The Pseudotumor Cerebri Syndrome: A Unifying Pathophysiological Concept for Patients with Isolated Intracranial Hypertension with Neither Mass Lesion Nor Ventriculomegaly.

In 1991 we proposed that while the syndrome of isolated intracranial hypertension might have many definite and probable causes, it has nonetheless a single unifying pathophysiological mechanism: namely, impairment of cerebrospinal fluid (CSF) reabsorption. For that reason, we also proposed then that it is best described by a single, unifying, inclusive term, namely, pseudotumor cerebri syndrome. Although it appears that there is, as far as nomenclature is concerned, now international agreement, there is as yet no agreement on pathophysiology and classification. Herein we outline our views on these matters and give our reasons.

Cranial venous outflow obstruction and pseudotumor Cerebri syndrome.

The pathophysiology of PTS including idiopathic intracranial hypertension or 'BIH', remains controversial. The older literature frequently referred to pathology in the cerebral venous drainage but more modern imaging techniques (CT and early MR) failed to reveal gross venous pathology. The role of impaired cranial venous outflow has recently been re-examined in the light of new methods of investigation (advanced MR venography and direct microcatheter venography with manometry) and of treatment (venous sinus stenting). Venous sinus obstruction in PTS is a more common factor in the pathogenesis of the condition than previously recognised. Venous obstruction may be primary, that is, it is the underlying aetiological factor in PTS. Venous sinus obstruction may also be secondary to raised CSF pressure which may exacerbate problems with intracranial compliance and raised CSF pressure. Early experience with venous stenting suggests that it may be a helpful treatment for patients with PTS but more experience and longer follow-up is required to define the subgroups of patients for whom it is most appropriate.

Performance of patients with a "frozen pelvis" in an in vitro fertilization program.

It is now possible to identify and study the performance of different subgroups of patients in in vitro fertilization (IVF) programs. Patients with severe pelvic adhesions due to pelvic inflammatory disease (PID) or endometriosis were classed as having a frozen pelvis if less than or equal to 20% of total ovarian surface was visible and if the rest of the ovary was bound down with significant adhesions. IVF offers the only hope of pregnancy for these patients. Fifty-one treatment cycles in 23 such patients were matched against 51 cycles in 48 patients with adhesion-free ovaries. The study group had a significantly higher number of cancelled oocyte retrievals because of poor estradiol (E2) response. They also had a significantly lower rate of E2 rise and a lower peak value of E2 before and after the administration of human chorionic gonadotropin. These patients took longer to respond to a hyperstimulation regime, and when a response occurred they formed fewer follicles, as measured with the use of ultrasound. Lower numbers of oocytes were obtained from this group, but the fertilization rate of oocytes was the same for both groups. One pregnancy occurred in the study group and 11 in the control group. It is possible that disruption of ovarian blood supply or mechanical factors due to the pressure of significant adhesions prevent a good follicular response in patients with a frozen pelvis.

Vein of Galen malformation: diagnosis and management.

The vein of Galen malformation is a midline arteriovenous fistula with aneurysmal dilatation of the vein of Galen. The clinical details of diagnosis and treatment in 13 patients with such lesions together with a review of 232 cases collected from the literature are presented in this report. There were 132 males, 77 females, and 36 cases in which the sex was not stated. Eighty patients presented as neonates, 82 were 1 to 12 months old, 39 were 1 to 5 years old, 22 were 6 to 20 years old, and 22 were over the age of 20. The most common presenting symptoms were congestive cardiac failure (110 cases), raised intracranial pressure secondary to hydrocephalus (94 cases), cranial bruit (57 cases), focal neurological deficit (37), seizures (26 cases), and hemorrhage (25 cases). The most characteristic vascular supply to the midline fistula involved multiple bilateral vessels, although bilateral posterior cerebral and unilateral posterior cerebral supply was relatively common. The overall figures for treatment and outcome showed that 91 patients (37.1%) were treated by direct operation and 29 patients (11.3%) were treated by other forms of operation, predominantly shunting or remote vessel ligation. Forty-six patients (18.8%) were treated by medical means (digoxin, diuretics, and ventilatory support). In 79 patients (22.2%), there was no treatment or no details of treatment were available. There was an overall series mortality of 55.6% (no details were available in 33 cases) and a 37.4% mortality for surgically treated cases. After operation, there was a 46.3% incidence of significant morbidity in surviving patients. Neonatal patients fared worst, with an overall mortality of 64 of 70 cases (91.4%) where details were available. The outcome was equally bad for surgically and conservatively treated cases. Operation in the 1- to 12-month age group was more successful, but still carried a mortality of 31.7%, with a significant morbidity in approximately half of the surviving patients. Over the age of 1 year, the surgically treated patients had a 25.6% mortality and a 42.3% major morbidity in survivors. Consideration is given to some of the ways in which these figures may be improved, in particular a staged approach during the neonatal period, with the use of selective embolization or occlusion of vessels to reduce the volume of the arteriovenous shunt until the patient is older and better able to tolerate major operation.

Normal perfusion pressure breakthrough complicating surgery for the vein of Galen malformation: report of three cases.

Three cases are described of infants who developed malignant brain swelling (and in one case hemorrhage) after surgery for vein of Galen malformations. The cause for the brain swelling was felt to be due to hyperperfusion, or the "normal perfusion pressure breakthrough" syndrome. Although well-described for cerebral parenchymal arteriovenous malformations, cases of this complication occurring in vein of Galen malformations have not previously been reported. It is concluded from these cases that infants with large arteriovenous shunts, as attested by cardiac failure and cerebral atrophy, have an increased risk of developing this complication.

Concurrent pineoblastoma and unilateral retinoblastoma: a forme fruste of trilateral retinoblastoma?

A 10-month-old boy who presented with strabismus and symptoms of intracranial hypertension was found to have a pineoblastoma and a unilateral ocular retinoblastoma. Despite enucleation of the eye, subtotal removal of the pineoblastoma, and craniospinal axis irradiation, the patient died 6 months later from disseminated intracranial neoplasm. As there was no clinical evidence of bilateral retinoblastoma, this case may represent a forme fruste of the trilateral retinoblastoma complex. The clinicopathological features of this unusual syndrome are reviewed.

A ventricular infusion technique for the evaluation of treated and untreated hydrocephalus.

Patients considered to have a possible disorder of the circulation of the cerebrospinal fluid (CSF) were prospectively randomized on clinical and computed tomographic grounds into one of four categories: low probability of a disorder of circulation of the CSF (n = 14); high probability of a disorder of the circulation of the CSF (n = 10); low probability of shunt malfunction (n = 10); and high probability of shunt malfunction (n = 9). Patients with possible disorders of the circulation of the CSF who did not meet the entry criteria for each of these categories were excluded from this study. A ventricular catheter connected to a subgaleal Rickham reservoir not in continuity with a shunt system (if this was present) either was inserted into each patient or was in place from previous surgery. Infusion studies were conducted by the infusion of 1 ml/min of normal saline through a 25-gauge needle inserted through the skin into the Rickham reservoir. A separate 25-gage needle was inserted into the Rickham reservoir for continuous recording of intracranial pressure. There were 43 infusion studies that were included in the four categories. Recordings of baseline intracranial pressure for a high probability of a disorder of the circulation of the CSF did not differ significantly from a low probability of a disorder of the circulation of the CSF. Baseline intracranial pressure for a high probability of shunt malfunction was significantly higher than the low probability of a disorder of the circulation of the CSF group and the low probability of shunt malfunction group; there was, however, marked overlap in values between these groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Spinal cord monitoring during surgery by direct recording of somatosensory evoked potentials. Technical note.

A simple method of spinal cord monitoring that can be readily used during surgery for spinal disorders in children or adults is described. A spinal subdural recording electrode is placed rostral to the site of surgery and the peroneal nerve is stimulated in the popliteal fossa; in this way, large-amplitude polyphasic spinal somatosensory evoked potentials (SEP's) can be directly recorded. The large amplitude of the spinal SEP's recorded intrathecally facilitates spinal cord monitoring by allowing: 1) rapid acquisition of the evoked response, which provides continuous monitoring during surgery; 2) relatively easy interpretation of the signal, there being no significant ultrashort- or long-latency components to the waveform; and 3) signal acquisition in an electrical environment that would be unacceptable using standard methods of spinal and cortical SEP recording.

Intracranial pressure changes in arrested hydrocephalus.

Continuous intracranial pressure (ICP) monitoring was used to assess 46 children and adolescents in whom a clinical diagnosis of arrested hydrocephalus had been made. Thirty patients (Group A) had previously been treated with cerebrospinal fluid diversion and 16 patients (Group B) had no prior treatment of their hydrocephalus. All patients in Group A either had a confirmed nonfunctioning shunt or had undergone shunt removal. Continuous ICP monitoring showed that 80% of the patients in Group A and 63% of those in Group B had episodic or persistent intracranial hypertension. In four patients (25%) whose initial ICP had been normal or equivocal, repeat ICP monitoring later revealed decompensation or reversal of arrest. When serial psychometric testing demonstrated a fall in cognitive functioning, ICP monitoring revealed abnormal ICP's in 88% of patients. This study shows that many patients with apparent arrest of hydrocephalus in fact have an insidiously progressive disorder. Monitoring of ICP and serial psychometric evaluation are therefore valuable tools in the continuing assessment of arrested hydrocephalus.

Recording of spinal somatosensory evoked potentials for intraoperative spinal cord monitoring.

The authors' experience with intradural and epidural recording of spinal somatosensory evoked potentials (SSEP's) during 26 cases of spinal surgery is described. The techniques of monitoring spinal cord function provided good quality SSEP waveforms in patients both with and without neurological deficits. The SSEP configuration and peak latencies remained stable for up to 5 hours during anesthesia with nitrous oxide, halothane, and fentanyl. Patterns of baseline SSEP's were characteristic of different spinal segments. Distortion and asymmetry of these baseline patterns were seen in several patients with spinal neoplasms. Loss of waveform components during surgery occurred with profound hypotension, overdistraction of the vertebral axis, dorsal midline myelotomy, and removal of intramedullary tumors. Persistent loss of waveform components was associated with an acquired neurological deficit. Fluctuations in the amplitude of the SSEP's were common but were not associated with postoperative neurological deficits. Spinal cord monitoring by means of SSEP recording would appear to be useful during extradural spinal surgery, but there are limitations associated with this technique during some types of intradural surgery.

The arrest of treated hydrocephalus in children. A radionuclide study.

A prospective study was made of the incidence of arrest of treated non-neoplastic hydrocephalus in 30 neonates and infants over a 5-year period. Radionuclide assessment of shunt function and cerebrospinal fluid (CSF) dynamics was carried out at intervals over this period, using a method that allowed injection of the radionuclide into the ventricular system independent of the shunt apparatus. The radionuclide scanning results were correlated with computerized tomography and clinical findings. Of 24 patients still available for analysis at the end of 5 years, four patients showed restoration of CSF circulation independent of the shunt apparatus and, in three of these, the shunt has either been clipped or clipped and removed without any ill effects. Clinical details of these three patients are provided. Two initially had communicating hydrocephalus, and one had probable aqueduct stenosis.

Disseminated hematogenous metastases from a pineal germinoma in an infant. Case report.

A pineal germinoma in a 9-month-old boy is described. After surgical resection and cerebrospinal fluid diversionary shunting, the child developed hematogenous metastases which showed marked increased uptake on radionuclide gallium-67 scans.

Cystic schwannoma of the trochlear nerve mimicking a brain-stem tumor. Case report.

A case is reported of a rare cystic schwannoma of the fourth cranial nerve which was interpreted as a probable intrinsic brain-stem lesion. The clinical approach to brain-stem tumors in terms of empirical treatment or surgical biopsy is discussed.

Treatment of ophthalmofacial-hypothalamic arteriovenous malformation (Bonnet-Dechaume-Blanc syndrome). Case report.

A 17-year-old girl with unilateral blindness and exophthalmos was found to have Bonnet-Dechaume-Blanc syndrome without retinal arteriovenous communications. The arteriovenous malformation was managed by combined intracranial resection, ophthalmic artery ligation, and selective embolization of the external carotid component.

Complications of surgery for arteriovenous malformations of the brain.

A series of 112 patients undergoing complete surgical resection of arteriovenous malformations (AVM's) of the brain between 1974 and 1990 were analyzed for complications and 12-month outcomes. The cohort consisted of 44 patients with small AVM's (< 2 cm in diameter), 43 patients with medium-sized AVM's (2 to 4 cm in diameter), and 25 patients with large AVM's (> 4 cm in diameter). There was a 3.6% series mortality rate and an 18% morbidity rate. One of the four deaths was caused by normal perfusion pressure breakthrough. Analysis of logistic regression found that the most important factor influencing the occurrence of complications in this series was AVM size (p = 0.005) and that the occurrence of complications (p < 0.001) and the neurological grade at the time of surgery (p < 0.004) both significantly contributed to the outcome at 12 months. This study stresses the importance of defining complications in terms of rigid criteria when analyzing AVM series in order to allow for a correct evaluation of the risk:benefit ratio of surgery. Furthermore, it emphasizes the need for a separate analysis of the importance of complications upon outcome.

Dermoid of cavernous sinus resulting in isolated oculomotor nerve palsy.

Intracranial dermoid cysts and acquired oculomotor nerve palsies are individually rare in childhood. This report describes a 4-year-old boy with acute oculomotor nerve palsy and pupillary sparing secondary to a dermoid within the lateral wall of the cavernous sinus. The clinical signs resolved after complete surgical excision of the tumor with no evidence of recurrence on computed tomography 1 year later. This is the first case report in childhood of a dermoid within the cavernous sinus and of an isolated oculomotor nerve palsy due to a dermoid cyst.

Hydrocephalus, lumbar canal stenosis and Maroteaux-Lamy syndrome (mucopolysaccharidosis type 6). Case report.

A case of communicating hydrocephalus and lumbar canal stenosis in a child with mucopolysaccharidosis type 6 is reported. We review the literature and discuss the aetiology of communicating hydrocephalus in this condition.

Intracranial pressure changes in craniostenosis.

Intracranial pressure changes occurring in patients with craniostenosis were studied by continuous monitoring of intracranial pressure in 20 children. Although clinical or radiologic evidence of intracranial hypertension was present in only one patient, 13 (65%) had persistent or episodic raised intracranial pressure. Intracranial hypertension occurred with involvement of both single and multiple sutures and in four of six patients with hydrocephalus and craniostenosis. Recordings after surgical treatment in nine patients revealed that several months elapsed before intracranial pressure improved significantly or returned to normal, despite apparently adequate bony decompression. This study confirms that continuous monitoring of intracranial pressure adds significantly to clinical assessment in determining the need for, and the efficacy of, surgical treatment in craniostenosis.

Short latency somatosensory-evoked potentials in children--Part 2. Effects of spinovertebral disorders.

Surface-recorded spinal and cortical somatosensory-evoked potentials (SEPs) following tibial or median nerve stimulation were studied in 26 children aged from 12 months to 13 years. Fifteen patients had caudal or dysraphic spinal malformations, often with a tethered cord syndrome, while the remaining patients had spinal tumors (4), syringomyelia (3), spinal canal stenosis (2), or demyelinating syndromes (2). Somatosensory-evoked potential abnormalities were found in 13 patients. Loss of a SEP at or rostral to the site of spinal pathology was the most common finding. Prolongation of central conduction times or delay in SEP peak latencies was documented in only four patients. Correlations between clinical and electrophysiological findings revealed that all patients with sensory dysfunction had abnormal SEPs, whereas patients with motor or sphincteric dysfunction, but intact sensation, usually had normal SEPs. These relationships between SEPs and clinical findings were constant irrespective of the etiology and location of the spinal pathology. The results from this study suggest that although SEP studies provide information regarding the somatosensory pathways, their clinical utility as a method of assessing spinal cord function in children with spinal disorders is limited by technical, clinical, and anatomical factors.

Short latency somatosensory-evoked potentials in children--Part 3. Findings following head injury.

Fourteen children aged 3 to 11 years who suffered from coma for at least 6 hours had somatosensory-evoked potential studies performed within 24 hours of neurotrauma. The upper cervical (Cv2) and bilateral cortical somatosensory-evoked potentials were recorded for calculation of the central somatosensory conduction time. Despite the fact that the SEP recordings were performed in the intensive care unit and the patients were receiving opiate and barbiturate therapy, satisfactory somatosensory-evoked potentials were recorded in all patients. Symmetrical short latency cortical somatosensory-evoked potentials were recorded bilaterally in 10 patients. Two patients with hemorrhagic cerebral contusions and unilateral cerebral edema had ipsilateral abnormalities of the cortical somatosensory-evoked potential. These patients all had normal central somatosensory conduction times and all had satisfactory neurological recoveries, although the two patients with abnormal cortical somatosensory-evoked potentials had focal neurological deficits. Two patients whose head injuries were complicated by hypoxia and refractory intracranial hypertension had bilaterally abnormal cortical somatosensory-evoked potentials, and both had vegetative outcomes. There was no correlation between the Glasgow Coma Score and central somatosensory conduction time; however, the number of components to the cortical somatosensory-evoked potential was related to the Glasgow Coma Score. The results suggest that the recording of somatosensory-evoked potentials can provide useful information about the functional status of central and cortical somatosensory pathways in children following major head injury.