The lateral sellar nerve plexus and its connections in humans

Gross and Micro-Anatomical Study of the Cavernous Segment of the Abducens Nerve and Its Relationships to Internal Carotid Plexus: Application to Skull Base Surgery

The present study aims to provide detailed observations on the cavernous segment of the abducens nerve (AN), emphasizing anatomical variations and the relationships between the nerve and the internal carotid plexus. A total of 60 sides underwent gross-anatomical study. Five specimens of the AN were stained using Sihler’s method. An additional five specimens were subjected to histological examination. Four types of AN course were observed: a single nerve along its entire course, duplication of the nerve, division into separate rootlets at the point of contact with the cavernous part of the internal carotid artery (ICA), and early-branching before entering the orbit. Due to the relationships between the ICA and internal carotid plexus, the cavernous segment of the AN can be subdivided into a carotid portion located at the point of contact with the posterior vertical segment of the cavernous ICA and a prefissural portion. The carotid portion of the cavernous AN segment is a place of angulation, where the nerve always directly adheres to the ICA. The prefissural portion of the AN, in turn, is the primary site of fiber exchange between the internal carotid plexus and either the AN or the lateral wall of the cavernous sinus.

Tolosa-Hunt Syndrome: Long-Term Outcome and Role of Steroid-Sparing Agents

Background:

Tolosa-Hunt Syndrome (THS) is one of the causes of cavernous sinus syndrome causing painful ophthalmoplegia. Literature on long-term outcome of this rare condition is scarce.

Aims and Objectives:

The aim is to study the recurrence and role of steroid-sparing agents in THS.

Methodology:

All cases of THS treated at a tertiary-level teaching hospital during a 10-year period were studied. Clinical and radiological profile, response to treatment and recurrences were noted.

Results:

A total of 44 cases were studied. The mean age was 49.5 years, Males constituted 23/44 (52%). The first symptom was pain in 90%. Ptosis with ophthalmoplegia was the most common deficit 29/44 (66%). Lesions confined to cavernous sinus 27/44 (61%) was the most frequent magnetic resonance imaging finding. All patients received steroids as the initial treatment and 15/44 (34%) received steroid-sparing agents. Follow-up ranged from 6 to 120 months (Mean 39 months). Two patients had alternative diagnosis of leptomeningeal malignancy and hypertrophic pachymeningitis on follow-up. Recurrences occurred in 18/37 (48.6%). Time for recurrence varied from 8 months to 7 years. (Mean 18 months). No clinical or radiological predictors for recurrence were identified. Patients who received steroid-sparing agents had a significantly lower recurrence 3/15 (20%) versus 14/26 (53.8%)P < 0.034.

Conclusions:

Around 50% of patients with THS can have recurrence. Steroid-sparing agents appear to prevent recurrence. A prospective multicenter randomized controlled trial may help to evaluate the risk and benefits of steroid-sparing therapy and to identify any possible predictors for recurrence.

Superior Cerebellar Artery Aneurysms Causing Facial Pain: A Comprehensive Review

BACKGROUND

Trigeminal neuralgia caused by superior cerebellar artery aneurysms (TGN-SCAAs) is a rare event without previous analysis.

OBJECTIVE

To describe the features of TGN-SCAA based on 8 cases (7 from literature +1 illustrative case).

METHODS

All cases were thoroughly studied with gathering of their epidemiological, radiological, clinical, therapeutic, and outcome data.

RESULTS

The mean age at diagnosis was 61 yr. Gender distribution showed a female predominance (M: F = 2:6). Side distribution had a left dominance (75%). The aneurysms mean size was 15.4 mm (range: 5-27). All 5 proximal SCAAs (SCA-Basilar junction) presented a lateral-posterior projection, while all 3 distal SCAAs (s2 segment) had variable projections but constant direct trigeminal nerve (TN) contact. No hemorrhage occurred. TGN was the clinical onset in all 8 cases. The most frequent pain distribution was V1-2-3 (n = 3), followed by V1-2 (n = 1) and V1 alone (n = 1). Proximal SCAAs caused TGN through direct TN compression (n = 1), third nerve compression (n = 1), cavernous sinus compression (n = 1), or a combination thereof (n = 2). However, all distal SCAAs caused TGN by direct TN compression (n = 3). Two different treatment options were used: clipping (n = 4) and coiling (n = 4). The post-treatment Barrow Neurological Institute score for pain control was I in all cases (100%). The mRS score was 0 in 75% of cases.

CONCLUSION

TGN-SCAAs are infrequent lesions, characterized by large size, variable TGN mechanisms depending on their anatomic location, and mostly affecting the first and second trigeminal divisions. Both SCAA clipping and coiling were used equally, providing good neurological and pain relief results.

Supraorbital Nerve and Cavernous Sinus Invasion with Poorly Differentiated Carcinoma of Unknown Primary

A 50-year-old man presented with a 4-month history of right-sided trigeminal neuropathy in the V1 and V2 distribution, right sixth nerve palsy and Horner syndrome. Magnetic resonance imaging (MRI) showed enhancement and thickening along the right ophthalmic nerve and supraorbital nerve and fullness at the right cavernous sinus extending to Meckel's cave. Evaluation for a primary tumour was negative. Cavernous sinus biopsy showed infiltrating poorly differentiated carcinoma; the patient underwent radiation therapy. To our knowledge this is the only case of poorly differentiated carcinoma involving the supraorbital nerve presenting with trigeminal neuropathy and Horner syndrome in the English ophthalmic literature.

Collision tumors composed of meningioma and growth hormone-secreting pituitary adenoma in the sellar region: Case reports and a literature review

RATIONALE

Collision tumor is a rare disease that represents the coexistence of two histologically distinct neoplasms in the same area without histological admixture or an intermediate cell population zone. To our best knowledge, 13 cases besides our 2 cases have been reported till now, and our report represents the first publication regarding a collision tumor composed of growth hormone (GH)-secreting pituitary adenoma and sellar meningioma.

PATIENT CONCERNS

We collected two cases of collision tumors composed of meningioma and GH-secreting adenoma in the sellar region from 2014 to 2015 at Peking Union Medical College Hospital (PUMCH).

DIAGNOSIS

Two cases were diagnosed with solid sellar tumors, and two tumor types were suspected with magnetic resonance imaging (MRI). Blood hormone tests revealed increased insulin-like growth factor 1 (IGF-1) and GH levels.

INTERVENTIONS

Both cases underwent transsphenoidal microsurgical resection of pituitary adenoma.

OUTCOMES

The tumor was completely resected, and the pathological examination after the operation revealed meningioma and GH-secreting pituitary adenoma.

LESSONS

Collision tumors consisting of pituitary adenomas with other sellar neoplasms are rare. Histological examination is necessary because preoperative studies cannot guarantee an accurate diagnosis. If a collision tumor is suspected prior to operation, a craniotomy may need to be considered before other operation methods to avoid reoperation.

Posterior communicating artery aneurysms causing facial pain: A comprehensive review

Posterior communicating aneurysms are commonly associated with oculomotor nerve palsy. However, trigeminal nerve involvement among these aneurysms is a rare event with no previous analysis. In order to describe the main features of posterior communicating aneurysms causing trigeminal neuralgia (TGN-PComAAs) eight cases (six from the literature plus two more illustrative cases) were included in the present series. All cases were thoroughly studied in order to collect their epidemiological, radiological, clinical, therapeutic, pathogenic, and outcome data. The mean age at diagnosis was 57 years. Gender distribution showed a female predominance (M-to-F ratio 3:5), while side distribution showed a slight left dominance (62%). The aneurysms mean size was 24.7mm (range: 7-40mm). In 7 cases (87.5%) the PComAA was reported to project posteriorly, associated with cavernous sinus extension/compression in two of them and posterior fossa extension in three. No case presented with hemorrhage. Facial pain was the clinical onset in all eight cases, which was reported as an atypical TGN (continuous with exacerbating fits) in 87.5%. Trigger points were absent in all cases but one (87.5%). The most frequent anatomical distribution of the pain was V2 alone (n=3), followed by V1-2 (n=2) and V1-2-3 (n=2). Three different mechanisms for trigeminal neuralgia were observed, namely, cavernous sinus compression (n=4), direct trigeminal root compression (n=3), and oculomotor nerve compression (n=1). Three different treatment options were performed: surgery (n=6), trigeminal thermo-rhizotomy (n=1) and medical management (n=1). According to the Barrow Neurological Institute (BNI) score the pain control after main treatment was I (no pain with no medication) in 7 cases (87.5%). The average modified Rankin scale (mRS) score was 1. In sum, TGN-PComAAs are infrequent lesions characterized by large size and posterior-medial-inferior projection. They mainly cause atypical TGN, most commonly involving the first and second trigeminal distributions (V1-V2). Surgical aneurysmal clipping has been the most frequent treatment option for these aneurysms, providing good neurological results in a vast majority and complete trigeminal pain relief in all cases.

Computed tomography and magnetic resonance imaging findings of intrasellar schwannoma: A case report and literature review

Intrasellar schwannoma is extremely rare, and only a few cases have been reported in the literature to date. In the present study, the clinical, radiological and pathological features of a 50-year-old male patient with primary intrasellar schwannoma are presented. The patient presented with decreased visual acuity, and a subsequent computed tomography (CT) scan revealed a giant well-demarcated intrasellar mass with suprasellar extension, without cavernous sinus invasion. The lesion was slightly hyperdense with heterogeneous enhancement. On magnetic resonance imaging (MRI), the mass was isointense on T1 weighted images (WI), and slightly hyperintense on T2WI, with significant heterogeneous enhancement. Previous literature was reviewed to summarize the CT and MRI characteristics of intrasellar schwannoma. Despite the rarity of this tumor, intrasellar schwannoma must be included in the differential diagnosis of intrasellar lesions.

Hard calcified intrasellar schwannoma mimicking pituitary adenoma: a case report and review of the literature

BACKGROUND

Intrasellar location of schwannoma is extremely rare, although intracranial schwannomas are common in the central nervous system. The aim of the present study is to describe a calcified intrasellar schwannoma case.

MATERIALS AND METHODS

We represent a 45-year-old woman who had suffered from headaches; right side facial pain and visual disturbance which had worsen during the last week prior to admission. Physical examinations were normal except for the bitemporal visual field hemianopia which match with perimetry examination. MRI demonstrated an unusual seemingly calcified mass lesion in the sellar region which was mimicking pituitary macro adenoma.

RESULT

Total resection of the tumor achieved through endoscopic transnasal transsphenoidal approach by extracapsular dissection and pathologic examination of the tumor revealed calcified schwannoma.

CONCLUSION

The differential diagnoses of sellar and suprasellar lesions include pituitary adenomas, craniopharyngiomas, meningiomas, and many others. However, schwannoma is not usually included, because the occurrence of schwannoma in the sellar or suprasellar region is extremely rare. Only few cases of intrasellar schwannomas have been reported in the literature, all of which presented a suprasellar extension similar to that of our case. Fascinating surgical point is managing very firm tumor through transsphenoidal corridor which we handle it by very sharp, debulking and extracapsular removal.

Configuration of fibrous and adipose tissues in the cavernous sinus

Objective

Three-dimensional anatomical appreciation of the matrix of the cavernous sinus is one of the crucial necessities for a better understanding of tissue patterning and various disorders in the sinus. The purpose of this study was to reveal configuration of fibrous and adipose components in the cavernous sinus and their relationship with the cranial nerves and vessels in the sinus and meningeal sinus wall.

Materials and Methods

Nineteen cadavers (8 females and 11 males; age range, 54–89 years; mean age, 75 years) were prepared as transverse (6 sets), coronal (3 sets) and sagittal (10 sets) plastinated sections that were examined at both macroscopic and microscopic levels.

Results

Two types of the web-like fibrous networks were identified and localized in the cavernous sinus. A dural trabecular network constituted a skeleton-frame in the sinus and contributed to the sleeves of intracavernous cranial nerves III, IV, V₁, V₂ and VI. A fine trabecular network, or adipose tissue, was the matrix of the sinus and was mainly distributed along the medial side of the intracavernous cranial nerves, forming a dumbbell-shaped adipose zone in the sinus.

Conclusions

This study revealed the nature, fine architecture and localization of the fine and dural trabecular networks in the cavernous sinus and their relationship with intracavernous cranial nerves and vessels. The results may be valuable for better understanding of tissue patterning in the cranial base and better evaluation of intracavernous disorders, e.g. the growth direction and extent of intracavernous tumors.

Neurochemical Characterization of Pterygopalatine Ganglion Branches in Humans

Background

Pterygopalatine ganglion (PPG) branches, seem to be involved in the pathophysiology of facial pain. The functions of these branches, including a recently discovered orbital branch, are not completely known but could be of clinical significance. This study was designed to characterize PPG branches through immunohistochemical stain and study their anatomy, specifically the orbital branches.

Methods

In a cadaver study of four specimens, the pterygopalatine fossa (PPF) was dissected out of its bony surroundings as a tissue block. Subsequently, cryostat sectioning of these blocks was performed. In one specimen the PPF was microscopically dissected. Recently discovered neural structures were identified, dissected out of the tissue block, and cryosectioned. All cryostat sectionings were immunohistochemically stained for protein gene product (PGP) 9.5, nitric oxide synthase (NOS), and tyrosine hydroxylase (TH).

Results

A recently discovered neural connection between the PPG and the ophthalmic nerve could be confirmed and classified as an orbital PPG branch. The connection stained throughout for PGP 9.5 and partially stained for NOS. In other orbital branches, both NOS and TH+ nerve fibers were found. The PPG contained NOS+ cells. TH labeling was also found in nerve fibers running through the PPG and the vidian nerve.

Conclusion

The recently discovered orbital PPG branch is of a mixed parasympathetic and sensory nature. In the other orbital branches, sympathetic fibers were shown as well. This knowledge may add to understanding the symptomatology and therapies of headache syndromes such as nerve block.

A Previously Undescribed Branch of the Pterygopalatine Ganglion

Background

Endonasal and infrazygomatic pterygopalatine ganglion (PPG) block for facial pain provides pain relief in a broader area than expected on anatomic grounds. The aim of this study was to search for neural structures in the pterygopalatine fossa (PPF) that could explain unexpected pain relief after PPG blockage.

Methods

The neural PPF content was explored through human cadaver study and nerve-specific staining. Five human PPF specimens were dissected as whole-mount preparations with the aid of an operation microscope and stained for acetylcholinesterase. One of these specimens was partially sectioned and analyzed through nitric oxide synthase (NOS) immunohistochemistry.

Results

A previously unknown nerve was identified. The nerve runs between the PPG and the ophthalmic nerve and was identified in all five specimens. NOS-containing nerve fibers were present but did not occupy the complete nerve area.

Conclusion

Because it is likely that the nerve contains sensory fibers, our findings may provide an anatomic basis for unexplained pain relief in the ophthalmic area after PPG blockage.

Biological sciences related to headache

Headache can occur as a result of activation of pain-sensitive cranial structures, such as the dura mater, vasculature, and the cranial and cervical muscles and ligaments, which are innervated by primary afferent neurons originating from the trigeminal and dorsal root ganglia of the upper cervical spinal nerves. Similar to general nociceptive sensation, C fibers and Adelta fibers are known to play an important role in headache perception. Findings from nerve stimulation studies indicate that C fibers transmit aching, throbbing, or burning pain that builds up slowly, whereas the Adelta fibers conduct sharper initial pain sensation. These primary afferent nerve fibers transmit nociceptive information from the pain-sensitive endings in the cranial structures through the trigeminal and first and second spinal dorsal root ganglia to the brainstem at the pontine level. The nociceptive fibers then project to the central pain-conducting pathways at the spinal trigeminal nucleus. In this chapter, we discuss the anatomy in relation to headache, including the meninges, dural sinuses, blood vessels, sensory ganglia, cranial and neck muscles, and the central pain-conducting pathways.

Collision sellar lesions: experience with eight cases and review of the literature

The concomitant presence of a pituitary adenoma with a second sellar lesion in patients operated upon for pituitary adenoma is an uncommon entity. Although rare, quite a great variety of lesions have been indentified coexisting with pituitary adenomas. In fact, most combinations have been described before, but an overview with information on the frequency of combined pathologies in a large series has not been published. We present a series of eight collision sellar lesions indentified among 548 transsphenoidally resected pituitary adenomas in two Neurosurgical Departments. The histological studies confirmed a case of sarcoidosis within a non-functioning pituitary adenoma, a case of intrasellar schwannoma coexisting with growth hormone (GH) secreting adenoma, two Rathke's cleft cysts combined with pituitary adenomas, three gangliocytomas associated with GH-secreting adenomas, and a case of a double pituitary adenoma. The pertinent literature is discussed with emphasis on pathogenetic theories of dual sellar lesions. Although there is no direct evidence to confirm the pathogenetic relationship of collision sellar lesions, the number of cases presented in literature makes the theory of an incidental occurrence rather doubtful. Suggested hypotheses about a common embryonic origin or a potential interaction between pituitary adenomas and the immune system are presented.

Intra-sellar schwannoma co-existing with GH-secreting pituitary adenoma

BACKGROUND

We present a unique example of an intra-sellar schwannoma co-existing with a growth hormone (GH)-secreting pituitary adenoma.

METHOD AND FINDINGS

The patient presented with acromegaly and magnetic resonance imaging (MRI) revealed an intra-sellar mass. The tumour was totally resected via a sub-labial trans-sphenoidal approach. Histopathology demonstrated the presence of a GH-secreting adenoma as well as a schwannoma at the periphery of the adenoma. After surgical excision, remission of the acromegaly occurred. Follow-up monitoring showed no evidence of recurrence of the adenoma two years after surgery.

CONCLUSION

To the best of our knowledge, this is the first example of an intra-sellar schwannoma co-existing with a GH-secreting pituitary adenoma.

Primary intrasellar schwannoma: clinical, aetiopathological and surgical considerations

Schwannomas originating within the sella turcica are extremely rare. We describe the clinical, radiological and intraoperative findings of a patient with an intrasellar and suprasellar schwannoma. Gross total tumour removal was performed by a trans-sphenoidal approach. Perivascular or ectopic Schwann cells, lateral nerve plexus within the cavernous sinus, as well as Schwann cells from small nerve twigs of the dura are some of the current histopathological hypotheses for the origin of these lesions.

Intra-suprasellar schwannoma originating from the diaphragma sellae

A 49-year-old woman presented with headache, vomiting and visual disturbance. Neurological examination revealed bitemporal hemianopsia with poor visual acuity. Magnetic resonance imaging showed a bulky intra-suprasellar mass, which was isointense with brain parenchyma on T1-weighted images, and slightly hyperintense on T2-weighted images. After gadolinium administration, the mass was homogeneously enhanced. The mass was partially removed by the endonasal transsphenoidal approach and then the remnant mass was totally removed by the transcranial approach five months later. We found a yellowish mass which was attached to the diaphragm sellae in operation field. Histopathological examination of the tumor revealed the characteristic features of a schwannoma. We report an unusual case of an intra-suprasellar schwannoma resembling a non-functioning pituitary macroadenoma both clinically and radiologically.

Human orbital sympathetic nerve pathways

PURPOSE

To determine pathways of sympathetic nerves from the orbital apex to the eyelids in human cadaver tissue using immunohistochemistry.

METHODS

Human cadaver orbit tissue was sectioned and immunolabeled with a monoclonal antityrosine hydroxylase antibody.

RESULTS

In the orbital apex, the nasociliary, frontal, lacrimal, and maxillary branches of the trigeminal nerve demonstrated intense staining upon entering the orbit. Immunoreactive axons from the nasociliary and frontal nerves were observed to join the extraocular motor nerves in the posterior orbit. A plexus of immunolabeled nerves was observed to accompany the ophthalmic artery as it entered the orbital apex. The ophthalmic artery and its branches throughout the orbit demonstrated staining of nerve fibers in the peripheral muscularis. The nasociliary nerve contributed sympathetic branches to the ciliary ganglion. Nerves passing through the ciliary ganglion and a few ganglion cell bodies demonstrated mild to moderate tyrosine hydroxylase reactivity. Axons within the short and long ciliary nerves demonstrated strong tyrosine hydroxylase reactivity and were observed to enter the posterior sclera and the suprachoroidal space. The lacrimal gland demonstrated mild pericapillary staining and occasional stromal nerve fibers reactive to the antityrosine hydroxylase antibody. Müller muscle and the inferior tarsal muscle possessed a strong tyrosine hydroxylase-reactive nerve supply that appeared to originate from the anterior terminal branches of the nasociliary and lacrimal nerves.

CONCLUSIONS

Sympathetic nerves enter the orbit via the first and second divisions of the trigeminal nerve and a plexus of nerves surrounding the ophthalmic artery. Extraocular motor nerves receive a sympathetic nerve supply from the sensory nerves in the posterior orbit. Some ciliary ganglion cell bodies demonstrated tyrosine hydroxylase-like reactivity, suggesting a sympathetic modulatory role for the ciliary ganglion. Sympathetics innervate ocular structures via the posterior ciliary nerves. Sympathetic axons travel anteriorly in the orbit via the nasociliary and lacrimal nerves to innervate the sympathetic eyelid muscles. Sympathetic nerves also travel with the frontal branch of the ophthalmic nerve to innervate the forehead skin. The ophthalmic artery and all of its branches contain a perivascular sympathetic nerve supply that may be involved in regulation of blood flow to ocular and orbital structures.

A 61-year-old man with hyponatremia

The case of a 61-year-old man presenting with dizziness, nausea, vomiting, reduced serum osmolality, and hyponatremia is reported. Endocrinologically, low levels for ADH, cortisol and testosterone as well as low-normal values for ACTH, LH and FSH were detected. Cranial computed tomography and MRI scans revealed an intra- and suprasellar tumor of adenoma-like appearance with elevation of the optic chiasm. No infiltration of the cavernous sinus was seen. After transsphenoidal resection of the tumor, no additional anterior lobe insufficiencies or diabetes insipidus occurred. Histological examination revealed a tumor consisting of spindle-shaped cells of uniformly high cellularity with no evidence of hypocellular areas. A cellular schwannoma was diagnosed. An intrasellar cellular schwannoma clinically and radiologically mimicking a non-secreting pituitary adenoma is uncommon. However, rare entities like schwannomas, melanocytomas or pituicytomas have to be considered in addition to the more common tumors like pituitary adenomas and meningiomas.

Intrasellar malignant peripheral nerve sheath tumor (MPNST)

Intracranial malignant peripheral nerve sheath tumors (MPNST) and intrasellar schwannomas are rare tumors. We describe a case of an intrasellar schwannoma with progression to a MPNST, a finding that, although very rare, extends the differential diagnosis of intrasellar lesions.

Innervation of the wrist joint and surgical perspectives of denervation

PURPOSE

Because our experience with the techniques used in denervation surgery of the wrist joint often has proven insufficient in treating chronic pain we conducted an anatomic study to clarify the exact contributions of the nerves supplying the wrist joint. Our goal was to reveal all periosteal and capsular nerve connections and if necessary adjust our technique used in denervation surgery.

METHODS

Innervation of the wrist joint was investigated by microdissection and histologic examination of 18 human wrists. An acetylcholinesterase method was used to identify the nerves, both in whole-mount preparations and in sections.

RESULTS

We found that the main innervation to the wrist capsule and periosteal nerve network came from the anterior interosseous nerve, lateral antebrachial cutaneous nerve, and posterior interosseous nerve. The palmar cutaneous branch of the median nerve, the deep branch of the ulnar nerve, the superficial branch of the radial nerve, and the dorsal branch of the ulnar nerve also were found to have connections with the capsule. The periosteal nerve branches did not appear to play a major role in the innervation of the capsule and ligaments; here the specific articular nerve branches proved more important. The posterior and medial antebrachial cutaneous nerves did not connect to the wrist capsule or periosteum but rather terminated in the extensor and flexor retinaculum.

CONCLUSIONS

Based on our findings we propose to denervate the wrist by making 2 incisions. With one palmar and one dorsal incision it should be possible to disconnect the periosteum from the capsule and interrupt the majority of the capsular nerve branches.

Raeder's syndrome after embolization of a giant intracavernous carotid artery aneurysm: pathophysiological considerations

We present the case of a 47 years old woman submitted to an endovascular trapping of a left cavernous internal carotid artery aneurysm, in which the distal balloon was inflated, as usually done, within the cavernous segment of the internal carotid artery, different from the proximal one which was inflated inside the carotid canal due to technical problems. Consequently, a clinical picture of Raeder's paratrigeminal neuralgia took place. This is the first case report in the literature with theses characteristics. A review of the anatomic pathways and further considerations about the possible pathophysiological mechanisms involved are presented.

Demonstration of PACAP-immunoreactive intrapineal nerve fibers in the golden hamster (Mesocricetus auratus) originating from the trigeminal ganglion

By using immunohistochemistry, a network of nerve fibers containing pituitary adenylate-cyclase activating polypeptide (PACAP) was demonstrated in the pineal gland of the golden hamster, a photoperiodic species often used in pineal and circadian rhythm research. The nerve fibers are present in the capsule from where they permeate into the pineal perivascular spaces and parenchyma. Immuno-electron microscopy showed the PACAPergic nerve terminals, with clear transmitter vesicles, to terminate in the interstitial spaces between the pinealocytes or in the perivascular spaces. Some of the PACAPergic nerve terminals made synapse-like contacts with the pinealocytes. The origin of the PACAP-containing nerve fibers innervating the pineal gland of the hamster was investigated by combined retrograde tracing with fluorogold and immunohistochemistry for PACAP. A 2% fluorogold solution was injected iontophoretically into the superficial pineal gland and the animals were allowed to survive for 1 wk. After perfusion fixation of the rats, the location of the tracer was investigated in the brain, the parasympathetic sphenopalatine, and otic ganglia, as well as in the sensory trigeminal ganglia. The tracer was found in perikarya of all the investigated ganglia. However, co-localization with PACAP was found only in the trigeminal ganglion.

Immunohistochemical determination of the sympathetic pathway in the orbit via the cranial nerves in humans

Object.The present study was undertaken to elucidate the extent and precise distribution of the postganglionic sympathetic fibers in the cranial nerves projecting to the orbit and to reconstruct sympathetic routes in the orbit in humans. For this purpose, the authors made an immunohistochemical determination of the sympathetic fibers by using an antibody against norepinephrine-synthetic enzyme, tyrosine hydroxylase (TH).

Methods.Specimens containing the orbit and the cavernous sinus were obtained from formalin-fixed human cadavers. First, it was confirmed that the superior cervical ganglion contained strongly immunostained TH-positive neuronal cell bodies and fibers. After careful dissection of the cranial nerves projecting to the orbit, different segments of each cranial nerve were processed for immunohistochemical analysis for TH. All of the intraorbital cranial nerves contained TH-positive sympathetic fibers, although the amounts were very different in each cranial nerve. At the proximal site of the common tendinous ring, TH-positive fibers were found mainly in the abducent and trochlear nerves. At the distal site of this ring, TH-positive fibers were lost or markedly reduced in number in the abducent and trochlear nerves and were distributed mostly in the ophthalmic and oculomotor nerves. Among the cranial nerves projecting to the orbit, the ophthalmic nerve and its bifurcated nerves—frontal, lacrimal, and nasociliary—contained numerous TH-positive fibers.

Conclusions.The authors conclude that the postganglionic sympathetic fibers are distributed to all cranial nerves projecting to the orbit and that the ophthalmic nerve provides a major sympathetic route in the orbital cavity in humans.

The effects of the electrical stimulation of the nasal mucosa on cortical cerebral blood flow in rabbits

The cerebral vessels have sympathetic, parasympathetic, and sensory innervations. A sensory innervation of the cerebral vessels originating in the trigeminal ganglion has been described in a number of species by several investigations. It has been shown that the electrical stimulation of the trigeminal ganglion causes an increase of cerebral blood flow (CBF). The aim of our present study is to stimulate the trigeminal ganglion with an extracranial and non-invasive method. A stimulating electrode was put in the nasal mucosa via right nares of rabbits and trigeminal ganglion was stimulated orthodromically via nasociliary nerve (NCN). Variations in the cortical CBF were evaluated by laser Doppler flowmetry. In experiment group, CBF increased together with the beginning of electrical stimulation. The flow values were remained high as long as the stimulation. In post-stimulation period, the CBF was decreased gradually and returned to the baseline values at 120s. This study demonstrated that the electrical stimulation of the NCN branch of the trigeminal nerve increases the cortical CBF under physiological conditions.

Intrasellar Schwannomas: Report of Two Cases

OBJECTIVE AND IMPORTANCE

The complex regional anatomic features surrounding the sella turcica make the differential diagnosis of intrasellar and parasellar lesions complicated. Sellar and parasellar schwannomas are rare. With the exclusion of parasellar schwannomas arising from cranial nerves within the cavernous sinus and extending into the sella, there have been only two reported cases of true intrasellar schwannomas.

CLINICAL PRESENTATION

We describe the clinical, radiological, and pathological features of two cases in which the histopathological diagnosis of schwannoma was confirmed with immunohistochemical analyses and/or electron microscopy.

INTERVENTION

The two cases were grossly resected via a transsphenoidal approach. Follow-up monitoring revealed no evidence of recurrence.

CONCLUSION

Schwannomas may atypically occur in the sellar region, in which they demonstrate the typical light microscopic, immunohistochemical, and ultrastructural features observed in the peripheral nervous system. New and existing hypotheses regarding the histopathogenesis of intrasellar and parasellar schwannomas are presented.

Internal carotid plexus schwannoma of the cavernous sinus: case report

OBJECTIVE AND IMPORTANCE

Schwannomas of the central nervous system usually originate from the vestibular nerve and occasionally originate from the trigeminal nerve. Sympathetic plexus schwannomas are extremely rare and have never been noted within the cavernous sinus.

CLINICAL PRESENTATION

A 23-year-old man experienced occasional double vision for a period of 6 months. Magnetic resonance imaging studies revealed an isointense lesion, with enhancement after gadolinium administration, located inferomedial to the internal carotid artery within the left cavernous sinus.

INTERVENTION

We explored the cavernous sinus via a left-sided extradural-pterional approach and found the tumor inferomedial to the cavernous segment of the internal carotid artery. Microsurgical gross total resection of the tumor was performed. The IIIrd (oculomotor) to VIth (abducens) cranial nerves within the cavernous sinus were not related to the tumor and were preserved. The operative findings and the anatomic location of the tumor demonstrated that it originated from the internal carotid plexus within the cavernous sinus. The patient's postoperative course was uneventful, and he exhibited no cranial nerve deficits. However, incomplete Horner's syndrome was present on the treated side.

CONCLUSION

We present the first reported case of an internal carotid plexus schwannoma, and we describe in detail its anatomic and neuroradiological characteristics. The microneurosurgical resection of this unusual tumor within the cavernous sinus was successful and without morbidity.