Michel Zerah

Congenital lumbosacral lipomas

Abstract Congenital lumbosacral lipomas can be responsible for progressive defects. The general feeling is that tethering of roots, filum, or cord probably explains this evolution, and that untethering of these structures could prevent late deterioration. Like the vast majority of neurosurgeons, we too have routinely and systematically operated on lumbosacral lipomas, even in the absence of neurological deficits. This policy stemmed from our belief that spontaneous neurological deterioration was frequent, recovery from preoperative deficits rare, and surgery both efficient and benign in nature. After 22 years of experience, we felt that it was necessary to review our series of 291 lipomas (38 lipomas of the filum and 253 of the conus) operated on from 1972 to 1994. To reassess the value of pro-phylactic surgery, we attempted an accurate evaluation of (1) the risk of pathology, (2) the risks involved in surgery, (3) the postoperative outcome with respect to preoperative deficits, and (4) the postoperative outcome in asymptomatic patients at 1 year and at maximum follow-up. Special attention was paid to 93 patients whose postoperative follow-up was more than 5 years (average 8.7, median 8, range 5–23 years). Of these 93 patients, 39 were asymptomatic preoperatively (7 with lipoma of the filum and 32 with lipoma of the conus). Lipomas of the filum and of the conus are entirely different lesions and were studied separately. In 6 cases prenatal diagnosis had been possible. The mean age at surgery was 6.4 years. Low back skin stigmata were present in 89.4% of cases. Preoperative neurological deficits existed in 57% of the patients and were congenital in 22%. Clinical signs and symptoms recorded were pain in 13.3% of the patients and/or neurological deficits affecting sphincter (52%), motor (27.6%) and sensory (22.4%) functions. Deficits were progressive in 22.4% of cases, slowly progressive in 58.8% of these and rapidly progressive in the remaining 41.2%. In 36 patients (13.2%) the lipomas were seen to grow either subcutaneously or intraspinally. Among these patients, 21 were infants, 2 were obese adolescents, and 10 were pregnant women. The metabolism of the fat within the lipomas was studied in 11 patients and found to be similar to that at other sites. Lipomas were associated with various other malformations, either intra- or extraspinal. These associated anomalies were rare in the case of lipomatous filum (5.2%) but frequent with lipomas of the conus, except for intracranial malformations (3.6%). Therapeutic objectives were spinal cord untethering and decompression, sparing of functional neural tissue and prevention of retethering. Procedures used to achieve these goals were subtotal removal of the lipoma, intraoperative monitoring, duroplasty, and sometimes closure of the placode. Histologically, lipomas consisted of normal mature fat. However, 77% of them also included a wide variety of other tissues, originating from ectoderm, mesoderm, or entoderm. This indicates that lipomas are either simple or complex teratomas. The results of the study are as follows. (1) Surgery was easy and safe when performed for treatment of lipomas of the filum (no complications), but difficult and hazardous in the case of lipomas of the conus (20% local, 3.9% neurological complications). (2) All types of deficit could be improved by surgery, which was beneficial in all cases of lipoma of the filum and 50% of cases of lipoma of the conus. (3) In asymptomatic patients long-term surgical results depended on the anatomical type of the lipoma. They were excellent in lipomas of the filum. In lipomas of the conus they were good in the short term but eroded with time. At more than 5 years of follow-up only 53.1% of the patients were still free of symptoms. (4) Reoperations were performed in 16 patients (5.5%), 5 (31.2%) of whom improved postoperatively, while in 7 (43.7%) progression stopped, in 3 (18.7%) deterioration continued and in 1 (6.2%) the condition was worse after surgery. (5) The natural history of the malformation, that is to say the risk of spontaneous aggravation, has only been evaluated in hospital in-patients, so that the true level of risk remains unknown. This means we cannot interpret the actuarial curve following surgery for asymptomatic lipoma of the conus. In conclusion, there are two different types of lipoma: lipoma of the filum, for which surgery is harmless and beneficial in both the short and the long term, and lipoma of the conus, for which surgery involves considerable risks and is of questionable benefit in the long term. This raises the question as to whether prophylactic surgery is indicated for patients with asymptomatic lipomas of the conus, and whether the outcome is any better than it would be if the lipoma were left to take its natural course. The lack of basic information remains a stumbling block to management of these patients. Until this is remedied, we are unable to recommend prophylactic surgery in patients with asymptomatic lipomas of the conus.

The role of endoscopic third ventriculostomy in the management of shunt malfunction.

OBJECTIVE To evaluate the effectiveness of third ventriculostomy as an alternative to shunt revision in the management of shunt malfunction and infection in obstructive hydrocephalus. METHODS All of the clinical notes of 30 patients treated with third ventriculostomy for malfunctioning or infected shunts between January 1, 1974, and December 31, 1996, were retrospectively reviewed. Third ventriculostomy was performed under fluoroscopic control in the first seven patients and endoscopically in the remainder. A successful outcome was achieved if further shunt revision surgery was avoided. The median follow-up duration was 8.7 years RESULTS Twenty-three patients (76.7%) experienced successful outcomes, resulting in shunt independence. Of the seven failures, three were technical failures at the time of surgery and the remaining four were manifest within a median of 10 days, resulting in shunt revision. There have been no delayed failures. CONCLUSION Third ventriculostomy is a valuable alternative to shunt revision in patients affected by obstructive hydrocephalus presenting with shunt malfunction or infection. It should be considered in all suitable cases as the first-line treatment for obstructive hydrocephalus of all causes. Because all failures were manifest within a short time, it is likely that these successes will be durable.

Cerebral arteriovenous malformations in children - Management of 179 consecutive cases and review of the literature

Over the past 10 years (1982–1992), we have been actively involved in the management of 179 cerebral arteriovenous malformations (CAVMs) in children and infants. Seventy-seven were true vein of Galen malformations (VGAMs) and 102 were pial AVMs (PAVMs), i.e., developed in the subpial space. Hemorrhage occurred as the first symptom in 50% of the children with pial AVMs, but was present in none of the VGAM cases. Only 31 children were found to be unsuitable for endovascular treatment, and in 124 cases embolization was indicated as the primary treatment (104 embolization performed). Only 21 children underwent a direct surgical approach (none in the VGAM group). In the embolized group in whom treatment has been completed (n = 56), 8 children died, 39 have an anatomical cure, and 34 are clinically normal. In the group under treatment (n = 56), 16 are not normal. The problems are timing and the aims (total or partial treatment) of the therapeutic procedures. In the nonembolized group (n = 31), 8/13 of the pial lesions were operated on (no mortality, 2 patients with moderate neurological deficits). In the VGAM group 13/18 died and 4 had spontaneous thrombosis (only 1 is neurologically normal). In the nonembolized group 13 lesions have been completely excluded, but only 5 patients are neurologically normal. This fact again stresses the need for prognostic evaluation before treatment and a clear definition of the treatment aims. Analysis of a large number of published series on the management of children with AVMs (1017 cases) reveals inconsistencies that hamper proper evaluation and comparison. In our experience, endovascular treatment always seems to be the best primary treatment in both VGAMs and PAVMs. However, management of children with these lesions requires a large multidisciplinary team, which is the only way of offering the most suitable and effective treatment, the sole guarantee of a good result.

Stereotactic biopsy of diffuse pontine lesions in children

OBJECT Empirical radiotherapy is the current treatment for children with diffuse pontine lesions that have imaging characteristics of an infiltrative malignant astrocytoma. The use of chemotherapeutic agents is, however, currently under investigation in the treatment of these tumors. To be included into a trial, patients need a definitive histological diagnosis. The authors present their prospective study of the stereotactic biopsy of these lesions during a 4-year period. METHODS A suboccipital, transcerebellar approach was used to obtain biopsy samples in 24 children. RESULTS Two patients suffered deficits. Both had a transient (< 2 months) new cranial nerve palsy; one of these patients also experienced an exacerbation of a preoperative hemiparesis. No patient died during the perioperative period. A histological diagnosis was made in all 24 patients as follows: 22 had a malignant infiltrative astrocytoma, one had a low-grade astrocytoma, and one had a pilocytic astrocytoma. The diagnosis of the latter two patients affected the initial treatment after the biopsy. CONCLUSIONS The findings of this study imply that stereotactic biopsy sampling of a diffuse pontine tumor is a safe procedure, is associated with minimal morbidity, and has a high diagnostic yield. A nonmalignant tumor was identified in two of the 24 patients in whom the imaging findings were characteristic of a malignant infiltrative astrocytoma. With the advent of new treatment protocols, stereotactic biopsy sampling, which would allow specific tumor characterization of diffuse pontine lesions, may become standard.

Conservative Management of Asymptomatic Spinal Lipomas of the Conus

OBJECTIVEThe natural history of spinal lipomas of the conus (SLCs) has not been well studied. Because of disappointing long-term results with early surgical treatment of asymptomatic children with SLCs, we have followed a protocol of conservative management for these patients. The results are presented in this report. METHODSSince 1994, all asymptomatic children with SLCs who were examined at Necker-Enfants Malades Hospital were subject to a protocol of conservative management. The records for those patients were reviewed, to determine the incidence and timing of neurological deterioration. The findings were compared with those for a previously reported historical cohort of asymptomatic patients who underwent early surgery at our institution. RESULTSFifty-three asymptomatic children (35 girls and 18 boys) with SLCs were monitored, with conservative management. During a mean follow-up period of 4.4 years (range, 12 mo to 9 yr), 13 patients (25%) exhibited neurological deterioration. At 9 years, the actuarial risks of deterioration, as determined with the Kaplan-Meier method, were 33% for the conservatively treated patients and 46% for the surgically treated patients. With a Cox proportional-hazards model, there was no significant difference in the risks of neurological deterioration for patients who were treated conservatively and those who underwent early surgery. CONCLUSIONThe incidences and patterns of neurological deterioration seemed to be very similar, regardless of whether early surgery was performed. These results suggest that conservative treatment of asymptomatic patients is a reasonable option. A more definitive randomized study will be required to clarify the relative efficacy of early surgery for SLCs among asymptomatic patients.

Hydrodynamics in vein of Galen malformations

Forty-three patients with vein of Galen aneurysmal malformations (VGAM) referred to us for endovascular treatment between 1985 and 1990 and 335 additional cases published in the literature were reviewed with particular attention to the presence of ventricular enlargement and outcome after shunting. Hydrocephalus was the second most frequent symptom (46.8%); it is more frequent in infants (73%) than in children, adults (30%) or neonates (15%). Of the patients reported in the literature, 17.9% had undergone shunting. Within the shunted population there was an overall morbidity of 41% and a mortality of 10% (especially in the infant group). In our series 17 patients (39.5%) were shunted and a significant difference in the clinical outcome was noted between the shunted and the nonshunted group. Of the nonshunted patients, 66.6% were free of any neurological deficit or mental retardation and fewer than 5% presented with significant mental retardation. On the other hand, only 33.3% of the shunted patients had a favorable outcome and more than 15% developed significant mental retardation. Among the various causes of hydrocephalus in patients with VGAMs, such as obstruction of the aqueduct, subarachnoid hemorrhage, or ex vacuo hydrocephalus, high venous pressure may be of particular importance. In this article a physiopathological interpretation of the hydrodynamics in VGAMs is developed and a speculative explanation for CSF disorders related to ventricular shunting proposed. Treatment of hydrocephalus in VGAMs can be achieved through obliteration of the malformation or at least diminishing the venous pressure; surgical ventricular shunting does not have to be the first treatment of hydrodynamic disorders associated with VGAMs, especially in infants.

Nongalenic cerebral arteriovenous malformations in neonates and infants. Review of 26 consecutive cases (1982-1992).

We present 26 consecutive cases of nongalenic pial arteriovenous malformations (PAVMs) diagnosed in the neonatal period or in infancy. No diagnosis was made antenatally. Presenting symptoms in neonates were systemic cardiac manifestations (54%), seizures (31%), and hemorrhages (15%). In infants, hemorrhagic strokes and hydrodynamic disorders (external or internal hydrocephaly, macrocephaly, atrophy) both occurred in 38% of cases. Systemic cardiac manifestations and seizures were rare at that age (respectively 16% and 8%). Sixty-two percent of neonates and 31% of infants already had neurocognitive disorders (assessed by pediatric neurocognitive testing: Brunet-Leizine and Denver tests) when referred. The venous drainage and its anomalies (ectasias, stenoses, thromboses) were the main causes of symptoms. Atrophy and leukomalacic lesions occurred rapidly; they express local hydrovenous disorders and are specific to this population group. Untreated neonates and infants have a poor prognosis. Endovascular treatment, although partial and challenging in all instances, represents the treatment of choice in our series. Of the eight neonates treated, one improved to normal (12.5%), while four remained stable (50%): two neurologically normal, two with mild neurological deficit. Three (37%) died despite embolization (heart failure, multiorgan failure, postoperative death). Transient neurological complications occurred in two cases (25%): hemiparesis in one patient with a rolandic and in one with a thalamic AVM. Of the eight infants successfully embolized, one was significantly improved (12.5%) and is now neurologically normal, while five remained stable (62.5%): four neurologically normal, one with mild neurological deficit. One died between two sessions of embolization from intracerebral hemorrhage (12.5%). Hemianopsy occurred in one case (12.5%) after embolization of an occipital AVM. In one additional case in a normal child we failed to embolize the last small pial AVM of four after the three others had spontaneously thrombosed. With a minimal follow-up of 18 months and a maximum of 7 years, the review of our series shows 53% of the initial group of neonates and infants growing neurologically normal after therapeutic management in our institution; 23.5% died despite treatment, and the remaining 23.5% present minor neurological deficit. When targeted at the points of angioarchitectural weakness, embolization contributes to stabilizing a lesion. It should be undertaken rapidly to avoid loss of brain substance secondary to hemorrhage, atrophy, or leukomalacia, and to allow neurocognitive recovery and normal brain maturation. In our experience, theses lesions are the most aggressive ones for the maturating brain, and the most difficult to approach technically. They represent a new therapeutic field and have their own specific anatomy and physiology.

Is the sitting or the prone position best for surgery for posterior fossa tumours in children

Background: The aim of this study was to compare complications in children operated for posterior fossa tumours in the sitting position with those in the prone position.

Failure of third ventriculostomy in the treatment of aqueductal stenosis in children.

OBJECT The goal of this study was to analyze the types of failure and long-term efficacy of third ventriculostomy in children. METHODS The authors retrospectively analyzed clinical data obtained in 213 children affected by obstructive triventricular hydrocephalus who were treated by third ventriculostomy between 1973 and 1997. There were 120 boys and 93 girls. The causes of the hydrocephalus included: aqueductal stenosis in 126 cases; toxoplasmosis in 23 cases, pineal, mesencephalic, or tectal tumor in 42 cases; and other causes in 22 cases. In 94 cases, the procedure was performed using ventriculographic guidance (Group I) and in 119 cases by using endoscopic guidance (Group II). In 19 cases (12 in Group I and seven in Group II) failure was related to the surgical technique. Three deaths related to the technique were observed in Group I. For the remaining patients, Kaplan-Meier survival analysis showed a functioning third ventriculostomy rate of 72% at 6 years with a mean follow-up period of 45.5 months (range 4 days-17 years). No significant differences were found during long-term follow up between the two groups. In Group I, a significantly higher failure rate was seen in children younger than 6 months of age, but this difference was not observed in Group II. Thirty-eight patients required reoperation (21 in Group I and 17 in Group II) because of persistent or recurrent intracranial hypertension. In 29 patients shunt placement was necessary. In nine patients in whom there was radiologically confirmed obstruction of the stoma, the third ventriculostomy was repeated; this was successful in seven cases. Cine phase-contrast (PC) magnetic resonance (MR) imaging studies were performed in 15 patients in Group I at least 10 years after they had undergone third ventriculostomy (range 10-17 years, median 14.3 years); this confirmed long-term patency of the stoma in all cases. CONCLUSIONS Third ventriculostomy effectively controls obstructive triventricular hydrocephalus in more than 70% of children and should be preferred to placement of extracranial cerebrospinal shunts in this group of patients. When performed using ventriculographic guidance, the technique has a higher mortality rate and a higher failure rate in children younger than 6 months of age and is, therefore, no longer preferred. When third ventriculostomy is performed using endoscopic guidance, the same long-term results are achieved in children younger than 6 months of age as in older children and, thus, patient age should no longer be considered as a contraindication to using the technique. Delayed failures are usually secondary to obstruction of the stoma and often can be managed by repeating the procedure. Midline sagittal T2-weighted MR imaging sequences combined with cine PC MR imaging flow measurements provide a reliable tool for diagnosis of aqueductal stenosis and for ascertaining the patency of the stoma during follow-up evaluation.

Long-Term Outcome of 106 Consecutive Pediatric Ruptured Brain Arteriovenous Malformations After Combined Treatment

Background and Purpose— Childhood intracerebral hemorrhage is mainly attributable to underlying brain arteriovenous malformations (bAVMs). Multimodal treatment options for bAVMs include microsurgery and embolization, allowing an immediate cure, and radiosurgery, entailing longer obliteration times. Follow-up data on pediatric ruptured bAVMs are scarce, making it difficult to assess the risk of subsequent intracerebral hemorrhage. Our aim was to assess the clinical and angiographic outcome and to analyze risk factors for rebleeding during and after combined treatment of pediatric bAVMs. Methods— A prospectively maintained database of children referred to our institution between January 1997 and October 2012 for bAVMs was retrospectively queried to identify all consecutive ruptured bAVMs treated by surgery, embolization, and radiosurgery. The impact of baseline clinical and bAVM characteristics on clinical outcome, rebleeding rate, annual bleeding rate, and bAVM obliteration was studied using univariate and multivariate Cox regression analysis. Results— One hundred six children with ruptured bAVMs were followed up for a total of 480.5 patient-years (mean, 4.5 years). Thirteen rebleeding events occurred, corresponding to an annual bleeding rate of 2.71±1.32%, significantly higher in the first year (3.88±1.39%) than thereafter (2.22±1.38%; P<0.001) and in the case of associated aneurysms (relative risk, 2.68; P=0.004) or any deep venous drainage (relative risk, 2.97; P=0.002), in univariate and multivariate analysis. Partial embolization was associated with a higher annual bleeding rate, whereas initial surgery for intracerebral hemorrhage evacuation was associated with a lower risk of rebleeding. Conclusions— Associated aneurysms and any deep venous drainage are independent risk factors for rebleeding in pediatric ruptured bAVMs. Immediate surgery or total embolization might be advantageous for children harboring such characteristics, whereas radiosurgery might be targeted at patients without such characteristics.