Management of idiopathic normal-pressure hydrocephalus: a multiinstitutional study conducted in Japan.

OBJECT: A cooperative study was undertaken to identify factors that could be used to predict a favorable outcome after extracranial cerebrospinal fluid (CSF) diversion (shunting) in patients with suspected idiopathic normal-pressure hydrocephalus (NPH). METHODS: Questionnaires concerning patients with suspected idiopathic NPH were sent to 14 members of the Committee for Scientific Research on Intractable Hydrocephalus, sponsored by the Ministry of Health and Welfare of Japan. After the questionnaires were returned, a retrospective analysis of the responses was undertaken. To be included in the study, patients had to be 65 years of age or older and had to have undergone surgery between October 1995 and October 1998. Clinical measures included degrees of gait disturbance, dementia, and urinary incontinence as evaluated before. 3 months after, and 3 years after shunt placement. Diagnostic tests in various combinations included lumbar puncture in which CSF was withdrawn; intracranial pressure monitoring; measurements of CSF outflow resistance, level of serum alpha-1-antichymotrypsin, cerebral arteriovenous differences of oxygen content, and cerebral blood flow; and computerized tomography cisternography. In this study, 120 patients were identified as having idiopathic NPH and these patients underwent placement of shunts. A ventriculoperitoneal shunt with a programmable valve was used in two thirds of the patients. At the end of 3 months (early assessment), there was an 80% overall rate of clinical improvement, which dropped to 73.3% of the 105 patients who could be evaluated at the end of the 3-year study. Of the three variables, gait disturbance was most improved, both at early and late testing periods. Shunt complications occurred in 22 (18.3%) of the patients. CONCLUSIONS: Patients suspected of having idiopathic NPH did not form a homogeneous group, making it difficult to select those who would most likely respond to CSF diversion. Of the diagnostic studies, the most reliable result was improvement in clinical symptoms following a lumbar puncture in which CSF was withdrawn. The use of a programmable valve is recommended because it offers advantages in preventing problems of over- and underdrainage.     

The effects of fenestration of the interpeduncular cistern membrane arousted to the opening of lamina terminalis in patients with ruptured ACoA aneurysms: a prospective, comparative study

Summary Background. The incidence of chronic hydrocephalus requiring shunt placement is a well-known and common complication of aneurysmal subarachnoid hemorrhage (aSAH). It was suggested that fenestration of the lamina terminalis (LT) during microsurgery for aSAH may be associated with a reduced rate of shunt-dependent chronic hydrocephalus (SDCH). We analyzed that, fenestrations of the LT and Liliequist membrane (LM) would reduce rate of SDCH and improve rate of favorable outcome. Methods. 145 patients who were analyzed in the study were treated in our department with ruptured anterior communicating artery (ACoA) aneurysms. We compared the rate of shunting and clinical outcome in patients in whom only fenestration of the LT (Group 1) was performed with that in patients in whom fenestrations of both the LT and LM (Group 2) were performed. Results. Chronic hydrocephalus requiring shunting amounted to 9.8% (7 patients) in Group 1 and 4% (3 patients) in Group 2 (p = 0.203). Also, there were no differences in the rate of shunt dependent hydrocephalus between the two groups in patients with Fisher’s CT grades 3 (p = 0.343) and 4 (p = 0.667), and HH grades 4 (p = 0.306) and 5 (p = 0.361). Favorable clinical outcomes were observed with rates of 74.6% in Group 1 and 79.7% in Group 2 (p = 0.693). Also there were no differences in the rates of favorable clinical outcome between the two groups in patients with Fisher’s CT grades 3–4, HH grades 4–5. Conclusions. Our study shows that fenestration of the LM coupled with the opening of the LT reduced-relatively-the incidence of SDCH; this however was not significant. This positive effect was particularly noticeable in patients in whom a cisternal “overflow” was observed at surgery when opening the LM. This corresponded to cases with ventricular dilatation and a IV^th ventricle with clots.     

Postoperative hydrocephalus in cranial base surgery

The incidence of postoperative hydrocephalus and factors relating to it were analyzed in 257 patients undergoing cranial base surgery for tumor resection. A total of 21 (8%) patients developed postoperative hydrocephalus, and all required shunting, Forty-two (17%) patients developed cerebrospinal fluid (CSF) leak that required placement of external drainage systems (ventriculostomy or lumbar drain, or both); 10 (23%) of these 42 patients eventually needed shunt placement to stop the leak because of hydrocephalus. Prior craniotomy, prior radiation therapy, and postoperative CSF infection were also associated with an increased risk of developing hydrocephalus (48% versus 6%, 19% versus 8%, and 14% versus 7%, respectively). Prior radiation and postoperative CSF infection increased the risk of CSF leak in patients with hydrocephalus (30% versus 18% and 30% versus 9%, respectively). CSF leak and hydrocephalus commonly occurred in patients who underwent resection of a glomus tumor. In conclusion, 8% of patients who underwent cranial base surgery for tumors developed de novo hydrocephalus; half of them also had CSF leak in addition to hydrocephalus; and all required shunt placement for CSF diversion.     

Postoperative Hydrocephalus in Cranial Base Surgery

The incidence of postoperative hydrocephalus and factors relating to it were analyzed in 257 patients undergoing cranial base surgery for tumor resection. A total of 21 (8%) patients developed postoperative hydrocephalus, and all required shunting, Forty-two (17%) patients developed cerebrospinal fluid (CSF) leak that required placement of external drainage systems (ventriculostomy or lumbar drain, or both); 10 (23%) of these 42 patients eventually needed shunt placement to stop the leak because of hydrocephalus. Prior craniotomy, prior radiation therapy, and postoperative CSF infection were also associated with an increased risk of developing hydrocephalus (48% versus 6%, 19% versus 8%, and 14% versus 7%, respectively). Prior radiation and postoperative CSF infection increased the risk of CSF leak in patients with hydrocephalus (30% versus 18% and 30% versus 9%, respectively). CSF leak and hydrocephalus commonly occurred in patients who underwent resection of a glomus tumor. In conclusion, 8% of patients who underwent cranial base surgery for tumors developed de novo hydrocephalus; half of them also had CSF leak in addition to hydrocephalus; and all required shunt placement for CSF diversion.     

Results of surgical treatment of neurocysticercosis in 69 cases

The clinical course of 69 patients with neurocysticercosis who underwent surgery to control increased intracranial pressure (ICP) or cyst removal is analyzed. Increased ICP was caused by hydrocephalus in 63 patients, by cerebral edema in four, and by giant cysts in two. Skull x-ray films showed calcifications in 14% and signs of elevated ICP in 46%. Examination of cerebrospinal fluid (CSF) revealed pleocytosis with eosinophils in 52% of cases and a positive complement fixation test for cysticercosis in 66%. Ventriculography allowed localization of the CSF obstruction and ventricular cysts, and generally differentiated between an obstruction due to cysts and an inflammatory process. Computerized tomography showed cysts in the cerebral parenchyma and ventricular dilatation. Ventricular cysts were best seen when intraventricular metrizamide was used. Intracranial shunting and posterior fossa exploration were less effective in the treatment of hydrocephalus than was ventriculoatrial (VA) or ventriculoperitoneal (VP) shunting, although VA or VP shunting was associated with a high percentage of complications. Quality of survival was good in 87% of the cases in the first 3 postoperative months and in 93% of patients who survived 2 years after surgery. Forty-seven patients (68%) were readmitted one or more times for CSF shunt revision; 14 of them for shunt infection (meningitis). The early operative mortality rate was 1.8% for patients with VA or VP shunt placement and 5.3% for those with posterior fossa exploration. The authors conclude that placement of CSF shunts is indicated in the treatment of hydrocephalus, and cyst removal is indicated only when the cyst exhibits tumor-like behavior. Surgical exploration is also indicated when the diagnosis is uncertain.     

Endoscopic treatment of hydrocephalus in children: a controlled study using newly developed Yamadori-type ventriculoscopes.

Although cerebrospinal fluid (CSF) shunting is the most common neurosurgical treatment for hydrocephalus, the long-term results have still been unsatisfactory because of a wide variety of shunt complications. We have recently developed flexible ventriculoscopes (Yamadori-type) which have excellent image quality, maneuverability, and capabilities for endoscopic operation. Here we report the efficacy of the new treatment in 88 children with hydrocephalus who initially underwent either ventriculoscopic operation or shunting surgery. The primary outcome measures were the rate of shunt independency and/or shunt complications with a follow-up of 2 years in each group. We performed endoscopic third ventriculostomy in cases of aqueductal stenosis, cyst fenestration, and choroid plexus coagulation in limited cases of communicating hydrocephalus. Overall, thirty-three (75%) of the 44 children initially treated endoscopically did not require ventriculoperitoneal (VP) shunts. The endoscopic procedures were repeated in the remaining 11 children (25%) mostly less than 1-year-old who ultimately required endoscope-guided VP shunting. Even in such patients, there was virtually no need for shunt revisions and no major complications such as slit-like ventricle, meningitis, and intraventricular hemorrhage. These results were statistically highly significant (p < 0.0001) compared to a control group of 44 patients treated initially by VP shunting. Our data demonstrate that therapeutic ventriculoscopy is safe and clinically effective as the first-line treatment of hydrocephalus in children.     

A clinical audit of the Hakim programmable valve in patients with complex hydrocephalus

The objective of the investigation was to determine the pattern of use of the Hakim (Medos) programmable valve implanted in patients with complex hydrocephalus and their clinical outcome. A prospective audit of patients with complex hydrocephalus undergoing Hakim programmable valve implantation between 1989 and 1994 in the United Kingdom and Ireland, was followed-up for a minimum of 5 years. Surgical practice and complications were audited together with clinical outcome. One-hundred-and-thirty-nine patients (80 male, 59 female; mean age 43.4 years; median 47 years; range 1 month-84 years) with complex hydrocephalus due to a wide range of aetiologies were implanted with the Hakim programmable valve. Eighty-eight (63%) had large or massive ventricles prior to implantation; seven (5%) were slit. Fifty-five (40%) had previously been shunted with a fixed pressure system. One-hundred-and-thirty-one (94%) of the Hakim programmable shunts were ventriculoperitoneal; four (3%) ventriculoatrial; two (1.4%) cystoperitoneal; and two (1.5%) lumboperitoneal. The initial opening pressure selected ranged from 50 to 200 mmH2O (median 120). Valves were reprogrammed on average 1.7 times with 143 reprogrammings in the first year after implantation; 67 in the second; 19 in the third; three in the fourth; two in the fifth. Forty-nine (36%) valves were never reprogrammed after implantation. During the 5 years audit period, there were 70 (50%) shunt revisions, 40 of which were performed within 1 year of implantation. Thirty-six (27%) shunts were removed. There were 24 (18%) shunt infections. Subdural collections were identified in 37(27%) patients after Hakim programmable valve implantation; 10 (27%) required surgical drainage. Five (3.7%) patients developed symptomatic slit ventricles after Hakim programmable valve implantation. Headache was improved following reprogramming in 27(71%) of the 38 patients with refractory headache. After Hakim programmable valve implantation, patients underwent an average of 4.6 CT scans (range 1-25); 0.3 MRI (range 1-5) and 1.8 skull radiographs (range 1-20). The mean hospital stay per patient over 5 years was 26 days (range 1-110 days). Five years after implantation, the Glasgow Outcome scale was favourable in 64% of patients. The Hakim programmable valve is useful in the management of patients with complex hydrocephalus and may reduce the need for shunt revision for headache. Non-haemorrhagic, post-shunting, subdural collections identified on routine postoperative CT may be treated by reprogramming.     

Efficacy of Lumbo-Peritoneal Versus Ventriculo-Peritoneal Shunting for Management of Chronic Hydrocephalus Following Aneurysmal Subarachnoid Haemorrhage

Summary ? Background. The clinical usefulness of lumboperitoneal (LP) shunts in selecting patients with communicating hydrocephalus after aneurysmal subarachnoid haemorrhage (SAH) was compared with that of ventriculoperitoneal (VP) shunts.  Method. Chronic hydrocephalus was defined as clinically and radiographically demonstrated hydrocephalus which lasted 3 weeks or longer after the original haemorrhage and which required shunting. Indications for a CSF shunt were assessed on the basis of neurological symptoms and signs, CT findings, and isotope cisternogram findings. The patients were treated with either LP or VP shunts. A significant response to shunting was defined as an improvement of function to a higher grade. The functioning of the shunt was evaluated by the location of the catheter on x-ray studies, CT features, and isotope cisternograms. The operation groups were checked for comparability of demographic and clinical variables including age, Fisher grade, hypertension, vasospasm, shunt interval, preshunt functional grade, and CT findings. A comparative analysis of the outcome was carried out between the two operation groups.  Findings. Fifty-six patients underwent shunt placements (LP shunts: 22, VP shunts with medium pressure valve: 2, VP shunts with high pressure valve: 32). There was no statistically significant difference in patient demographics and clinical characteristics between the patients with LP shunts and those with VP shunts. A follow-up time of 3 months to 8 years revealed clinical improvement in 11 cases (50.0%) of patients with LP shunts and 31 cases (91.1%) in VP shunts was seen (Fisher's exact test, P<0.005).  Interpretation. These findings suggest that VP shunts are a better choice of treatment than LP shunts in treating chronic hydrocephalus after aneurysmal SAH.     

Ventriculoperitoneal shunts with the use of pressure-adjustable valve in the management of hydrocephalus

Sixteen patients with hydrocephalus of varied etiology who underwent ventriculo-peritoneal shunts utilizing pressure-adjustable valves were reviewed, and the usefulness of the pressure-adjustable valve in the management of hydrocephalus was evaluated. Before shunting all patients had CT evidence of hydrocephalus with Evans' Index greater than 30%. High-, medium- and low-pressure settings were chosen in 3, 11 and 2 patients respectively, according to the CSF pressure as measured during lumber puncture or ventricular drainage. Following the shunting procedures with programmable pressure valves, hydrocephalus was alleviated with Evans' Index being 27% on the average, as evaluated by CT scans. Such clinical symptoms as disturbed consciousness, dementia and increased intracranial pressure all subsided. There were no mortality, infection or revision during the follow-up period of 5 to 16 months. Of particular note was that, among these 16 cases, there were three illustrative cases in which programmable pressure valves were found useful in coping with newly developed subdural effusion and low-intracranial-pressure syndrome, by manually adjusting the valves to higher pressure settings.     

Ventriculosagittal sinus shunt placement: technical case report

OBJECTIVE AND IMPORTANCE: Determining an appropriate site for distal catheter placement for ventricular shunting for some hydrocephalic patients can be difficult. We describe a simplification of the technique for sagittal sinus shunt placement using a guidewire. CLINICAL PRESENTATION: A 20-month-old infant with hydrocephalus secondary to Alexander's disease developed erosion of her parieto-occipital ventriculoperitoneal shunt reservoir through an occipital decubitus scalp ulceration. Her hydrocephalus was temporarily treated with a ventriculostomy; however, she developed pneumatosis intestinalis while in the hospital. TECHNIQUE: The patient underwent placement of a ventriculosagittal sinus shunt. The ventricular catheter and shunt valve were placed through a burr hole at Kocher's point, and the distal end of the catheter was placed in the superior sagittal sinus by using the Seldinger technique. CONCLUSION: Ventriculosagittal sinus shunting may be used as an alternative to traditional methods for patients for whom distal shunt placement is problematic. Our technique has the theoretical advantage of reducing the risks of blood loss or air embolism by not requiring a scalpel incision into the sinus.     

Valve inclination influences the performance of gravity-assisted valve

BACKGROUND: The performance of GAV may be affected by its inclination as a tantalum sphere in the valve, which generates a downhill force in proportion to the sine of the angle with respect to level. Accordingly, the aim of this study was to evaluate the effect of valve inclination relative to the vertical on shunt performance. METHOD: In 24 adult patients who underwent ventriculoperitoneal shunting using a GAV for hydrocephalus, valve inclination relative to the vertical was measured using AP and lateral projections of skull x-rays that were taken in a standing position, and the relationship between valve inclination and ventricular volume change after ventriculoperitoneal shunting in CT scans was evaluated. RESULTS: The Pearson correlation coefficient between valve inclination in a sagittal plane and ventricular volume change was -0.768 (P < .01), whereas lateral valve inclination had no correlation with ventricular volume change. Eleven patients with a posterior valve inclination relative to the vertical exhibited a greater ventricular volume reduction of 34.1% +/- 8.2% compared to the volume reduction of 13.4% +/- 9.2 % in 13 other patients with an anterior valve inclination (P = .000). Two (40%) of 5 patients with a severe anterior valve inclination of more than 20 degrees relative to the vertical underwent shunt revision for underdrainage. CONCLUSIONS: A severe anterior inclination of the valve by more than 20 degrees relative to the vertical can lead to underdrainage owing to an increased OP in a lying position, especially in patients who are nonambulatory at the time of GAV implantation.     

Volumetric measurements in the detection of reduced ventricular volume in patients with normal-pressure hydrocephalus whose clinical condition improved after ventriculoperitoneal shunt placement

OBJECT: The syndrome of normal-pressure hydrocephalus (NPH) refers to the clinical triad of gait disturbance, dementia, and urinary incontinence in association with idiopathic ventriculomegaly and normal intracranial pressure. Ventriculoperitoneal (VP) shunt placement often yields significant clinical improvements, sometimes without apparent reduction of ventricular size. The authors hypothesized that careful volumetric measurements would show a decrease in ventricular volume in these patients. METHODS: Twenty consecutive patients with NPH underwent placement of VP shunts equipped with programmable valves. In 11 patients pre- and postoperative neuroimaging was performed, which allowed volumetric analysis. Volumetric measurements of the lateral ventricles were calculated in triplicate by National Institutes of Health image-processing software to assess standard computerized tomography (CT) scans (eight patients) or magnetic resonance (MR) images (three patients) obtained before and after shunt placement. Ventricular volumes were also assessed by an independent neuroradiologist. Postoperative studies were performed at a time of clinical improvement, between 1 and 9 months postsurgery (mean 5 months). Preoperative and postoperative Unified Parkinson's Disease Rating Scale evaluations were performed in four patients. Significant clinical improvement occurred in all patients after shunt placement (mean follow-up period 17.5 months). Although 10 (91%) of 11 patients demonstrated a calculable decrease in volume in the lateral ventricles (mean decrease 39%), formal interpretation of neuroimages indicated a definite decrease in lateral ventricular volume in only three (27%) of 11 patients. CONCLUSIONS: Volumetric measurements obtained to compare preoperative and postoperative CT or MR studies obtained in patients with NPH in whom clinical improvement was seen after shunt placement surgery show a demonstrable decrease in ventricular size. Volumetric measurements may be helpful in clinical assessment postoperatively and in guiding programmable valve pressure settings.     

Ventriculoperitoneal shunting in childhood tuberculous meningitis

Hydrocephalus is a common complication of tuberculous meningitis (TBM) in children. In this study, 217 patients with stage II and III TBM and hydrocephalus (TBMH) were reviewed. Ventriculoperitoneal shunting (VPS) was performed in the acute stage if the hydrocephalus was non-communicating or following failed medical therapy if the hydrocephalus was communicating. Following this protocol only 65 of 217 (29.9%) patients eventually required VPS. Non-communicating hydrocephalus was present in 38 of 65 (58.5%) and communicating hydrocephalus in 27 of 65 (41.5%) of the shunted cases. These 65 cases were followed for 6 months and their outcome assessed. Good outcome or moderate disability was seen in 55.4% and 12.3% died. Different factors relating to outcome are discussed. The shunted patients in this study had a high complication rate of 32.3%, with shunt infection and shunt obstruction each occurring in 9 of 65 (13.5%) of cases. TBM complicated by hydrocephalus remains a devastating condition and VPS in these patients has a high complication rate. Identifying those patients who may be managed without shunting will save costs and reduce complications, however early VPS in patients with non-communicating hydrocephalus is still indicated.     

Role of cerebrospinal fluid shunting for human immunodeficiency virus-positive patients with tuberculous meningitis and hydrocephalus

OBJECTIVE: Tuberculous meningitis (TBM) and its complications continue to have devastating neurological consequences for patients. Budgetary constraints, especially in developing countries, have made it necessary to select patients for shunting who are likely to experience good recoveries. To date, the value of cerebrospinal fluid shunting for human immunodeficiency virus (HIV)-positive patients with TBM has not been clearly established. METHODS: Thirty patients with TBM and hydrocephalus were prospectively evaluated. Coincidentally, one-half of the patients were HIV-positive. All patients underwent uniform treatment, including ventriculoperitoneal shunt placement and antituberculosis treatment. CD4 counts were measured for all patients. Outcomes were assessed at 1 month. RESULTS: No complications related to shunt insertion were noted. The HIV-positive group fared poorly (death, 66.7%; poor outcome, 64.7%), compared with the HIV-negative group (death, 26.7%; poor outcome, 30.8%). Despite cerebrospinal fluid shunting, no patient in the HIV-positive group experienced a good recovery (Glasgow Outcome Scale score of 5). This is in contrast to the six patients (40%) in the HIV-negative group who, with the same treatment, experienced good recoveries (Glasgow Outcome Scale scores of 5) at discharge (P<0.14). No patient (either HIV-positive or HIV-negative) who presented in TBM Grade 4 survived, whereas no HIV-positive patient who presented in TBM Grade 3 survived. A significant relationship was noted between CD4 counts and patient outcomes (P<0.031). CONCLUSION: In the absence of obvious clinical benefit, HIV-positive patients with TBM should undergo a trial of ventricular or lumbar cerebrospinal fluid drainage, and only those who exhibit significant neurological improvement should proceed to shunt surgery.     

Analysis of risk factors for infection in coplacement of percutaneous endoscopic gastrostomy and ventriculoperitoneal shunt

Patients with severe neurological impairment requiring tube feeding may have concomitant hydrocephalus. Coplacement of percutaneous endoscopic gastrostomy (PEG) and ventriculoperitoneal (VP) shunting is currently standard in such cases. The present study investigated the risk factors for shunt infection in such patients. The medical records of 23 patients with PEG and VP shunting were retrospectively reviewed. Correlations between shunt system infection and potential risk factors were analyzed including order of PEG and VP shunting, position of abdominal shunt catheter, diabetes mellitus, tracheostomy, and activities of daily living. Twelve patients underwent VP shunting after PEG and 11 underwent PEG after VP shunt placement. Four patients experienced shunt infection, and three required shunt revision. Three of these four patients underwent VP shunting after PEG. The period between PEG and VP shunt placement was 18, 19, and 25 days, shorter than the mean period of 29.3 days. VP shunting can be combined with PEG, but a larger study is required to clearly identify the risk factors. Administration of prophylactic antibiotics and a period of at least 1 month between the procedures are recommended, particularly if the shunt is placed after the PEG tube.     

Management of hydrocephalus in pediatric patients with posterior fossa tumors: the role of endoscopic third ventriculostomy.

OBJECT: The authors undertook a study to evaluate the effectiveness of endoscopic third ventriculostomy in the management of hydrocephalus before and after surgical intervention for posterior fossa tumors in children. METHODS: Between October 1, 1993, and December 31, 1997, a total of 206 consecutive children with posterior fossa tumors underwent surgery at H?pital Necker-Enfants Malades in Paris. Excluded were 10 patients in whom shunts had been placed at the referring hospital. The medical records and neuroimaging studies of the remaining 196 patients were reviewed and categorized into three groups: Group A, 67 patients with hydrocephalus present on admission in whom endoscopic third ventriculostomy was performed prior to tumor removal; Group B, 82 patients with hydrocephalus who did not undergo preliminary third ventriculostomy but instead received conventional treatment; and Group C, 47 patients in whom no ventricular dilation was present on admission. There were no significant differences between patients in Group A or B with respect to the following variables: age at presentation, evidence of metastatic disease, extent of tumor resection, or follow-up duration. In patients in Group A, however, more severe hydrocephalus was demonstrated (p < 0.01): the patients in Group C were in this respect different from those in the other two groups. Ultimately, there were only four patients (6%) in Group A compared with 22 patients (26.8%) in Group B (p = 0.001) in whom progressive hydrocephalus required treatment following removal of the posterior fossa tumor. Sixteen patients (20%) in Group B underwent insertion of a ventriculoperitoneal shunt, which is similar to the incidence reported in the literature and significantly different from that demonstrated in Group A (p < 0.016). The other six patients (7.3%) were treated by endoscopic third ventriculostomy after tumor resection. In Group C, two patients (4.3%) with postoperative hydrocephalus underwent endoscopic third ventriculostomy. In three patients who required placement of CSF shunts several episodes of shunt malfunction occurred that were ultimately managed by endoscopic third ventriculostomy and definitive removal of the shunt. There were no deaths; however, there were four cases of transient morbidity associated with third ventriculostomy. CONCLUSIONS: Third ventriculostomy is feasible even in the presence of posterior fossa tumors (including brainstem tumors). When performed prior to posterior fossa surgery, it significantly reduces the incidence of postoperative hydrocephalus. The procedure provides a valid alternative to placement of a permanent shunt in cases in which hydrocephalus develops following posterior fossa surgery, and it may negate the need for the shunt in cases in which the shunt malfunctions. Furthermore, in patients in whom CSF has caused spread of the tumor at presentation, third ventriculostomy allows chemotherapy to be undertaken prior to tumor excision by controlling hydrocephalus. Although the authors acknowledge that the routine application of third ventriculostomy in selected patients results in a proportion of patients undergoing an "unnecessary" procedure, they believe that because patients' postoperative courses are less complicated and because the incidence of morbidity is low and the success rate is high in those patients with severe hydrocephalus that further investigation of this protocol is warranted.     

A positron emission tomography study of cerebrovascular reserve before and after shunt surgery in patients with idiopathic chronic hydrocephalus.

OBJECT: In this study the authors use positron emission tomography (PET) to investigate cerebral blood flow (CBF) and cerebrovascular reserve (CVR) in chronic hydrocephalus. METHODS: Ten patients whose mean age was 67 +/- 10 years (mean +/- standard deviation [SD]) were compared with 10 healthy volunteers who were 25 +/- 3 years of age. Global CBF and CVR were determined using (15)O-H2O and PET prior to shunt placement and 7 days and 7 months thereafter. The CVR was measured using 1 g acetazolamide. Neurological status was assessed based on a score assigned according to the methods of Stein and Langfitt. Seven months after shunt placement, five patients showed clinical improvement (Group A) and five did not (Group B). The average global CBF before shunt deployment was significantly reduced in comparison with the control group (40 +/- 8 compared with 61 +/- 7 ml/100 ml/minute; mean +/- SD, p < 0.01). In Group A the CBF values were significantly lower than in Group B (36 +/- 7 compared with 44 +/- 8 ml/100 ml/minute; p < 0.05). The CVR before surgery, however, was not significantly different between groups (Group A = 43 +/- 21%, Group B = 37 +/- 29%). After shunt placement, there was an increase in the CVR in Group A to 52 +/- 37% after 7 days and to 68 +/- 47% after 7 months (p < 0.05), whereas in Group B the CVR decreased to 14 +/- 18% (p < 0.05) after 7 days and returned to the preoperative level (39 +/- 6%) 7 months after shunt placement. CONCLUSIONS: The preliminary results indicate that a reduced baseline CBF before surgery does not indicate a poor prognosis. Baseline CBF before shunt placement and preoperative CVR are not predictive of clinical outcome. A decrease in the CVR early after shunt placement, however, is related to poor late clinical outcome, whereas early improvement in the CVR after shunt placement indicates a good prognosis.     

Diamox® Challenge Test to Decide Indications for Cerebrospinal Fluid Shunting in Normal Pressure Hydrocephalus

Summary ? Objective. The indications for cerebrospinal fluid (CSF) shunting in patients with normal pressure hydrocephalus (NPH) have not been established. Establishment of clear-cut indications for this procedure is essential to ensure cost-effective, and safe treatment. We report the usefulness of the Diamox^? challenge test in evaluating indications for CSF shunting in patients with NPH.  Methods. Pre- and post-operative responses in cerebral blood flow (CBF) and intracranial pressure (ICP) to intravenous administration of Diamox^? 1000mg (Diamox^? administration) were analysed in 41 patients with NPH who were treated by ventriculoperitoneal (VP) shunt with a programmable valve and an on-off valve.  Results. The preoperative response of ICP to Diamox^? administration was more than 10 mmHg in most patients in whom the shunt was effective (shunt effective group), however, it was less than 10 mmHg in most patients in whom the shunt was ineffective (shunt non-effective group). Furthermore, the postoperative response of ICP to Diamox^? administration decreased to less than 10 mmHg in most patients in the shunt effective group. The increases in CBF in response to Diamox^? administration were similar in the two groups both before and after placement of the VP shunt.  Conclusion. Patients in whom ICP increased by more than 10 mmHg in response to Diamox^? administration were regarded to have poor CSF circulation and to thus be candidates for CSF shunting. The Diamox^? challenge test is a simple, safe procedure, useful in evaluating the response to treatment.     

Lumboperitoneal shunt for the treatment of hydrocephalus in premature infants

Summary Four premature infants weighing less than 2,500 grams underwent lumboperidoneal shunt for their communicating hydrocephalus. Using a microscope, mini-laminectomy and exact placement of the proximal end of the shunt tube into the subarachnoid space was achieved. After the lumboperitoneal shunting, hydrocephalus in all four patients was relieved without any complications. The author discusses the availability of lumboperitoneal shunt for hydrocephalus in premature infants.     

Experience with a programmable valve shunt system.

OBJECT: The goal of this study was to clarify the efficacy of the Codman Hakim programmable valve. Clinical data obtained in 179 patients with hydrocephalus or other intracranial fluid-accumulating diseases were analyzed. METHODS: Shunt placement operations were effective in 168 patients, approximately one half (50.6%) of whose devices required reprogramming of opening pressure postoperatively. This was a significantly larger number of shunts than the authors had thought would need reprogramming. Extremely narrowed ventricles observed on computerized tomography scans, as well as clinical symptoms related to inadequate or excessive cerebrospinal fluid drainage, improved in patients after shunt reprogramming. Shunt reprogramming frequently was necessary in patients with posthemorrhagic acute hydrocephalus; the programmable valve proved particularly beneficial for such patients. Subdural effusion and arachnoid cyst also proved to be good indications for use of the valve. Twelve patients (7%) suffered complications postoperatively. The most common complication was valve obstruction, which occurred in five patients, most of whom had brain tumors. CONCLUSIONS: The programmable valve was beneficial for the treatment of hydrocephalus and other intracranial fluid-accumulating diseases. It is important to be careful in selecting patients for treatment with the programmable valve, because complications involving the valve seem more likely in brain tumor cases. The valve proved to be poorly resistant to magnetic fields; therefore, it is essential to confirm opening pressure after every magnetic resonance imaging examination. The authors recommend that an identification system for patients be developed so that medical personnel will be aware of the presence of the valve and the previous setting of opening pressure.