Surgical anatomy of the internal carotid plexus branches to the abducens nerve in the cavernous sinus.

OBJECTIVE: Sympathetic branches to the abducens nerve derived from the internal carotid artery sympathetic plexus, while in the cavernous sinus, have been scantly described in the extant literature. Therefore, the present cadaveric study was performed to better elucidate this anatomy. PATIENTS AND METHODS: Eighteen cadaveric sides underwent dissection. RESULTS: The number of branches derived from the sympathetic plexus traveling with the internal carotid artery in the cavernous sinus was one on 11.1 %, two in 11.1 %, and three in 72.2 %. One side was found to have no branches (5.6 %). The mean diameter of the distance from the posterior border of the internal carotid artery, length, and diameter of the branches was 7.0 ±â€¯4.1 mm, 2.9 ±â€¯1.3 mm, and 0.4 ±â€¯0.1 mm, respectively. Of 44 of 45 sympathetic branches, 97.8 % originated from the lateral wall of the cavernous part of the internal carotid artery with only one from the medial wall. CONCLUSION: Based on our cadaveric findings, sympathetic connections between the internal carotid artery and the abducens nerve are common. Therefore, surgeons who operate in or near the cavernous sinus should be aware of such connections in order not to place unwanted tension on the cavernous part of the internal carotid artery or abducens nerve during dissection.

Sympathetic Effects of Internal Carotid Nerve Manipulation on Choroidal Vascularity and Related Measures.

Purpose: To investigate specific effects of denervation and stimulation of the internal carotid nerve (ICN) on the choroid and retina. Methods: Female Sprague Dawley rats underwent unilateral ICN transection (n = 20) or acute ICN electrical stimulation (n = 7). Rats in the denervation group were euthanized 6 weeks after nerve transection, and eyes were analyzed for changes in choroidal vascularity (via histomorphometry) or angiogenic growth factors and inflammatory markers (via ELISA). Rats in the stimulation group received acute ICN electrical stimulation with a bipolar cuff electrode over a range of stimulus amplitudes, frequencies, and pulse widths. Choroidal blood flow and pupil diameter were monitored before, during, and after stimulation. Results: Six weeks after unilateral ICN transection, sympathectomized choroids exhibited increased vascularity, defined as the percentage of choroidal surface area occupied by blood vessel lumina. Vascular endothelial growth factor (VEGF) and VEGF receptor-2 (VEGFR-2) protein levels in denervated choroids were 61% and 124% higher than in contralateral choroids, respectively. TNF-α levels in denervated retinas increased by 3.3-fold relative to levels in contralateral retinas. In animals undergoing acute ICN electrical stimulation, mydriasis and reduced choroidal blood flow were observed in the ipsilateral eye. The magnitude of the reduction in blood flow correlated positively with stimulus frequency. Conclusions: Modulation of ICN activity reveals a potential role of the ocular sympathetic system in regulating endpoints related to neovascular diseases of the eye.

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.

Neuro-ophthalmological presentation of giant intracavernous carotid artery aneurysm in a child.

An otherwise healthy, 11-year-old boy presented with a long-standing history of right eye esotropia associated with a right head turn. Following a mild blunt facial trauma, he was brought to an ophthalmologist for binocular horizontal diplopia. Cranial CT scan revealed a large, enhancing lesion in the right cavernous sinus. Neuro-ophthalmological evaluation showed abduction deficit of the right eye, right corneal anaesthesia, right upper lid ptosis and a smaller right pupil suggesting involvement of the intracavernous segments of the right abducens nerve, ophthalmic nerve and oculosympathetic fibres. Cerebral angiography confirmed a large aneurysm involving the petrous, lacerum and cavernous segments of the right internal carotid artery. The child underwent successful clipping of the aneurysm by the neurosurgery service.

Sympathetic Plexus Schwannoma of Carotid Canal: 2 Cases with Surgical Technique and Review of Literature.

Carotid sympathetic plexus schwannomas are rare, and only 3 cases have been reported to the best of our knowledge. We report the fourth and fifth cases and define its origin on the basis of the exact division of the plexus from which the tumor arises. The surgical approach and technique in each variety and the postoperative outcome are also described. The relationship of partial Horner syndrome with the sympathetic plexus schwannoma of the internal carotid artery is discussed in detail.

Extra- and intracranial blood flow regulation during the cold pressor test: influence of age.

We determined how the extra- and intracranial circulations respond to generalized sympathetic activation evoked by a cold pressor test (CPT) and whether this is affected by healthy aging. Ten young [23 ± 2 yr (means ± SD)] and nine older (66 ± 3 yr) individuals performed a 3-min CPT by immersing the left foot into 0.8 ± 0.3°C water. Common carotid artery (CCA) and internal carotid artery (ICA) diameter, velocity, and flow were simultaneously measured (duplex ultrasound) along with middle cerebral artery and posterior cerebral artery mean blood velocity (MCAvmean and PCAvmean) and cardiorespiratory variables. The increases in heart rate (~6 beats/min) and mean arterial blood pressure (~14 mmHg) were similar in young and older groups during the CPT (P < 0.01 vs. baseline). In the young group, the CPT elicited an ~5% increase in CCA diameter (P < 0.01 vs. baseline) and a tendency for an increase in CCA flow (~12%, P = 0.08); in contrast, both diameter and flow remained unchanged in the older group. Although ICA diameter was not changed during the CPT in either group, ICA flow increased (~8%, P = 0.02) during the first minute of the CPT in both groups. Whereas the CPT elicited an increase in MCAvmean and PCAvmean in the young group (by ~20 and ~10%, respectively, P < 0.01 vs. baseline), these intracranial velocities were unchanged in the older group. Collectively, during the CPT, these findings suggest a differential mechanism(s) of regulation between the ICA compared with the CCA in young individuals and a blunting of the CCA and intracranial responses in older individuals.NEW & NOTEWORTHY Sympathetic activation evoked by a cold pressor test elicits heterogeneous extra- and intracranial blood vessel responses in young individuals that may serve an important protective role. The extra- and intracranial responses to the cold pressor test are blunted in older individuals.

Endoscopic Repair of the Injured Internal Carotid Artery Utilizing Oxidized Regenerated Cellulose and a Free Fascia Lata Graft.

OBJECTIVE: To introduce appropriate surgical procedures for the endoscopic repair of the internal carotid artery (ICA) injury. METHODS: Two patients with ICA injury during the endoscopic endonasal approach surgery were reviewed. RESULTS: Internal carotid artery injury during the endonasal skull-base approach was a rare complication. Once ICA injury occurred, 2 large bore suctions were placed immediately for drainage and the bleeding point was located. Then, an oxidized regenerated cellulose was quickly pressed onto the bleeding point and was held there to stop the bleeding. Afterward, a free graft of fascia lata was inserted and the free fat graft was compressed for repair. Absorbable packing materials were used for nasal packing. CONCLUSIONS: Endoscopic repair utilizing oxidized regenerated cellulose and a free fascia lata graft is a safe and feasible surgical option for ICA injury.

Selective α1-adrenergic blockade disturbs the regional distribution of cerebral blood flow during static handgrip exercise.

Handgrip-induced increases in blood flow through the contralateral artery that supplies the cortical representation of the arm have been hypothesized as a consequence of neurovascular coupling and a resultant metabolic attenuation of sympathetic cerebral vasoconstriction. In contrast, sympathetic restraint, in theory, inhibits changes in perfusion of the cerebral ipsilateral blood vessels. To confirm whether sympathetic nerve activity modulates cerebral blood flow distribution during static handgrip (SHG) exercise, beat-to-beat contra- and ipsilateral internal carotid artery blood flow (ICA; Doppler) and mean arterial pressure (MAP; Finometer) were simultaneously assessed in nine healthy men (27 ± 5 yr), both at rest and during a 2-min SHG bout (30% maximal voluntary contraction), under two experimental conditions: 1) control and 2) α1-adrenergic receptor blockade. End-tidal carbon dioxide (rebreathing system) was clamped throughout the study. SHG induced increases in MAP (+31.4 ± 10.7 mmHg, P < 0.05) and contralateral ICA blood flow (+80.9 ± 62.5 ml/min, P < 0.05), while no changes were observed in the ipsilateral vessel (-9.8 ± 39.3 ml/min, P > 0.05). The reduction in ipsilateral ICA vascular conductance (VC) was greater compared with contralateral ICA (contralateral: -0.8 ± 0.8 vs. ipsilateral: -2.6 ± 1.3 ml·min(-1)·mmHg(-1), P < 0.05). Prazosin was effective to induce α1-blockade since phenylephrine-induced increases in MAP were greatly reduced (P < 0.05). Under α1-adrenergic receptor blockade, SHG evoked smaller MAP responses (+19.4 ± 9.2, P < 0.05) but similar increases in ICAs blood flow (contralateral: +58.4 ± 21.5 vs. ipsilateral: +54.3 ± 46.2 ml/min, P > 0.05) and decreases in VC (contralateral: -0.4 ± 0.7 vs. ipsilateral: -0.4 ± 1.0 ml·min(-1)·mmHg(-1), P > 0.05). These findings indicate a role of sympathetic nerve activity in the regulation of cerebral blood flow distribution during SHG.

Long term safety and efficacy of internal carotid artery adventitial stripping in carotid sinus syndrome.

BACKGROUND: To investigate the long term efficacy of carotid denervation by adventitial stripping of the internal carotid artery (ICA) for carotid sinus syndrome (CSS). Secondly, the long term safety of this technique is investigated with emphasis on the effects on blood pressure (BP), heart rate (HR) and carotid artery diameter. METHODS: Characteristics of patients that were operated for CSS in a single institute between 1980-2007 were studied by a retrospective chart review. Alive and fit patients additionally received a standardized interview investigating symptoms of residual CSS or baroreflex failure. They underwent a test panel consisting of office BP measurement, carotid sinus massage (CSM), table tilt testing, 24-hour ECG and ambulatory BP measurement (ABPM) and carotid duplex. Unoperated, age- and sex- matched individuals without CSS served as controls. RESULTS: After a total follow up of 91±34 months, 22 of 26 patients (85%) were asymptomatic and 20 of them (77%) without a pacemaker. Of the 7 surviving and fit patients, six were free of CSS symptoms (follow up 114 ± 81 months). Recurrence of CSS after an initial successful carotid denervation was not observed. BP level, BP variability and carotid diameters were not different compared to controls. CONCLUSION: Carotid denervation by adventitial stripping of the ICA for CSS seems effective and safe on the long term. A randomized controlled trial comparing the efficacy and safety of carotid denervation, pacing and medical treatment is needed for optimal future treatment of patients suffering from CSS.

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.

Postganglionic horner syndrome in three patients with coincident middle ear infection.

Three patients developed a postganglionic Horner syndrome during the course of an ipsilateral uncomplicated middle ear infection. The mechanism may be an effect on the middle ear caroticotympanic sympathetic plexus, for which there is considerable anatomic and physiologic evidence. Why Horner syndrome does not occur more often after middle ear infection is a mystery.

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.

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.

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.

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.