Chronic migraine-cephalgia related to trigeminal artery: a case report of innovative regenerative approach

Persistent trigeminal artery (PTA) originates from the posterior bend or lateral wall of the intra-cavernous carotid artery and is the most common occurring type of remnant primitive fetal arteries. In literature, there is limited number of reports on migraine-cephalgia (MC) associated with coexisting PTA. The primitive anastomose arteries that fully belong to the intracranial arterial vascular system are not supposed to perform any supportive functional activity; usually they are subjected to normal biological decay caused by the aging process and metabolic dysfunctions. The hypothesis suggests that these primitive fetal arteries such as PTA may not undergo a fast and structural deterioration but they might be active contributors to a series of mechanisms that can cause a variety of idiopathic complaints. Consequently this would bring a different therapeutic approach other than their surgical removal, which is the accepted option today as a solution for these problems. In this case report, a chronic unilateral MC due to coexisting PTA adjacent to trigeminal nerve is presented. The caliber and location of the PTA was confirmed by a CT-Angiography. The MC treatment was achieved by administration of bio-identical testosterone, human placenta extract (HPE), b-nicotinamide adenine dinucleotide (NADH) and low dose amlopidine.

Sympathetic reinnervation of peripheral targets following bilateral axotomy of the adult superior cervical ganglion

The ability of adult injured postganglionic axons to reinnervate cerebrovascular targets is unknown, yet these axons can influence cerebral blood flow, particularly during REM sleep. The objective of the present study was to assess quantitatively the sympathetic reinnervation of vascular as well as non-vascular targets following bilateral axotomy of the superior cervical ganglion (SCG) at short term (1 day, 7 day) and long term (8 weeks, 12 weeks) survival time points. The sympathetic innervation of representative extracerebral blood vessels [internal carotid artery (ICA), basilar artery (BA), middle cerebral artery (MCA)], the submandibular gland (SMG), and pineal gland was quantified following injury using an antibody to tyrosine hydroxylase (TH). Changes in TH innervation were related to TH protein content in the SCG. At 7 day following bilateral SCG axotomy, all targets were significantly depleted of TH innervation, and the exact site on the BA where SCG input was lost could be discerned. Complete sympathetic reinnervation of the ICA was observed at long term survival times, yet TH innervation of other vascular targets showed significant decreases even at 12 weeks following axotomy. The SMG was fully reinnervated by 12 weeks, yet TH innervation of the pineal gland remained significantly decreased. TH protein in the SCG was significantly decreased at both short term and long term time points and showed little evidence of recovery. Our data demonstrate a slow reinnervation of most vascular targets following axotomy of the SCG with only minimal recovery of TH protein in the SCG at 12 weeks following injury.

Effective surgical treatment of the carotid sinus sindrome

Elderly patients frequently suffer from dizziness and syncope; however, an underlying disease may not always be identified. Three patients aged 69, 71 and 56, respectively, experienced spells of dizziness and syncope. Massage of the carotid sinus demonstrated the presence of a carotid sinus syndrome (CSS), an abnormal baroreflex response of the carotid sinus that leads to asystole and extreme hypotension. Conventional treatment is generally by insertion of a pacemaker. These patients, however, were referred to the vascular surgery department of our hospital for removal of adventitial layers of proximal portions of the internal carotid artery. Recovery was uneventful; all three are now free of symptoms. CSS should be considered in the differential diagnosis of dizziness and syncope. Surgical denervation of the carotid artery is a valid treatment option, especially in the vasodepressive or mixed type of CSS.

Anatomical variations of the common carotid artery bifurcation

BACKGROUND

The correlation of the common carotid artery (CCA) bifurcation and its surrounding structures is poorly described. The aim of this study was to describe the anatomy of the CCA bifurcation relative to its surrounding structures.

METHOD

We dissected a total of 67 carotid specimens from 36 embalmed cadavers. CCA bifurcation occurred at the superior border of thyroid cartilage in 39% and at the body of hyoid bone in 40% of specimens.

RESULTS

The superior thyroid artery arose more commonly from the CCA (52.3%) than the external carotid artery (46.2%). The vagus nerve was posterior to the carotid bifurcation in 40 (60%), posterior-lateral in 24 (36%), posterior-medial in 2 (3%) and anterior-lateral in 1 specimen (1.5%). The hypoglossal nerve was closer to the CCA bifurcation when the CCA bifurcated at the level of the hyoid bone than when it bifurcated at the superior border of the thyroid cartilage (P < 0.05). The correlation of the common facial vein and the carotid artery was highly variable.

CONCLUSION

The presence of a high CCA bifurcation should caution surgeons that the hypoglossal nerve lies in closer proximity and is more vulnerable. Preoperatively documenting the level of the CCA bifurcation may be helpful in identifying those patients at increased risk of iatrogenic injury.

Different Patterns of Vasoactive Intestinal Polypeptide (VIP)-Immunoreactive and Acetylcholinesterase (AChE)-Positive Innervation in the Internal Carotid Artery and Cerebral Arterial Tree of the Quail

The innervation pattern of vasoactive intestinal polypeptide-immunoreactive (VIP-IR) nerves in the quail internal carotid artery (ICA) and cerebral arterial tree was investigated and compared with that of acetylcholinesterase-positive (AChE-P) nerves. The supply of VIP-IR nerves to the two arterial systems was distinctly richer than that of AChE-P nerves. It was focused mainly on the walls from the distal ICA to the caudal half of the anterior ramus (AR) through the cerebral carotid artery (CCA). Indeed, double staining clearly showed that numerous VIP+/AChE-axons were distributed over these arterial regions where VIP+/AChE+ or AChE+/VIP- axons were sporadic or often lacking. The finding that nerve bundles accompanying the ICA within the carotid canal contained abundant VIP+/AChE- nerve cells suggests that cerebrovascular VIP-IR nerves in the quail have their major source at these neurons and enter the cranial cavity through the CCA. Another significant finding was that a small number of nerve cells, which were mostly stained for AChE alone and occasionally for VIP alone or both, occurred in the major arteries located more rostral than the middle AR. Thus, the quail cerebral arterial tree, at least the rostral segment of the anterior circulation, is multiply innervated by these three distinct categories of the extracranial and intracranial VIP-IR and AChE-P neurons.

On the atrophy of the internal carotid artery in capybara

Capybara might be a useful model for studying changes in cerebral circulation as the natural atrophy of the internal carotid artery (ICA) occurs in this animal at maturation. In this study, confocal and electron microscopy combined with immunohistochemical techniques were applied in order to reveal the changes in morphology and innervation to the proximal part of ICA in young (6-month-old) and mature (12-month-old) capybaras. Some features of the basilar artery (BA) were also revealed. The ICA of young animals degenerated to a ligamentous cord in mature animals. Immunolabelling positive for pan-neuronal marker protein gene product 9.5 but negative for tyrosine hydroxylase was observed in the proximal part of ICA at both ages examined. Axon varicosities positive for synaptophysin were present in the adventitia of ICA of young animals but were absent in the ligamentous cord of mature animals. In the ICA of young animals, adventitial connective tissue invaded the media suggesting that the process of regression of this artery began within the first 6 months of life. An increase in size of the BA was found in mature animals indicating increased blood flow in the vertebro-basilar system, possibly making capybara susceptible to cerebrovascular pathology (e.g. stroke). Capybara may therefore provide a natural model for studying adaptive responses to ICA regression/occlusion.

Effects of chronic baroreceptor unloading on blood pressure in the dog

We have developed a new model of chronic baroreceptor unloading (CBU) in the dog. Initial characterization of the model indicated that CBU increased mean arterial pressure (MAP) by an average of 22 mmHg for 7 days. The goal of the present study was to replicate the previous study using telemetry to record MAP continuously and to determine the effects of CBU (n = 7) on chronic regulation of MAP. We also prepared a group of dogs with sinoaortic denervation (SAD, n = 6) to compare the time course of changes in MAP in the two models. Control levels (7 day average +/- SE) of MAP in the CBU and SAD groups were 94 +/- 2 and 94 +/- 1 mmHg, respectively. MAP averaged 124 +/- 8 and 103 +/- 4 mmHg during the first and second weeks after SAD (both P < 0.05) and then declined to levels not different from control during weeks 3-5. In the CBU group, MAP averaged 120 +/- 4 mmHg during the first week, declined to 111 +/- 4 mmHg during the second week, and stabilized at 104 mmHg during weeks 3-5 (all P < 0.05 compared with control). Plasma norepinephrine levels were increased significantly for the first week after SAD and for 2 wk after CBU but were not different from control for the remainder of the study. These results indicate that the initial increase in MAP after CBU is not sustained but declines to a level that is modestly higher than control. However, because MAP did not fall to control levels, the results are compatible with the hypothesis that baroreceptor input can influence the long-term level of MAP.

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.

Carotid sinus nerve blockade during carotid surgery: a randomised controlled trial

OBJECTIVES

we investigated whether carotid sinus nerve infiltration with lignocaine reduced blood pressure lability during the first 24h following carotid endarterectomy (CEA).

DESIGN

prospective randomised double-blind controlled trial.

MATERIALS

eighty patients undergoing CEA for significant symptomatic stenosis of the internal carotid artery.

METHODS

after initial dissection, 5 ml of 1% lignocaine or normal saline placebo according to randomisation was infiltrated around the carotid sinus nerve. Blood pressure was measured by intra-arterial cannula during surgery and for four hours afterwards every 15 min, then manually, hourly for 18 h.

RESULTS

patients having excision of the carotid sinus nerve were grouped separately for analysis: 29 patients had lignocaine, 33 placebo and 17 excision (one early death with incomplete data was excluded). Mean systolic, diastolic and pulse pressures did not differ significantly between the three groups before carotid sinus nerve infiltration. After infiltration, those patients who had carotid sinus nerve excision, had significantly higher systolic [mean (SD)=155 (16)mmHg] and diastolic [75 (9)mmHg] pressures than those receiving LA [systolic=136 (15)mmHg, diastolic=65 (10)mmHg] or placebo [systolic=136 (19)mmHg, diastolic=65 (9)mmHg], (p<0.005 ANOVA). Nerve excision also resulted in wider variability of blood pressure as defined by the mean of individual standard deviations (systolic=25 mmHg, diastolic=13 mmHg) compared to LA (systolic=19 mmHg, diastolic=12 mmHg) or placebo (systolic=18 mmHg, diastolic=10 mmHg) (p<0.05 ANOVA). Normotensive patients had significantly lower mean diastolic pressures (p<0.001 ANOVA) and variability (p<0.05) if they received lignocaine although this did not influence pulse pressure.

CONCLUSIONS

lignocaine injection of the carotid sinus nerve has no benefit in those patients with existing treated hypertension and only marginal effects in normotensives. It is more important to preserve the carotid sinus nerve if possible.

Anomalous artery directly connecting the external and internal carotid arteries

An anomalous artery directly connecting the external with the internal carotid artery was encountered on the right side of a 68-year-old Japanese female cadaver. This anomalous artery (5 mm in diameter, 12 mm in length) branched out from the posterior aspect of the external carotid at the level of the origin of the lingual artery, ran obliquely upward posteriorly along the course of the hypoglossal nerve, and was confluent with the anterior aspect of the internal carotid artery. No other variations were found in the morphological aspects of, or in the anatomical relationships between, the carotid arteries and their surrounding structures on either side. The carotid body-like structure was observed at the carotid bifurcation and was innervated by small branches of the glossopharyngeal, the vagus and the sympathetic trunk. Embryologically, it is conceivable that this anomalous artery may have derived from the right second branchial arch artery, although there is no abnormality in other derivative structures of the second pharyngeal arch. There may have been no effect from this anomaly on the functions of the arterial blood flow and blood supply under normal circumstances in the present case, but this report may be of embryological significance and contribute some insight into the mechanisms of the formation of the carotid circulation systems.

The sympathetic nerves of the parasellar region: pathways to the orbit and the brain

Sympathetic nerves innervate targets in the orbit and the brain. They issue from the superior cervical ganglion and reach the parasellar region via the internal carotid nerve. Information on their further parasellar course and distribution is scant and contradictory. In this study the parasellar sympathetic pathways of 30 human infants and 6 human fetuses were investigated by microdissection and histologically. A common parasellar sympathetic trunk, which reunites all the nerve fibers emanating from the lateral and medial internal carotid plexus, is described as well as its further divisions. It was found that the posterior knee of the infant carotid siphon is free of large sympathetic nerve bundles. In addition a ganglion is described, which is situated in the parasellar adipose body. It is reached by nerve fibers coming from the parasellar sympathetic pathways. Fibers that issue from this ganglion join the periorbita and the orbital muscle of Müller. These anatomical facts are of immediate importance for preventing nerve damage during cavernous sinus surgery. Furthermore, the study improves the anatomical knowledge of the parasellar region and suggests a new concept for the innervation of the orbital muscle.

Decreased neuronal nitric oxide synthase-immunoreactivity and NADPH-diaphorase activity in rat pterygopalatine ganglion parasympathetic neurons and cerebrovascular innervation following long-term sympathectomy

Neural control of tissue perfusion is mediated predominantly by sympathetic vasoconstrictor and, in some tissues, parasympathetic vasodilator systems. The objective of this study was to determine if changes occur within parasympathetic vasodilator neurons supplying cranial vessels after sympathectomy. Cranial sympathetic innervation was excised unilaterally, and 6 weeks later pterygopalatine ganglion neurons were evaluated for expression of neuronal nitric oxide synthase immunoreactivity (NOS-ir) and NADPH-diaphorase activity. Relative to the unoperated side, the number of parasympathetic neurons staining densely either for NOS or for NADPH-diaphorase decreased by 37% and 47%, respectively, whereas unstained somata increased by 51% and 48%. Internal carotid artery NOS-ir innervation density was reduced by 35%. These findings are consistent with a down-regulation of nitrergic properties in some cranial parasympathetic neurons after sympathectomy.

Influence of cerebrovascular sympathetic, parasympathetic, and sensory nerves on autoregulation and spontaneous vasomotion

The effect of removal of cerebrovascular sympathetic, parasympathetic or sensory nerve on brain cortical blood flow and spontaneous vasomotion during changes in systemic blood pressure was studied by laser-Doppler flowmetry in anaesthetized rats. Selective section of sympathetic fibres along the internal carotid artery markedly affected the ability to autoregulate, as measured in microvessels of the middle cerebral arterial territory. Removal of the parasympathetic nerves tended to reduce the ability to autoregulate, whereas no significant influence was found after sensory denervation. Following the denervations, spontaneous vasomotion was not significantly affected in frequency or amplitude.

The duration of sprouted cerebrovascular axons following intracranial infusion of nerve growth factor

We reported previously that a 2-week infusion of the trophic protein nerve growth factor (NGF) into the lateral ventricle of the adult rat brain elicits a sprouting response by perivascular axons associated with the intradural segment of the internal carotid artery. In the present study, we used electron microscopy to determine whether the sprouted axons persist following cessation of NGF delivery and, if not, to determine the time course of their disappearance. Our results demonstrate that NGF-induced sprouted axons do not persist following cessation of NGF delivery. The total number of axons at 1 week following the end of the NGF infusion was elevated compared to control values, but significantly reduced compared with NGF cases sacrificed immediately following the infusion period. Three weeks following the end of the NGF infusion, the total number of axons was similar to controls although there were no signs of axonal degeneration. These results suggest that continued elevation of NGF levels is necessary to maintain the sprouted axons and that endogenous levels of NGF, or other factors produced by the vascular target tissue, are not sufficient to maintain the newly formed axons. The demonstration that mature perivascular axons proliferate and disappear as a function of exogenous NGF exposure supports the accumulating evidence for continued plasticity in the mature nervous system.

Anatomy of the sympathetic pathways in the cavernous sinus

We studied sympathetic fibres in the cavernous sinus in 40 unfixed specimens obtained from human cadavers. Sympathetic fibres in the cavernous sinus are understood to be grouped in a plexiform configuration surrounding the internal carotid artery and have a diffuse distribution among the sympathetic nerves. Our study, however, suggests that a more systematic arrangement of sympathetic pathways exists in the cavernous sinus. A detailed anatomical description of intracavernous sympathetic fibres contributes to academic anatomical knowledge and may have practical applications for 1. diagnostic interpretation of pathologic conditions involving the cavernous sinus, 2. recognition and orientation of anatomical structures during intracavernous surgical procedures, and 3. a deeper understanding of the sympathetic nerve supply to cerebral vasculature.

The internal carotid artery has a sleeve of increased innervation density within the cavernous sinus in monkeys

The numerical density of nerve terminals of the internal carotid artery was measured using interrupted serial sections and compared with densities sampled from the major cerebral arteries of cynomolgus and rhesus monkeys. In its course through the carotid canal and the foramen lacerum the artery received few terminals. Nerve terminal density increased substantially within the cavernous sinus in 13 of 19 animals, reaching a peak shortly before emerging to join the circle of Willis. The density dropped rapidly on leaving the sinus. The increase was present in both species and rose to a mean nerve terminal density at least ten times that of any other artery measured. In 6 monkeys terminal incidence was unchanged through the sinus. The possible relevance of the nerve terminal sleeve to cerebral vasodynamics and to vascular head pain is discussed.

Transynaptic regulation of low-affinity p75 nerve growth factor receptor mRNA precedes and accompanies lesion-induced collateral neuronal sprouting

The bilateral sympathetic innervation of the rat pineal gland from the two superior cervical ganglia (SCG) is a useful model system to investigate the mechanisms by which intact neurons compensate for neuronal losses. Cutting of the internal carotid nerve (ICN) on one side has been shown to result in the removal of approximately one-half of the innervation to the pineal gland within 2 days. This denervation is followed by the development of collateral neuronal sprouting from the contralateral "intact" SCG, most of which takes place during the next 2 days. Using a solution hybridization protection assay, levels of low-affinity NGF receptor p75NGFR mRNA (pg/microgram total RNA) were found to be increased 25%, with no change in cyclophilin mRNA, in the SCG contralateral to the lesion performed 1 or 3 days earlier. In situ hybridization with a 35S riboprobe complementary to p75NGFR mRNA demonstrated a large increase in this mRNA in some cells of this intact SCG at both 1 and 3 days after a contralateral ICN cut lesion. The clustering of these cells toward the rostral portion of the SCG suggests that they may overlap with the population of sympathetic neurons which provides innervation to bilaterally innervated structures such as the pineal gland. The nature of the signals involved in the regulation of NGF receptor mRNA levels and their role in initiating and maintaining collateral sprouting remain to be fully established. Nevertheless, the time course of the changes in mRNA levels suggests that regulation of the low-affinity NGF receptor gene may be involved in the sequence of events associated with the collateral sprouting response by intact sympathetic nerve cells following partial denervation.

Vasomotor responses in the isolated perfused external and internal carotid vascular beds of the rat

1. The external (ECB) or the internal (ICB) carotid vascular beds of the rat were isolated and perfused with Krebs-Henseleit solution at constant flow (1 ml/min). Changes in perfusion pressure (PP) were recorded after cervical sympathetic stimulation and after the administration of norepinephrine (NE) and serotonin (5-HT). 2. Sympathetic stimulation induced an increase in PP (vasoconstriction) in both vascular beds, however, this effect was significantly higher in the ECB than in the ICB. 3. Exogenous NE also induced a significantly higher contractile response in the ECB. 4. Prazosin (10(-8) M) significantly inhibited the response to sympathetic stimulation and to NE both in the ECB and in the ICB, but yohimbine (10(-7) M) had no effect, suggesting that the vasoconstriction was mainly due to the activation of alpha 1-adrenoceptors. 5. 5-HT induced a contractile response both in the ECB and the ICB. In contrast with the response to NE, the contraction induced by 5-HT in the ICB was significantly higher than in the ECB. 6. Ketanserine (10(-8) M) antagonised both responses, indicating the involvement of 5-HT2 receptors. 7. The contractile effect of 5-HT in the ECB was significantly enhanced by a subthreshold sympathetic stimulation that did not modify the PP by itself. This effect was not seen in the ICB. 8. The differential perfusions of the ECB or the ICB demonstrated a different reactivity of ECB and ICB, both to sympathetic stimulation and to the administration of exogenous NE or 5-HT. 9. Furthermore, the response to 5-HT in the ECB was modulated by a subthreshold sympathetic stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Electron microscopic structure and innervation of the carotid baroreceptor region in the rock hyrax (Procavia capensis)

Semi-thin plastic sections reveal that the carotid baroreceptor region in the rock hyrax comprising the origin of the internal carotid artery has a preponderantly elastic structure and a thick tunica adventitia. In contrast, the common carotid artery has a musculoelastic structure, whereas the cranial segment of the internal carotid artery (immediately distal to the baroreceptor areas) shows the features of a muscular artery. Electron microscopy discloses the presence of sensory nerve endings within the parts of the tunica adventitia adjoining the preponderantly elastic zone of the internal carotid artery. These nerve endings are characterized by varicose regions containing a large quantity of mitochondria. Bundles of collagen fibers in the tunica adventitia form convolutions or whorls around the nerve terminals and often terminate on the surface of the elastic fibers or into the basement membranes of the neuronal profiles. The large content of elastic tissue in the tunica media of the baroreceptor region may render the vessel wall highly distensible to intraluminal pressure changes. This, in turn, would facilitate the transmission of the stimulus intensity to the sensory nerve terminals located in the tunica adventitia. It is suggested that the stretching of elastic fibers may form the main mechanical event leading to the distortion of the associated nerve terminals. However, a change in the geometrical configuration of the bundles of collagen under the influence of the elastic fibers may provide a better insight into the mechanisms of distortion of the baroreceptors related to and/or in contact with collagen fibers.

The canine internal carotid system: regional differences in reactivity to nerve stimulation, noradrenaline and 5-hydroxytryptamine

Reactivity of the canine internal carotid system to field electrical stimulation, noradrenaline and 5-hydroxytryptamine was determined isometrically using 4-mm cylindrical rings from the cervical and cavernous portions and middle cerebral artery. Electrical stimulation at supramaximal voltage (0.5-4 Hz, 0.2 ms duration) produced a frequency-dependent contraction that was similar in cervical and cavernous portions and lower in the middle cerebral artery. This response was blocked by tetrodotoxin (10(-6) M) or phentolamine (10(-6) M). Noradrenaline (10(-9) - 3 x 10(-4) M) produced concentration-dependent contractions and the sensitivity was: cervical portion = cavernous portion greater than middle cerebral artery, and this effect was blocked by phentolamine (10(-6) M). 5-hydroxytryptamine (10(-9) - 10(-5) M) caused concentration-dependent contractions and the sensitivity was: cervical portion less than cavernous portion less than middle cerebral artery. This response was depressed by lysergic acid diethylamide (10(-6) M). The results indicate that reactivity of the internal carotid system: (a) to alpha adrenergic activation by endogenous and exogenous noradrenaline is lower in the distal segment (middle cerebral artery) than in the proximal segments (cervical and cavernous internal carotid artery) and (b) to tryptaminergic activation increases as it courses toward the brain. Therefore, functional characteristics could be related to embryological origin which the segments of this vascular system are derived from.

[Carotid sinus and cardiopulmonary baroreceptor reflex in patients with hypertension]

The nature of sinocarotid and cardiopulmonary baroreceptor reflex was examined in 33 patients with labile hypertensive disease (HD). The mechanic receptors of the sinocarotid area was activated by a neck barochamber; lower extremity decompression was used to test the vasoconstrictor cardiopulmonary baroreflex. The studies demonstrated that the activation of the mechanic receptors led to less severe bradycardia in hypertensives than in healthy persons. At the same time blood pressure fall with a decrease in neck chamber pressure achieved higher values in the patients than in normotensives, which was due to vasodilation in most patients. A direct relation was proved to exist between the degree of a decrease in the cardiochronotropic baroreflex component, presence of its vasomotor component, and disease duration. The hypertensives displayed increased in vasoconstrictor cardiopulmonary baroreceptor reflex.

Arterial baroreflex sensitivity and blood pressure variabilities before and after carotid surgery

Carotid surgery is frequently associated with postoperative blood pressure alterations. The role of baroreceptors with regard to these alterations was assessed in 50 patients by determining the pre- and postoperative mechanoreceptor sensitivity after Valsalva maneuver and intravenous injections of angiotensin and nitroglycerine as described by Smyth, Sleight and Pickering. In addition, blood pressure was monitored perioperatively and renin and aldosterone levels were measured. In patients with arterial hypertension a postoperative increase of receptor reactivity can be seen necessitating a reduction of antihypertensive therapy in more than 50% of cases. In normotensive patients no uniform response can be observed. A possible explanation for this effect might be the local increase of pressure in the operated vascular segment. The postoperative reintegration of receptor areas which had been adjusted to a reduced pressure level might induce a more sensitive response than can be seen for the remaining receptors, which usually are less responsive in hypertensive patients.

Anatomical basis for a parasympathetic and sensory innervation of the intracranial segment of the internal carotid artery in man. Possible implication for vascular headache

Two ganglionic cell groups, located close together and called the internal carotid ganglion, not described before in man, were demonstrated extradurally on the ventrolateral surface of the human internal carotid artery (ICA), where the greater superficial petrosal nerve is joined by the (greater) deep petrosal nerve to form the vidian nerve. The two ganglionic cell groups have fiber connections to the ICA, and consist of 50-70 cells each. By immunohistochemistry the majority of cells in one of the groups were shown to contain vasoactive intestinal polypeptide (VIP) and choline acetyltransferase (ChAT) indicating a parasympathetic function, whereas most cells in the other group contained substance P (SP) and possibly calcitonin gene-related peptide (CGRP), transmitters in pain fibers. Lateral to the intracavernous segment of ICA 10-150 scattered or aggregated VIP- and ChAT-positive cells were found, with fiber connections to the ophthalmic nerve, the ICA, the abducent nerve and the sphenopalatine ganglion. These cells may represent aberrant parasympathetic (sphenopalatine) ganglia, here referred to as cavernous ganglion. By radioimmunoassay substantial amounts of VIP, SP and CGRP were measured in both the extradural and the intracavernous segment of the ICA. Thus, the intracranial segment of the ICA is most likely innervated by parasympathetic and pain fibers from the internal carotid ganglion, sensory fibers from the ophthalmic division of the trigeminal ganglion, and parasympathetic fibers from the sphenopalatine and/or cavernous ganglion. Clinical implications for the activation of these nerves to cause pain, dilatation and edema in this segment of the ICA during attacks of cluster headache and painful ophthalmoplegic syndromes are discussed.

Activation of pain fibers to the internal carotid artery intracranially may cause the pain and local signs of reduced sympathetic and enhanced parasympathetic activity in cluster headache

Several clinical and circulatory physiological observations indicate that the internal carotid artery (ICA) with proximal pial and orbital-periorbital branches, as well as external carotid vessels adjacent to the orbital region, are involved in the autonomic symptoms of an attack of cluster headache. Evidence is presented here that an activation of pain fibers innervating the intracranial segment of ICA may cause not only the retroorbital pain of an attack but also, via the mechanical effect of a neurogenic inflammation in the vessel wall, the local symptoms of a sympathetic defect and, via a reflex are to the parasympathetic pathway along the greater superficial petrosal nerve, the local symptoms from glands and vessels of parasympathetic discharge. Dilation of the intracranial ICA due to activation of this parasympathetic pathway may aggravate pain. Possible mechanisms behind such a local pain fiber activation are discussed.

Post-endarterectomy headache and the role of the oculosympathetic system

A study was carried out on headache after carotid endarterectomy. A specific type of headache, similar in its characteristics to "cluster headache", occurred on the operative side in 30% of 54 patients, whereas no such headache occurred after extra-intracranial bypass or peripheral vascular surgery. This postoperative headache was not spontaneously reported by 56% of patients unless they were specifically asked about it. Pharmacological pupillary testing performed in 37 patients revealed that a decreased oculosympathetic activity (with or without adrenoceptor supersensitivity) was constantly associated with post-endarterectomy headache. Although this same abnormality was also observed in 54% of the patients without headache, a statistically significant (p less than 0.01) higher prevalence of decreased oculosympathetic responses was found in the patients with headache. The results suggest that damage to the sympathetic plexus due to the surgical procedure is involved in the development of postoperative "cluster-like" headache.

The distribution pattern of the sympathetic nerve fibers to the cerebral arterial system in rat as revealed by anterograde labeling with WGA-HRP

To clarify the projection route and the expansion of the terminal plexus of the sympathetic nerve fibers innervating the cerebral arterial system in rat, we labeled the postganglionic fibers originating in the superior cervical ganglion and traced their entire course by anterograde labeling with wheat germ agglutinin-horseradish peroxidase. Sympathetic innervation of the internal cerebral artery by labeled fibers actually began just at the portion where it enters the intradural space, and innervated it up to the small pial arteries located in the subarachnoid space, but not the intracerebral arterioles. On the main arteries in the circle of Willis, bundles of nerve fibers ran parallel to the long axis of the vessels and branched perpendicularly their terminal twigs with regular intervals to form a rib-structure pattern. On the arterial branches derived from the circle of Willis, a fine nerve bundle and delicate terminal axons formed a meshwork instead of a rib-structure pattern. These observations confirmed the existence of differences in the distribution pattern of the nerve plexus, which strongly affects the strength and quality of vasoconstriction by sympathetic activation in each level of the cerebral arterial system.

Intracerebral NGF infusion induces hyperinnervation of cerebral blood vessels

The use of intracerebral NGF (nerve growth factor) infusions as a therapeutic tool to prevent the degeneration of cholinergic neurons in humans suffering from Alzheimer's disease has recently been suggested. In the present study, intracerebroventricular infusion of nerve growth factor into the adult rat brain was found to induce axonal sprouting of mature, uninjured axons associated with the intradural segment of the internal carotid artery. Following NGF infusion, a three-fold increase in the total number of axons associated with the vessel wall was observed when compared with vehicle-infused animals. This vascular hyperinnervation might also occur in humans. Before NGF infusion therapy is initiated, more research is necessary concerning the specificity, mechanisms, and functional significance of the sprouting response observed in this study.

In vitro reactivity of dog cavernous carotid artery to stretch and adrenergic stimulation

The reactivity of the dog cavernous carotid artery to stretch, field electrical stimulation, and norepinephrine was studied using arterial segments under isometric conditions. Light microscopy revealed that this artery is of muscular type and its external surface is covered by venous endothelium, and fluorescence microscopy showed a dense adrenergic innervation. On stretch, arteries exhibited an immediate, transient contraction (phasic response) and a late, maintained contraction (tonic response) that were unaffected by tetrodotoxin (10(-6) M) or endothelium removal but were reduced by the inhibitors of cyclooxygenase indomethacin (10(-6) M), acetylsalicylic acid (3 x 10(-5) M), or meclofenamate (10(-5) M). Electrical stimulation (0.5-4 Hz) contracted the arteries in a frequency-dependent manner, and the response was reduced by tetrodotoxin, phentolamine, (10(-6) M), or the inhibitors of cyclooxygenase used but was unaffected by endothelium removal. Norepinephrine (10(-9)-3 x 10(-4) M) caused dose-dependent contraction that was blocked by phentolamine and by the inhibitors of cyclooxygenase but was not modified by endothelium removal. The results indicate that the dog cavernous carotid artery develops myogenic tone on stretch and contracts on adrenergic stimulation. They also suggest that in these responses prostaglandins but not the endothelium are involved. Therefore, the cavernous carotid artery, because of its location and reactivity, could be of relevance in regulating blood flow or pressure within the cerebral circulation when arterial pressure or adrenergic activity increases.

Intraventricular NGF infusion in the mature rat brain enhances sympathetic innervation of cerebrovascular targets but fails to elicit sympathetic ingrowth

The ability of peripheral axons to regenerate long distances in the peripheral nervous system (PNS) is well documented; however, examples of axonal elongation within the adult mammalian central nervous system (CNS) are rare. One example of axonal growth in the mature brain is the sprouting of sympathetic axons into the hippocampal formation following disruption of the septohippocampal pathway. A current hypothesis is that elevated hippocampal NGF levels, secondary to loss of retrograde transport by septal neurons, elicits sympathetic ingrowth, In this study, we sought to determine whether elevation of hippocampal NGF activity without septal denervation is sufficient to elicit sympathetic sprouting. Forty-one female rats were infused for two weeks with NGF or cytochrome C in the right lateral ventricle through cannulae connected to an osmotic minipump. In some animals the brains were sectioned and stained for acetylcholinesterase (AChE) activity and norepinephrine histofluorescence; in others, CNS tissue was assayed for nerve growth factor (NGF) content with a two-site ELISA. A Farrand microspectrophotometer was used to measure the intensity of catecholamine fluorescence around the internal carotid artery. The average fluorescence intensity of the sympathetic innervation of the internal carotid artery in the NGF-injected animals was over twice that of vehicle-injected rats indicating that the infused NGF was both accessible to the sympathetic axons and biologically active. However, in none of the cases with elevated hippocampal NGF levels were sympathetic axons observed within the hippocampal formation or any other brain region. These results suggest that simple elevation of brain NGF, while perhaps necessary, is insufficient to permit the growth of sympathetic axons into the mature mammalian CNS.

Origins of substance P- and calcitonin gene-related peptide-containing nerves in the internal carotid artery of rat

An aggregation of substance P (SP)- and calcitonin gene-related peptide (CGRP)-containing nerve cells (internal carotid mini-ganglion) is described at the junction between the greater superficial petrosal nerve and the internal carotid nerve close to the internal carotid artery. A retrograde tracer dye technique demonstrates that this ganglion and the trigeminal and superior vagal ganglia supply the internal carotid artery with SP/CGRP fibers at, above and below this level, respectively. Implications of this finding for cranial painful syndromes in man are discussed.

Trigeminal nerve pathways to the cerebral arteries in monkeys

Two or three or sometimes more fine intracavernous branches were traced from the ophthalmic nerve using serial section reconstruction and induced nerve degeneration. They joined the cavernous plexus and were distributed forward with autonomic nerves to the adventitia of the internal carotid artery, emerging from the sinus with the artery. A strong recurrent branch from the plexus joined the abducent nerve, passed back and left the nerve at pontine level to innervate the basilar artery and the caudal circle of Willis. The recurrent nerve was absent from one side of two animals and showed asymmetry in others. No branch issued intracranially to the plexus from the maxillary nerve, but in the pterygopalatine fossa the orbitociliary branch of the maxillary nerve gave off one or two filaments that re-entered the cranial cavity through the medial infraorbital fissure and joined the cavernous plexus. Their content augmented the ophthalmic afferent distribution. All plexus branches with trigeminal fibres also contained autonomic fibres. The results show, firstly, that the cavernous plexus consists of a mixture of sensory and autonomic nerves (sympathetic and parasympathetic) and, secondly, that afferents of the internal carotid artery and rostral circle of Willis and those to the basilar artery and caudal circle of Willis are distributed separately.

Stimulation of the trigeminal ganglion increases flow in the extracerebral but not the cerebral circulation of the monkey

The trigeminal ganglion of 9 anesthetized paralysed artificially ventilated Macaca nemestrina monkeys was electrically stimulated with frequencies varying from 0.2 to 200 Hz. This stimulation led to a frequency-dependent decrease in external carotid resistance but no significant change in internal carotid resistance was recorded. The response is probably mediated as previously described in the cat, i.e. predominantly through the greater superficial petrosal branch of the facial nerve and a small proportion through antidromic activation of the trigeminal system. Elucidation of the physiological and pharmacological mechanisms underlying such a response may aid in a better understanding of the pathophysiology of vascular headache.

Sympathetic innervation and excitability of arterioles originating from the rat middle cerebral artery

The densities of the adrenergic innervation of the internal carotid and middle cerebral arteries and their extracerebral branches have been determined using fluorescence histochemistry. The density of the nerve plexus on the internal carotid artery was greater than that of the middle cerebral artery. The density of the plexus on the middle cerebral artery decreased with increasing distance from its origin. The density and the peripheral extent of the nerve fibre plexus on the arterioles arising from the carotid artery were greater than those arising from the middle cerebral artery. On any arteriole the density of innervation decreased with increasing distance from its origin. The passive electrical properties of proximal and distal middle cerebral arteriolar segments were compared. Both proximal and distal arteriolar segments had similar resistances and time constants in the order of 100 M omega and 250 ms respectively. Small regenerative responses could be elicited in all proximal middle cerebral arteriolar segments but only in a proportion of corresponding distal segments. The addition of external tetraethylammonium ions (TEA) provided much larger regenerative responses. Action potentials in proximal middle cerebral arteriolar segments had larger peak amplitudes and faster rise times than those of corresponding distal segments. Distal carotid arteriolar segments had similar voltage-dependent excitability as proximal segments of middle cerebral arterioles but generated less inward current for a given voltage step. There was a direct correlation between the density of innervation and the voltage-dependent excitability of arteriolar smooth muscle cells. The possibility that the presence of nerves is correlated with the density of calcium channels is discussed.

[Autoradiographic analysis of transcription in sympathetic neurocyte nuclei following axonal injury]

One of the trunks of the inner carotid nerve of the cranial cervical sympathetic ganglion of the rabbit was intersected. The level of transcription in nervous cells at the height of the development of the morphological signs of the axonal reaction was determined by autoradiography. The method is based on the demonstration of the activity of RNA polymerases. Injury of the process causes a considerable decrease in the total and nucleoplasmic labeling of the nuclei of retrogradely changed neurocytes. The level of nucleolar labeling was not changed.

[Mechanism of "autoregulation" of the cerebral circulation: role of neurogenic and myogenic vascular reactions]

The neurogenic and pure myogenic responses of the dog circulatory isolated internal carotid artery were studied under conditions of controlled intraluminal pressure changes. The artery was continuously perfused with the oxygenated bicarbonate Ringer-Krebs solution, and the vascular responses were estimated as changes in the perfusion fluid flow rate recorded with a drop-flowmeter. The quantitative analysis of the vascular responses showed that a comparatively constant perfusion fluid flow independent of the rate of perfusion pressure changes only occurred when the neurogenic control of the artery was preserved. The pure myogenic responses of the artery were only observed in 25% of tests, were four times weaker and present only within the narrow limits and at a specific rate of the intraluminal pressure changes.

Differential effects on the internal and external carotid circulation of the monkey evoked by locus coeruleus stimulation

Electrical stimulation at 1-200/s of the locus coeruleus in 12 Macaca nemestrina monkeys caused a frequency-dependent drop in vascular resistance in the extracerebral circulation which was twice as great on the side stimulated. Accompanying this dilatation of the extracerebral vasculature was a frequency-dependent rise in internal carotid vascular resistance, usually seen only on the side ipsilateral to stimulation. This constrictor response was maximal at low frequencies of stimulation and minimal at higher frequencies. Neither the dilator nor constrictor responses were affected by sectioning of the vagus nerve or sympathetic trunk in the neck. The simultaneous occurrence of intracranial vasoconstriction and extracranial vasodilatation has not been demonstrated previously, and bears a remarkable resemblance to the vascular changes of migraine.

[Arterial nerve cells of the base of the brain in the Peking duck]

Neural cell of the arteries in the Peking duck basis cerebri have been studied by means of Koelle's method. Multipolar effector neurocytes 21X26 mcm in their size have been revealed possessing a high acetylcholinesterase activity, as well as bipolar sensitive neural cells of Dogeal' II type 8X10--11X17 mcm in their size possessing a low enzymatic activity. The cells are distributed separately, but more often--in small groups, 3--8 cells in each. Their greatest amount is concentrated in the wall of large arteries--the internal carotid artery and its cranial branch, as well as at the places where the blood vessels branch. Presence of the effector and sensitive neurocytes in the cholinergic neural plexus of the cerebral arteries testifies to a possibility of local reflective arcs existence ensuring a quick response of the cerebral blood vessels to certain changes in the environment.

A histochemical study on the innervation of the cerebral blood vessels in bats

The adrenergic and cholinergic nerves innervating the cerebral blood vessels of four species of Japanese chiropterids (Rhinolophus ferrumequinum, Murina leucogaster, Vespertilio superans and Miniopterus schreibersi) have been investigated using specific histochemical techniques. In all these species of bats arteries of the internal carotid system are poorly developed, whereas those of the vertebro-basilar system are well developed. The adrenergic and cholinergic nerves innervating these cerebral arteries, however, all originate from the stem nerve bundles entering the cranial cavity along the internal carotid artery. Both nerve plexuses are among the densest of any vertebrate species so far investigated. Adrenergic nerve plexuses are usually composed of complicated meshworks of fine fibres, while cholinergic ones are composed of rather longitudinally arranging meshworks of both thick and thin fibres, exhibiting a very high acetylcholinesterase activity. Small parenchymal arteries and arterioles are also dually innervated by adrenergic and cholinergic nerve fibres of peripheral origin. Intracerebral capillaries, on the other hand, are in several places directly connected with both adrenergic and cholinergic fibres of parenchymal origin. Capillaries in the cerebral and cerebellar cortices, diencephalon and cochlear nucleus in v. superans exhibit a heavy non-nervous acetylcholinesterase activity in their walls, but in R. ferrumequinum and M. schreibersi, the response is weak or negative, except for that in the cochlear nucleus.

An electron microscopic study of the baroreceptors in the internal carotid artery of the spontaneously hypertensive rat

The carotid baroreceptor field of normotensive (NTR) and spontaneously hypertensive rats (SHR) examined in this study extends for about 0.5 mm along the length and about 1/3 to 1/2 of the circumference of the wall of the internal carotid artery opposite to the carotid body. The vascular wall of the baroreceptor field exhibits neither a marked dilation to form a carotid sinus nor histological differences in the intima and media compared to other parts of the carotid artery. Histologically the adventitia of the baroreceptor field is characterized by (1) an increased thickness and by less well developed elastic lamellae in comparison with other parts of the arterial wall, (2) a profuse blood and nerve supply, and (3) a richness of cellular elements. The presumptive baroreceptor terminals are localized in the inner 1/3 of the adventitia and display local enlargements that appear to show preferential association with the cell body or processes of the Schwann cell but not with other components of the adventitia. the enlargements are characterized by an accumulation of very densely packed mitochondria, and glycogen particles. No morphological alterations were noted in the baroreceptor terminals of SHR except for proliferated basal laminae that invest the terminals. Our work does not support the concept that resetting of the baroreceptors is due to degeneration of the terminals.

[Cholinergic and adrenergic innervation of the arteries of the base of the brain in certain lower vertebrates]

The arteries in the encephalon base have been investigated by Koelle's and Falck's methods in Teleostei (Anarhichas lupus, Eleginus navaga, Leuciscus brandti, Pelingas), amphibians (Rana temporaria, Rana semiplicata, Bufo bufo) and in reptiles (Testudo horsfieldi, Trionyx chinensis). Cholin- and adrenergic nerve fibres of the encephalic arteries have been revealed in all the vertebrates studied, but their concentration is far from being equal. In fishes and reptiles neural conductors from scarse plexus with wide loops. Concentration of effector neural fibres only in Bufo bufo exceeds that of fishes. In some cases, the arteries of frogs have equal or less density of cholin- and adrenergic neural conductors as compared with those of Pelingas. Certain individual peculiarities are noted in distribution of the effector neural fibres of the encephalic arteries of the vertebrates. In reptiles, the neural apparatus of the encephalic blood vessels reaches a considerable development; it is definitely differentiated into two plexuses - superficial and deep, having a close interconnection. The development of the effector vascular plexus in vertebrates corresponds to increasing mass of the brain and the vascular diameters. Taking into consideration structural peculiarities of the neural conductors and their concentration, it should be recognized that the role of the neural factor in regulation of the cerebral circulation increases in the following order: fishes - amphibians - reptiles.

Sites of transition between functional systemic and cerebral arteries of rabbits occur at embryological junctional sites

The vascular smooth muscle of cerebral blood vessels is relatively insensitive to sympathomimetic stimulation compared with muscle from systemic vessels. The transition in the vertebral artery occurs just rostral to the emergence of that artery from the foramen of the lateral process of the atlas and in the internal carotid artery just before it enters the carotid canal. These sites in the adult correspond to embryological junctions between segments of the vertebral and internal carotid arteries derived from the primitive dorsal aortas and their branches with vessels originating locally from the bilateral longitudinal neural arteries. Topographic patterns of vascular properties may in some cases be explained by the different sites of origin of their primordial mesodermal cells.

The cholinergic pathway to cerebral blood vessels. I. Morphological studies

The application of cobalt chloride to the peripheral cut end of the greater superficial petrosal nerve (g.s.p.n.) in rats revealed that only a few fibers in the plexus of nerves on the adventitial surface of the internal carotid artery were in axonal continuity with the g.s.p.n. A similarly small contribution of cholinergic fibers to cerebral blood vessels from this nerve was suggested by the observation that section of the g.s.p.n. resulted in an insignificant reduction in the density of the AChE-staining plexus in the internal carotid and cerebral arteries and in the incidence of at most 2% degenerate terminals of those observed on the middle cerebral artery. Alternative explanations of the results are discussed: that the AChE-staining fibers are postganglionic, that the time course for degeneration is unusually slow and that non-cholinergic fibers stain non-specifically for AChE. It is concluded that a cholinergic dilator pathway is most probably carried by the g.s.p.n. but that it is not unique.

Sympathetic innervation of the carotid bifurcation in the rabbit and cat: blood vessels, carotid body and carotid sinus. A fluorescence and electron microscopic study

Two postganglionic branches of the superior cervical ganglion enter the area of the carotid bifurcation in the rabbit and the cat. The common and external carotid arteries receive a rich adrenergic nerve supply, which can be demonstrated by fluorophores of biogenic amines appearing after formaldehyde treatment. The internal carotid artery is only sparsely innervated; however, it shows a dense sympathetic supply at the site of pressor receptors. Following removal of the superior cervical ganglion, a total loss of fluorescent adrenergic nerves occurs and degeneration of nerve endings possessing dense core vesicles is conspicuous. These nerve terminals are situated mainly subendothelially in the carotid body sinusoids; they only rarely terminate on type I cells.

[Innervation of the human internal carotid arteries under normal conditions and in stenosis]

The neurohistological investigation of a portion of the internal carotid artery removed in operation on the occasion of occlusion revealed afferent, cholinergic and adrenergic nerve elements randomly located in the examined area. The histochemical and electronmicroscopic investigation of the superior cervical sympathetic ganglion removed from 42 patient operated on the occasion of occlusion of the carotid artery revealed a depletion in the ganglia of synaptic active zones, focal absence of catecholamines and neurohistological materials suggests that a substantial role in the process of stenosing of vascular walls is played by sophisticated effects of innervation connections upon the vessel sheaths.