How often do you get the goosebumps?" "Only for a minute or two once a day. Maybe twice." The man was in his thirties. He looked well and had no medical problems in his past.

I wondered why he was so worried about symptoms that only lasted one minute a day. What he described seemed almost trivial to me. "Well, the good news is that the tests are totally normal," I told him. "I don''t think you have anything to worry about." I was revving up my reassuring speech, hoping that he was one of the worried well. Maybe all he needed was to be told that everything was okay. "But what is it then?" Oh no. His voice was anxious.

A normal test result was not good news to him. He wanted a better explanation than I could give. "I''m not convinced that what you describe can be fully explained . but most symptoms that can''t be explained just disappear when left alone. I mean . goosebumps? Is it the temperature in your office . the air conditioning?" I was clutching at straws and we both knew it. "I don''t think you understand," his voice was getting higher, "they are goosebumps that stand up like anthills on my skin.

It isn''t normal . it''s . it''s . unnatural." I blush easily when I am uncomfortable and out of my depth. I felt the redness crawl up my neck towards my face. I felt goosebumps creeping over my own skin. "Let me look at your arms again," I suggested, buying myself some thinking time.

I asked him to sit on the couch and take off his shirt. I looked at his muscles and they seemed normal. I tapped his reflexes with my tendon hammer and they were normal too. I poked at his arm with a blunt pin to check sensation. Normal. I tested his strength. It was possible his grip was not as strong in the right hand as the left but I had a sense that he wasn''t trying very hard. Perhaps he needed me to find something wrong.

"I don''t think I can explain this," I said eventually. Just for a second I thought I saw him roll his eyes. I took that as my cue that I needed help. "If you don''t mind waiting I need to go and discuss the problem with my consultant," I told him. "Thank you," he said, obviously relieved. As I walked across the corridor towards my boss''s office I cringed. I didn''t want to interrupt him just to ask his advice about a man with occasional goosebumps. I knocked lightly on the door and it swung open.

"Aah, here''s trouble," John said as he beckoned me in, laughing. He had also come to the consultant to discuss a patient. Our relationship was one in which he teased me about every small thing I missed, and reminded me of them as often as possible. I made sure to get my own back at every opportunity. We liked each other. Rivalry is a part of working in medicine. Mistakes, even understandable ones, tend to be remembered. I closed the door behind me.

"Can I get your advice on this man?" I asked, indicating the notes in my hand. "How many more patients are out there?" the consultant asked. We had all been holed up in our rooms working as quickly as possible, but with no sense of how many people we had seen between us. "There''s quite a big pile of notes left on the trolley," I told him, "but can you please talk to this guy I''m seeing? I''m not sure what to do with him. He has goosebumps in his right arm, but that''s it. I thought maybe a radiculopathy. I sent him for nerve-conduction studies last time but the results were normal. Should I scan his neck, maybe? I''m not sure because it''s not clearly dermatomal.

There''s nothing to find on exam." Dermatomes are one of the many anatomical patterns of the nervous system that neurologists use to trace a patient''s symptoms to a location in the network of nerves and spinal cord and brain. They refer to the areas of the skin known to receive their nerve supply from the spinal nerve roots. The skin of the arm is divided into seven dermatomes. If you have altered sensation in a single dermatome - a patch over your shoulder or hand, for example - then it implies a lesion in a specific spinal nerve root. I had not been able to make proper sense of my patient''s problem. The odd feelings in his arm did not fit into one neat dermatomal package, but it was as close as I could get. I had focused my investigations on the spinal nerve roots wondering if he had a trapped nerve in his neck.

The tests told me I was wrong. "Did you talk to me about this man the last time he was here?" the consultant asked. "Yes." At every clinic I saw as many patients as I could. I discussed the difficult cases with the consultant as soon as I had seen them so he had the chance to see them too. The people who were more straightforward we discussed when the clinic was over. Of course, this system meant that the consultant depended entirely on my judgment and on the quality of the information I gave him. The consultant, John and I walked back to my clinic room.

I thought I heard the other patients in the waiting room heave a collective sigh. They were still watching the pile of notes, waiting for their turn. When none of us picked up a new set they knew they were in for a further delay. The consultant introduced himself to my patient. "So I''ve been hearing about these odd feelings in your arm. Can you explain it to me again, if you don''t mind?" The man didn''t mind. He looked relieved to be seen by a more serious-looking doctor. "So I get this slow wave of goosebumps pass over my skin and then it''s gone.

" He ran his hand over his forearm to indicate which area was affected. "How long does it take for the wave to pass?" "I guess about a minute. Maybe less. It is an awful feeling. Really horrible." "Does it feel the same every time?" "Yes." "What does the arm feel like at other times?" "Not quite right. I can''t fully explain it.

" "And everything else is okay? The other arm? The legs? No headaches or anything else I should know about?" "Nothing." The consultant took his ophthalmoscope and moved close to the patient to look at the back of his eyes. Then he tested the strength and sensation in the limbs. "Right hand maybe a bit less strong than the left?" He looked over his shoulder at me as he spoke. "I wasn''t sure," I answered. "Does it happen day and night?" the consultant asked the patient. "It can happen anywhere. I can wake in the middle of the night with it or I can get it walking down the street.

Always exactly the same.