What is a Neurosurgeon?

It isn’t (only) brain surgery. A Neurosurgeon treats disorders of the nervous system with, and without, surgery.  And their work is not restricted to the brain. They also treat disorders of the spinal cord and the neurons that enervate the most distant parts of the body. They may be called on to correct problems with the blood supply to the brain or even to perform surgical procedures on the pituitary gland.

Ancient History of Neurosurgery

Archaeologists have found many examples of human skulls that show signs of having recovered from primitive cranial surgery. The ancient practice of cutting into and removing part of the skull is called “trepanning.”  It certainly was practiced in the Stone Age and has persisted throughout history.

It seems that ancient people understood that consciousness had its seat in the brain and problems like epilepsy, headaches, depression, etc. could be addressed there. They may have thought they were letting bad spirits out of the head. The procedure could have actually helped patients with cerebral swelling, but was not effective treatment for many of the conditions for which it was used.

Acupuncture originated around 100 BC in China and was originally based on the idea that vital energy, chi, circulated through the body through channels called meridians. The chi could be manipulated by the insertion of needles at key points in the body. The existence of the chi has never been demonstrated but the use of acupuncture has been rationalized in Western Medicine by assuming that it works on the peripheral nerves, outside the brain and spinal cord. Its use as an alternative medicine remains controversial, but it has been used to alleviate pain.

One of the earliest examples of purely scientific thinking is the writings of the ancient Greek, Hippocrates, (c. 430 BC) who is traditionally considered the founder of European medicine. Medical students recite a version of the Hippocratic Oath upon graduation from medical school.  His writings on the neurological condition epilepsy are especially interesting. At that time epilepsy was considered to be a ‘divine visitation’ or sacred disease. The following passage is a translation of his description of epilepsy from Charles Singer’s A Short History of Scientific Ideas.

“As for this disease called divine, surely it has its nature and its causes, as have other diseases. It arises -like them- from things that enter and quit the body, such as cold and sun and the winds, things ever changing and never at rest. Such things are divine or not- as you will, for the distinction matters not- and there is no need to make such division anywhere in nature, for all are alike divine or all are alike natural. All have their antecedent causes which can be found by those who seek them.”

This passage illustrates the basic ingredient of all scientific thinking, which looks for natural causes to explain events rather than looking for supernatural explanations.

The Middle Ages

Abulcasis, working in what is Muslim Spain around 1000 CE, was the greatest of the greatest of the Medieval surgeons. He wrote The Method of Medicine, a 30 volume review of all that was known about the field at that time- drawn from Greek, Byzantine, and even some Indian sources.  He made novel contributions himself, even designing drills for trepanning. His writing had its greatest impact at the University of Bologna which was the birthplace of intellectually rigorous surgery in Medieval Europe. This university-based surgery was distinct from that of the barber.

Barbers, Physicians, and Surgeons

If you go to a barbershop today they will cut your hair and may go as far as applying a styptic to a cut. In medieval Europe they also performed medical procedures such as amputating limbs and applying leeches to draw blood. Physicians were university-trained and preferred not to get their hands dirty. However, they might recommend concoctions to relieve symptoms.

Surgeons have traditionally straddled these two traditions- at times struggling for recognition from their fellow MDs. At other times they have reveled in an athletic approach to treatment. A famous American neurosurgeon, Harvey William Cushing, donated a cast of his hands to the Royal College of Surgeons where it is still on display. This gesture demonstrates the celebration of the physical skills that is common among neurosurgeons. The ability to concentrate for long hours in the operating room is also important.

Sir Victor Horsley

 A giant of Neurosurgery at the turn of the twentieth century was Sir Victor Horsley (1857-1916) who by all accounts he was a wonderful person. He campaigned against tobacco use, cautioned against war, and supported women’s suffrage. He died from heat stroke at age 59 while volunteering in Iraq during World War I, after walking miles in incredible heat to see a patient.

He developed several new surgical techniques including: the laminectomy, in which he attacked a spinal tumor by removing a part of the vertebrae; the skin flap, in which a piece of skin is transplanted from one part of the patient to another; the use of bone wax to staunch bleeding from bones during surgery; and most importantly he helped develop stereotactic surgery, which uses a 3D map of the brain based on anatomical landmarks as well as a clamps for holding the skull in place. With this system probes or electrodes can be positioned precisely, and it allows the surgeon to cause minimal damage to healthy tissues.

And yet, he was the first Neurosurgeon appointed to a hospital anywhere and could only perform surgery when invited to by a physician.

Harvey Cushing

America’s most important Neurosurgeon was Harvey Cushing (1869-1939). Cushing was a vainglorious piece of work- brilliant, colorful, witty, a great speaker, a great writer, and a great big pain in the neck with which to work. During World War I, he was almost court-martialed for criticizing the surgical technique of his British commanding officer in a private letter to Mrs. Cushing that was intercepted. Nothing came of it.

He studied under the best physicians and surgeons in Europe including Victor Horsley, Victor Krönecker, and Theodore Kocher, among others.

Cushing was great friends with Sir William Osler a Canadian who helped to start Johns Hopkins Hospital and is often considered the ‘founder of modern medicine.” Cushing won the Pulitzer Prize for his biography Osler.

Many think his greatest achievement was the introduction of blood pressure measurements to the US.  He picked up this insight from Dr. Scipione Riva-Rocci on an Italian trip in 1896.

However, he felt his greatest achievement was his promotion of the proper procedure for closing wounds after neurosurgery. Under his watch death rates after neurosurgery declined from about 40% to about 8%.

A fistful of syndromes are named after him, but he is best known for his work on Cushing’s Reflex. In this reflex blood pressure increases, heart beat rate decreases, and breathing becomes irregular- all in response to increased pressure inside the skull. It can be the result of injury or occur during surgery. It is extremely dangerous and will most likely result in death if not resolved.

As outlined below, he made important contributions to the understanding of the pituitary gland. This is despite the fact that he doggedly clung to an incorrect theory on the physiology of this gland for many years after others had demonstrated his speculation was wrong. In the end, he did eat crow in public.

Robert W. Rand

The achievements of Robert W. Rand (1928-2013) also deserve mention. He invented the field of micro neurosurgery, bringing the microscope into the operating theatre. The aim again being to work precisely to avoid collateral damage. With this aim he also developed cryosurgery to selectively freeze parts of the brain causing Parkinson tremors, he developed another procedure that used a superconducting magnet to hold an iron containing liquid in place while it solidified and destroyed malformed blood vessels, and he brought the gamma knife, which precisely directs radiation to tumors within the brain, to the US.

The Career of a Neurosurgeon

In the United States, after four years of post-graduate education in medical school, a neurosurgeon is expected to undergo seven years of residency (paid training and practice).  Laboratory research is often a requirement of residency and also is often required in continuing professional development throughout a career. Neurosurgeons may also undergo additional training to enter a subspecialty.

On average, they work about 58 hours a week. It could be a good deal more. Reports on annual salaries vary widely but range from $395,000 for those starting practice to over a $1,000,000 for experienced private-practice neurosurgeons.

Neurosurgeons often complain about stresses on their family life deriving from their workload.

Professional Organizations for Neurosurgeons

The American Association of Neurological Surgeons was originally founded as the Harvey Cushing Society in 1931. It “promotes the highest quality of patient care and advances the specialty of neurological surgery.” (AANS, http://www.aans.org/en/About-Us)

The American Board of Neurological Surgery administers a voluntary certification. Neurosurgeons that meet their standards are “board certified.” This establishes standards for training and continued professional development above and beyond the minimum legal standards to practice medicine.

Disorders Treated by Neurosurgeons: Disorders of the Vascular Supply

The vascular system is composed of the “pipes” for blood: arteries, veins, and capillaries. They are also known as blood vessels.

Cerebrovascular Neurosurgery is the subspecialty that deals with problems with the blood supply to the brain. These problems may include: vessel narrowing, clot formation, rupture of a blood vessel, blood vessel blockage, or malformations of the blood vessels.

The Cerebrovascular Neurosurgeon may perform cerebral angioplasty to visualize the blood vessels of the brain. Usually, a long, flexible tube (a catheter) is inserted through an incision in the leg. This tube is pushed through the circulatory system till it reaches the neck and a dye is released into the vessels of the brain.  The position of the catheter is known from a real-time x-ray projection.

Another procedure performed by the Cerebrovascular Neurosurgeon is the carotid ultrasound. The carotids are the two main arteries bringing blood from the aorta to the head and brain. An ultrasound can detect plaques and clots blocking blood flow through these vessels.

Disorders Treated by Neurosurgeons: Disorders of the Pituitary Gland

The pituitary gland is situated just over the mouth and under the brain. Some nerves run directly from the brain to this gland. Given its location, it is the province of the neurosurgeon. Cushing Disease is a condition discovered by Harvey Cushing in which the pituitary is too active, perhaps because it contains a tumor. Patients with this condition display weight gain around their midsection and upper back, weight loss in their legs, acne, and aches and pains. The neurosurgeon may remove the tumor from the pituitary gland.

Disorders Treated by Neurosurgeons: Parkinson’s Disease

Parkinson’s disease is a chronic condition in which there are tremors in the extremities. Alim Louis Benabid of France developed deep brain stimulation treatment for this condition. In this procedure an electrical device called a neurostimulator delivers an electrical impulse deep into the brain. No one knows why, but this alleviates some of the symptoms of Parkinson’s disease.

Disorders Treated by Neurosurgeons: Pain

Some neurosurgeons specialize in pain management. The techniques are not always “neurological” in an obvious way. These include the following treatments, considered from the less invasive to the more invasive: anticonvulsants, acupuncture, chiropractic, topical electrical stimulation, epidurals, Botox injections, neurostimulation, and cingulotomy.  Cingulotomy uses a laser to destroy the part of the brain that is responsible for the sensation of chronic pain.

Disorders Treated by Neurosurgeons: Trauma

According to the Centers for Disease Control, there are 1,700,000 traumatic brain injuries every year. Treatment of severe head injuries usually involves relatively noninvasive procedures designed to lower excessive pressure inside the skull and the onset of Cushing’s Reflex (see above). However, if those methods don’t work the modern equivalent of trepanation (see above) might be brought to bear.

Injuries to the spine require immobilization to avoid further injury. Monitoring of blood pressure is important because there is the possibility of low heart output.  Steroids may be used to reduce swelling in spinal cord injuries.

Trauma surgeons often express satisfaction that can save lives through their direct action.

Disorders Treated by Neurosurgeons: Tumors and Cancers in the Nervous System

Tumors in the brain and spinal cord may derive from the central nervous system itself, or they might be a metastasis (cancers cells that have migrated from another tissue). Surgery to remove the tumor is often indicated. The stereotactic techniques first developed by Horsley (see above) have been enhanced with the help of computers in elaborate surgical navigation systems.

Cancer cells reproduce too often, that is what makes them a problem in the first place. However, this property also makes them hypersensitive to the effects of radiation which damage chromosomes and cause problems for reproducing cells. X-rays have been used against cancer since the late 1800s.

A recent improvement to this strategy is the proton beam. The proton beam is a form of radiation that is more easily blocked by tissue and is less likely to cause damage to unaffected areas. The gamma knife and the cyber knife use multiple beams of radiation, precisely targeted, to pinpoint the tumor.

Laser Thermal Ablation involves inserting a laser probe in a tube, or catheter, to kill the tumor with heat.  Anytime a tissue is destroyed in a surgical procedure, without being removed, it is called “ablation.”

The excessive reproduction of cancer cells also makes them sensitive to certain chemicals that are toxic to reproducing cells. These chemicals are the traditional chemotherapies.  They present two problems to the neurosurgeon.  First, they hurt all reproducing tissue. Patients receiving traditional chemotherapy experience problems with their skin, hair, digestive tract, and immune system. Second, evolution has made the brain especially impervious to toxins with the “blood-brain barrier.”  The blood vessels of the brain are wrapped up especially tight and don’t allow the passage of a wide variety of chemicals. The neurosurgeon could implant devices within the brain to dispense the drug on the other side of the barrier.

Newer chemotherapies are based on a more detailed understanding of the control of cell growth and tend to have less painful side effects.

Disorders Treated by Neurosurgeons: Meningitis

Meningitis is an infection of the membranes that cover the brain and spinal cord, the meninges. There are several types. The type most dangerous to the most people is bacterial meningitis, which requires immediate treatment with antibiotics.

Viral meningitis is much less dangerous and usually requires no treatment.

A rare but frightening meningitis is amebic meningitis in which a one celled organism, Naegleria fowleri, enters the body through the nose. This usually happens when swimming in warm fresh water.  After gaining access, it attacks the brain. Between 2006 and 2015, 37 people were infected in the US and 2 survived.

Disorders Treated by Neurosurgeons: Epilepsy

Earlier in this document, there is a quote from the fonder of European medicine, Hippocrates, on epilepsy. Many people in his day thought it was a possession by spirits.  He proposed that it was due to the environment surrounding the patient. We admire his theory because it was a rational one. However, it was also incorrect.

Epilepsy results from unusual bursts of electrical impulses in the brain. These may affect the patient’s consciousness, movement, and senses. Some originate in specific locations of the brain and are called “partial seizures.” Others arise globally from a widespread area of the brain, usually involving both sides (the sides are also known as hemispheres). This widespread seizure is called a “primary generalized seizure.”

70% of patients can control their seizures with drugs. Others benefit from high-fat diets. Patients that do not respond to these treatments may need surgery.

Those with primary generalized seizures are less likely to do well in surgery. Too many parts of the brain are involved. These surgeries are only attempted if the seizures are extremely debilitating or life threatening. They may involve cutting nerves that connect one side of the brain to the other.  Often new parts of the brain learn to carry out the function lost during surgery.

A “surgical strike” on the area causing the partial seizure is much more likely to avoid damaging areas controlling important functions, like speech or memory. Even in these cases, extensive mapping of brain function and lesion in the patient is carried out. This way the absolute lowest cost to benefit ratio can be achieved. This mapping includes measuring electrical activity in electroencephalography or with implanted electrodes.

Neurostimulators have been used to reduce epileptic seizures.

Miscellaneous Tools and Procedures of the Neurosurgeon

One of the interesting procedures performed by neurosurgeons includes “Awake Brain Surgery.” This is a strategy employed when the area of the brain to be removed or ablated is very close to critical areas of the brain- the speech center for example. The patient is usually not conscious as a section of the skull is removed. They also are not aware of any pain while the procedure is performed. When the neurosurgeon is considering removing a section of the brain, he/she disrupts its function with an electrode and then asks the patient to perform a task, like talking, to see if that particular function is impaired. During the surgery the neurosurgical team must make cost/benefit decision as to whether or not that particular structure should be removed.

Computed tomography (CT scan or CAT scan) is a computer-processed three-dimensional image produced from many x-rays taken from different angles.  It is very good at distinguishing blood, bone and brain. So, it could be used to see damage to skull or vertebrae. It is also good for seeing internal bleeding in the brain.

The Positron Emission Tomography scan (PET scan) detects radiation incorporated into biologically active molecules. It often works in conjunction with the CAT scan. It has been used to measure brain activity and the early onset of Alzheimer’s disease.

The spinal tap removes a small sample of cerebrospinal fluid from the spinal cord.  The neurosurgeon can examine this fluid for blood to see if there is evidence of internal bleeding.

Surgery may also be needed to relieve blockage of the flow of the cerebrospinal fluid that bathes the brain and spinal cord.

The Magnetic Resonance Imager (MRI) is machine familiar to any sports fan. Sports injuries are often analyzed with this machine. The body is full of hydrogen atoms, which can be detected by the MRI when its subjects them to strong magnetic fields. This device can produce good images of nerve tissue and detect strokes.

Neurosurgeons also use chisels, probes, forceps, robots, and hand-held power saws.

Conclusion

It seems that may people are attracted to neurosurgery not only by the chance to help others, but by the challenges it presents. This specialty requires skill and intense concentration in the operating room, ingenuity in the solving of real world problems, and the ability to carry out cutting edge laboratory research.

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