Asymmetric brain edema after cardiac transplantation: cerebroautoregulatory failure and relative hyperperfusion.

Asymmetric brain edema is a rare neurologic complication after cardiovascular surgery. We describe the clinical and imaging features of an asymmetric brain edema syndrome in a 52-year-old man following cardiac transplantation who presented with facial myoclonus and left hemiparesis in the postoperative period. To our knowledge, this is the first case report of asymmetric brain edema syndrome after cardiac transplant and the second following cardiac surgery. Arterial bypass cannula malposition in the ascending aorta or brachiocephalic artery with subsequent cerebral hypoperfusion and subsequent hyperperfusion appears to be the most likely physiologic cause.

Mechanisms of cerebrovascular dilation by ether in monkeys.

We hypothesized that when the depth of ether anesthesia is increased from 2 to 5%, cerebral vessels dilate secondary to circulating catecholamine stimulation of cerebral metabolism. Cerebral blood flow (CBF) by 133Xe clearance and cerebral metabolic rate for oxygen (CMRO2) were measured on 2% and then 5% ether in air in two groups of seven monkeys each during mechanical ventilation. Propranolol, 0.5 mg/kg i.v., was infused over 5 min in one group, and the other received saline. All measurements were repeated on 5% and 2% ether. Cerebrovascular resistance (CVR) fell by 30%, from 2.28 +/- 0.61 (mean +/- SD) to 1.51 +/- 0.28 mm Hg ml-1 100 g-1 min-1 (p less than 0.01), with the increase in ether from 2 to 5%. CBF and CMRO2 were unaltered from values of about 45 ml 100 g-1 min-1 and 2.3 ml 100 g-1 min-1, respectively. During 5% ether anesthesia, propranolol had no effect on CBF, CMRO2, or CVR. On 2% ether, it increased CVR twofold, from 1.5 +/- 0.30 to 3.0 +/- 1.0 mm Hg ml-1 100 g-1 min-1, and decreased CBF by 33%, from 48 +/- 8 to 32 +/- 10 ml 100 g-1 min-1. Plasma epinephrine was two-fold higher on 2% compared to 5% ether, both before and after saline or propranolol infusion. In monkeys, cerebrovascular dilation by ether at 5% compared to 2% is not secondary to catecholamine stimulation of CMRO2. It may result from a direct effect of either plasma catecholamines or ether on the cerebrovasculature.

Cerebrovascular response to infused noradrenalin and its modification by a catecholamine metabolism blocker.

Despite many studies, the cerebrovascular action of infused noradrenalin is still unclear. The study reported here tested the hypothesis that infused noradrenalin is prevented from reaching the adrenoreceptors by being avidly taken up and metabolized in the vascular smooth muscle. Cerebral blood flow was measured by the xenon133 clearance technique in nine baboons before and during blockade of the enzyme catechol-O-methyl transferase, which is known to be important in inactivation of circulating noradrenalin. The cerebral blood flow responses to noradrenalin infused at 8, 16, and 32 mug per minute were also determined. Responses indicated vasodilatation before but vasoconstriction after blockade, with a significant noradrenalin. It is suggested that the cerebral circulation is normally protected against sympathetic vasoconstriction by the avid uptake and metabolism of noradrenalin in extraneuronal and possibly neuronal sites.

Spontaneous remission of paraneoplastic ocular flutter and saccadic intrusions.

We report two women with ocular flutter and saccadic intrusions, documented by electro-oculography, who had complete spontaneous remission of their ocular motor findings prior to the appearance of a primary neoplastic process remote from the nervous system. Transient elevation of blood HVA and VMA levels was detected in one patient who subsequently had breast cancer. These cases indicate that spontaneous remission of saccadic oscillations does not necessarily imply a benign outcome. Patients with this ocular motor abnormality should be followed closely for signs of a remote neoplasm even if initial investigation is negative.

Vascular compression, hemifacial spasm, and multiple cranial neuropathy.

Hemifacial spasm is usually an isolated symptom resulting from facial nerve root compression. Three patients had, in addition, tinnitus, hearing loss, facial sensory loss, diminished gag reflex, dysphagia, and dysarthria. Acoustic reflexes were abnormal, and facial nerve conduction studies showed evidence of ephaptic transmission and ectopic excitation. Brain CT and metrizamide cisternography were normal. Surgical exploration showed compression of cranial nerve roots by posterior inferior cerebellar artery branches. After decompression, symptoms abated, and electrical signs of hemifacial spasm disappeared. Vascular compression of nerve roots in the cerebellopontine recess may cause multiple cranial neuropathy.

Management of patients receiving interferon beta-1b for multiple sclerosis: report of a consensus conference.

Results of a double-blind, placebo-controlled study in ambulatory patients with relapsing-remitting MS showed that interferon beta-1b reduced the rate of exacerbations by one-third compared with placebo and limited new disease activity in the brain as evidenced by MRI. Interferon beta-1b, administered subcutaneously at a dosage of 0.25 mg (8 million IU) every other day is indicated for the treatment of ambulatory patients with relapsing-remitting MS. Interferon beta-1b may help a wider range of patients, but it should be prescribed only for patients with a diagnosis of clinically definite or laboratory-supported definite MS. The decision to treat a patient with interferon beta-1b should be individualized; that is, based on each patient's clinical presentation and course of MS. The most common adverse effects include (1) injection-site reactions and (2) flu-like symptoms, which are generally manageable and usually abate after the first few months of treatment. Spasticity may increase. Patients with severe depression or suicidal ideation should be monitored carefully, and symptomatic treatment should be pursued. Interferon beta-1b is contraindicated in pregnant and nursing women. Interferon beta-1b is effective in reducing the progression of total disease burden as seen on MRI in patients with MS. Its use is relatively straightforward and generally does not require alteration in the symptomatic treatment of MS. Patient education and support remain the mainstays of maintaining compliance through the early phases of therapy.

The effect of intracarotid infusion of dexamethasone and 5-hydroxytryptamine on cerebral blood flow and metabolism in baboons.

The effect of intracarotid infusion of dexamethasone on cerebral blood flow and cerebral oxygen utilization was measured in baboons using the xenon-133 clearance technique. The cerebrovascular response to intracarotid infusion of 5-hydroxytryptamine (5-ht) was then determined during simultaneous infusion of the steroid. Infusion of dexamethasone alone and infusion with 5-HT produced no significant change in cerebral blood flow or cerebral oxygen utilization when compared to baseline values. The study indicates that neither dexamethasone nor 5-HT with dexamethasone modify cerebral blood flow when infused via the internal carotid artery.

Cerebrovascular complications associated with the use of artificial circulatory support services.

Neurologic complications are associated with the use of total artificial hearts and with ventricular support systems. Among these complications, thromboembolic events are the most severe and the most frequent, resulting from flow disturbances associated with the artificial devices or occurring within the artificial heart. However, alterations in blood viscosity, abnormalities in the coagulation system, and infection all may play a part in the generation of thrombi. Anticoagulation may play a role in controlling the events that lead to thromboembolism, but the most effective therapeutic regimen has yet to be defined. Although neurologic complications constitute a significant risk, disabling strokes have been relatively rare and appear to relate to the duration of support on the device. The majority of subjects who sustained device-related strokes have made an excellent recovery following transplantation. LVADs constitute an important therapeutic development in the treatment of end stage heart failure. They may cause neurologic complications, but they have the capability of sustaining life until a suitable donor heart is found.

Tc-99m hexamethylpropylene amine oxime scintigraphy in the diagnosis of brain death and its implications for the harvesting of organs used for transplantation.

PURPOSE: Diagnosing brain death is important in managing the comatose patient for whom the continuation of life support is being questioned and when organ harvesting is being considered. The virtual immediate localization of Tc-99m HMPAO to cerebral and cerebellar tissue provides an index of blood perfusion, and its absence denotes brain death. Other methods for assessing brain death include cerebral angiography, MRI, CT imaging after inhalation of stable xenon, electroencephalography, and clinical examination. The contrast material used for angiography may damage harvested organs, and the other studies have significant errors. MRI, CT imaging, and angiography are unsuitable for bedside use. METHODS: Twenty-three patients, who presented with head trauma, prolonged anoxia or intrinsic brain disease (e.g., glioblastoma multiforme) and who were brain-dead by clinical examination criteria, were referred to the nuclear medicine division for verification of brain death. For adults, approximately 25 mCi Tc-99m hexamethylpropylene amineoxime (HMPAO) was administered intravenously. All patients but one were imaged using a mobile scintillation camera at the bedside. RESULTS: We demonstrated (1) both cerebral and cerebellar perfusion, (2) neither cerebral nor cerebellar perfusion, (3) cerebral without cerebellar perfusion, and (4) cerebellar without cerebral perfusion. Patients without cerebral perfusion were diagnosed as brain-dead. The significance of a viable cerebellum in the absence of cerebral viability was not fully appreciated, although organs were harvested from such patients. We determined how well the clinical examination criteria held up in the diagnosis of brain death against the new gold standard of Tc-99m HMPAO scintigraphy: Clinical examination criteria correctly predicted brain death only 83% of the time compared with HMPAO scintigraphy. CONCLUSIONS: Brain death assessment by Tc-99m HM-PAO scintigraphy has proved to be a reliable, safe, and cost-effective bedside method and may have practical application in the assessment of brain death in potential cadaveric donors.

Multiple cranial neuropathy as a feature of internal carotid artery dissection.

The traditional presentation of spontaneous internal carotid artery dissection includes ipsilateral hemicranial headache, oculosympathetic paresis, and contralateral focal cerebral ischemic deficits. However, we describe two cases with multiple cranial nerve involvement ipsilateral to the dissection as the principal feature. The first patient, a 36-year-old man, had involvement of the 9th, 10th, 11th, and 12th cranial nerves. The second case was a 53-year-old man with abnormalities of the 5th, 7th, 9th, 10th, and 12th cranial nerves. In both, magnetic resonance imaging revealed a ring-like area of abnormal signal intensity surrounding the carotid artery at the skull base. Carotid angiography was consistent with the suggestion of dissection on the magnetic resonance studies in both cases. The patients recovered without anticoagulation. Internal carotid artery dissection may thus present with multiple cranial nerve palsies, which could be mistaken for an infiltrating tumor of the skull base. Magnetic resonance imaging is useful in identifying the condition.

Treatment of a cluster headache patient in a hyperbaric chamber.

A patient with severe cluster headaches was treated in a hyperbaric chamber on two occasions. Her symptoms had been refractory to other treatment modalities including conventional oxygen therapy. On both occasions her pain was promptly relieved while breathing 100% oxygen at two atmospheres of pressure. This is the first known reported case of a cluster headache treated with hyperbaric oxygen. A prospective study is needed to substantiate the efficacy of this treatment modality for cluster headaches.

Modification of the cerebrovascular response to noradrenaline by bile duct ligation.

The effects of intracarotid infusions of noradrenaline on the cerebral vasculature were studied in seven baboons with bile duct ligation. Infusion of 8 mug and 16 mug/min of noradrenaline resulted in a significant decrease in cerebral blood flow in the jaundiced animals. In normal baboons, these doses produced cerebrovascular dilatation. These results indicate that there is an increased cerebrovascular sensitivity to noradrenaline in the obstructive jaundice which follows bile duct ligation. It is postulated that noradrenaline smooth muscle uptake mechanisms are disturbed allowing a greater concentration of the amine at the receptor sites.

Prevalence of bowel dysfunction in multiple sclerosis. A population survey.

An unselected outpatient population of 280 individuals with multiple sclerosis was surveyed to determine the prevalence of bowel dysfunction and to define their characteristics and their relationship to the nongastrointestinal manifestations of the disease. Constipation was present in 43%, was similar in frequency in both sexes, and was more common in patients, regardless of degree of disability, than in a control population. Frequency of constipation also correlated with duration of disease and genitourinary symptoms but did not correlate with use of any medications in mildly disabled patients. Fecal incontinence had occurred at least once in the preceding 3 mo in 51% of patients and once per week or more frequently in 25% of patients who were questioned in more detail with a follow-up questionnaire. Correlations of fecal incontinence with disability, duration of disease, and presence of genitourinary symptoms were similar to constipation. The prevalence of bowel dysfunction (constipation and/or fecal incontinence) in the multiple sclerosis population was 68%, and this manifestation was common even in mildly disabled subjects. Bowel dysfunction can be a source of considerable ongoing social disability in patients with multiple sclerosis. Further studies are needed to characterize the pathophysiology of this common disorder so that effective therapeutic strategies can be identified.

Barrier and uptake mechanisms in the cerebrovascular response to noradrenaline.

Cerebral blood flow (CBF) was measured in 20 baboons by the intra-arterial xenon-133 injection method. The CBF responses to intra-arterial infusions of noradrenaline (NA) were determined. These responses were normally found to be vasodilator and mediated by beta adrenoreceptors. After infusion of substances blocking extraneuronal uptake of NA or opening of the blood-brain barrier, this vasodilation was either abolished or converted to an alpha-receptor mediated vasoconstriction. This suggests that normally the cerebral circulation is protected against noradrenergic vasoconstriction by mechanisms reducing the concentration of NA in the tunica media to below threshold for alpha-adrenoreceptor stimulation.