Dr. Ravish Patwardhan comments… Movement, Sensation, & Pain in the Brain

Dr.Ravish Patwardhan has encountered numerous patients with problems related to movement and sensation of pain.  Yet, the pathways of how movement or sensation travel, either from or to the brain from the body, are important to consider in every instance.

Movement of the left side of the body is located in the right half of the brain, along the motor cortex.  If someone wanted to move her left arm, for example, her motor cortex would fire, sending a message through the area called the internal capsule, then via the brainstem where they cross over to the other side, and go down the left spinal cord to the level of the arm, where peripheral nerves would then be relayed this message, which relays the message to the muscle that contracts.

 Sensation is divided into broad categories of “fine touch” and separately, “pain.”  For fine touch, sensation that is felt in the fingertips then travels through peripheral nerves to the spinal cord (on the same side), up the brainstem, and then crossing in the upper brainstem to the opposite side of the brain’s parietal lobe.  Vibration sensation, position sensation, and fine touch are mediated in this way.

Pain is more complicated, in the sense that if the left hand touches a hot stove, then the peripheral nerve again mediates this from skin receptors to the opposite spinal cord (crossing immediately).  Then, travelling up the spinal cord, these fibers travel up the brainstem to an area of the brain called the thalamus.

What is important to realize is that this simplistic model, though accurate in many ways, is mediated by other nerves not already mentioned here.  For example, nerves in the spinal cord and brain mediate the signal, modifying it or inhibiting it.  So, if pain is felt in some nerves, en route to the brain this signal may be modified by an inhibitory neuron, so that the brain may not feel the same magnitude of pain it would otherwise have felt.  This important discovery, notes Dr.Ravish Patwardhan, that a neurosurgeon can intervene by placing an electrode wire next to the spinal cord (outside the dura, or lining of the spinal cord, called an “epidural” approach) and run a low current which will help patients who suffer from severe pain syndromes.

There are also reports in the literature about intervening for pain control by placing a stimulator electrode series within the brain.  Obviously, many of these techniques are used only as last resorts.  In addition, techniques where a small portion of the spinal cord is sectioned have also been employed, and these have varying success rates.

Peripheral nerves which are cut (i.e. nerves after they have left the spinal cord) have an ability to regenerate at about 1 mm per day (about an inch a month); though this rate is slow, it is present, and if a nerve is cut from a knife stab wound, it may be sewn together to allow regeneration of some function over time.  Nerves cut in the spinal cord or brain, however, don’t have such capacity.

Much more can be said about movement and sensation, and new research always seems to be ongoing for pain control, notes Dr. Ravish Patwardhan.

Dr. Ravish Patwardhan comments on… Memory Loss: Can it be cured?

One of the most interesting and troubling areas studied in medicine, according to Dr. Ravish Patwardhan, is loss of memory. As widely described on the news, experienced by families, and supported by foundation after foundation, memory loss continues to be a problem of near-epidemic proportions.

The most common form of memory loss, or dementia, is Alzheimer’s disease. Presently incurable, the drugs which help marginally do so; in many cases, the disease progresses despite medications, and patients become completely “in their own world,” not recognizing family members or friends, receding from society. Many of such family members are reluctantly placed into nursing homes, to live out the rest of their lives. Research is being conducted at a great rate to try to find the mechanism, progression, early detection, and possibly cure of the disease.

Despite the poor prognosis presently of Alzheimer’s disease, there are other types of dementia which can be helped. For example, vitamin deficiency can be associated with memory loss. In addition, a condition called “normal pressure hydrocephalus” or NPH is associated with three findings: (1) memory loss; (2) walking difficulty; and (3) urinary incontinence. The reason this is called “NPH,” according to Dr. Ravish Patwardhan, is that many times when the pressure is measured in the brain, it is normal. However, when the pressure is monitored over several days, occasional waves called “plateau waves” can be seen. Another way to diagnose this problem is to have a patient walk in front of his or her family, and then do a spinal tap, withdrawing about 20 cc of fluid. Immediately afterward, if a marked improvement is noted in walking (by the patient, family, and clinical staff), then the patient may benefit from a shunt being placed. This shunt, called a ventriculoperitoneal shunt, connects a tube from the fluid-filled chamber within the brain to the belly (technically, the “peritoneal cavity”). To avoid over-drainage of the fluid, a valve is placed in between. Since this involves an operation under general anesthesia, albeit a short operation, there are risks involved – among them are infection, bleeding within the brain, difficulty placing the shunt (since it is essentially a blind pass), and other risks. However, the majority of such patients, even elderly ones, have appeared to tolerate this operation well, and many have improved their walking ability. This is substantiated by the literature, as the body of evidence continues to grow according to Dr. Ravish Patwardhan.

The key decisions obviously include whether a patient will likely benefit from a shunt. In some patients, marked improvement in walking is noted but not as much in memory; others have both improve; another subset may notice improvement in all three symptoms of the triad: incontinence may also improve.

Much of the cause of this type of memory loss, associated with NPH, remains unknown. Proposed theories include stretching of the brain’s memory circuit fibers, or deterioration over time. New areas of research focus upon learning more. A group at UCLA has shown, for instance, that in younger patients not necessarily suffering from NPH, stimulation of a certain part of the brain actually appears to improve memory. Further research, according to Dr. Ravish Patwardhan, may focus on the memory-related structures of the brain, including the hippocampus and surrounding regions.