Rhoton cranial anatomy and surgical approaches pdf

 
    Contents
  1. Rhoton's Cranial Anatomy and Surgical Approaches | Neurosurgery | Surgery
  2. Albert L. Rhoton Jr., MD: His Philosophy and Education of Neurosurgeons
  3. Rhoton's Cranial Anatomy and Surgical Approaches
  4. Rhoton cranial anatomy and surgical approaches

This edition of Rhoton's Cranial Anatomy and Surgical Approaches includes a lengthy section on Operative Techniques and Instrumentation for. Rhoton's Cranial Anatomy and Surgical Approaches, a hardbound collection of the complete and classic supplements to Neurosurgery, official. Download PDF Rhoton Cranial Anatomy And Surgical Approaches, PDF Download Rhoton Cranial Anatomy And Surgical Approaches.

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Rhoton Cranial Anatomy And Surgical Approaches Pdf

rhoton cranial anatomy and surgical approaches pdf download rhoton anatomy pdf - wordpress rhoton's cranial anatomy and surgical approaches pdf rhotons. Get this from a library! Rhoton cranial anatomy and surgical approaches. [Albert L Rhoton]. Book the latest updates of specialized neurosurgical and spine, PDF, Kindle, Rhoton's Cranial Anatomy and Surgical Approaches, a hardbound collection of.

Cranial surgery, Craniotomy, Instrumentation, Microneurosurgery, Microsurgery, Operative techniques, Surgical instruments, Surgical microscope The introduction of the operating microscope for neurosurgery brought about the greatest improvements in operative techniques that have occurred in the history of the specialty. The microscope has resulted in profound changes in the selection and use of instruments and in the way neurosurgical operations are completed. The advantages provided by the operating microscope in neurosurgery were first demonstrated during the removal of acoustic neuromas 4. The benefits of magnified stereoscopic vision and intense illumination provided by the microscope were quickly realized in other neurosurgical procedures. The operating microscope is now used for the intradural portion of nearly all operations involving the head and spine and for most extradural operations involving the spine and cranial base, converting almost all of neurosurgery into a microsurgical specialty. Microsurgery has improved the technical performance of many standard neurosurgical procedures e. It has improved operative results by permitting neural and vascular structures to be delineated with greater visual accuracy, deep areas to be reached with less brain retraction and smaller cortical incisions, bleeding points to be coagulated with less damage to adjacent neural structures, nerves distorted by tumor to be preserved with greater frequency, and anastomosis and suturing of small vessels and nerves not previously possible to be performed. Its use has resulted in smaller wounds, less postoperative neural and vascular damage, better hemostasis, more accurate nerve and vessel repairs, and surgical treatment of some previously inoperable lesions. It has introduced a new era in surgical education, by permitting the observation and recording for later study and discussion of minute operative details not visible to the naked eye. Some general considerations are reviewed before discussion of instrument selection and operative techniques.

Reprinted from Rhoton AL Jr. B: Illustration showing the relationships between the acoustic neurinoma and the seventh and eighth cranial nerves. The facial nerve courses anterior to the tumor. Republished with permission of Oxford University Press, from Microsurgical relationships of the anterior inferior cerebellar artery and the facial-vestibulocochlear nerve complex, by R.

Martin, J. Grant, D. Peace, C. Theiss, and A. C: Illustrations showing the neurovascular relationships of the sphenoid sinus. The project was done for pituitary tumor surgery. Reprinted from Fujii K et al: J Neurosurg —39, D: Illustrations showing the microsurgical anatomy of the anterior cerebral artery—anterior communicating artery—recurrent artery complex.

The project was done for aneurysm surgery. E: Illustrations showing the surgical approach to the cavernous sinus. The project was done for skull base surgery. Republished with permission of Oxford University Press, from Surgical approaches to the cavernous sinus: a microsurgical study, by T. An effort is made to position scalp incisions so that they are behind the hairline and not on the exposed part of the forehead.

A bicoronal incision located behind the hairline is preferable to extension of an incision low on the forehead for a unilateral frontal craniotomy. An attempt is made to avoid the branch of the facial nerve that passes across the zygoma to reach the frontalis muscle. Incisions reaching the zygoma more than 1. The superficial temporal and occipital arteries should be preserved if there is the possibility that they will be needed for an extracranial- intracranial arterial anastomosis.

Rhoton's Cranial Anatomy and Surgical Approaches | Neurosurgery | Surgery

During elevation of a scalp flap, the pressure of the surgeon's and assistant's fingers against the skin on each side of the incision is usually sufficient to control bleeding until hemostatic clips or clamps are applied.

The skin is usually incised with a sharp blade, but the deeper fascial and muscle layers may be incised with a cutting Bovie electrocautery. The ground plate on the electrocutting unit should have a broad base of contact, to prevent the skin at the ground plate from being burned. Achieving a satisfactory cosmetic result with a supratentorial craniotomy often depends on preservation of the bulk and viability of the temporalis muscle.

This is best achieved by avoiding the use of the cutting Bovie electrocautery during elevation of the muscle from the bone. Both the vascular and neural supplies of the temporalis muscle course tightly along the fascial attachments of the muscle to the bone, where they could easily be damaged with a hot cutting instrument [14], see Fig. Optimal preservation of the muscle's bulk is best achieved by separation of the muscle from the bone via accurate dissection with a sharp periosteal elevator.

Bipolar coagulation is routinely used to control bleeding from the scalp margins, on the dura, and at intracranial sites. At sites where even gentle bipolar coagulation could result in neural damage, such as around the facial or optic nerves, an attempt is made to control bleeding with a gently applied hemostatic gelatinous sponge Gelfoam; Upjohn Co.

Venous bleeding can often be controlled with the light application of gelatinous sponges. Metallic clips, which were often used on the dura and vessels in the past, are now applied infrequently except on aneurysm necks, because they interfere with the quality of computed tomographic scans; if they are used, they should be composed of nonmagnetic alloys or titanium.

Neurosurgery Books Full Use of a series of burr holes made with a manual or motordriven trephine connected to a Gigli saw for elevating bone P.

Albert L. Rhoton Jr., MD: His Philosophy and Education of Neurosurgeons

Commonly, a hole is prepared by using a cutting burr on a high-speed drill and a tool with a foot plate, to protect the dural cuts around the margins of the flap. Extremely long bone cuts should be avoided, especially if they extend across an internal bony prominence, such as the pterion, or across a major venous sinus.

The risk of tearing the dura or injuring the brain is reduced by drilling several holes and making shorter cuts. A hole is placed on each side of a venous sinus and the dura is carefully stripped from the bone, after which the bone cut is completed, rather than the bone being cut above the sinus as part of a long cut around the whole margin of the flap.

Bleeding from bone edges is stopped with the application of bone wax. Bone wax is also used to close small openings into the mastoid air cells and other sinuses, but larger openings in the sinuses are closed with other materials, such as fat, muscle, or pericranial grafts, sometimes in conjunction with a thin plate of methylmethacrylate or other bone substitute.

Sites commonly marked on the scalp before application of the drapes, including the coronal, sagittal, and lambdoid sutures, the rolandic and sylvian fissures, and the pterion, inion, asterion, and keyhole. Approximation of the sites of the sylvian and rolandic fissures on the scalp begins with observation of the positions of the nasion, inion, and frontozygomatic point.

The nasion is located in the midline, at the junction of the nasal and frontal bones. The inion is the site of a bony prominence that overlies the torcula. The frontozygomatic point is located on the orbital rim, 2. The sylvian fissure is located along a line that extends backward from the frontozygomatic point, across the lateral surface of the head, to the three-quarter point. The pterion, i. The rolandic fissure is located by identifying the upper and lower rolandic points.

The lower rolandic point is located where a line extending from the midpoint of the upper margin of the zygomatic arch to the upper rolandic point crosses the line defining the sylvian fissure. A line connecting the upper and lower rolandic points approximates the rolandic fissure.

The lower rolandic point is located approximately 2. Another important point is the keyhole, the site of a burr hole that, if properly placed, has the frontal dura in the depths of its upper half and the periorbita in its lower half. It is approximately 3 cm anterior to the pterion, just above the lateral end of the superior orbital rim and under the most anterior point of attachment of the temporalis muscle and fascia to the temporal line from, Rhoton AL Jr: The cerebrum.

Rhoton's Cranial Anatomy and Surgical Approaches

Neurosurgery 51[Suppl 1]:SS1- 51, [15]. After elevation of the bone flap, it is common practice to tack the dura to the bony margin with a few black silk sutures brought through the dura and then through small drill holes in the margin of the cranial opening Fig. Care is taken to avoid placing drill holes for tack-up sutures that might extend into the frontal sinus or mastoid air cells. Tack-up sutures are more commonly used for dura over the cerebral hemispheres than for dura over the cerebellum.

If the brain is pressed tightly against the dura, then the tack-up sutures are placed after treatment of the intradural pathological lesion, when the brain is relaxed and the sutures can be placed with direct observation of the deep surface of the dura. Tack-up sutures can also be led through adjacent muscles or pericranium, rather than a hole in the margin of the bone flap. In the past, there was a tendency for bone flaps to be elevated and replaced over the cerebral hemispheres and for exposures in the suboccipital region to be performed as craniectomies, without replacement of the bone.

Laterally placed suboccipital exposures are now commonly performed as craniotomies, with replacement of the bone flaps. Midline suboccipital operations are more commonly performed as craniectomies, especially if decompression at the foramen magnum is needed, because this area is protected by a greater thickness of overlying muscles. Bone flaps are usually held in place with nonmagnetic plates and screws or small metal discs or burr hole covers that compress and align the inner and outer tables of the bone flap and the adjacent cranium Fig.

Remaining defects in the P. The dura is closed with silk interrupted or running sutures. Small bits of fat or muscle may be sutured over small openings caused by shrinkage of the dura. Larger dural defects are closed with pericranium or temporalis fascia obtained from the operative site, with sterilized cadaveric dura or fascia lata, or with other approved dural substitutes. The deep muscles and fascia are commonly closed with , the temporalis muscle and fascia with , and the galea with synthetic absorbable sutures.

The scalp is usually closed with metallic staples, except at sites where some or nylon reenforcing sutures may be needed. Skin staples are associated with less tissue reaction than are other forms of closure with sutures. Fixation is best achieved with a pinion headholder, in which the essential element is a clamp Neurosurgery Books Full made to accommodate three relatively sharp pins.

When the pins are placed, care should be taken to avoid a spinal fluid shunt, thin bones such as those that overlie the frontal and mastoid sinuses , and the thick temporalis muscle where the clamp, however tightly applied, tends to remain unstable. The pins should be applied well away from the eye and areas where they would hinder the incision. Shorter pediatric pins are available for thin crania.

The pins should not be placed over the thin crania of some patients with a history of hydrocephalus.

After the clamp has been secured on the head, the final positioning is completed and the headholder is fixed to the operating table. Positioning of a pinion headholder for a craniotomy. Three pins penetrate the scalp and are firmly fixed to the outer table of the cranium.

A, position of the headholder for a unilateral or bilateral frontal approach. B, position for a pterional or frontotemporal craniotomy. C, position for a retrosigmoid approach to the cerebellopontine angle. D, position for a midline suboccipital approach.

E, position for a midline suboccipital approach with the patient in the semi-sitting position. The pins are positioned to avoid the thin bone over the frontal sinus and mastoid air cells and the temporalis muscle. The side arms of the head clamp should be shaped to accommodate the C-clamps holding the retractor system. The pinion headholder has a bolt that resembles a sunburst, for attachment to the operating table.

Placement of three sunburst sites on the head clamp, rather than only one, allows greater flexibility in attaching the head clamp to the operating table and provides extra sites for the attachment of retractor systems and instruments for instrument guidance.

This type of immobilization allows intraoperative repositioning of the head. The clamp avoids the skin damage that may occur if the face rests against a padded head support for several hours. The cranial clamps do not obscure the face during the operation as do padded headrests , facilitating intraoperative electromyographic monitoring of the facial muscles and monitoring of auditory or somatosensory evoked potentials.

Until recently, all head clamps were constructed from radiopaque metals, but the increasing use of intraoperative fluoroscopy and angiography has prompted the development of headholders constructed from radiolucent materials. The pinion headholder commonly serves as the site of attachment of the brain retractor system. The side arms of the head Neurosurgery Books Full clamp should be shaped to accommodate the C-clamps securing the retractor system.

Placement of three sunburst sites on the head clamp, rather than only one, allows greater flexibility in attachment of the head clamp to the operating table and provides extra sites for the attachment of retractor systems and components of the image guidance system. In the past, surgeons commonly used one set of instruments for conventional macrosurgery performed with P. A trend is to select instruments with handles and tactile characteristics suitable for both macrosurgery and microsurgery and to change only the size of the instrument tip, depending on whether the use is to be macrosurgical or microsurgical.

For example, forceps for macrosurgery have grasping tips as large as 2 to 3 mm and those for microsurgery commonly having tips measuring 0. Positioning of patients for acoustic neuroma removal and decompression for treatment of hemifacial spasm. A and B, the head of the table is elevated. In our initial use of the three-quarter prone position, the head of the operating table was tilted to elevate the head only slightly A.

It was later noted, however, that more marked tilting of the table significantly elevated the head and reduced the venous distension and intracranial pressure.

Rhoton cranial anatomy and surgical approaches

I usually perform operations to treat acoustic neuromas and hemifacial spasm sitting on a stool positioned behind the head of the patient. In recent years, we have tilted the table to elevate the head to such a degree that the surgeon's stool must be placed on a platform B. The patient should be positioned on the side of the table nearest the surgeon. C and D, the patient's head is rotated. There is a tendency to rotate the face toward the floor for acoustic neuroma removal C.

However, better operative access is obtained if the sagittal suture is placed parallel to the floor D. Rotating the face toward the floor C places the direction of view through the operating microscope forward toward the shoulder, thus blocking or reducing the operative angle.

Positioning the head so that the sagittal suture is parallel to the floor D allows the direction of view through the operating microscope to be rotated away from the shoulder and provides easier wider access to the operative field.

The position shown in D is also used for decompression operations for treatment of hemifacial spasm. The position shown in C is used for decompression operations for treatment of Neurosurgery Books Full trigeminal neuralgia, in which the surgeon is seated at the top of the patient's head, as shown in Figure 1.

E and F, it is better to gently tilt the head toward the contralateral shoulder than toward the ipsilateral shoulder. Tilting the vertex toward the floor, with the sagittal suture parallel to the floor, opens the angle between the shoulder and the head and increases operative access.

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