Intracranial baroreflex yielding an early cushing response in human

The Cushing response is a pre-terminal sympatho-adrenal systemic response to very high ICP. Animal studies have demonstrated that a moderate rise of ICP yields a reversible pressure-mediated systemic response. Infusion studies are routine procedures to investigate, by infusing CSF space with saline, the cerebrospinal fluid (CSF) biophysics in patients suspected of hydrocephalus. Our study aims at assessing systemic and cerebral haemodynamic changes during moderate rise of ICP in human. Infusion studies were performed in 34 patients. This is a routine test perform in patients presenting with symptoms of NPH during their pre-shunting assessment. Arterial blood pressure (ABP) and cerebral blood flow velocity (FV) were non-invasively monitored with photoplethysmography and transcranial Doppler. The rise in ICP (8.2 +/- 5.1 mmHg to 25 +/- 8.3 mmHg) was followed by a significant rise in ABP (106.6 +/- 29.7 mmHg to 115.2 +/- 30.1 mmHg), drop in CPP (98.3 +/- 29 mmHg to 90.2 +/- 30.7 mmHg) and decrease in FV (55.6 +/- 17 cm/s to 51.1 +/- 16.3 cm/s). Increasing ICP did not alter heart rate (70.4 +/- 10.4/min to 70.3 +/- 9.1/min) but augmented the heart rate variance (0.046 +/- 0.058 to 0.067 +/- 0.075/min). In a population suspected of hydrocephalus, our study demonstrated that a moderate rise of ICP yields a reversible pressure-mediated systemic response, demonstrating an early Cushing response in human and a putative intracranial baroreflex.

Shunting effects in patients with idiopathic normal pressure hydrocephalus; correlation with cerebral and leptomeningeal biopsy findings

Normal Pressure Hydrocephalus (NPH) is a potentially treatable syndrome with abnormal cerebrospinal fluid dynamics. Meningeal fibrosis and/or obliteration of the subarachnoid space have been suggested as one of the patho-anatomical substrates. However, other types of adult onset dementia, predominantly Alzheimer's disease and Vascular Dementia, may mimic the clinical NPH characteristics. The purpose of the present study was to correlate cerebral parenchymal and leptomeningeal biopsy findings to the clinical outcome after CSF shunting in a prospective group of idiopathic NPH (INPH) patients. The study comprises 27 patients with INPH, diagnosed and shunted according to generally accepted clinical, imaging and hydrodynamic criteria. In all patients a frontal leptomeningeal and brain biopsy was obtained prior to the shunt insertion. Degenerative cerebral changes, most often Alzheimer (6 cases) or vascular changes (7 cases) were described in 14 out of 27 biopsies. Arachnoid fibrosis was found in 9 of the 18 biopsies containing arachnoid tissue. Overall, nine patients (33%) improved, of whom 6 presented Alzheimer or vascular changes in their biopsies. No correlation was found between clinical outcome and the presence or absence of degenerative cerebral changes and/or arachnoid fibrosis. However, a tendency towards higher improvement rates was noted in the subgroups presenting degenerative cerebral changes or arachnoid fibrosis. The results suggest that no constant morphological element exists in the syndrome of INPH. Various aetiologies may be involved in the pathogenesis and possibly in some cases co-existing: Patients may also improve by shunting despite the presence of degenerative cerebral parenchymal changes.

Unusual clinical manifestations of disturbed CSF dynamics in hydrocephalic children

OBJECTS

Clinical symptoms and signs of increased intracranial pressure (ICP) may be nonspecific and unreliable, or even entirely absent, in hydrocephalic infants and children. Even with a radiological examination, it is often difficult to distinguish between "arrested hydrocephalus" and slowly progressive hydrocephalus requiring treatment.

METHODS

We present two cases with unusual and initially misleading clinical manifestations of increased ICP. In both cases, the disturbed cerebrospinal fluid (CSF) dynamics, i.e. raised ICP, were not recognised until demonstrated by a long-term ICP monitoring. In a 5-month-old boy with normal head circumference and normal psychomotor development, the sudden onset of episodes of torticollis and screaming were the only symptoms. No pathology underlying the developing hydrocephalus and the raised ICP could be established, but the boy's condition improved after a shunt operation. In the other case, symptoms and signs consisted primarily in a slowly progressive dilatation of the facial veins with onset at the age of 2-3 years. As the girl also presented a congenital subvalvular aortic stenosis, the venous congestion was initially thought to reflect a vena cava superior syndrome. Further radiological examinations, however, revealed an extensive sinus thrombosis underlying the raised ICP. The girl underwent shunt insertion, and the venous congestion was reduced.

CONCLUSIONS

The cases illustrate that though clinical and radiological findings may be very doubtful, or unusual for increased ICP, direct diagnostic long-term ICP monitoring should always be contemplated. Only ICP monitoring can reveal with certainty whether disturbed CSF dynamics are involved, requiring a CSF diverting operation to treat and stabilise the condition.

A multidisciplinary memory clinic in a neurological setting: diagnostic evaluation of 400 consecutive patients

This report describes the operation of a multidisciplinary university hospital memory clinic in a neurological setting, and the diagnostic evaluations in 400 consecutive patients referred for cognitive symptoms and possible dementia during a period of 27 months (1 September 1995-31 December 1997). The mean age of the patients was 63.6 years (range 19-97). On clinical and neuropsychological examination, 46% of the patients fulfilled DSM IV criteria for dementia, 5% had selective amnesia, and 14% had other selective cognitive deficits. The remaining patients had either no significant cognitive deficits (31%) or were not evaluable (4%). A wide range of disorders from the fields of neurology, psychiatry, neurosurgery and internal medicine were identified as the underlying etiologies for the cognitive symptoms. Potentially reversible conditions were observed in 26% of the patients, not including the 11% in whom no specific underlying disease was identified. Concomitant conditions or risk factors with a potential influence on cognitive functions were identified in 61% of the patients. Diagnostic evaluation of patients with mild to moderate cognitive symptoms and possible dementia is an integrated multidisciplinary task, which should focus on the identification of non-progressive and potentially reversible etiologies, co-morbidity, selective cognitive deficits, and rare or atypical neurological conditions, as well as on the early identification of common progressive dementia disorders.

Indications for shunt insertion or III ventriculostomy in hydrocephalic children, guided by lumbar and intraventricular infusion tests

The best therapeutic management for infantile hydrocephalus is not always obvious. Traditionally, shunt insertion has been performed when CSF dynamics have been considered abnormal. However, in cases of noncommunicating hydrocephalus endoscopic III ventriculostomy (ETV) has become a well-established treatment modality, but despite clinical and radiological information clinical improvement is not obtained in all cases. A reliable preoperative investigative procedure helping to select hydrocephalic children for ETV, shunt insertion or no operation, is urgently needed. We report three cases of infantile hydrocephalus, in which our operative management was guided by the results of cerebrospinal (CSF) infusion tests. With a lumbar infusion test we assessed the CSF resorption capacity, and thus whether shunting was indicated. Comparing the results with those of an intraventricular infusion test, we assessed the presence of any structural blockage of the CSF circulation between the ventricles and the subarachnoid compartment, which would indicate a possible effect of an ETV. Performance of both a lumbar infusion test and a subsequent intraventricular infusion test in hydrocephalic children seems to provide valuable information for the decision-making on surgery.

Frontal brain and leptomeningeal biopsy specimens correlated with cerebrospinal fluid outflow resistance and B-wave activity in patients suspected of normal-pressure hydrocephalus

OBJECTIVE

Normal-pressure hydrocephalus (NPH) is a potentially treatable syndrome with abnormal cerebrospinal fluid dynamics. Meningeal fibrosis and/or obliteration of the subarachnoid space has been suggested as the pathoanatomic basis. The purpose of the present study was to investigate whether meningeal fibrosis causes increased resistance to cerebrospinal fluid outflow (R(out)) and/or increased B-wave activity and whether pathological changes in the brain parenchyma after brain compliance, causing increased B-wave activity.

METHODS

The study involved a group of 38 consecutively studied patients with clinical and radiological evidence of idiopathic NPH, for whom a frontal brain biopsy was obtained. For 29 patients, hydrodynamic criteria of NPH were fulfilled and a ventriculoperitoneal shunt was performed.

RESULTS

Meningeal fibrosis was found in 12 of 25 biopsies containing arachnoid tissue, but no correlation with R(out) or B-waves was found. Pathological parenchymal changes, most often Alzheimer's disease (10 cases) or vascular changes (10 cases), were found in 21 biopsies, but no correlation with B-waves or R(out) was found.

CONCLUSION

The results suggest that leptomeningeal fibrosis is not the only pathoanatomic basis of increased R(out) and/or B-wave activity in patients with NPH and that various degenerative changes in the parenchyma may be responsible for the altered cerebrospinal fluid dynamics characteristic of NPH.