Posttraumatic ventriculomegaly: hydrocephalus or atrophy? A new approach for diagnosis using CSF dynamics

Outcomes after decompressive craniectomy for severe traumatic brain injury in children

OBJECT

Severe traumatic brain injury (TBI) is often accompanied by early death due to transtentorial herniation. Decompressive craniectomy, performed alone or in conjunction with evacuation of the mass lesion, can reduce the incidence of raised intracranial pressure (ICP). In this paper the authors evaluate mortality and morbidity and long-term outcomes in children who underwent decompressive craniectomy for severe TBI at a single institution.

METHODS

Children with severe TBI who underwent decompressive craniectomy at the Primary Children's Medical Center between 1996 and 2005 were identified retrospectively. Descriptive statistics were used to report postoperative mortality and morbidity rates. Long-term recovery in patients who survived was reported using the King's Outcome Scale for Closed Head Injury (KOSCHI). Fifty-one children with a mean follow-up period of 18.6 months were identified. Nonaccidental trauma accounted for 23.5% of cases. The mean preoperative Glasgow Coma Scale (GCS) score was 4.6. Six patients underwent decompressive craniectomy for elevated ICP only; all other patients underwent decompressive craniectomy in conjunction with removal of the mass lesion. The mean postoperative GCS score was 9.7, and 69.4% of patients had normal ICP levels immediately after surgery. Sixteen children (31.4%) died, including five of six children who underwent decompressive craniectomy for raised ICP alone. Among surviving patients, 2.9% required a tracheostomy, 11.4% required a gastrostomy, 40% experienced posttraumatic shunt-dependent hydrocephalus, and 20% suffered posttraumatic epilepsy requiring antiepileptic agents. The mean KOSCHI score at the last follow-up examination was 4.5 and the mean time to cranioplasty was 2.3 months.

CONCLUSIONS

Posttraumatic hydrocephalus and epilepsy were common complications encountered by children with severe TBI who underwent decompressive craniectomy. In patients who underwent decompressive surgery for raised ICP only, the mortality rate was exceedingly high.

Outcome after surgical decompression of severe traumatic brain injury

One of the factors that affects outcome following severe traumatic brain injury is development and progression of cerebral oedema with associated increase in intracranial pressure (ICP). Uncontrolled elevations of ICP may compromise energy metabolism of the injured brain and lead to secondary injury, affecting neurological outcome of the patient. Decompressive craniectomy has been used for over a century as a treatment of refractory brain swelling in a variety of neurological conditions. However, conclusive evidence of whether it has a beneficial or adverse affect on outcome is lacking. This article reviews the existing evidence on the role of decompressive craniectomy in management of patients with traumatic brain injury and stresses the need for randomised controlled trials.

Impact of Cerebrovascular Disease on the Surgical Treatment of Idiopathic Normal Pressure Hydrocephalus

OBJECTIVE:

The influence of cerebrovascular disease (CVD) on the short- and long-term results of surgery was evaluated in a series of consecutive patients with idiopathic normal-pressure hydrocephalus (iNPH).

METHODS:

Patients with suspected iNPH admitted to our department between June 1996 and June 2003 were evaluated with four clinical and handicap scales. CVD and risk factors for vascular disease were rated. All patients underwent intracranial pressure monitoring via a spinal catheter. Sixty-six patients received a ventriculoperitoneal shunt with a programmable valve. Prospective assessments were programmed at 2 weeks and 3 months after surgery (short-term follow-up). Long-term follow-up evaluations were arranged in June 2004 with patients and/or relatives and health/home care assistants.

RESULTS:

At the short-term follow-up examination, a significant clinical improvement was globally present in 89% of the patients (P < 0.05). CVD, such as leucoaraiosis or previous strokes, were present in 71% of the patients. Patients both with and without CVD and/or risk factors for vascular disease presented a significant improvement (P < 0.05) after shunting; 85 and 100% of the patients with and without CVD, respectively. At the long-term follow-up examination (mean, 52 ± 24.8 mo), 24% of the patients were dead and 8% had experienced stroke. Globally, 60% of the patients were still improved (P < 0.05); 52 and 79% of the patients with and without CVD, respectively.

CONCLUSION:

A high success rate in treatment of iNPH is possible in patients with and without CVD. Despite poorer short- and long-term treatment outcome of iNPH patients with CVD, a long-lasting improvement in their quality of life favors surgery.

Diagnostic method for differentiating external hydrocephalus from simple subdural hygroma

Object

The various terms used to describe subdural fluid collection—“external hydrocephalus,” “subdural hygroma,” “subdural effusion,” “benign subdural collection,” and “extraventricular obstructive hydrocephalus”—reflect the confusion surrounding the diagnoses of these diseases. Differentiating external hydrocephalus from simple subdural hygroma may be difficult, but the former appears to be a distinct clinical entity separate from the latter. In this report, the authors present a diagnostic method for differentiating external hydrocephalus from simple subdural hygroma, based on their clinical experience in treating subdural fluid collection after mild head trauma.

Methods

Twenty patients with subdural fluid collection after mild head trauma were included in this study. Ventricle size was measured using a modified frontal horn index (mFHI); that is, the largest width of the frontal horns divided by the bicortical distance in the same plane, instead of the inner table distance. Bur hole trephination was performed on the appearance of a subdural fluid collection thicker than 15 mm on computed tomography (CT), persistent (longer than 4 weeks) or increasing in size, and accompanied by neurological symptoms (confusion or memory impairment). During the procedure, subdural pressure was measured using a manometer before opening the dura mater. Subdural pressure varied among the patients, ranging from 3 to 27.5 cm H2O. Four patients with a subdural pressure greater than 15 cm H2O had hydrocephalus after surgery (p < 0.05). Hydrocephalus developed in a pediatric patient (2 years old) with a subdural pressure of 12 cm H2O. All of the patients in whom hydrocephalus developed after bur hole trephination had had enlarged ventricles (mFHI > 33%) on preoperative CT scans.

Conclusions

Monitoring subdural pressure may be a valuable tool for differentiating subdural hygroma from external hydrocephalus in patients with mild head trauma. Additionally, the mFHI reflects the nature of the subdural collection more accurately than the standard frontal horn index.

Magnetic resonance imaging flow void changes after cerebrospinal fluid shunt in post-traumatic hydrocephalus: clinical correlations and outcome

The assessment of the flow-void in the cerebral aqueduct of patients with post-traumatic hydrocephalus on magnetic resonance imaging (MRI) evaluation could concur the right diagnosis and have a prognostic value. We analysed prospectively 28 patients after a severe head injury (GCS<or=8), with radiological or clinical suspicion of post-traumatic hydrocephalus and a fast flow-void signal in the cerebral acqueduct on T2-weighted and proton density MRI. Twenty-two patients were shunted (n=19) or revised (n=3). Six patients were followed-up without surgery. Twenty out of 22 shunted patients (91%) showed variable reduction of the fast flow-void. Eighteen of the operated patients (82%) presented a significant clinical improvement at 6-month follow-up. All patients (n=2) who had no change of the fast flow-void after surgery did not clinically improve. The six non-shunted patients did not present any clinical or radiological improvement. In head-injured patients, fast flow-void in the cerebral aqueduct is diagnostic for post-traumatic hydrocephalus and its reduction after ventriculo-peritoneal shunt is correlated with a neurological improvement. In already shunted patients, a persistent fast flow-void is associated with a lack of or very slow clinical improvement and it should be considered indicative of under-drainage.

Early combined cranioplasty and programmable shunt in patients with skull bone defects and CSF-circulation disorders

OBJECTIVE

This study assesses the clinical outcome after early combined cranioplasty (own frozen bone) and shunt implantation (Codman-Medos programmable VP shunt) in patients with skull bone defects and cerebrospinal fluid (CSF) circulation disorders.

METHOD

Medical records were reviewed retrospectively for the last 100 patients with CSF disorders after trauma or subarachnoid hemorrhage (SAH), who previously underwent decompressive craniotomy owing to therapy-resistant brain swelling. Patients treated with early (5 to 7 weeks after injury) combined cranioplasty and shunt implantation were analysed and a follow-up for the survivors was obtained.

RESULTS

In 60 patients with a daily CSF external drainage over 150 ml and dilated ventricles in CT scan, a programmable VP shunt was implanted simultaneously with the cranioplasty within 5.1 weeks after decompression. The neurological condition 6 months later was good (independent patients) in 39 cases (65%); 12 patients (20%) survived with a severe disability; three patients (5%) remained in a persistent vegetative state and only six patients (10%) died. There were few complications: bone or shunt infection (three cases), post-operative intracranial bleeding (one case), transitory neurological impairment after bone reimplantation (two cases), bone resorption (two cases) and shunt dysfunction (three cases).

CONCLUSION

The early reimplantation of the patient's own skull bone combined to the employment of a programmable shunt system allowed us a dynamic adjustment of the intracranial pressure (ICP) changes. The combined treatment reduced the number of required surgical procedures, complications and unsatisfactory patient outcomes.

Ventricular enlargement after moderate or severe head injury: a frequent and neglected problem

The primary goal of this study was to determine the incidence of post-traumatic ventriculomegaly (Evans' index > or = 0.30) in 95 head-injured patients with a Glasgow Coma Scale (GCS) score of < or =13 at admission. Additional objectives were to determine the relationship between an increase in ventricular size and several clinical and radiological features and outcome. A planimetric study was carried out in the sequential control computed tomography (CT) scans of 34 moderately head-injured (GCS 9-13) and 61 severely head-injured (GCS 3-8) patients with a minimum follow-up of 2 months. Between two and six CT scans were evaluated in each patient. The presence of subarachnoid hemorrhage (SAH) was registered. Evans' index was determined in all CT scans. In the final CT scan of each patient, ventricular size was related to the admission GCS score, age, the presence of SAH in the initial CT scans, type of brain lesion (classified according to the final diagnosis in the Traumatic Coma Data Bank classification), and outcome. Ventriculomegaly was found in 39.3% of patients with severe head injury and in 27.3% of those with a moderate head injury. Increased ventricular size was evident 4 weeks after injury in 57.6% and 2 months after injury in 69.7%. No relationship was found between post-traumatic ventriculomegaly and age, initial GCS score, the presence of SAH, or type of lesion (focal or diffuse). Post-traumatic ventriculomegaly was significantly correlated with outcome. Post-traumatic ventriculomegaly is a frequent and early finding in patients with moderate or severe traumatic brain injury.

Hydrocephalus, ventriculomegaly and the vegetative state: a review

The revised guidelines from the Royal College of Physicians make it clear that structural problems such as hydrocephalus should be excluded before the diagnosis of vegetative state (VS) can be made. Ventriculomegaly is common after severe head injury but the distinction between atrophy and potentially treatable hydrocephalus cannot be made on the basis of conventional computerised tomographic (CT) or magnetic resonance (MR) scanning alone--physiological measurements of intracranial pressure (ICP) and cerebrospinal fluid (CSF) outflow resistance may be helpful. These techniques are reviewed together with the limited literature available that documents the effect of CSF diversion on outcome in "vegetative" patients.

Theoretical considerations on the pathophysiology of normal pressure hydrocephalus (NPH) and NPH-related dementia

Normal pressure hydrocephalus (NPH) is considered to be an example of reversible dementia although clinical improvement after shunting varies from subject to subject, and recent studies have pointed to a possible link with other dementia. The authors consider that the craniospinal compartment is a partially closed sphere with control device systems represented by the spinal axis and the sagittal sinus-arachnoid villi complex which interact with each other in the clinical patient setting. We hypothesise that changing spinal compliance by altering the flow process and CSF dynamics lead to hydrocephalus. Therefore four NPH types have been distinguished according to the alterations in spinal compliance, decrease in CSF absorption at the sagittal sinus or both occurrences. The authors consider that NPH and NPH-related diseases (NPH-RD) are initiated by the same common final pathway and demonstrate that NPH could represent an initial stage of NPH-RD. Progression of clinical signs can be explained as damage to the cerebral tissue by both intermittent increased intracranial pressure and pulse pressure waves leading to periventricular ischaemia. In addition, they believe that both volume equilibrium and spinal compliance are restored in patients who improve after CSF shunt, whereas in patients whose condition does not improve, only volume equilibrium is restored and not spinal compliance, which was the underlying cause of hydrocephalus in such cases. They therefore wonder whether cervical decompression should not be indicated in patients who show no improvement. Although attractive, this analysis warrants confirmation from clinical, radiological, and hydrodynamic studies.

Diagnosis and management of idiopathic normal-pressure hydrocephalus: a prospective study in 151 patients

Object. The diagnosis and management of idiopathic normal-pressure hydrocephalus (NPH) remains controversial, particularly in selecting patients for shunt insertion. The use of clinical criteria coupled with imaging studies has limited effectiveness in predicting shunt success. The goal of this prospective study was to assess the usefulness of clinical criteria together with brain imaging studies, resistance testing, and external lumbar drainage (ELD) of cerebrospinal fluid (CSF) in determining which patients would most likely benefit from shunt surgery.

Methods. One hundred fifty-one patients considered at risk for idiopathic NPH were prospectively studied according to a fixed management protocol. The clinical criterion for idiopathic NPH included ventriculomegaly demonstrated on computerized tomography or magnetic resonance imaging studies combined with gait disturbance, incontinence, and dementia. Subsequently, all patients with a clinical diagnosis of idiopathic NPH underwent a lumbar tap for the measurement of CSF resistance. Following this procedure, patients were admitted to the hospital neurosurgical service for a 3-day ELD of CSF. Video assessment of gait and neuropsychological testing was conducted before and after drainage. A shunt procedure was then offered to patients who had experienced clinical improvement from ELD. Shunt outcome was assessed at 1 year postsurgery.

Conclusions. Data in this report affirm that gait improvement immediately following ELD is the best prognostic indicator of a positive shunt outcome, with an accuracy of prediction greater than 90%. Furthermore, bolus resistance testing is useful as a prognostic tool, does not require hospitalization, can be performed in an outpatient setting, and has an overall accuracy of 72% in predicting successful ELD outcome. Equally important is the finding that improvement with shunt surgery is independent of age up to the ninth decade of life in patients who improved on ELD.

Cerebrospinal fluid dynamics

Hydrocephalus is far more complicated than a simple disorder of CSF circulation. Historically, it has been diagnosed using clinical and psychomotor assessment plus brain imaging. The role of physiological measurement to aid diagnosis becomes more appreciated in current clinical practice. This has been reflected by recently formulated guidelines for the management of normal pressure hydrocephalus. Clinical measurement in hydrocephalus is mainly related to intracranial pressure (ICP) and cerebral blood flow. This review lists and discusses most common forms of the methods: CSF infusion study, overnight ICP monitoring, assessment of slow ICP waves, testing pressure reactivity, cerebral autoregulation, CO2 reactivity and PET-CBF studies combined with MRI co-registration. The basics of CSF dynamics modelling are presented and the principles of the assessment of functioning of the implanted hydrocephalus shunts are also discussed. The descriptions of multiple forms of measurement along with clinical illustrations are mainly based on in-house experience of a multidisciplinary group of scientists and clinicians from Cambridge, UK.

Radiological assessment of hydrocephalus: new theories and implications for therapy

It is almost a century since Dandy made the first experimental studies on hydrocephalus, but its underlying mechanism has been unknown up to now. The conventional view is that cerebrospinal fluid (CSF) malabsorption due to hindrance of the CSF circulation causes either obstructive or communicating hydrocephalus. Analyses of the intracranial hydrodynamics related to the pulse pressure show that this is an over-simplification. The new hydrodynamic concept presented here divides hydrocephalus into two main groups, acute hydrocephalus and chronic hydrocephalus. It is still accepted that acute hydrocephalus is caused by an intraventricular CSF obstruction, in accordance with the conventional view. Chronic hydrocephalus consists of two subtypes, communicating hydrocephalus and chronic obstructive hydrocephalus. The associated malabsorption of CSF is not involved as a causative factor in chronic hydrocephalus. Instead, it is suggested that increased pulse pressure in the brain capillaries maintains the ventricular enlargement in chronic hydrocephalus. Chronic hydrocephalus is due to decreased intracranial compliance, causing restricted arterial pulsations and increased capillary pulsations. The terms "restricted arterial pulsation hydrocephalus" or "increased capillary pulsation hydrocephalus" can be used to stress the hydrodynamic origin of both types of chronic hydrocephalus. The new hydrodynamic theories explain why third ventriculostomy may cure patients with communicating hydrocephalus, a treatment incompatible with the conventional view.

Posttraumatic hydrocephalus: a clinical, neuroradiologic, and neuropsychologic assessment of long-term outcome 11No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated

OBJECTIVES

To detect the clinical and radiologic characteristics of posttraumatic hydrocephalus (PTH), to define its prognostic value, and to assess the effects of shunt surgery.

DESIGN

Correlational study on a prospective cohort.

SETTING

Brain injury rehabilitation center.

PARTICIPANTS

One hundred forty patients with severe traumatic brain injury (TBI) referred to an inpatient intensive rehabilitation unit of primary care in a university-based system.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The Glasgow Outcome Scale (GOS), Disability Rating Scale (DRS), FIM instrument, and Neurobehavioural Rating Scale (NRS), as well as single-photon emission computed tomography (SPECT) and magnetic resonance imaging.

RESULTS

PTH was found in 45% of patients. Risk factors for PTH were as follows: age (P<.04), duration of coma (P<.0001), and decompressive craniectomy (P<.0001). PTH correlated with the degree of hypoperfusion in the temporal lobes (P<.001). Patients who showed clinical deterioration improved after surgery. PTH correlated significantly with GOS, DRS, FIM, and NRS (P<.0001) 1 year after the trauma, and it influenced the appearance of posttraumatic epilepsy (P<.02).

CONCLUSIONS

PTH concerns about 50% of patients with severe TBI. It influences functional and behavioral outcome and the appearance of posttraumatic epilepsy. The selection of patients for surgery can be defined principally on a clinical basis. SPECT may be helpful for differentiating ventricular enlargement due to cortical atrophy and hydrocephalus.

Cranioplasty for patients with severe depressed skull bone defect after cerebrospinal fluid shunting

Cranioplasty is indicated for patients with a skull bone defect. Patients may achieve subjective and objective improvements after cranioplasty. Some patients with severe brain swelling treated with decompressive craniectomy may develop hydrocephalus associated with severe brain bulging or even herniation via the skull bone defect. Consequently, these patients require a ventriculoperitoneal (V-P) shunt to relieve hydrocephalus. However, after shunting for hydrocephalus, they may develop severe sinking at the skull defect. Subsequently, when doing a cranioplasty for such a depressed defect, it may result in the dysfunction of the underlying brain, or even hematoma formation due to the large dead space. In this study, we advocate a temporary procedure to occlude the V-P shunt tube to allow the expansion of a depressed scalp flap to facilitate the subsequent cranioplasty. We report four patients with severe depression of the skull defect resulting from previous traumatic brain swelling followed by decompressive craniectomy and V-P shunting for communicating hydrocephalus. A simple subcutaneous clipping of the shunt tube was performed to allow the expansion of the depressed scalp to obliterate the dead space before the cranioplasty. All four patients obtained a satisfactory result without complications and achieved good functional recovery. A temporary occlusion of the shunt tube with an aneurysm clip before cranioplasty for patients with a severely depressed scalp flap is a simple and useful procedure. This procedure can safely and effectively eliminate the dead space between the skull plate and the dura to facilitate the cranioplasty, and thus prevent the potential complication of intracranial hematoma.

Adenovirus-mediated transfer and expression of beta-gal in injured hippocampus after traumatic brain injury in mice

In models of focal cerebral ischemia, adenoviral gene transfer is often attenuated or delayed versus naive. After controlled cortical impact (CCI)-induced traumatic brain injury in mice, CA1 and CA3 hippocampus exhibit delayed neuronal death by 3 days, with subsequent near complete loss of hippocampus by 21 days. We hypothesized that adenoviral-mediated expression of the reporter gene beta-Galactosidase (beta-Gal) in hippocampus would be attenuated after CCI in mice. C57BL6 mice (n = 16) were subjected to either CCI to left parietal cortex or sham (burr hole). Adenovirus carrying the beta-Gal gene (AdlacZ; 1 x 10(9) plaque-forming units [pfu]/mL) was then injected into left dorsal hippocampus. At 24 or 72 h, beta-Gal expression was quantified (mU/mg protein). Separate mice (n = 10) were used to study beta-Gal spatial distribution in brain sections. Beta-Gal expression in left hippocampus was similar in shams at 24 h (48.4 +/- 4.1) versus 72 h (68.8 +/- 8.8, not significant). CCI did not reduce beta-Gal expression in left hippocampus (68.8 +/- 8.8 versus 88.1 +/- 7.0 at 72 h, sham versus CCI, not significant). In contrast, CCI reduced beta-Gal expression in right (contralateral) hippocampus versus sham (p < 0.05 at both 24 and 72 h). Beta-Gal was seen in many cell types in ipsilateral hippocampus, including CA3 neurons. Despite eventual loss of ipsilateral hippocampus, adenovirus-mediated gene transfer was surprisingly robust early after CCI providing an opportunity to test novel genes targeting delayed hippocampal neuronal death.

Vascular components of cerebrospinal fluid compensation

OBJECT

The aim of the study was to assess how cerebrospinal fluid (CSF) pressure-volume compensation depends on cerebrovascular tone.

METHODS

In 26 New Zealand White rabbits, intracranial pressure (ICP), arterial blood pressure, and basilar artery blood flow velocity were measured continuously. Saline was infused into the cranial subarachnoid space to assess CSF compensatory parameters: the resistance to CSF outflow, the elastance coefficient, and the amplitude of the ICP pulsatile waveform. Infusions were repeated on two different levels of CO2 concentration in the arterial blood (PaCO2), at normotension and hypotension, and after the death of the animal. An increase in PaCO2 from a mean of 27 to 48 mm Hg was accompanied by an 18% increase in the resistance to CSF outflow (p<0.005) and a 64% increase (p<0.05) in the elastance coefficient. A decrease in arterial blood pressure from a mean of 100 to 51 mm Hg caused a 25% decrease in CSF outflow resistance (p<0.01) but did not affect the elastance coefficient. Postmortem, a 23% decrease in the CSF outflow resistance was associated with a 102% decrease in the elastance coefficient.

CONCLUSIONS

Cerebrovascular parameters have a limited but significant impact on CSF infusion studies. The vascular component of ICP may be identified as a significant factor contributing to this phenomenon. During infusion studies, physiological parameters influencing vascular conditions should be maintained as stable as possible.