CT and angiographic correlation of severe neurological disease in toxemia of pregnancy

The use of nimodipine in a patient with eclampsia: color flow Doppler demonstration of retinal artery relaxation

Color flow Doppler ultrasonography was used to demonstrate a significant and sustained reduction in the central retinal artery pulsatility index after administration of the calcium antagonist nimodipine to a patient with eclampsia. Nimodipine is an effective cerebral vasodilator and may be useful in the management of eclamptic patients with severe vasospasm.

Resolution of focal CT hypodense lesions in patients with subarachnoid hemorrhage

Cerebral infarction in the setting of vasospasm due to subarachnoid hemorrhage (SAH) is a known complication of aneurysmal rupture. Computed tomography (CT) has been instrumental in making this diagnosis; however, focal hypodense lesions on CT scan do not always represent infarcted tissue. Two patients are presented here who had CT hypodense lesions in regions of cerebral vasospasm following subarachnoid hemorrhage.

Delayed peripartum vasculopathy: cerebral eclampsia revisited

Over a 2-year period, we treated 4 postpartum patients with acute neurologic problems appearing 4 to 9 days after delivery. Three patients either had no proteinuria or edema and therefore did not meet all accepted clinical criteria for the diagnosis of eclampsia. Magnetic resonance imaging (MRI) of the brain in all patients demonstrated high-signal foci most prominent in the parieto-occipital regions and the subcortical white matter. Cerebral angiogram in 2 patients revealed diffuse vasospasm. In 3 patients, MRI abnormalities resolved. MRI and angiographic abnormalities in our patients are identical to those of patients meeting accepted criteria for eclampsia. Our experience suggests that the current criteria for the diagnosis of eclampsia are too stringent, both in terms of clinical picture and days postpartum to cerebral manifestations.

The effect of magnesium sulfate on maternal retinal blood flow in preeclampsia: a randomized placebo-controlled study

OBJECTIVES

Our purpose was to determine the effect of a 6 gm intravenous bolus of magnesium sulfate on maternal retinal blood flow velocity waveforms in patients with preeclampsia.

STUDY DESIGN

Twenty-two patients were randomized to two groups and were studied with color flow Doppler before and immediately after infusion of either 6 gm of magnesium sulfate or placebo. The central retinal and posterior ciliary arteries were studied.

RESULTS

Magnesium sulfate significantly reduced the pulsatility index (p < 0.005) in both vessels (change in pulsatility index = 0.26 +/- 0.23 for central retinal and -0.22 +/- 0.15 for posterior ciliary) when compared with placebo (change in pulsatility index = 0.02 +/- 0.10 for central retinal and -0.03 +/- 0.09 for posterior ciliary).

CONCLUSIONS

These data suggest that magnesium sulfate dilates the vessels distal to the central retinal and posterior ciliary arteries. Changes in pulsatility index in the retinal arteries may be indicative of similar changes in other cerebral vessels.

MRI white matter hyperintensity in neuroleptic malignant syndrome (NMS)--a clue to pathogenesis?

The case of a young female patient with neuroleptic malignant syndrome (NMS) and extended MRI white matter hyperintensity in the left parietal and both occipital lobes is reported. MRI lesions resembled findings in hypertensive encephalopathy, they were not readily compatible with CNS vasculitis. Venous sinus thrombosis could be ruled out. Vascular encephalopathy with transient white matter edema and a small residual left parietal lesion is suggested. Neurochemical implications are discussed with particular reference to a possible involvement of excitatory amino acids in NMS pathogenesis.

In vivo and in vitro effects of magnesium sulfate in the cerebrovascular bed of the goat

The effects of magnesium sulfate in the cerebrovascular bed were studied both in vivo, by measuring cerebral blood flow in conscious nonpregnant goats, and in vitro, by recording isometric tension in isolated goat middle cerebral arteries. Injections of increasing doses (10 to 300 mg) of magnesium sulfate directly into the cerebral circulation elicited transient and dose-dependent increases in cerebral blood flow and decreases in cerebral vascular resistance. Similar results were obtained when increasing doses (0.3 to 3 gm/15 min) of magnesium sulfate were infused intravenously, although the vasodilatations reached a stable plateau that remained when the infusions finished. Cumulative addition of magnesium sulfate (10(-5) to 3 x 10(-2) mol/L) did not change the isometric tension of isolated arterial segments at resting tone, but relaxed in a concentration-dependent manner the arterial segments preconstricted with 10(-5) mol/L prostaglandin F2 alpha. These results demonstrate that magnesium sulfate acts as a dilator in the cerebral circulation by acting directly on the cerebral arteries. This could explain, at least in part, its beneficial effects on preeclampsia-eclampsia.

Perioperative stroke. Part I: General surgery, carotid artery disease, and carotid endarterectomy

Although stroke, defined as a focal neurological deficit lasting more than 24 hr, is uncommon in the perioperative period, its associated mortality and long-term disability are high. No large-scale data are available to identify the importance of recognized risk factors for stroke in the perioperative period. A review of the literature shows that the incidence and mechanism of its occurrence are influenced by the presence of cardiovascular disease and the type of surgery. The most common cause of perioperative stroke is embolism. In non-cardiac surgery, the incidence of perioperative stroke is higher among the elderly. Properly administered, controlled hypotension is associated with minimal risk of stroke. Cerebral vasospasm may be the cause of focal cerebral ischaemia in eclamptic patients, and the aggressive treatment of hypertension may exacerbate the neurological damage. The risk of stroke associated with carotid endarterectomy is closely related to the preoperative neurological presentation, and the experience of the surgical/anaesthetic team. Symptomatic cerebrovascular disease, acute stroke, asymptomatic carotid lesions, preoperative assessment of risk, local and general anaesthesia, cerebral protection and monitoring during carotid endarterectomy are discussed with reference to reducing the risk of perioperative stroke. Adequate monitoring and protection have minimized the risk of ischaemia from carotid clamping, and the major mechanism of stroke is embolization.

MR of uncommon congenital and vascular lesions of the intracranial visual pathways

The MR findings of two patients with rare congenital abnormalities of the optic pathways are reported and illustrated, including one case of unilateral aplasia of the optic chiasm, tract, and visual radiations and another patient with anophthalmos. In three other patients with unusual vascular causes of visual disturbance, MR was important in early establishment of an accurate diagnosis and had consequent implications for decisions regarding further patient management.

Widespread cerebral ischaemia treated with nimodipine in a patient with eclampsia

Images

Computed tomographic changes of the brain in toxaemia of pregnancy

Four cases of toxaemia of pregnancy examined with computed tomography scans of the brain are reported. A review of the literature reveals 19 other cases with previously reported CT brain scans. The review shows intracerebral oedema as the main finding. Haemorrhage, massive or punctate was noted in four cases. The pathogenesis of the CT changes and the clinico-radiological correlation of the visual disturbances are discussed.

Magnetic resonance evaluation of severe neurological disorders in eclampsia

A patient with eclampsia and severe but reversible neurological disorders is presented. Initial magnetic resonance imaging (MRI) revealed multiple hyperintense areas throughout the brain and brainstem that were consistent with ischemia and/or edema. Despite these diffuse lesions extending to the brainstem, the patient made a progressive neurological recovery and a follow-up MRI on day 21 demonstrated complete resolution of the hyperintense foci. MRI abnormalities were found to correlate more closely with clinical and electrophysiological data than CT findings.

Action of magnesium sulfate in the treatment of preeclampsia-eclampsia

Recent evidence supports the concept that cerebral vasospasm is involved in the pathogenesis of eclampsia. Magnesium, which has a beneficial effect in eclampsia, may act by opposing calcium-dependent arterial constriction, thereby relieving vasospasm. Magnesium may also antagonize the increase in intracellular calcium concentration caused by ischemia and thus prevent cell damage and death. Magnesium might have a role in the treatment of cerebral vasospasm and ischemia, such as occurs in subarachnoid hemorrhage, ischemic stroke, and brain trauma.

Blindness in eclampsia: CT and MR imaging

Three cases of cortical blindness complicating eclampsia are described, with magnetic resonance imaging (MRI) and X-ray computed tomography (CT). The correspondence of MRI lesions (hyperintense on T2 weighted, and hypointense on T1 weighted sections) and low attenuation lesions on CT scan indicated ischaemia rather than haemorrhage as the pathological mechanism.