Vein conduits used to enhance arterial microsurgical end-to-end suture repair: A randomized comparative study

Wrapping microsurgical sutures with a vein conduit is a well-described procedure for microsurgical nerve repair. While this has rarely been described in the context of vascular repair, this technique could increase the permeability of the sutured vessels. As part of a University Diploma in Microsurgery, 9 junior surgeons performed a comparative study of 18 microsurgical repairs on rats with and without vein sleeve. The vessels used were an external jugular vein sleeve on the end-to-end anastomosis of the common carotid artery and comparing it to this same anastomosis without a sleeve. The data analyzed were rat weight, suture time with carotid clamping time, number of stitches used, complications as well as vascular leakage and permeability of the repair at 0 and 5minutes evaluated with a patency test. The average rat body weight was 255g. Mean suture time was 52minutes in group A (sleeved repairs) and 41minutes in group B (standard repairs). The number of stitches placed was 5.1 points on average in group A and 5.6 points in group B. The time to perform the repair and the number of stitches was not statistically different between groups. The patency test was positive in 100% of cases in group A and in 78% of cases in group B. There was a significant difference between the permeability rate of the repairs, with better results in group A (p=0.03). There were two anastomotic leaks after declamping in the sleeve group and five in the standard suture group, thus 2.5 times more leaks in the group without a sleeve (p<0.01). The addition of a vein sleeve around an end-to-end arterial suture repair seems to improve its permeability and therefore its reliability.

Ptosis and vertical diplopia after ligation of ethmoidal arteries

The treatment of epistaxis is well codified, ligation of the ethmoidal arteries being the last resort. We report the case of a 25-year-old pregnant patient, who has had a ligation of the anterior and posterior ethmoidal arteries after a persistent epistaxis. Postoperatively, she presented a complete ptosis and an impaired eye elevation without any visual acuity disorders, evoking a lesion of the upper branch of the common oculomotor nerve (third cranial nerve). The patient totally recovered after 3 months. Anatomical study shows that the upper branch of the third cranial nerve is lying very close to the optic nerve and cannot be affected by surgery without any associated damage of the optic nerve. Thus, a vascular etiology seems to be the best explanation of the complication experienced by our patient. Ligation of the posterior ethmoidal artery should be done with caution.

Lower third clivus and foramen magnum intradural tumor removal: The plea for a simple posterolateral approach

BACKGROUND

Anterior or anterolateral lesions of the lower third clivus and/or foramen magnum require a surgical exposure that provides a clear visualization of both pathological and normal anatomy without retraction of neural or vascular structures. The posterolateral approach permits access to the anterolateral intradural aspect of the brainstem. The aim of this study was to stress that there is no need for vertebral artery transposition, occipital condyle drilling, occipitocervical fixation or trans-oro-pharyngeal access to remove these lesions.

METHODS

All five consecutive patients treated surgically for an intradural foramen magnum lesion in the Department of Neurosurgery at Angers University Hospital, between May 2012 and January 2015, were included in this retrospective study. In 4 cases, patients were referred to us for a second opinion after an initial surgical proposal at another institution. For all patients, the data collected were age at diagnosis, clinical signs, and quality of rostral and caudal exposure of the lesion, quality of resection, complications and postoperative neurological deficits.

RESULTS

All patients were operated on with a control of the rostrocaudal part of the lesion, without touching the vertebral artery, or the use of occipital condyle drilling. There was no need for occipitocervical fixation. Total resection was achieved in 4 cases, subtotal resection in one. All had watertight dural closure with no dural patch, or postoperative neurological deficits. No recurrence occurred between 6 and 30 months after surgery.

CONCLUSION

Based on these results, the posterolateral approach was a simple, effective and safe procedure for anterior and anterolateral intradural lesion of the foramen magnum.

Vascular microanatomy of the pontomedullary junction, posterior inferior cerebellar arteries, and the lateral spinal arteries

SUMMARY

This study of 25 brains at the pontomedullary junction defined the different possible origins of the perforating arteries and lateral spinal arteries in relation to the posterior inferior cerebellar arteries (PICAs). - If the PICA emerges from the common trunk of the AICA-PICA coming from the basilar artery, it never gives perforating arteries or a lateral spinal artery on the lateral surface of the brain stem but supplies blood to a part of the ipsilateral cerebellar hemisphere. - If the PICA arises extradurally at C1, it never gives perforating arteries for the lateral surface of the brain stem, but it gives pial branches for the posterior surface of the medulla oblongata and is always the origin of the lateral spinal artery. - If the PICA emerges in the intradural vertebral artery, it is the source of the perforating arteries for the lateral surface of the brain stem and of the blood supply of the ipsilateral cerebellum.

Surgical anatomy of the jugular foramen

The jugular foramen (JF) is a canal that makes communication between the posterior cranial fossa and the upper neck for one third of the cranial nerves and for the main venous channel of the brain. From a lateral view, the JF is protected by multiple layers of muscles and by the outer surface of the petrous bone. Surgical exposure of the JF is usually justified by the removal of benign tumors that grow in this region. In the first part of the present study we describe the surgical anatomy of the JF Then, we detail the relevant points of a stepwise surgical progression of three lateral skull base approaches with a gradual level of exposure and invasiveness. The infralabyrinthine transsigmoid transjugular-high cervical approach is a conservative procedure that associates a retrolabyrinthine approach to a lateral dissection of the upper neck, exposing the sinojugular axis without mobilization of the facial nerve. In the second step, the external auditory canal is transsected and the intrapetrous facial nerve is mobilized, giving more exposure of the carotid canal and middle ear cavity. In the third step, a total petrosectomy is achieved with sacrifice of the cochlea, giving access to the petrous apex and to the whole course of the intrapetrous carotid artery. Using the same dissection of the soft tissues from a lateral trajectory, these three approaches bring solutions to the radical removal of distinct tumor extensions. While the first step preserves the facial nerve and intrapetrous neurootologic structures, the third one offers a wide but more aggressive exposure of the JF and related structures.

Surgical anatomy of the petrous apex and petroclival region

Surgical exposure of the clivus, the ventral or lateral aspect of the brain stem, and all the intradural structures of the petroclival area remains difficult because of the presence of the petrous apex and peripetrous complex. However, a lateral skull base approach to the petroclival area is the most suitable approach if the lesion to be resected lies medial to the fifth nerve, in front of the acousticofacial bundles, extending towards the midline. The purpose of this study is to review the topographic anatomy of the petrous apex and peripetrous structures, with emphasis on the relationships important to the lateral approaches to the petroclival area. Such anatomical knowledge allows us to study the surgical technique, exposure, and pitfalls of the main lateral transpetrosal skull base approaches used to reach the petroclival area.

Anatomical basis of an original pedal approach to the great saphenous vein for surgery

Varicose vein repair often necessitates a distal approach to the great saphenous vein (GSV). The classic method involves a medial pre-malleolar approach. We propose a more distal approach via the medial surface of the foot where there is a cutaneous landmark, which can be used to locate the GSV in a simple, reliable and reproducible fashion. In 20 cadaveric feet, we dissected out the GSV exploiting the above-mentioned cutaneous landmark. We then extended the dissection up as far as the medial pre-malleolar region (from where the GSV is classically approached) in order to be able to compare the diameter of the vein at the two different points (in the foot and in the pre-malleolar region). We also compared the cutaneous landmark with ultrasonographic location of the GSV in 22 feet of healthy subjects. Both dissections and ultrasound examinations demonstrated the reliability of the cutaneous landmark. Moreover, no significant difference was detected in the diameter of the GSV at the two different approach points. This original distal approach to the GSV requires only minor modifications of current practice for varicose veins surgical treatment.

Anatomy of the orbit and its surgical approach

A micro anatomical and surgical study of the orbit was conducted on cadaver specimens. First of all we reviewed the anatomy of the orbit with special emphasis on microanatomical structures. Three neurosurgical approches are then described with all structures encountered along these routes. The superior approach which provides a good access to the superior part of the orbit is the only route which can explore all parts of the optic nerve even in the optic canal. The lateral compartment of the orbit could be exposed by the lateral approach above or below the lateral rectus muscle. It is the only route that could give access to the inferior part of the orbit. The supero lateral approach is the largest route and has advantages of the two preceding routes. It gives access to the superior part of the orbit but not the optic canal and gives also a good exposition to the lateral part of the orbit but less than the lateral route in the inferior part. These approaches could be used to remove all intra orbital lesions apart from those located in the infero medial part of the orbit.

Surgical anatomy of calvarial skin and bones--with particular reference to neurosurgical approaches

This chapter on surgical anatomy is addressed to young neurosurgeons and could be used as an introduction to basic neurosurgical technique. It aims to cover the basic anatomy relevant to making incisions in the scalp and creating bone flaps, an essential preliminary to any form of intracranial surgery. We will examine the anatomy of the scalp, its arterial and venous supply and its nervous system, as well as providing some technical points related to the cranial vault and the base of the skull. It will be explained how a well-grounded knowledge of the anatomical details makes it possible to execute correctly two of the most common approaches in neurosurgical practice, namely the pterional approach and an approach around the sinuso-jugular axis.

Crossed retroperitoneal approach to the internal iliac artery: a preliminary anatomical study

The internal iliac arteries (IIA), and especially the distal segment, course very deep in the pelvis and are generally difficult to access surgically. The recent development of simple and reliable methods to investigate proximal ischemia of the lower extremities has led to discovery of more candidates for elective revascularization of the IAA. The classic approaches to the IAA, i.e., the transperitoneal and homolateral retroperitoneal routs have certain disadvantages. We present a new crossed retroperitoneal approach to the IAA and the results of such method in six cadavers. In all six cases, the entire IAA could be exposed without any particular problems. This novel approach to the IAA seems to be both simple and reproducible.

Double hepatomesenteric artery: a rare anatomical variant

A case of a "double hepatomesenteric artery", i.e. two persisting hepatic arteries arising from the superior mesenteric artery, is reported. Also observed was a lack of systematisation of the pancreaticoduodenal arteries. The variant, which does not appear to have been previously reported in the literature, was observed when dissecting the vessels of the duodenal bulb in a preserved male cadaver injected with neoprene latex. Its embryological origin, as well as the clinical, radiological (diagnostic or interventional) and surgical implications, are discussed.

Surgical anatomy of the infratemporal fossa using the transmaxillary approach

In this study we evaluated the ability of the transmaxillary route to expose the elements of the infratemporal fossa (ITF). Five adult cadaver heads were dissected on both sides, after making a paralateronasal incision. The maxillary branch of the trigeminal nerve served as a superior landmark to progress into the retroantral space and pterygopalatine fossa. The maxillary artery, lateral pterygoid muscle, pterygoid venous plexus, foramen rotundum and foramen ovale were identified. Distances between those elements and angle of approaches of the foramen ovale and foramen rotundum were measured in the horizontal plane. In all cases, the anterior loop of the maxillary artery and the sphenopalatine artery were located in the proximal retroantral fatty space and could be ligated without optic magnification. The maxillary nerve could be followed up to the foramen rotundum at a 44 mm mean distance from the opening. The mean angle of vision to the foramen rotundum was 31 degrees. Under the greater sphenoid wing and lateral to the pterygoid process, desinsertion and partial resection of the lateral pterygoid muscle were required to identify the pterygoid venous plexus and foramen ovale. The pterygoid venous plexus was organized as a compact network of channels between and superior to the muscle fibers; it was in close relation with the foramen ovale. Access to the foramen ovale was deep (mean 56 mm) and narrow (20 degrees). Our results indicate that the transmaxillary approach is a minimally invasive procedure that gives an appropriate window to the structures of the retroantral space and to the pterygomaxillary fissure and pterygopalatine fossa. Monitoring of the retropterygoid portion of the infratemporal fossa by this route is inadequate.

Lateral interscalenic multilevel oblique corpectomies to repair ventral root avulsions after brachial plexus injury in humans: anatomical study and first clinical experience

OBJECT

Because central nervous system white matter exerts a powerful inhibitory effect on axonal growth, implantation of nerve grafts or rootlets into the cervical spinal cord following ventral root avulsion injury should, ideally, be performed directly through the ventral root exit zone (VRExZ), which is located near the anteromedial aspect of the anterior horn; the grafts/rootlets should not be implanted into the white matter of the lateral cord. This is not possible when using a conservative posterior approach. Therefore, the authors have studied the anatomy encountered when using the anterolateral approach and evaluated the technique in the particular case of avulsed ventral nerve roots. They also present a case illustration of the procedure, which is used currently in their department.

METHODS

Anterior access to the rootlets is obtained using a lateral interscalenic approach; the vertebral artery is exposed and mobilized, and oblique drilling of the vertebral bodies (VBs) is performed. Because the articular processes and half of the VBs are preserved, fusion is not required. The approach allows the surgeon to expose the anterior aspect of the cervical dura and the entire length of the emerging spinal nerves. The anterior aspect of the dura is opened at the desired levels for VRExZ exposure. and the position is ideal for implantation of the graft/rootlets. The interscalenic dissection is mandatory so that the lesions of the supraclavicular plexus can be evaluated and repaired. If necessary, the anterior approach allows for exploration of the infraclavicular plexus during the same procedure.

CONCLUSIONS

The use of a true anterior approach to the ventral rootlets appears to be a valuable and appropriate approach that avoids extensive laminectomy/facetectomy while reimplantation is performed through the anterolateral sulcus itself. In this approach, however, reimplantation of dorsal roots into the spinal cord remains impossible.

Ideal intraspinal implantation site for the repair of ventral root avulsion after brachial plexus injury in humans. A preliminary anatomical study

The advances made to date in root reimplantation for avulsion of the brachial plexus are modest considering that there are only reports from ten patients in the literature. However, the results are promising and should be applauded. The problem with reimplantation, in addition to the difficult surgical exposure, is to determine the ideal intraspinal implantation site for the graft. Given the non-permissive substrate properties of the CNS white matter, the outcome of grafts elsewhere in the spinal cord need to be evaluated. An inappropriate implantation site might explain the still modest recovery in this challenging group of patients. Consequently the microscopic anatomy of the cervical spinal cord segments C5 to T1 was studied. The aims were to 1--determine the relationships between the ventral gray horn and the ventrolateral sulcus of the spinal cord, and 2--analyse the location and course of the motoneuron fibres passing through the white matter to reach the ventral root. On the basis of the present findings it is proposed that reimplantation of nerve grafts or rootlets should be performed directly through the ventral root exit zone in contact with the ventromedial region of the ventral gray horn at a depth of 2 mm, rather than into the white matter of the lateral aspect of the cord. Initially we used a posterior approach with total facetectomies. An anterior approach is now evaluated for current use.

[Dermal sinus and dermoid cyst revealed by abscess formation in posterior fossa. Report of 2 pediatric cases and review of the litterature]

Cranial dermal sinus, usually associated with dermoid cyst, is the persistance of an abnormal embryonal communication between the skin and the central nervous system. It may be the source of intracranial infection, most often a meningitis and rarely an abscess formation. Two cases of little girls (18 months and 2 years) having dermal sinus with dermoid cyst revealed by cerebellar abscess formations are reported. In the first case there were multiple cerebellar abscesses with hydrocephalus leading to a raised intracranial pressure. In the second case there was an abscess formation adjacent to the dermoid cyst. CT scan showed cysts and abscesses but MRI, achieved in the second case, was useful in demonstrating the sinus tract as well as the associated cyst and abscess. The two patients underwent a posterior fossa surgery with antibiotic therapy. In the first case abscess drainage and ventricular external drainage were necessary before sinus and cyst excision. Two months after surgery the two patients were neurologically intact and developping well. Surgery with total excision of dermal sinus and dermoid cyst, even sometimes difficult, must be preferred to the simple abscess drainage and antibiotic therapy.

Anatomical bases of the posterior approach to the brachial plexus for repairing avulsed spinal nerve roots

Avulsion of nerve roots from the cervical spinal cord has always been considered as an untreatable injury, even by surgeons with expertise in this area. However, numerous experimental studies in animals, as well as a human case report, showed that if continuity is restored between the spinal cord and nerve roots, axons from spinal motor neurons can regrow into the peripheral nerve graft with a subsequent recovery of motor function. The posterior subscapular approach, based on the evolution of the posterolateral approach for removal of the first rib, is the only way to expose the entire brachial plexus from C5 to T1 from the ventral and dorsal roots to the distal nerve trunks. The purpose of this study is to investigate the topographic anatomy of the brachial plexus, with particular emphasis on the relationships important to the posterior approach and reimplantation of the ventral rootlets within the cord, either directly or using peripheral nerve grafts. The major advantage of the procedure is the proximal exposure of the plexus, with evaluation of the lesions being excellent (intradural, foraminal and proximal trunks). Reimplantation of ventral roots into the cord is relatively easy from C5 to C7, more difficult for C8 and problematic for T1, whereas reimplantation of dorsal roots into the cord is easy from C5 to T1. The disadvantages of this approach for exposure of the plexus and nerve root avulsion repair are significant: the surgical technical steps are difficult mainly because of the cervical paraspinal muscle mass, which cannot be easily "elevated and retracted" despite previous descriptions; bleeding from the venous plexus can be excessive as suggested by dissection and our own experience; the stability of the cervical spine may be compromised following extensive laminectomy with total unilateral facetectomy; exposure of the plexus distal to the division of the trunks is difficult; there may be injury to the long thoracic nerve and subsequent winging of the scapula; and pneumothorax. This approach is therefore only applicable in highly selected cases involving multiple avulsed roots with proximal lesions extending as far as the division of the trunks.

High and low lateral approaches to the popliteal artery

Using a series of 20 dissections and two anatomic transverse sections of a lower limb, the authors investigated the lateral approaches to the popliteal artery. The high lateral approach (above the knee) is not very aggressive and gives access to the retro-genicular part of the popliteal artery. After cutaneous and fascial incision, a simple gap between the vastus lateralis and biceps femoris mm. allows easy exposure of the popliteal vessels after backward retraction of the sciatic nerve. The low lateral approach to the artery (below the knee) is very aggressive for the vessels, nerves, and ligaments of the area. It involves the resection of the upper fourth of the fibula and the isolation and protection of the common peroneal nerve Nevertheless, these lateral approaches must be known and used when classic approaches (medial and posterior) are impossible.

[Intracranial meningiomas revealed by hemorrhage. Report of three cases and literature review]

Three cases of meningioma revealed by hemorrage are reported. The first patient, 65 presented with a temporal hematoma associated with intraventricular contamination. The diagnosis of a tumoral origin of the hemorrhage was made only few weeks later when the total hematoma resorption was ended. The second patient, 49 presented with a sudden right hemiplegia. CTscan and MRI revealed a left frontal tumor surrounded by hematoma. The third patient, 46, presented with a transient aphasia and superior limb dysesthesia. CT scan showed a temporal hematoma; a carotid angiography revealed a typical meningioma blush. A review of the literature collected 54 additional cases of meningioma associated with hemorrage. Clinical findings and mechanisms are discussed.

Descriptive anatomic study of the fourth perforating artery of the femoral system

The existence of the fourth perforating artery of Paturet [7], a collateral branch of the superficial femoral artery in its lower third, is the subject of much debate. This artery has so far only been the subject of radio-anatomic descriptions based on arteriographies carried out within the context of arteriopathy of the lower limbs. We present a descriptive anatomic study of this artery based on 14 observations on 32 dissections. Three types of approach were carried out: exposure of the artery of the femoral quadriceps muscle up to its ending in the vastus lateralis; a lateral "orthopaedic" approach to the lower third of the femur; and a "vascular" approach by a medial incision to the femoro-popliteal axis in the lower third of the thigh. Its main relations are described, passing in front of the superficial femoral vein and then behind the femur before ending at the vastus lateralis muscle. These relations explain the possibility of anastomoses with collateral or terminal branches of the deep femoral artery (vastus lateralis artery, third perforating artery). The fourth perforating artery of Paturet [7] must be protected in traumatologic and vascular surgery. It is the main collector of vascular anastomoses between the deep femoral artery and the femoro-popliteal axis in the event of proximal occlusion of the superficial femoral artery. Its removal, in such a case, can aggravate an underlying arteriopathy.

Arterial supply of the duodenal bulb: an anatomoclinical study

An anatomic and radio-anatomic study of 15 specimens enabled us to reconsider the arterial vascularization of the duodenal bulb and to propose a new classification based on anatomoclinical criteria. The two arterial pedicles (infra- and supraduodenal) reach the bulb on its posterior aspect; each pedicle is made up of two sorts of blood currents (right and left); the posterior aspect of the bulb seems to be the most vascularized one, explaining, apart from bleeding from gastroduodenal a. erosion, the hemorrhagic character of ulcers of the posterior aspect of the bulb. The predominance of the left-hand currents explains the possible ischemia of the duodenal bulb and/or rupture of the duodenal stump after their interruption.

Persistent sciatic artery: report of an original aneurysm-associated case

Persistent sciatic artery (PSA) is a rare embryologic abnormality and can sometimes be bilateral. It may be discovered because of a gluteal aneurysm or ischemic or embolic complications in the lower limb. The case we report was a unilateral type III aneurysm-associated PSA. Since the abnormal artery may be the only source of blood supply to the lower limb, a thorough knowledge of the artery and its embryologic origins is essential.

Anatomic and radioanatomic study of the lateral genicular arteries: application to prevention of postoperative hemarthrosis after arthroscopic lateral retinacular release

Arthroscopic lateral retinacular release can be complicated by hemarthrosis in 10 to 18% of cases. The vascular structures involved are the lateral vascular pedicles of the knee. This study examines the topography of these pedicles. Anatomic and radioanatomic studies carried out in 50 specimens defined the route of the vascular pedicles at the lateral aspect of the knee. From the measurements carried out, we noted the relative homogeneity of the routes taken by the different proximo-lateral vascular pedicles, which are highly vulnerable, and the variability of the disto-lateral arterial routes. A tracing-paper study identified two distinct routes for the disto-lateral vascular pedicle and evaluated the risk of injury to it in surgical approaches to the lateral aspect of the knee. Finally, the topographic data of the study suggest the possibility of preventive hemostasis of the proximo-lateral pedicle via a minimal approach close to the patella. Furthermore, it seems possible to avoid cutting the disto-lateral pedicle if it is localised by cutaneous trans-illumination at the beginning of the operation.

Dermal sinus and intramedullary spinal cord abscess. Report of two cases and review of the literature

Intramedullary abscesses of the spinal cord are uncommon. Most of them occur in association with heart, pulmonary or urogenital infections. We report two cases of intramedullary spinal cord abscesses secondary to congenital dermal sinus. Only 14 cases of such an association have previously been reported. In our cases, dermal sinus was associated with an epidermoid tumour. The clinical presentation, pathogenesis, magnetic resonance imaging findings, surgical management and outcome are discussed.

Anatomic study of the deep plantar artery: potential by-pass receptor site

The deep plantar artery is the main anastomosis between the dorsal and plantar arterial systems of the foot; with no change of calibre it unites the dorsalis pedis artery to the deep plantar arch, the second segment of the lateral plantar artery, passing into the first intermetatarsal space. Our anatomic study of 20 dissections of the deep plantar artery allowed us to verify the near-constancy of its descriptive anatomy and relationships. The deep plantar artery, when present, only found in 16 of our 20 cases, is totally linked to the dorsalis pedis artery. Its easy accessibility via the dorsal route, its medium calibre and the absence of collateral branches make this artery a possible anatomic site for the performance of a distal bypass, the last option before an amputation of the foot becomes necessary, although such a case remains exceptional.

[The retro-auricular, transmastoid, infralabyrinth approach. A simple route for excision of tumors of the jugular foramen]

BACKGROUND

The jugular foramen is a complex area of the skull base. Its contents, the anatomical relationships in the region, and its location at the skull base, are responsible for problematic surgical approaches. The classical infratemporal surgical routes remain complex and difficult to perform. The lateral approach through a mastoidectomy is almost always associated with an anterior transposition of the facial nerve although that transposition is usually unnecessary.

METHODS

Progressive drilling along the sinusojugular axis, inferior to the labyrinth and medial to the third portion of the facial nerve, combined with a simple neck dissection, allows the surgeon to nicely expose the jugular foramen. The surgical procedure is described, following a brief anatomical reminder of the essential relationships in the area. A clinical observation is used to illustrate the purpose.

RESULTS

Most schwannomas of lower cranial nerves and small glomus jugulare tumors should be resected using this approach, which is a simplified lateral approach, without post operative facial palsy or cophosis.

CONCLUSIONS

The infralabyrinthine approach is a simple way to expose the jugular foramen region compared with infratemporal complex and time-consuming approaches.

An anatomical study of the motor distribution of the mandibular nerve for a masseteric-facial anastomosis to restore facial function

On account of the complex anatomy at the base of skull, surgery here may result in post operative cranial n. deficits. Facial palsy is often feared and its effects upon the patient's psychological and emotional well-being can be catastrophic. The modest results and the side effects of the facio-hypoglossal anastomosis used for facial rehabilitation have led us to consider an anastomosis between a motor branch of the trigeminal n. and the facial n. Dissection has allowed us to demonstrate that the masseteric n. offers the characteristics and the relationships which should make such an anastomosis feasible.

Anastomosis between the internal carotid and vertebral artery in the neck

We report a case of anastomosis between the internal carotid and vertebral a. in the cervical region. This anatomic variation is due to incomplete migration during embryogenesis of the branchial aa., collaterals of the dorsal aorta, towards the ventral aorta. It does not involve persistence of a type I proatlantal a., as described by Lasjaunias. Such anastomoses must be recognised since they may modify surgical tactics in the context of endarterectomy for carotid stenosis.

Reconstruction of the aortic arches of a 28-day human embryo (stage 13) using the Born technique

We present a reconstruction of the aortic arches of a human embryo at stage 13. Only a few original observations have been reported during the last 110 years and only two with three-dimensional reconstructions. The reconstruction technique originated in 1885. Modern computerized reconstruction techniques have no evident advantages and are more expensive. Aortic arch malformations are responsible for disorders which cannot be understood without a knowledge of their embryology. The embryonic aortic system is a typical example of Haeckel's law of recapitulation. A human embryo at stage 13 was prepared in 5 mm sagittal sections so as to reconstruct the entire dorsal aorta, the second (transient) arch, the third and fourth arches, and the sixth arches responsible for the pulmonary artery, pharynx, larynx and tracheoesophageal axis. They are only 5 pairs of arches in man. At this stage, the most important vessel is represented by the dorsal aorta with a cerebral route, due to predominance of the development of the central nervous system and its vascularisation over other organs. Vascularisation of the lower limbs appears before their macroscopic development and is probably one of the factors responsible for their growth. Many such reconstructions are necessary if conclusions are not to be based on too few specimens to be sound. A better knowledge of embryology lead to a new understanding of aortic arch malformations.

[Epidural hematoma. Myth and reality, based on 3 exemplary cases]

The acute epidural hematoma is a real surgical emergency with a good outcome if the operation is performed in reasonable delays. In 1994, too many young patients eventually died or were left with major disabilities, because of an unacceptable and almost always avoidable loss of time. We do emphasize some rules which have to be followed to avoid catastrophic events.

Surgical anatomy and dissection of the petrous and peripetrous area. Anatomic basis of the lateral approaches to the skull base

The purpose of this study is to review the topographic anatomy of the petrous and peripetrous structures, with emphasis on the relationships important to the lateral approaches to the posterior and lateral skull base. Surgical exposure of the clivus, the posterior aspect of the petrous bone, the ventral aspect of the brain stem, and of all the intradural structures in the area, remains difficult because of the presence of the so-called "petrous and peripetrous complex". However, the lateral approach to the skull base is the most suitable approach if the lesion lies lateral to the cavernous portion of the internal carotid artery, and of course if the lesion develops laterally behind the petrous apex. Consequently, neurosurgeons should be familiar with the anatomy of the intrapetrous cavities and their contents, and with the relationships in the area. Middle cranial fossa dissections (dry and fresh specimens) allow us to study the anatomical relationships between the intrapetrous carotid artery, the facial nerve, the porus, the cochlea, the geniculate ganglion and the petrosal nerves, the trigeminal ganglion and nerve, the auditory tube and the middle ear. While briefly reviewing some approaches (anterior petrosectomy, sub-temporal preauricular infratemporal fossa approach, pre-sigmoid approach), we explore the concept of the approach and the limitations of surgical technique and exposure.