OPINION
NEWMAN, Justice.
We granted allocatur in this matter to address the issue of whether a defendant must present medical literature to justify a “two schools of thought” instruction.
In March of 1988, Hiren S. Gala (Appellant) underwent surgery for removal of a schwannoma, a benign tumor on a nerve in his neck. His wife, who is a pathologist, first noticed the lump on her husband’s neck in December 1987. Ralph Hamilton, M.D., a plastic surgeon, and Michael O’Connor, M.D. a neurosurgeon, (Appellees), performed the operation. Prior to the surgery, Appellees did not know which nerve was involved in the schwannoma because the area of the neck level [468]*468with the larynx and close to the base of the skull contains many nerves. They suspected that the vagus nerve, which controls the vocal chords, the larynx, and certain aspects of the esophagus, the heart and the intestines, might be involved. However, it was also possible that a branch of the spinal accessory nerve was involved. The surgical plan was to operate under local anesthesia so that Appellees could obtain a stimulus response from the patient during surgery when they palpated areas in the surgical field. Through such a response, the surgeons expected they would be able to identify the nerve around which the schwannoma had grown.
Once the procedure began, Appellees saw that the schwannoma had grown completely around what they thought to be a branch of the spinal accessory nerve, and they realized that to remove the tumor they would have to cut the nerve. They determined that repairing the damage would not be feasible because of the potential damage to other nerves if they attempted to perform a graft in the crowded area at the base of the skull where the carotid artery, the jugular vein and a number of nerves are located. Following surgery, Appellant was unable to speak, and Appellees determined that the schwannoma had grown around the vagus nerve, and not a branch of the spinal accessory nerve as they had previously believed. Appellant eventually regained his voice.
Appellant filed suit in the Court of Common Pleas of Philadelphia County (trial court), alleging that Appellees’ failure to exercise reasonable care in removing the tumor caused permanent injury to his vagus nerve, and that he suffers from a speech impediment and difficulty swallowing and coughing. At trial, Appellant’s expert testified that performing the operation under local anesthesia was negligent because it restricted the operative field and the ability of the surgeon to observe the operative field adequately. He testified that the use of local anesthesia increased the risk and was the cause of the injury to the vagus nerve. Each Appellee presented expert testimony supporting the decision to remove the tumor under local anesthesia. Eugene Meyers, M.D., a board-certified otolaryngologist with a sub-specialty in head and neck sur[469]*469gery, testified for Appellee Hamilton. He testified that local anesthesia was used by a considerable number of reputable, respected physicians throughout the world in 1988 to remove tumors in the area of the neck where Appellant’s tumor was located. He further testified that he has excised masses in that area of the neck under local anesthesia many times. Dr. Meyers cited the example of a doctor trained in otolaryngology who traveled to India where she would remove hundreds of thyroid tumors under local anesthesia. He noted that one potential complication of thyroid surgery is damage to the vagus nerve. In addition, he testified that the choice of anesthesia, whether general or local, does not make a difference in the outcome of the operation, and that excellent exposure of the surgical field is possible with either approach. Dr. Meyers also testified that the literature discussing removal of tumors from the neck does not indicate the type of anesthesia to be used.
Appellee O’Connor presented the testimony of a board-certified otolaryngologist, William M. Keane, M.D., who also has a sub-specialty in head and neck tumor surgery. He testified that performing surgery under local anesthesia allows for monitoring of nerve function, and that use of local anesthesia in surgery deep in the neck is a recognized technique. Furthermore, he noted that surgeons often use local anesthesia when operating on the carotid artery, which is located next to the vagus nerve. He testified that the literature regarding surgical excision of schwannomas does not indicate that general, rather than local anesthesia should be used. He also stated the choice of anesthesia does not affect the ability to determine the nerve involved with the schwannoma.
During the jury charge, the trial court gave the following instruction:
Where there are two schools of thought in the use of local anesthesia, a physician may rightfully choose to practice under either school of thought. If you the Jury find as a fact that the Defendants followed a procedure recognized by reputable and respected, considerable number of medical experts in the use of local anesthesia, even if in the [470]*470minority, the Defendants would not be deemed negligent or in violation of the standard of care in the use of local anesthesia in 1988 and you must find for the defendants on this issue.
N.T. 7-26-94 at 77. The jury returned a verdict in favor of the Appellees, and the Superior Court affirmed. This Court granted allocatur on the limited question of whether medical literature must exist to support a two schools of thought jury instruction.
In Jones v. Chidester, 531 Pa. 31, 610 A.2d 964 (1992), this Court thoroughly reviewed the development of the two schools of thought doctrine, noting that it first appeared in modern Pennsylvania law in Remley v. Plummer, 79 Pa.Super. 117 (1922).1 The Court made the following definitive statement regarding the standard applied in this Commonwealth:
Where competent medical authority is divided, a physician will not be held responsible if in the exercise of his judgment he followed a course of treatment advocated by a considerable number of recognized and respected professionals in his given area of expertise.
In recognizing this doctrine, we do not attempt to place a numerical certainty on what constitutes a ‘considerable number.’ The burden of proving that there are two schools of thought falls to the defendant. The burden, however, should not prove burdensome. The proper use of expert witnesses should supply the answers. Once the expert states the factual reasons to support his claim that there is a considerable number of professionals who agree with the [471]*471treatment employed by the defendant, there is sufficient evidence to warrant an instruction to the jury on the two ‘schools of thought.’ It then becomes a question for the jury to determine whether they believe that there are two legitimate schools of thought such that the defendant should be insulated from liability.
Jones, 531 Pa. at 40-41, 610 A.2d at 964. Initially, we note that Jones uses the general terms “competent medical authority,” “the proper use of expert witnesses” and “factual reasons to support [the expert’s] claim.” Jones
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OPINION
NEWMAN, Justice.
We granted allocatur in this matter to address the issue of whether a defendant must present medical literature to justify a “two schools of thought” instruction.
In March of 1988, Hiren S. Gala (Appellant) underwent surgery for removal of a schwannoma, a benign tumor on a nerve in his neck. His wife, who is a pathologist, first noticed the lump on her husband’s neck in December 1987. Ralph Hamilton, M.D., a plastic surgeon, and Michael O’Connor, M.D. a neurosurgeon, (Appellees), performed the operation. Prior to the surgery, Appellees did not know which nerve was involved in the schwannoma because the area of the neck level [468]*468with the larynx and close to the base of the skull contains many nerves. They suspected that the vagus nerve, which controls the vocal chords, the larynx, and certain aspects of the esophagus, the heart and the intestines, might be involved. However, it was also possible that a branch of the spinal accessory nerve was involved. The surgical plan was to operate under local anesthesia so that Appellees could obtain a stimulus response from the patient during surgery when they palpated areas in the surgical field. Through such a response, the surgeons expected they would be able to identify the nerve around which the schwannoma had grown.
Once the procedure began, Appellees saw that the schwannoma had grown completely around what they thought to be a branch of the spinal accessory nerve, and they realized that to remove the tumor they would have to cut the nerve. They determined that repairing the damage would not be feasible because of the potential damage to other nerves if they attempted to perform a graft in the crowded area at the base of the skull where the carotid artery, the jugular vein and a number of nerves are located. Following surgery, Appellant was unable to speak, and Appellees determined that the schwannoma had grown around the vagus nerve, and not a branch of the spinal accessory nerve as they had previously believed. Appellant eventually regained his voice.
Appellant filed suit in the Court of Common Pleas of Philadelphia County (trial court), alleging that Appellees’ failure to exercise reasonable care in removing the tumor caused permanent injury to his vagus nerve, and that he suffers from a speech impediment and difficulty swallowing and coughing. At trial, Appellant’s expert testified that performing the operation under local anesthesia was negligent because it restricted the operative field and the ability of the surgeon to observe the operative field adequately. He testified that the use of local anesthesia increased the risk and was the cause of the injury to the vagus nerve. Each Appellee presented expert testimony supporting the decision to remove the tumor under local anesthesia. Eugene Meyers, M.D., a board-certified otolaryngologist with a sub-specialty in head and neck sur[469]*469gery, testified for Appellee Hamilton. He testified that local anesthesia was used by a considerable number of reputable, respected physicians throughout the world in 1988 to remove tumors in the area of the neck where Appellant’s tumor was located. He further testified that he has excised masses in that area of the neck under local anesthesia many times. Dr. Meyers cited the example of a doctor trained in otolaryngology who traveled to India where she would remove hundreds of thyroid tumors under local anesthesia. He noted that one potential complication of thyroid surgery is damage to the vagus nerve. In addition, he testified that the choice of anesthesia, whether general or local, does not make a difference in the outcome of the operation, and that excellent exposure of the surgical field is possible with either approach. Dr. Meyers also testified that the literature discussing removal of tumors from the neck does not indicate the type of anesthesia to be used.
Appellee O’Connor presented the testimony of a board-certified otolaryngologist, William M. Keane, M.D., who also has a sub-specialty in head and neck tumor surgery. He testified that performing surgery under local anesthesia allows for monitoring of nerve function, and that use of local anesthesia in surgery deep in the neck is a recognized technique. Furthermore, he noted that surgeons often use local anesthesia when operating on the carotid artery, which is located next to the vagus nerve. He testified that the literature regarding surgical excision of schwannomas does not indicate that general, rather than local anesthesia should be used. He also stated the choice of anesthesia does not affect the ability to determine the nerve involved with the schwannoma.
During the jury charge, the trial court gave the following instruction:
Where there are two schools of thought in the use of local anesthesia, a physician may rightfully choose to practice under either school of thought. If you the Jury find as a fact that the Defendants followed a procedure recognized by reputable and respected, considerable number of medical experts in the use of local anesthesia, even if in the [470]*470minority, the Defendants would not be deemed negligent or in violation of the standard of care in the use of local anesthesia in 1988 and you must find for the defendants on this issue.
N.T. 7-26-94 at 77. The jury returned a verdict in favor of the Appellees, and the Superior Court affirmed. This Court granted allocatur on the limited question of whether medical literature must exist to support a two schools of thought jury instruction.
In Jones v. Chidester, 531 Pa. 31, 610 A.2d 964 (1992), this Court thoroughly reviewed the development of the two schools of thought doctrine, noting that it first appeared in modern Pennsylvania law in Remley v. Plummer, 79 Pa.Super. 117 (1922).1 The Court made the following definitive statement regarding the standard applied in this Commonwealth:
Where competent medical authority is divided, a physician will not be held responsible if in the exercise of his judgment he followed a course of treatment advocated by a considerable number of recognized and respected professionals in his given area of expertise.
In recognizing this doctrine, we do not attempt to place a numerical certainty on what constitutes a ‘considerable number.’ The burden of proving that there are two schools of thought falls to the defendant. The burden, however, should not prove burdensome. The proper use of expert witnesses should supply the answers. Once the expert states the factual reasons to support his claim that there is a considerable number of professionals who agree with the [471]*471treatment employed by the defendant, there is sufficient evidence to warrant an instruction to the jury on the two ‘schools of thought.’ It then becomes a question for the jury to determine whether they believe that there are two legitimate schools of thought such that the defendant should be insulated from liability.
Jones, 531 Pa. at 40-41, 610 A.2d at 964. Initially, we note that Jones uses the general terms “competent medical authority,” “the proper use of expert witnesses” and “factual reasons to support [the expert’s] claim.” Jones does not hold that the defendant’s expert witness may only establish through medical literature that the defendant followed a course of treatment approved by a considerable number of recognized and respected professionals. However, Appellant asserts that such a requirement is implicit in Jones, and suggests that “the type of literature recognizing a school of thought should at a minimum be a current recognized medical text, a current respected peer review journal or the current recommendations of a national association.” Appellant’s brief at 11. Essentially, Appellant asks this Court to define “sufficient evidence to warrant an instruction” as a specific type of written evidence. However, Appellees assert that when this Court in Jones referred to “evidence,” it did so recognizing the broad meaning of the term, which is defined as, “Any species of proof or probative matter, legally presented at the trial of an issue, by the act of the parties and though the medium of witnesses, records, documents, exhibits, concrete objects, etc. for the purpose of inducing belief in the minds of the court or jury as to their contention.” Black’s Law Dictionary 555 (6th ed.1990). Appellees suggest that by not placing restrictions on the comprehensive term “evidence,” the Jones Court elected to allow medical experts to use any form of admissible proof to establish the existence of a school of thought.
The determination not to put strict limitations on the term “evidence” is consistent with the Court’s decision not “to place a numerical certainty on what constitutes a ‘considerable number’ ” of “recognized and respected professionals.” Id. at 40, 610 A.2d at 969. In further support of maintaining a broad [472]*472definition of “evidence,” Appellees note the following statement by this Court in Jones: “The burden of proving that there are two schools of thought falls to the defendant. The burden, however, should not prove burdensome.” Id. at 40, 610 A.2d at 969. Limiting evidence to medical literature would have the effect of preventing expert witnesses from testifying to the existence of a school of thought based on their experience as practitioners and on information they obtained during their medical training and while attending lectures and other educational programs sponsored by institutions and professional societies. Furthermore, in cases where medical literature is silent with regard to certain techniques or treatments, the lack of written materials would necessarily be fatal to the defendant’s claim. Such a rule is inimical to the flexible standard established in Jones.
In support of his position, Appellant turns to Pennsylvania case law and relies upon the Superior Court’s decision in Tesauro v. Perrige, 437 Pa.Super. 620, 650 A.2d 1079 (1994). In Tesauro, a patient developed a dry socket after an oral surgeon removed a damaged molar in 1984. Following the extraction, the doctor administered an injection of alcohol near the area. Mrs. Tesauro was later diagnosed with muscle spasms caused by a damaged trigeminal nerve. She filed a dental malpractice action alleging that Dr. Perrige was negligent in administering the alcohol injection so close to the trigeminal nerve. The jury returned a verdict in favor of Mrs. Tesauro, and the oral surgeon appealed to the Superior Court. He asserted, inter alia, that the trial court erred by refusing to instruct the jury on the two schools of thought defense. At trial, Dr. Perrige testified that he was following a procedure discussed in a text published in 1975 by Dr. Archer, the former chief of oral surgery at the University of Pittsburgh. As his first expert witness he presented Dr. Totian, who testified that he had never given an alcohol injection to treat dry sockets and did not teach the procedure to students. Furthermore, he never testified that alcohol injections were proper and widely used in the treatment of dry sockets. Dr. Perrige then presented a second expert, Dr. Guernsey, who [473]*473supported the use of alcohol to treat dry sockets by citing the 1975 text referred to by Dr. Perrige and a reference manual written by a Dr. Shira during Dr. Guernsey’s residency from 1959 to 1961. He testified that he never gave an alcohol injection to treat a dry socket and did not teach residents to follow this procedure.
The Superior Court noted that the manual by Dr. Shira was out of date, and that Dr. Archer’s 1975 text arguably was also. Furthermore, the writings of one doctor are an insufficient basis to establish that a considerable number of practitioners agree with a course of treatment. In light of the fact that none of the defense experts testified that they had used alcohol injections to treat dry sockets, the Superior Court held that Dr. Perrige had failed to meet the burden of establishing two schools of thought.
Based on Tesauro, the Appellant asserts there must be competent medical literature to support a minority school of thought before a two schools instruction may be given to the jury. However, a careful reading of Tesauro indicates that it was not the lack of current medical literature, but the fact that none of the experts who testified at trial ever used alcohol injections to treat dry sockets, which led the court to reject the proffered defense. Had the expert witnesses testified to their personal use of the technique in question instead of relying on outdated materials, the result might have been different. Accordingly, Tesauro stands for the position that while factual support is required for a two schools instruction, it need not be in the form of medical literature, but may be testimonial.
Appellant also cites Levine v. Rosen, 532 Pa. 512, 616 A.2d 623 (1992), in which one of the issues raised was the defendant-physician’s negligence in failing to order a yearly mammogram for the plaintiff. This Court stated:
With respect to whether the doctor should have ordered a yearly mammogram, Mrs. Levine introduced evidence that the American Cancer Society recommended a yearly test for women over fifty years of age. The defendant introduced [474]*474evidence that the American College of Obstetricians and Gynecologists recommended that mammography be performed ‘regularly’ for that same group.
Unquestionably, the evidence established that there were a considerable number of respected physicians who subscribed to each school of thought - regular vs. yearly mammograms.
Id. at 520, 616 A.2d at 628. While recommendations of a professional society are a type of evidence that may be introduced to establish the existence of a school of thought, we are not persuaded that the Court’s decision in Levine supports the Appellant’s position that written materials are the exclusive means by which to prove the existence of a school of thought. Furthermore, we note that in Jones, where the issue was the use of a tourniquet to create a bloodless field for orthopedic surgery, the evidence that formed the basis for the two schools instruction was “testimony by medical experts supporting their positions.” Id. at 33, 610 A.2d at 966. Similarly, in Sinclair v. Block, 534 Pa. 563, 633 A.2d 1137 (1993), a case involving the use of forceps to deliver a baby who had stopped moving through the birth canal, medical testimony established the existence of two schools of thought.
The two schools of thought doctrine has been part of Pennsylvania jurisprudence for more than seventy-five years, yet neither this Commonwealth nor any other jurisdiction has held that medical literature is a predicate to its application. The testimony presented in the instant matter illustrates why it would be imprudent to place such a restriction on the kind of evidence a defendant may present in support of a two schools of thought instruction. At trial, Appellee Hamilton testified as follows regarding the rarity of a tumor growing on a nerve, and his personal experience in performing neck surgery:
Q: And of the surgeries in the neck area that you have done, how many of those surgeries involved surgery of nerves either in close proximity to a tumor or involving a tumor itself?
A: Well, probably about 400 or so of those operations.
[475]*475Q: And specifically of those about how many have been specific surgeries involving a tumor of a nerve itself, whatever cranial nerve it might be?
A: That’s a very rare event. Generally, the dissection of nerves in the neck have to do with separating the nerve from an adjacent tumor of a different structure.... But the primary tumors of the nerves themselves are very relatively rare.
Q: How many of those would you say you have done?
A: Probably a dozen.
Q: Of the type of surgeries that you have been performing over the years ... you do surgery of this type under local from time to time, local anesthesia ... ?
A: Yes, local anesthesia as the combination of monitored anesthetic care with an anesthesiologist, intravenous sedation, and also local anesthetic, shorthand for which we call local anesthetic.
Q: And how many surgeries would you estimate you performed under local in the area of the neck that we are talking about?
A: About one in five would be performed under those circumstances.
N.T. 7-25-94 at 29-30.
Q: And in terms of creating the exposure to see what you are doing, was that affected by whether you use a general anesthesia or local anesthesia?
A: No, you could get excellent exposure with either form of anesthesia. Depending upon other factors, really, is the choice of anesthesia.
N.T. 7-25-94 at 37.
Appellee O’Connor testified as follows regarding the use of anesthetics in neck surgery:
Q: When you made your suggestion ... in your letter to Dr. Hamilton that a local anesthetic be considered, did you think that it was a radical suggestion?
[476]*476A: Well, I knew it wasn’t radical because I knew that rather deep operations were done in the neck, and I mean specifically carotid endarterectomies, which happened to be an area that I was very much involved in. And also thyroid tumors were done under local.
Q: Well, why isn’t it just better for any kind of serious operation, why isn’t it always a better idea just to use a general?
A: Well, I already said for feedback purposes I use it where general might seem to be used. It is the magnitude of the operation. You might say gee, this could be done under general. As it turns out, you could do an awful lot under local.
And in most cases, virtually all you can do under general. But under general has its own risk....
Q: And in your letter where you made this suggestion about a local anesthetic, was your motivation because you didn’t think a general would be safe for Mr. Gala or because you hoped to gain an advantage?
A: No, I hope I would be able to identify nerves in that area by, as I said, stimulus response. Not just necessarily the nerve that the tumor was on, but if we were inadvertently near another nerve that we might get a signal that this nerve is in the area even though it might be too small to see.
N.T. 7-25-94 at 135-137.
Dr. Meyers, Appellee Hamilton’s expert witness, testified regarding his personal experience and that of his fellow physicians:
Q: Doctor, based on your knowledge and experience, are excisions of neck masses in this area done under local anesthesia?
A: Many are done under local, many are done under general. It depends on a number of things, not the least of which is the patient’s choice. Some people hate the idea of being under general anesthesia, they are afraid they are going to die.... So if it doesn’t make any difference [477]*477surgically in terms of exposure or relaxation of the patient and so forth, we usually leave it up to the patient as to whether they want a local or a general.
Q: Have you yourself used both local and general anesthesia in excisions that you have performed for masses in the neck area?
A: Many times.
Q: And would that include excision of tumors as we are talking about?
A: Yes.
Q: In various parts of the anatomy in the neck?
A: Yes.
Q: And, Doctor, to the best of your knowledge, your information and experience, is it within accepted medical standards, was it within accepted medical standards to perform surgery of the type involved in this case under local anesthesia back in March of 1988?
A: Yes, it is, the approach itself doesn’t make any difference, I mean the anesthetic doesn’t make a difference....
Q: To the best of your knowledge and in your opinion, was the use of local anesthesia for excision in the area of the neck such as this something that was used by a considerable number of reputable, respected physicians back in 1988?
A: Yes, I think it is safe to say that throughout the country, and in fact throughout the world, there are many patients that are done under, where lumps in the neck are taken out under local anesthesia. There are some very good examples of that.
N.T. 7-21-94 at 39. On cross-examination, Dr. Meyers testified:
Q: Doctor, are you familiar with reported cases aside from here where physicians removed a schwannoma from the vagus nerve using local anesthesia?
A: The literature really doesn’t - let me start over again. If you review the literature on the ... few series that there are of people’s experience with removing neurilemmomas in [478]*478the neck, it doesn’t deal with what type of anesthesia is used. It deals with the surgical technique, it deals with the review ordinarily of the pathology report. The series deal with how did the patients do afterwards. Well, what functional problems did they have. It has to do with did they have a recurrence or not. I don’t know that I’ve ever seen mention in the literature about whether local or general was used.
N.T. 7-21-94 at 109-110.
Dr. Keane, Appellee O’Connor’s expert witness testified as follows on cross-examination regarding anesthesia and neck surgery:
Q: In fact, you said you did all this research of the literature: Have you found any case reported in the medical literature where they recommend using local anesthetic for surgery for removal of a schwannoma of the vagus nerve?
A: No, but I am not aware of a paper that says that you should use general, either. I mean I think there are techniques that you could describe when you do surgery.
Q: So as far as you know, Doctor, from your personal experience and from your research of the literature, the only doctors who opted to use local anesthesia to remove a schwannoma form the vagus nerve are these world-class surgeons; correct?
A: That’s true.
Q: If I understand correctly on direct testimony you told us that it was accepted practice to use local anesthesia to remove a schwannoma from a vagal nerve?
A: I said that it was appropriate to use local anesthesia with dissection and surgery of the neck. That is a question of individual surgical preference....
N.T. 7-20-94 at 107-108.
In the instant matter the parties agree that there is no medical literature regarding the use of local or general anesthesia when removing a schwannoma from the vagus nerve. Accordingly, if we were to adopt Appellant’s position, the trial court’s decision to instruct the jury on two schools of thought [479]*479would be error. We believe it more prudent to allow juries to receive such an instruction where the testimony of expert witnesses alone establishes that a considerable number of recognized and respected professionals advocate the course of treatment followed by the defendant. Plaintiffs are free to challenge the basis for the expert’s testimony on cross-examination, and the lack of medical literature supporting the expert’s position may be raised at that time, and duly considered by the jury. To limit a two schools of thought instruction to cases where medical literature exists is antithetical to Jones, where this Court stated that the defendant’s burden “should not prove burdensome.” Id. at 40, 610 A.2d at 969.
For these reasons, we affirm the decision of the Superior Court.
CAPPY, J., files a concurring opinion.
NIGRO, J., files a dissenting opinion in which CASTILLE, J., joins.