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Use of ultrasound in neurosurgical operations: a preliminary report
Use of Ultrasound in Neurosurgical Operations: A Preliminary Report George J. Dohrmann, M.D., Ph.D.,* and Jonathan M. Rubin, M.D., Ph. D. ?
Real-time ultrasound scanning has considerable potential in the neurosurgical operating room for the localization and further characterization of intracranial lesions as well as for planning and guiding the approach to such lesions. With further refinements, the ultrasound scanner may well be considered a surgical instrument and become a valued part of the neurosurgical armamentarium.
Materials and Methods
An ATL§ rotating sector ultrasound scanner (Fig. 1) was used in this study, and a specifically adapted prototype inline scan head containing transducer elements of three different frequencies (3, 5, and 7.5 megahertz [mHz]) was employed. Therefore, it was possible to adjust transducer frequency from the console of the scanner without having Dohrmann GJ, Rubin JM: Use of ultrasound in to change the scan head itself. This made it possible to neurosurgical operations: a preliminaryreport. Surg alter image resolution and depth of field instantaneously Neurol 16:362-366, 1981 during the operative procedure. The ultrasonographer and the ultrasound scanner were Ultrasound has been used successfully for the diagnosis of present in the neurosurgical operating room during the inabdominal, cardiac, and pelvic disorders, but it has not tracranial procedures (Fig. 2); the dura mater was exposed been identified as having a role in the neurosurgical by burr hole, craniectomy, or craniotomy. A sterile, transoperating room. This is because most of the devices previ- parent plastic drape was placed over the in-line transducer ously employed for intraoperative studies have given only and the associated cord after acoustic gel was applied over one-dimensional data and could provide only limited diag- the surface of the transducer. The surgeon placed the transnostic or localizing information. Recently, however, high ducer in contact with the dura mater (Fig. 3), and acoustic resolution, real-time ultrasound sector scanners$ have coupling was achieved by irrigating the dura mater with made intraoperative ultrasound scanning feasible. Through saline solution. According to the orientation of the transa craniotomy, craniectomy, or burr hole, these devices can ducer and the position of the exposed dura mater, the brain reliably image most of the intracranial contents, demonstrat- was imaged in either sagittal, transaxial, or coronal planes ing normal and abnormal anatomy as well as physiological on the video monitor of the scanner. The penetration and motion, such as vascular pulsations. Since most intracranial resolution were changed by raising the transducer frequency lesions occur subcortically or beneath the brain, a method from 3 to 5 to 7.5 mHz, thereby decreasing penetration and for visualizing these in the operating room would be most increasing resolution, and vice versa. Magnification of the useful. In a sense it would allow the neurosurgeon to video image was done when necessary. To determine the explore the brain before operating on it. The surgeon could depth of the lesion or the structure of interest, the video locate the lesion and chart the best approach to it, using image was frozen on the screen and the distance between the point of contact of the transducer with the dura mater the real-time scanner without opening the dura mater. The purpose of the present study is to report the use of and the surface of the lesion was calculated by computer real-time ultrasound in the operating room for visualizing (Fig. 4). All imaging was continuously recorded on a videotape recorder attached to the ultrasound scanner. intracranial structures prior to opening the dura mater.
Illustrative Case Reports :~Termeda real-time scanner because the framerate of 30 per second gives an effectsimilarto fluoroscopy,and physiologicalmotion is visualizedas it happens. From the *Section of Neurosurgeryand "~Departmentof Radiology, University of Chicago Medical Center, Chicago, IL. Address reprint requests to Dr. George J. Dohrmann, Section of Neurosurgery, Surgery-Brain Research Institute, University of Chicago Medical Center, 950 East 59th St., Chicago, IL 60637. Key words: ultrasound; brain imaging; brain tumors; tumor localization; brain abscesses;brain cysts.
Patient I The patient was a 41-year-old, right-handed man who was first seen because of headaches and generalized seizures. A computed tomographic (CT) scan of the head showed a tumor in the medial aspect of the left parietal lobe abutting the falx (Fig. 5). The lesion was determined to be avascular on angiographic study. Because of the location, it was
§Advanced TechnologyLaboratories, Inc., Bellevue, WA.
362 0090-3019/81/110362-05501.25 © 1981 by Little, Brown and Company (Inc.)
Dohrmann and Rubin: Ultrasound in Neurosurgical Operations
363
Fig. 2. Imaging the brain during a neurosurgical operation using a real-time ultrasound scanner. The neurosurgeon holds the in-line transducer (covered by a sterile transparent plastic bag) against the dura mater, and the ultrasonographer displays the image on the video screen. All imaging is recorded on videotape.
Fig. I. An A T L real-time ultrasound scanner. Video screen is at top right and a video recorder is on top. The in-line transducer (arrow) is in a holder at the side of the machine and is connected to the console of the scanner by a long flexible cord. Wheeled mounting provides ease of movement in the operating room.
Fig. 3. In-line transducer in sterile transparent plastic bag being applied to the surface of the dura mater that has been exposed by craniectomy.
thought to be a meningioma arising from the falx; however, because of the patient's history of having had a neoplasm resected from the lung, a single metastatic lesion located adjacent to the falx was also a possibility. A left parietal craniotomy was performed with the medial aspect of the bone flap 2 cm to the left of the midline. Prior to opening the dura mater, the transducer of the real-time ultrasound scanner was placed on the surface of the dura mater and sagittal and coronal images were obtained. The tumor was
localized and a posterior approach was planned. The dura mater was opened just over this area. The distance to the lesion was known as were the dimensions of the lesion. By ultrasound it was determined that the tumor arose from the cerebral hemisphere, not from the falx (Figs. 6, 7). The mass was precisely localized and resected in toto. On histopathological examination, the tumor was determined to be an adenocarcinoma. Postoperatively the patient did well and subsequently was discharged.
364
SurgicalNeurology Vol 16 No 5 November 1981
rement of of lesion remenl of ter of lesion
Fig. 4. Diagram showing the in-line transducer in contact with the exposed dura mater. The real-time ultrasound scanner images the lesion; after the image has been frozen on the video screen, measurements of the depth and diameter of the lesion can be made.
Fig. 6. Patient I. Sa~ttal ultrasound section of the brain as imaged intraoperatively. Tumor (T) is well seen and has a sulcus (arrow) running to it (note: sulci are echogenic). A portion of the left lateral ventricle (V) is shown. (The left side of the image is anterior.)
Fig. 7. Patient 1. Coronal ultrasound section of the brain as imaged during operation. The tumor (T) is seen to be separate from the falx (arrow). This was the first evidence that the tumor was not a meningtoma and was in fact a metastatic lesion. Distance from the dura mater to the tumor as well as the optimal direction of approach to the tumor were both quickly determined at surgery by ultrasound.
Fig. 5. Patient 1. C T scan showing a left posterior parietal lesion that apparently is continuous with the falx. From the degree of contrast enhancement and the location, the tumor was considered to resemble a falcine menin~oma.
Patient 2
An ll-year-old, right-handed boy had developed a very slowly progressive right hemiparesis over the preceding three years before admission; mild right hemiatrophy was also present. A C T scan of the brain showed a mass lesion in the region of the left thalamus and internal capsule; the lesion was determined to be avascular on angiographic studies. A
left craniotomy was performed in the region of the coronal suture. The transducer of the real-time ultrasound scanner was applied to the dura mater and the tumor was visualized. The distance to the tumor was calculated and the best angle of approach was determined. At this point a stellate opening approximately 1 cm in diameter was made in the dura mater. A Dorsey cannula was introduced and, with ultrasound guidance, was passed to the surface of the tumor (Fig. 8). The tumor was firm and could be seen being displaced as the cannula was advanced. The movement of the cannula could be seen by ultrasound as it pierced the surface of the tumor; a biopsy was obtained. (See Figures 9 to 11.)
Dohrmann and Rubin: Ultrasound in Neurosurgical Operations
Fig. 8. Diagram showing the technique of biopsy of deep intracranial lesions using the real-time ultrasound scanner. Dura mater is exposed by craniotomy and the in-line transducer is applied to the dura mater; the lesion is then imaged. Through a small dural incision, the cannula is advanced into the brain and imaged also; then it is guided into the lesion and a biopsy is obtained under direct ultrasound guidance. Therefirce, there is no doubt about the possible location oJ the cannula or the region from which the biopsy was taken.
365
Fig. IO. Patient 2. Sagittal section of intraoperative ultrasound scan of the brain. This was taken through a craniotomy in the region of the left coronal suture. Tumor is well seen (white arrow) at the base of the thalamus (Th). The lateral ventricle (V) is superior and posterior to the thalamus; the choroid plexus (black arrow) is quite echogenic and can be seen in the body of the lateral ventricle. (Left side of image is anterior.)
Fig. l 1. Patient 2. Coronal section of intraoperative ultrasound scan of the brain. The lateral ventricles (arrows) are seen; the falx (large black arrow) and the thalamic tumor (T) are well visualized. Long arrow lateral to the left frontal horn depicts the path of the cannula into the tumor. The actual cannula, although well seen on the videotape, is difficult to resolve on the still images.
Fig. 9. Patient 2. C T scan showing a tumor in the region of the left thalamus~internal capsule. The mass has areas of high density at the center consistent with calcification.
On frozen section, the tumor was reported to be an "astrocytoma, grade I," or "gliosis, perhaps at the periphery of tumor." Since the ultrasound scanner showed the biopsy to have been taken from within the tumor, it was clear that this was a low-grade astrocytoma; therefore, there was no need for further specimens and the operative procedure was concluded. The patient did well and returned to school within two weeks following the operation.
366
SurgicalNeurology Vol 16 No 5 November 1981
Comment Real-time ultrasound scanning is of great use in the neurosurgical operating room for localizing small lesions within the substance of the brain. In addition, surgical intervention is facilitated by knowing the depth of the lesion and the angle of approach to it (see Fig. 4). Deep tumors could be biopsied under ultrasound guidance, and abscesses or cysts could be drained in this manner as well (see Fig. 8). Further information about intracranial lesions would be available to the surgeon, such as possible attachment of tumor to dura mater as opposed to abutment of tumor on
the dura mater, relationship of a mass to the ventricular system, localization of large blood vessels within the brain substance supplying or draining a tumor or arteriovenous malformation, determination of the degree of thrombosis of aneurysms, defining septae or loculations in cysts, and finding and draining cystic areas in tumors. As technological advances lead to greater resolution, better imaging, and transducer miniaturization, the real-time ultrasound scanner of the future will probably be even more useful during intracranial procedures and possibly in intraspinal procedures as well.
Book Review Advances and Technical Standards in Neurosurgery, Vol. 7
Edited by Prof. Hugo Krayenbi&l, New York, Vienna, Springer-Verlag, 1980 247 pp., $57. 90 Reviewed by Paul C. Bucy, M.D., Editor These volumes which have appeared annually for the past seven years have become classic works in the continuing education of practicing neurological surgeons and for young prospective neurosurgeons still in training. They are prepared under the guidance of an editorial board consisting of nine prominent European neurological surgeons. The volumes are designed "to present fields of neurosurgery and related areas in which important recent advances have been made." They also present "detailed descriptions of standard operative procedures . . . mainly but not exclusively" by European neurosurgeons. The first part of this book consists of a detailed presentation of various aspects of the treatment of meningiomas of the base of the posterior fossa. This section has been written by Prof. M. G. Ya~argil and his associates from Zurich, Switzerland. This thorough presentation begins with an historical background covering diagnosis, surgical technique, and results, including their complications. The next section by Landolt and Strebel of Zurich is concerned with a discussion of transsphenoidal operations for pituitary adenomas. It includes a very long presentation of the history of many such operations and a discussion of
their advantages and disadvantages, the surgical anatomy of the sella turcica, the surgical techniques in use at the present time, and postoperative treatment. The last section of the book is concerned with the surgical treatment of facial paralysis. Extratemporal operations for restoration of the function of the facial nerve as well as plastic surgical procedures upon the tissues of the face are presented. This section is the work of Prof. H. Millesi of Vienna. The subject of intracranial repair of the facial nerve is the work of Dr. S. Mingrino of Padua, Italy. It is a rather short chapter of six pages. The surgical technique is briefly described. The author and his associates have operated to re"pair the facial nerves of 12 patients following removal of acoustic tumors. They achieved 7 good and 4 fair results, with only 1 failure. The last chapter, by Prof. U. Fisch of Zurich, discusses palsy resulting from lesions of the facial nerve in the temporal bone. Diagnosis, selection of cases, and results of treatment are discussed. The author stresses the importance of early operations upon this type of disorder. Details of surgical technique are quite minimal. The value of this book to all neurological surgeons cannot be questioned, so far as the subjects it covers are concerned. This book should be required reading for every neurological surgeon and neurosurgical resident who is not already an expert in these areas. The book should also be available in every medical library where it may be consulted by medical students, internists, neurologists, and otolaryngologists.
Real-time ultrasound scanning has considerable potential in the neurosurgical operating room for the localization and further characterization of intracranial lesions as well as for planning and guiding the approach to such lesions. With further refinements, the ultrasound scanner may well be considered a surgical instrument and become a valued part of the neurosurgical armamentarium.
Materials and Methods
An ATL§ rotating sector ultrasound scanner (Fig. 1) was used in this study, and a specifically adapted prototype inline scan head containing transducer elements of three different frequencies (3, 5, and 7.5 megahertz [mHz]) was employed. Therefore, it was possible to adjust transducer frequency from the console of the scanner without having Dohrmann GJ, Rubin JM: Use of ultrasound in to change the scan head itself. This made it possible to neurosurgical operations: a preliminaryreport. Surg alter image resolution and depth of field instantaneously Neurol 16:362-366, 1981 during the operative procedure. The ultrasonographer and the ultrasound scanner were Ultrasound has been used successfully for the diagnosis of present in the neurosurgical operating room during the inabdominal, cardiac, and pelvic disorders, but it has not tracranial procedures (Fig. 2); the dura mater was exposed been identified as having a role in the neurosurgical by burr hole, craniectomy, or craniotomy. A sterile, transoperating room. This is because most of the devices previ- parent plastic drape was placed over the in-line transducer ously employed for intraoperative studies have given only and the associated cord after acoustic gel was applied over one-dimensional data and could provide only limited diag- the surface of the transducer. The surgeon placed the transnostic or localizing information. Recently, however, high ducer in contact with the dura mater (Fig. 3), and acoustic resolution, real-time ultrasound sector scanners$ have coupling was achieved by irrigating the dura mater with made intraoperative ultrasound scanning feasible. Through saline solution. According to the orientation of the transa craniotomy, craniectomy, or burr hole, these devices can ducer and the position of the exposed dura mater, the brain reliably image most of the intracranial contents, demonstrat- was imaged in either sagittal, transaxial, or coronal planes ing normal and abnormal anatomy as well as physiological on the video monitor of the scanner. The penetration and motion, such as vascular pulsations. Since most intracranial resolution were changed by raising the transducer frequency lesions occur subcortically or beneath the brain, a method from 3 to 5 to 7.5 mHz, thereby decreasing penetration and for visualizing these in the operating room would be most increasing resolution, and vice versa. Magnification of the useful. In a sense it would allow the neurosurgeon to video image was done when necessary. To determine the explore the brain before operating on it. The surgeon could depth of the lesion or the structure of interest, the video locate the lesion and chart the best approach to it, using image was frozen on the screen and the distance between the point of contact of the transducer with the dura mater the real-time scanner without opening the dura mater. The purpose of the present study is to report the use of and the surface of the lesion was calculated by computer real-time ultrasound in the operating room for visualizing (Fig. 4). All imaging was continuously recorded on a videotape recorder attached to the ultrasound scanner. intracranial structures prior to opening the dura mater.
Illustrative Case Reports :~Termeda real-time scanner because the framerate of 30 per second gives an effectsimilarto fluoroscopy,and physiologicalmotion is visualizedas it happens. From the *Section of Neurosurgeryand "~Departmentof Radiology, University of Chicago Medical Center, Chicago, IL. Address reprint requests to Dr. George J. Dohrmann, Section of Neurosurgery, Surgery-Brain Research Institute, University of Chicago Medical Center, 950 East 59th St., Chicago, IL 60637. Key words: ultrasound; brain imaging; brain tumors; tumor localization; brain abscesses;brain cysts.
Patient I The patient was a 41-year-old, right-handed man who was first seen because of headaches and generalized seizures. A computed tomographic (CT) scan of the head showed a tumor in the medial aspect of the left parietal lobe abutting the falx (Fig. 5). The lesion was determined to be avascular on angiographic study. Because of the location, it was
§Advanced TechnologyLaboratories, Inc., Bellevue, WA.
362 0090-3019/81/110362-05501.25 © 1981 by Little, Brown and Company (Inc.)
Dohrmann and Rubin: Ultrasound in Neurosurgical Operations
363
Fig. 2. Imaging the brain during a neurosurgical operation using a real-time ultrasound scanner. The neurosurgeon holds the in-line transducer (covered by a sterile transparent plastic bag) against the dura mater, and the ultrasonographer displays the image on the video screen. All imaging is recorded on videotape.
Fig. I. An A T L real-time ultrasound scanner. Video screen is at top right and a video recorder is on top. The in-line transducer (arrow) is in a holder at the side of the machine and is connected to the console of the scanner by a long flexible cord. Wheeled mounting provides ease of movement in the operating room.
Fig. 3. In-line transducer in sterile transparent plastic bag being applied to the surface of the dura mater that has been exposed by craniectomy.
thought to be a meningioma arising from the falx; however, because of the patient's history of having had a neoplasm resected from the lung, a single metastatic lesion located adjacent to the falx was also a possibility. A left parietal craniotomy was performed with the medial aspect of the bone flap 2 cm to the left of the midline. Prior to opening the dura mater, the transducer of the real-time ultrasound scanner was placed on the surface of the dura mater and sagittal and coronal images were obtained. The tumor was
localized and a posterior approach was planned. The dura mater was opened just over this area. The distance to the lesion was known as were the dimensions of the lesion. By ultrasound it was determined that the tumor arose from the cerebral hemisphere, not from the falx (Figs. 6, 7). The mass was precisely localized and resected in toto. On histopathological examination, the tumor was determined to be an adenocarcinoma. Postoperatively the patient did well and subsequently was discharged.
364
SurgicalNeurology Vol 16 No 5 November 1981
rement of of lesion remenl of ter of lesion
Fig. 4. Diagram showing the in-line transducer in contact with the exposed dura mater. The real-time ultrasound scanner images the lesion; after the image has been frozen on the video screen, measurements of the depth and diameter of the lesion can be made.
Fig. 6. Patient I. Sa~ttal ultrasound section of the brain as imaged intraoperatively. Tumor (T) is well seen and has a sulcus (arrow) running to it (note: sulci are echogenic). A portion of the left lateral ventricle (V) is shown. (The left side of the image is anterior.)
Fig. 7. Patient 1. Coronal ultrasound section of the brain as imaged during operation. The tumor (T) is seen to be separate from the falx (arrow). This was the first evidence that the tumor was not a meningtoma and was in fact a metastatic lesion. Distance from the dura mater to the tumor as well as the optimal direction of approach to the tumor were both quickly determined at surgery by ultrasound.
Fig. 5. Patient 1. C T scan showing a left posterior parietal lesion that apparently is continuous with the falx. From the degree of contrast enhancement and the location, the tumor was considered to resemble a falcine menin~oma.
Patient 2
An ll-year-old, right-handed boy had developed a very slowly progressive right hemiparesis over the preceding three years before admission; mild right hemiatrophy was also present. A C T scan of the brain showed a mass lesion in the region of the left thalamus and internal capsule; the lesion was determined to be avascular on angiographic studies. A
left craniotomy was performed in the region of the coronal suture. The transducer of the real-time ultrasound scanner was applied to the dura mater and the tumor was visualized. The distance to the tumor was calculated and the best angle of approach was determined. At this point a stellate opening approximately 1 cm in diameter was made in the dura mater. A Dorsey cannula was introduced and, with ultrasound guidance, was passed to the surface of the tumor (Fig. 8). The tumor was firm and could be seen being displaced as the cannula was advanced. The movement of the cannula could be seen by ultrasound as it pierced the surface of the tumor; a biopsy was obtained. (See Figures 9 to 11.)
Dohrmann and Rubin: Ultrasound in Neurosurgical Operations
Fig. 8. Diagram showing the technique of biopsy of deep intracranial lesions using the real-time ultrasound scanner. Dura mater is exposed by craniotomy and the in-line transducer is applied to the dura mater; the lesion is then imaged. Through a small dural incision, the cannula is advanced into the brain and imaged also; then it is guided into the lesion and a biopsy is obtained under direct ultrasound guidance. Therefirce, there is no doubt about the possible location oJ the cannula or the region from which the biopsy was taken.
365
Fig. IO. Patient 2. Sagittal section of intraoperative ultrasound scan of the brain. This was taken through a craniotomy in the region of the left coronal suture. Tumor is well seen (white arrow) at the base of the thalamus (Th). The lateral ventricle (V) is superior and posterior to the thalamus; the choroid plexus (black arrow) is quite echogenic and can be seen in the body of the lateral ventricle. (Left side of image is anterior.)
Fig. l 1. Patient 2. Coronal section of intraoperative ultrasound scan of the brain. The lateral ventricles (arrows) are seen; the falx (large black arrow) and the thalamic tumor (T) are well visualized. Long arrow lateral to the left frontal horn depicts the path of the cannula into the tumor. The actual cannula, although well seen on the videotape, is difficult to resolve on the still images.
Fig. 9. Patient 2. C T scan showing a tumor in the region of the left thalamus~internal capsule. The mass has areas of high density at the center consistent with calcification.
On frozen section, the tumor was reported to be an "astrocytoma, grade I," or "gliosis, perhaps at the periphery of tumor." Since the ultrasound scanner showed the biopsy to have been taken from within the tumor, it was clear that this was a low-grade astrocytoma; therefore, there was no need for further specimens and the operative procedure was concluded. The patient did well and returned to school within two weeks following the operation.
366
SurgicalNeurology Vol 16 No 5 November 1981
Comment Real-time ultrasound scanning is of great use in the neurosurgical operating room for localizing small lesions within the substance of the brain. In addition, surgical intervention is facilitated by knowing the depth of the lesion and the angle of approach to it (see Fig. 4). Deep tumors could be biopsied under ultrasound guidance, and abscesses or cysts could be drained in this manner as well (see Fig. 8). Further information about intracranial lesions would be available to the surgeon, such as possible attachment of tumor to dura mater as opposed to abutment of tumor on
the dura mater, relationship of a mass to the ventricular system, localization of large blood vessels within the brain substance supplying or draining a tumor or arteriovenous malformation, determination of the degree of thrombosis of aneurysms, defining septae or loculations in cysts, and finding and draining cystic areas in tumors. As technological advances lead to greater resolution, better imaging, and transducer miniaturization, the real-time ultrasound scanner of the future will probably be even more useful during intracranial procedures and possibly in intraspinal procedures as well.
Book Review Advances and Technical Standards in Neurosurgery, Vol. 7
Edited by Prof. Hugo Krayenbi&l, New York, Vienna, Springer-Verlag, 1980 247 pp., $57. 90 Reviewed by Paul C. Bucy, M.D., Editor These volumes which have appeared annually for the past seven years have become classic works in the continuing education of practicing neurological surgeons and for young prospective neurosurgeons still in training. They are prepared under the guidance of an editorial board consisting of nine prominent European neurological surgeons. The volumes are designed "to present fields of neurosurgery and related areas in which important recent advances have been made." They also present "detailed descriptions of standard operative procedures . . . mainly but not exclusively" by European neurosurgeons. The first part of this book consists of a detailed presentation of various aspects of the treatment of meningiomas of the base of the posterior fossa. This section has been written by Prof. M. G. Ya~argil and his associates from Zurich, Switzerland. This thorough presentation begins with an historical background covering diagnosis, surgical technique, and results, including their complications. The next section by Landolt and Strebel of Zurich is concerned with a discussion of transsphenoidal operations for pituitary adenomas. It includes a very long presentation of the history of many such operations and a discussion of
their advantages and disadvantages, the surgical anatomy of the sella turcica, the surgical techniques in use at the present time, and postoperative treatment. The last section of the book is concerned with the surgical treatment of facial paralysis. Extratemporal operations for restoration of the function of the facial nerve as well as plastic surgical procedures upon the tissues of the face are presented. This section is the work of Prof. H. Millesi of Vienna. The subject of intracranial repair of the facial nerve is the work of Dr. S. Mingrino of Padua, Italy. It is a rather short chapter of six pages. The surgical technique is briefly described. The author and his associates have operated to re"pair the facial nerves of 12 patients following removal of acoustic tumors. They achieved 7 good and 4 fair results, with only 1 failure. The last chapter, by Prof. U. Fisch of Zurich, discusses palsy resulting from lesions of the facial nerve in the temporal bone. Diagnosis, selection of cases, and results of treatment are discussed. The author stresses the importance of early operations upon this type of disorder. Details of surgical technique are quite minimal. The value of this book to all neurological surgeons cannot be questioned, so far as the subjects it covers are concerned. This book should be required reading for every neurological surgeon and neurosurgical resident who is not already an expert in these areas. The book should also be available in every medical library where it may be consulted by medical students, internists, neurologists, and otolaryngologists.