A Digital Mental Health Support Program for Depression and Anxiety in Populations With Attention-Deficit/Hyperactivity Disorder: Feasibility and Usability Study

BACKGROUND

A total of 1 in 2 adults with attention-deficit/hyperactivity disorder (ADHD) struggles with major depressive or anxiety disorders. The co-occurrence of these disorders adds to the complexity of finding utility in as well as adherence to a treatment option. Digital therapeutic solutions may present a promising alternative treatment option that could mitigate these challenges and alleviate symptoms.

OBJECTIVE

This study aims to investigate (1) the feasibility and acceptance of a digital mental health intervention, (2) participants' engagement and retention levels, and (3) the potential efficacy with respect to anxiety and depression symptoms in a population with ADHD. Our main hypothesis was that a digital, data-driven, and personalized intervention for adults with coexisting ADHD and depressive or anxiety symptoms would show high engagement and adherence, which would be accompanied by a decrease in depressive and anxiety symptoms along with an increase in quality of life and life satisfaction levels.

METHODS

This real-world data, single-arm study included 30 adult participants with ADHD symptomatology and coexisting depressive or anxiety symptoms who joined a 16-week digital, data-driven mental health support program. This intervention is based on a combination of evidence-based approaches such as cognitive behavioral therapy, mindfulness, and positive psychology techniques. The targeted symptomatology was evaluated using the Patient Health Questionnaire-9, Generalized Anxiety Disorder-7, and Barkley Adult ADHD Rating Scale-IV. Quality of life aspects were evaluated using the Satisfaction With Life Scale and the Life Satisfaction Questionnaire, and user feedback surveys were used to assess user experience and acceptability.

RESULTS

The study retention rate was 97% (29/30), and high engagement levels were observed, as depicted by the 69 minutes spent on the app per week, 5 emotion logs per week, and 11.5 mental health actions per week. An average decrease of 46.2% (P<.001; r=0.89) in depressive symptoms and 46.4% (P<.001; r=0.86) in anxiety symptoms was observed, with clinically significant improvement for more than half (17/30, 57% and 18/30, 60%, respectively) of the participants. This was followed by an average increase of 23% (P<.001; r=0.78) and 20% (P=.003; r=0.8) in Satisfaction With Life Scale and Life Satisfaction Questionnaire scores, respectively. The overall participant satisfaction level was 4.3 out of 5.

CONCLUSIONS

The findings support the feasibility, acceptability, and value of the examined digital program for adults with ADHD symptomatology to address the coexisting depressive or anxiety symptoms. However, controlled trials with larger sample sizes and more diverse participant profiles are required to provide further evidence of clinical efficacy.

Feasibility, engagement, and preliminary clinical outcomes of a digital biodata-driven intervention for anxiety and depression

Hypothesis

The main hypothesis is that a digital, biodata-driven, and personalized program would exhibit high user retention and engagement, followed by more effective management of their depressive and anxiety symptoms.

Objective

This pilot study explores the feasibility, acceptability, engagement, and potential impact on depressive and anxiety and quality of life outcomes of the 16-week Feel Program. Additionally, it examines potential correlations between engagement and impact on mental health outcomes.

Methods

This single-arm study included 48 adult participants with mild or moderate depressive or anxiety symptoms who joined the 16-week Feel Program, a remote biodata-driven mental health support program created by Feel Therapeutics. The program uses a combination of evidence-based approaches and psychophysiological data. Candidates completed an online demographics and eligibility survey before enrolment. Depressive and anxiety symptoms were measured using the Patient Health Questionnaire and Generalized Anxiety Disorder Scale, respectively. The Satisfaction with Life Scale and the Life Satisfaction Questionnaire were used to assess quality of life. User feedback surveys were employed to evaluate user experience and acceptability.

Results

In total, 31 participants completed the program with an overall retention rate of 65%. Completed participants spent 60 min in the app, completed 13 Mental Health Actions, including 5 Mental Health Exercises and 4.9 emotion logs on a weekly basis. On average, 96% of the completed participants were active and 76.8% of them were engaged with the sensor during the week. Sixty five percent of participants reported very or extremely high satisfaction, while 4 out of 5 were very likely to recommend the program to someone. Additionally, 93.5% of participants presented a decrease in at least one of the depressive or anxiety symptoms, with 51.6 and 45% of participants showing clinically significant improvement, respectively. Finally, our findings suggest increased symptom improvement for participants with higher engagement throughout the program.

Conclusions

The findings suggest that the Feel Program may be feasible, acceptable, and valuable for adults with mild or moderate depressive and/or anxiety symptoms. However, controlled trials with bigger sample size, inclusion of a control group, and more diverse participant profiles are required in order to provide further evidence of clinical efficacy.

Brain tissue water content in patients with idiopathic normal pressure hydrocephalus

Relatively little is known regarding the water content of brain tissue in idiopathic normal-pressure hydrocephalus (NPH) patients. The objective of our study was to determine absolute water content non-invasively in hydrocephalic patients, particularly in the anterior and posterior ventricular horns and in the periventricular white matter. Ten patients who were diagnosed and treated for idiopathic NPH in our clinic were selected for study. Magnetic resonance imaging (MRI) techniques were used to obtain anatomical image slices for quantitative brain water measurements. Apparent diffusion coefficient measures were also extracted from regions of interest. To our knowledge, this is the first study to confirm that periventricular lucency seen on MRI represents increased water content in the extracellular space that is markedly elevated prior to shunting.

Bolus tracer delivery measured by MRI confirms edema without blood-brain barrier permeability in diffuse traumatic brain injury

INTRODUCTION

Previous studies have shown that edema formation after diffuse traumatic brain injury (TBI) with secondary insult is cytotoxic and not vasogenic. This assumption is based on observations of reduced apparent diffusion coefficient (ADC) and lack of significant accumulation of intravascular tracer in brain tissue. However, ADC reduction does not exclude vasogenic edema, and intravascular tracer can only accumulate when it reaches the tissue and is not perfusion limited. This study aims to confirm tissue delivery of intravascular tracer and lack of BBB opening during a phase of rapid brain swelling after diffuse TBI.

METHODS

Rats were exposed to either TBI using the impact acceleration model combined with 30 minutes of hypoxia and hypotension, or sham injury. At 2 or 4 hours after injury, ADC and tissue water content were assessed using MRI. Gd-DTPA was given followed by a combination of rapid T2 imaging (60 seconds) and T1 imaging (30 minutes). Signal intensity changes were analyzed to determine a bolus effect (dynamic susceptibility contrast) and longer-term tissue accumulation of Gd-DTPA.

RESULTS

Mean increase in cortical water content on the left was 0.8% at 2 hours, 2.1% at 4 hours; on the right it was 0.5% at 2 hours and 1.7% at 4 hours (p < 0.05). Mean ADC reduction over 4 hours was 0.04 x 10(-3) mm2/s on the left and 0.06 x 10(-3) mm2/s on the right. Kinetic analysis of signal intensity changes after Gd-DTPA showed no significant difference in inward transfer coefficient (BBB permeability) between sham injury and 2 or 4 hours post-injury. T2 imaging showed consistent tissue delivery of a bolus of Gd-DTPA to the tissue at 2 and 4 hours post-injury, comparable to sham animals.

CONCLUSIONS

Progressive cerebral edema formation after diffuse TBI occurred during ADC reduction and without continued BBB permeability. Tissue delivery of Gd-DTPA was confirmed, verifying that lack of tracer accumulation is due to an intact BBB and not to limited perfusion.

Traumatic brain edema in diffuse and focal injury: cellular or vasogenic?

The objective of this study was to confirm the nature of the edema, cellular or vasogenic, in traumatic brain injury in head-injured patients using magnetic resonance imaging techniques. Diffusion-weighted imaging methods were quantified by calculating the apparent diffusion coefficients (ADC). Brain water and cerebral blood flow (CBF) were also measured using magnetic resonance and stable Xenon CT techniques. After obtaining informed consent, 45 severely injured patients rated 8 or less on Glasgow Coma Scale (32 diffuse injury, 13 focal injury) and 8 normal volunteers were entered into the study. We observed that in regions of edema, the ADC was reduced, signifying a predominantly cellular edema. The ADC values in diffuse injured patients without swelling were close to normal and averaged 0.89 +/- 0.08. This was not surprising, as ICP values for these patients were low. In contrast, in patients with significant brain swelling ADC values were reduced and averaged 0.74 +/- 0.05 (p < 0.0001), consistent with a predominantly cellular edema. We also found that the CBF in these regions was well above ischemic threshold at time of study. Taking these findings in concert, it is concluded that the predominant form of edema responsible for brain swelling and raised ICP is cellular in nature.

Mitochondrial injury measured by proton magnetic resonance spectroscopy in severe head trauma patients

The aim of this study was to evaluate the extent of mitochondrial injury by assessing N-Acetyl-Aspartate by MR spectroscopy in head injured patients and relating the extent of mitochondrial injury to outcome. The study population (n = 15) consisted of head injured patients (GCS < 8) in whom legal consent was obtained for MRS studies. Studies were performed on a 1.5 Tesla Vision/Siemens system. Size of Voxel equaled 8 cm3 with location determined from T1 images. Voxels were positioned adjacent to the lesion and in the contralateral hemisphere for focal and bilateral for diffuse. Mitochondrial impairment was considered as percent reduction in NAA/ Cr ratio compared to matched controls. Mitochondrial impairment gradually increases soon after injury reaching a nadir at 10 days. Subsequently, mitochondria recover in patients with favorable outcome, but remains impaired in patients with poor outcome. The prognostic value of NAA/Cr to assist in management and also to serve as a surrogate endpoint for clinical trials appears promising.

Application of chemical shift imaging for measurement of NAA in head injured patients

Neurochemical damage following brain injury can be assessed non-invasively by measurement of N-Acetyl-Aspartate (NAA) using Proton Magnetic Resonance Spectroscopy (1HMRS). This report documents results of applying Chemical Shift Imaging (CSI) postprocessing for measuring NAA in traumatically injured brain. Following stabilization, severely head-injured patients (GCS 8 or less) were transported to the MRI suite. Semi-quantitative measurement of NAA, creatine (Cr/PCr) and choline (Cho) were obtained from single voxels (8 cm3) and CSI for acquisition of smaller voxels (2 cm3) throughout areas of the brain. Studies were completed with no complication. In focal injury, SVS positioned at the site of lesion demonstrated reduced NAA, compared to contralateral hemisphere. In diffuse injury, CSI demonstrated uniform reduction of NAA throughout the brain. NAA/Cho showed normal levels within 24 hours of injury averaging 2.4 and decreased over the next 10 days reaching a plateau of 0.75. At 30 days, NAA showed no recovery in poor outcome patients. In patients with good outcome, NAA initially low recovered near baseline levels. CSI provides a comprehensive neurochemical assessment of neuronal damage. NAA decreases and remains low in patients with poor outcome. NAA recovers in patients with favorable outcome, suggesting marginal metabolic impairment and possible re-synthesis of the NAA pool.

Secondary insults worsen blood brain barrier dysfunction assessed by MRI in cerebral contusion

OBJECT

Understanding the cause of post-traumatic intracranial hypertension requires information about the pathophysiology of edema formation. Secondary insults are known to exacerbate edema formation following experimental contusion, however the influence of these insults on blood brain barrier (BBB) integrity is not known. This study non-invasively assesses the influence of hypoxia and hypotension on BBB permeability following experimental cortical contusion.

METHODS

Sprague-Dawley rats (350-380 g) were divided into three groups. Group A: (n = 3) Sham, Group B (n = 8) focal injury (controlled cortical impact 6.0 m/sec, 3 mm depth), Group C (n = 8), focal injury with secondary insult. Cortical BBB integrity was assessed four hours post-trauma using an i.v. bolus of 0.2 mmol/kg Gd-DTPA with serial T1 MR images, over 30 minutes. Absolute tissue concentrations of Gd were measured empirically using known references. The time course of accumulation was analyzed with respect to BBB permeability.

RESULTS

BBB permeability was greatest in the site of contusion, and Gd accumulation was greatly enhanced by secondary insult (p < 0.01). Regions of lowest ADC and maximal swelling correlated with regions of maximal BBB permeability (p < 0.05).

CONCLUSIONS

Secondary insults enhance BBB dysfunction in contusion. Positive relationships between low ADC, tissue swelling and BBB dysfunction suggest synergy between underlying cytotoxic swelling and BBB permeability in contusion. These data also suggest that restoration of BBB integrity after injury may be an energy dependent process. These findings have important implications for the pathophysiology of ICP elevations following cerebral contusion.

Contrasting effects of dopamine therapy in experimental brain injury

Management of cerebral perfusion pressure (CPP) is thought to be important for the treatment of traumatic brain injury (TBI). Vasopressors have been advocated as a method of increasing mean arterial blood pressure (mABP) and cerebral perfusion pressure (CPP) in the face of rising intracranial pressure (ICP). There are unresolved issues and theoretical risks about this therapy. This study therefore examined the effects of dopamine on physiological and MRI/MRS parameters in (1) a rodent model of rapidly rising intracranial pressure, caused by diffuse injury with secondary insult and (2) a model of cortical contusion. Dopamine was capable of restoring CPP in the model of rapidly rising ICP. This CPP restoration was associated with a partial restoration of CBF. Two profiles of change in the Apparent Diffusion Coefficient of water (ADCw) were seen; one in which ADCw recovered to baseline, and one in which ADCw remained persistently low. Dopamine did not alter these profiles. MRI assessed tissue water content was increased four hours after injury and dopamine increased cerebral water content in both subgroups of injury; significantly in the group with a persistently low ADCw (p < 0.01). In contusional injury, dopamine significantly worsened edema in both the ipsi- and contralateral hippocampus and temporal cortex. This occurred in the absence of ADCw changes, except in the contralateral hippocampus, where both water content and ADCw values rose with treatment, suggesting extracellular accumulation of water. In conclusion, although dopamine is capable of partially restoring CBF after injury, situations exist in which dopamine therapy worsens the swelling process. It is possible therefore that subgroups of patients exist who experience adverse effects of vasopressor treatment, and consequently the effects of vasopressor therapy in the clinical setting need to be more carefully evaluated.

The permissive nature of blood brain barrier (BBB) opening in edema formation following traumatic brain injury

The contribution of blood brain barrier opening to traumatic brain edema is not known. This study compares the course of traumatic BBB disruption and edema formation, with the hypothesis that they are not obligately related. Sprague-Dawley rats were divided into three groups: Group A (n = 47)--Impact Acceleration (IAM); Group B (n = 104)--lateral cortical impact (CCI); Group C (n = 26)--IAM + hypoxia & hypotension (THH). BBB integrity was assessed using i.v. markers (Evan's Blue, or gadolinium-DTPA). Edema formation was evaluated with gravimetry, and T1-weighted MRI. In IAM, BBB opened immediately but closed rapidly, and remained closed for at least the next 36 hours whilst 24-hour hemispheric water content (HWC) rose by 0.9% (p < 0.01). In CCI, BBB opened in both hemispheres for up to 4 hours; four hour HWC in the uninjured hemisphere was indistinguishable from Sham, where HWC in the injured hemisphere rose by approximately 1.5% (p < 0.005). We distinguished two THH animals based on Apparent Diffusion Coefficient (ADC) recovery: in ADC-recovery animals 4 hour cortical water content (CWC) was 80.4 +/- 0.6%, cf 81.4 +/- 1.3% in ADC-non-recovery (p < 0.05). In all animals the BBB was open, however two populations of permeability were seen which likely related to flow-limited extravasation of gadolinium. In IAM edema forms despite only brief BBB opening. Although there is diffuse BBB opening with lateral contusion, edema only forms in the injured hemisphere. In THH, edema formation in the face of a widely permeable barrier is driven by ADC changes or cell swelling. Edema formation clearly does not correspond with BBB opening and an open BBB is clearly not required for edema formation. However we hypothesize that a permeable BBB permissively worsens the process, by acting as a low resistance pathway for ion and water movement. These findings are consistent with our general hypothesis that edema formation after TBI is mainly cytotoxic.

Distinguishing between cellular and vasogenic edema in head injured patients with focal lesions using magnetic resonance imaging

Having determined that edema and not vascular engorgement is the major factor leading to traumatic brain swelling, the objective of this study was to determine which type of edema, cellular or vasogenic, is responsible for increased tissue water in patients with focal lesions. Severely head injured patients (GCS 8 or less) were transported to imaging suites for measurement of brain water and apparent diffusion coefficient (ADC) using magnetic resonance technique. Cerebral blood flow by stable Xenon method was also measured in the regions of interest. Brain water was increased significantly in the hemisphere with lesion. The increase in water was associated with reduced ADC signifying a predominant cellular edema. The ADC in the contralateral hemisphere was near normal value. Cerebral blood flow values in the regions of interest were above ischemic levels suggesting that factors other than ischemia are responsible for the cytotoxic swelling in patients with focal injury.

Characterizing edema associated with cortical contusion and secondary insult using magnetic resonance spectroscopy

It is traditionally believed that edema associated with brain contusion is vasogenic. The objective of this study was to quantify and characterize the edema in cortical contusion coupled with early hypoxia and hypotension. Sprague-Dawley rats were randomised into six groups: Sham, Trauma moderate (Tm), Trauma severe (Ts), Hypoxia and Hypotension (HH), Tm and Ts with HH (THHm; THHs). Trauma was induced with controlled cortical impact; associated secondary insults lasted 30 minutes. Water content was measured using tissue longitudinal relaxation time (T1). Apparent diffusion coefficient of water (ADC) was calculated from diffusion-weighted imaging and single voxel spectroscopy. In the trauma groups ICP increased at 30 minutes post trauma (p < 0.05) and then gradually decreased. Only in the THH groups, ICP showed a trend to continually rise. No ICP variations were seen in the others groups. The increase in water content at 4 hours post trauma was inversely related to ADC variation (p < 0.0001). A significant increase in water content with low ADC, developed in the injured region in Ts, THHm (p < 0.05) and THHs (p < 0.01) compared to Sham. Intracellular water rose in the whole brain in THH groups although more severely in the THHs (p < 0.01). Immediately after trauma ADC fell in the THH groups, but gradually increased in the THHm, whereas there was no recovery in THHs. The results indicate that the type of edema in the injured area, with and without superimposed secondary insult, is predominantly cytotoxic (cellular). Moreover, secondary insults act synergistically with focal injury to increase cellular water in both injured tissue and remote regions.

The effects of dopamine on edema formation in two models of traumatic brain injury

The risk of vasopressors worsening cerebral edema has been raised. Previously we have reported that dopamine was able to restore cerebral blood flow in a model of monotonically rising intracranial pressure. In this study the effects of dopamine on cortical contusion and diffuse injury with secondary insult are examined. Adult male rats were divided into two groups: group 1 (n = 32)--Impact Acceleration Injury (IAM) with 30 minutes hypoxia and hypotension; group 2 (n = 12)--controlled cortical impact (6.0 m/sec, 3 mm depth). Dopamine was administered 2 hours post-injury (10-60 micrograms/kg/min i.v.). Cerebral water content and apparent diffusion coefficients (ADC) values were measured at baseline and four hours post-injury using MRI. Preinjury water content was the same in each group. Group 1 was subdivided into Groups 1A & 1B based on the ADC profile. Post-injury water content in Group 1A did not differ between saline or dopamine treated animals. Water content was higher in Group 1B-dopamine (83.4 +/- 1.1%) than Group 1B-saline animals (81.4 +/- 1.3%, p = 0.006). Contusion caused significant edema formation, however there was no significant difference between the dopamine treated or untreated group when considering either ipsilateral or contralateral cortex. Dopamine however significantly worsened edema in ipsilateral and contralateral hippocampus and both temporal cortices. ADC remained unchanged except in the contralateral hippocampus where both water content and ADC rose with dopamine suggesting precipitation of a vasogenic edema. In this study dopamine clearly worsened edema formation in two models of traumatic brain injury, and we conclude that there may be analogous clinical situations; therefore pressors should not be considered a 'blanket' therapy for all patients with a low cerebral perfusion pressure.

Acute and late changes in N-acetyl-aspartate following diffuse axonal injury in rats: an MRI spectroscopy and microdialysis study

N-acetyl-aspartate (NAA) measured by proton nuclear magnetic resonance spectroscopy (1H-NMR) has been used as a marker of neuronal injury in many cerebral pathologies. Therefore, we evaluate the roles of microdialysis vs. 1H-NMR as techniques to assess NAA (NAAd; NAA/Creatine ratio) in the living brain, and compare the results with whole brain NAA (NAAw), analyzed by HPLC after diffuse traumatic brain injury (TBI). Acute (4 h post-injury survival) and late (48 h survival) changes were studied in a sham-operated group (Sham, n = 4), and two injured groups (TBI/4 h, n = 8; TBI/48 h, n = 7). Baseline NAAd was 8.17 +/- 1 microM, and there was no significant difference between groups. There was only a small (twice of control), but transient increase in NAAd in the TBI/4 h group after trauma. Baseline NAA/Cr ratio was 1.35 +/- 0.2, which did not change significantly between baseline, 1, 2, 3, 4 and 48 h or between groups after TBI. Whole brain NAAw (baseline 8.5 +/- 0.5 mmol kg-1 wet weight) did not differ significantly between groups before and after TBI. Diffuse TBI did not produce long-term changes in NAA, assessed by three different methods. These results may indicate that NAA is not a sensitive marker of the severity of diffuse axonal damage. However, further studies are needed to evaluate whether confounding factors such as microdialysis probe, voxel position and non-regional tissue homogenization might have influenced our data.

Detection of ultra-early brain damage after acute subdural hematoma in the rat by magnetic resonance imaging

We measured serial changes in diffusion-weighted magnetic resonance imaging (DW) and in apparent diffusion coefficient (ADC) 1 to 3 hours after induction of acute subdural hematoma (ASDH) in rats, to assess the rate of development of cytotoxic edema and ischemic brain damage observed in this model. Cortical ADC values underneath the hematoma in ASDH rats (n = 12) were significantly lower than those in sham-operated rats (n = 5) at 1 hour. By 3 hours, the area of ADC abnormality had further increased. The lesion areas, as percentage of hemispheric areas on 1- and 3-hour ADC maps, correlated significantly with those on the histologic sections stained with hematoxylin and eosin. The results indicate that DWI with ADC mapping may provide a valuable diagnostic tool for monitoring of early pathologic changes following subdural hematoma in head-injured patients.

Brain stem blood flow, pupillary response, and outcome in patients with severe head injuries

OBJECTIVE

Acute pupillary dilation in a head-injured patient is a neurological emergency. Pupil dilation is thought to be the result of uncal herniation causing mechanical compression of the IIIrd cranial nerve and subsequent brain stem compromise. However, not all patients with herniation have fixed and dilated pupils, and not all patients with nonreactive, enlarged pupils have uncal herniation. Therefore, we have tested an alternative hypothesis that a decrease in brain stem blood flow (BBF) is a more frequent cause of mydriasis and brain stem symptomatology after severe head injury. We determined the relation of BBF to outcome and pupillary response in patients with severe head injuries.

METHODS

One hundred sixty-two patients with a Glasgow Coma Scale score of 8 or less underwent stable xenon computed tomographic blood flow determination at the level of the superior colliculus, and this blood flow was correlated with pupillary features, intracranial pressure, computed tomographic scan pathology, and outcome.

RESULTS

A BBF of less than 40 ml/100 g/min was significantly associated with poor outcome (P < 0.009). In patients with bilaterally nonreactive pupils, the BBF was 30.5+/-16.8 ml/100 g/min, and in those with normally reactive pupils, the BBF was 43.8+/-18.7 ml/100 g/min (P < 0.001). Intracranial pressure and the presence of a brain stem lesion observed on the computed tomographic scan did not correlate with BBF, pupillary size, or reactivity. Unfavorable outcome at 12 months was directly related to age (P = 0.062) and inversely related to pupillary responsiveness (P = 0.0006), pupil size (P = 0.005), and BBF of less than 40 ml/100 g/min (P = 0.009).

CONCLUSION

These findings suggest that pupillary dilation is associated with decreased BBF and that ischemia, rather than mechanical compression of the IIIrd cranial nerve, is an important causal factor. More important, pupil dilation may be an indicator of ischemia of the brain stem. If cerebral blood flow and cerebral perfusion pressure can be rapidly restored in the patient with severe head injury who has dilated pupils, the prognosis may be good.

Pathogenesis of traumatic brain swelling: role of cerebral blood volume

The pathogenesis of traumatic brain swelling is unclear. Brain edema (increased water content) is considered an important cause of swelling, but there is also evidence that vasodilatation with increased cerebral blood volume (CBV) plays a role. We have evaluated early posttraumatic changes in CBV in 37 head-injured patients, using dynamic contrast-enhanced computerized tomography (CT) in combination with stable Xenon-enhanced CT for measurement of cerebral blood flow (CBF). This technique enables rapid determination of CBV without interfering with patient care. CBV values ranged from 2.0 to 10.1 ml/100 g. There was no relationship the time after injury at which the measurements were taken. CBV did not correlate with CBF in the early posttraumatic period. Patients with raised ICP (> 20 mm Hg) had significantly higher CBV that patients with normal ICP (5.4 +/- 2.1 vs 3.7 +/- 0.9 ml/100 g). Yet, the presence of signs of brain swelling on CT had no relation to the level of CBV. These data suggest that increased CBV may contribute to raised ICP, but that brain swelling is not caused by increased CBV alone, and is more likely accounted for by brain edema. We speculate that cerebral energy failure is the unifying cause of both intracellular edema and cerebral vasodilation leading to swelling of brain tissue.

Early cerebral blood volume after severe traumatic brain injury in patients with early cerebral ischemia

Recent early cerebral blood flow (CBF) studies on severe head injury have revealed ischemia in a substantial number of patients with a variety of CT diagnoses. However, the underlying derangements causing this early ischemia are unknown, but cerebral blood volume (CBV) measurements might offer some insight into this pathology. Therefore, acute CBF and CBV measurements were performed in 51 adult severely head injured patients within 24 hours after injury. For this purpose the stable Xenon-CT procedure was used for assessment of CBF, and a dynamic CT imaging technique was used for determining CBV. All ischemic patients were found among 35 subjects studied within 4 hours after injury (31%). Based on the occurrence of regional ischemia seven patients with varying anatomical lesions on CT were selected for comparison between CBF and CBV in ischemic and non-ischemic areas. Both CBF (p < 0.02) and CBV (p < 0.02) exhibited significantly lower values in the ischemic zones. Ten patients showing a subdural hematoma (SDH) were studied preceding surgery and seven were ischemic in at least one lobe or brainstem. Ipsilateral CBF was lower than CBF in the contralateral side (p < 0.1). CBV at the ipsilateral side was significantly reduced compared to the contralateral side (p < 0.05). Follow-up studies were performed in three ischemic patients and in one borderline ischemic patient immediately after removal of SDH showing a striking increase in both CBF and CBV. In the remaining 26 subjects follow-up studies were obtained between day 2 and day 8 and all patients showed CBF values within the normal range. These data evidently support the suggestion that compromise of the microvasculature is the cause of early ischemia, rather than vasospasm of the larger conductance vessels. This has implications for acute post-traumatic therapeutical strategies and management of the severely head injured patient and may lead to testing of new drugs that are effective in interfering with processes causing this ischemia.

Biphasic pathophysiological response of vasogenic and cellular edema in traumatic brain swelling

The objective of this study was to quantify the temporal water content changes and document the type of edema (cellular versus vasogenic) that is occurring during both the acute and the late stages of edema development following closed head injury. Adult Sprague rats (n = 50) were separated into two groups: Group I: Sham (n = 8), Group II: Trauma (n = 42). The measurement of brain water content (BWC) was based on T1, whereas the differentiation of edema on the measurement of the random, translational motion of water protons (apparent diffusion coefficients-ADC) by MRI. In trauma animals, we found a significant increase in ADC (105%) as well as in BWC (0.7 +/- 0.3%) during the first 60 minutes post injury indicating vasogenic edema formation. This transient increase; however, was followed by a continuing decrease in ADC beginning at 45 minutes post injury and reaching a minimum at days 7-14 (-103%). Since the BWC continued to increase during the next day (10.3%), it is suggested cellular edema formation started to develop soon after injury and became dominant between 1-2 weeks post injury. In conclusion we may consider, that there is a predominantly vasogenic edema formation immediately after injury and later a more widespread and slower edema formation due to a predominantly cellular swelling.

Acute blood-brain barrier changes in experimental closed head injury as measured by MRI and Gd-DTPA

The objective of this study was to determine the early time course of blood-brain barrier (BBB) changes in diffuse closed head injury (CHI) and to what extent BBB is affected by secondary insult. The BBB disruption was quantified using T1-weighted MRI following administration of Gd-DTPA. The maximal signal intensity (SI) enhancement was used to calculate BBB disruption. A new CHI model was used to induce injury. Adult SD rats were separated into four groups: Group I: Sham (n = 4), II: Hypoxia and Hypotension (HH, n = 4), III: Trauma alone (n = 23), and IV: Trauma coupled with HH (THH, n = 14). Following trauma, a 30 minute insult of hypoxia (PaO2 = 40 mmHg) and hypotension (MABP = 30 mmHg) were imposed. In trauma animals, SI increased dramatically immediately following impact. By 15 minutes, permeability decreased exponentially and by 30 minutes was equal to that of control. In THH animals, SI enhancement was lower after the trauma, consistent with reduced blood pressure and blood flow. However, the SI increased dramatically upon reperfusion and was equal to that of control after 60 minutes. In conclusion we may consider, that CHI is associated with a rapid and transient BBB opening which begins at the time of the trauma and lasts not more than 30 minutes. It has been also shown that addition of hypoxia and hypotension prolongs the time of BBB breakdown.

MRI diffusion-weighted spectroscopy of reversible and irreversible ischemic injury following closed head injury

The objective of this study was to detect the threshold between reversible and irreversible secondary insult of hypoxia and hypotension following closed head injury as measured by MRI. Adult Sprague rats were separated into 3 groups: I: Sham (n = 6), II: Trauma and hypoxia coupled with mild hypotension of 40-50 mmHg (n = 6), III: Trauma and hypoxia coupled with severe hypotension of 30-40 mmHg (n = 6). The measurement of brain water content (BWC) was based on T1, whereas the differentiation between reversible and irreversible secondary insult on the measurement apparent diffusion coefficient (ADC). The ADCs in both trauma and secondary insult groups decreased rapidly from a control level of 0.68 +/- 0.5 x 10(-3) to significantly different minimum levels of 0.52 +/- 0.5 x 10(-3) in Group II and 0.42 +/- 0.5 x 10(-3) mm2/second in Group III at 30 minutes. In Group II rats there was a complete recovery in ADC as well as in their clinical conditions, whereas ADC in Group III rats remained at the minimum level and the animals were brain dead. The BWC was also significantly different at four hours post injury (Group II: 80.3 +/- 0.7%, Group III: 81.8 +/- 0.8%). The data lead the authors to suggest that the threshold between reversible and irreversible posttraumatic secondary insult is very narrow, and the measurement of ADC can provide information that will enable the clinician to identify critical threshold beyond which recovery is not possible.

Traumatic brain swelling in head injured patients: brain edema or vascular engorgement?

Brain edema and vascular engorgement have been used interchangeably to describe brain swelling associated with severe brain trauma and their relative contribution of these compartments to the swelling process remains controversial. In this report, imaging techniques for measurement of brain water and blood volume have been used to study the relative contribution of blood volume and tissue water to the swelling process in severely brain injured patients. More specifically, magnetic resonance techniques for non-invasive tissue water measures founded on mathematical models and later substantiated in laboratory and clinical studies were used for measure of brain tissue water. These studies were combined with measures of cerebral blood volume utilizing indicator dilution methods. Studies indicated that brain water was increased while blood volume decreased. These studies provide compelling evidence that the major contributor to brain swelling is brain edema and not blood volume. Therapies should now be targeted toward preventing edema development and enhancing edema resolution.

Detection of brain atrophy following traumatic brain injury using gravimetric techniques

We hypothesized, that with atrophy, the correlation between water content and specific gravity of brain solids would break down signifying the onset of the atrophic process. The correlation between tissue water content, specific gravity of solids and ventricular size was studied in an impact acceleration model of closed head injury of the rat. Adult Sprague Dawley rats weighing 350 to 375 grams (n = 63) were separated into two groups: Group 1: Sham (n = 21), Group II: Trauma (n = 42). Water content was assessed using both gravimetric method and drying-weighing method at 1 hour, on days 1, 3, 7, 14, 28, and 42 in the trauma group as well as in the control group. Ventricular size was measured in cm2 on the MRI computer console in the coronal section at the coronal suture at the same time points. In the trauma group we found a significant increase (p < 0.01) in water content during the first week except on day 3 and there was a good correlation between the results of water content using both methods (p < 0.001). However, this relationship was poorly correlated after day 14 (p = 0.25). Although the ventricular size was the smallest at 1 hour post trauma, it significantly increased over the next 3 days (p < 0.001). On day 7 and 14 ventricular size decreased to normal size, yet gradually increased and then reached a significantly larger size on 42 days post trauma again (p < 0.01). We may consider, that brain edema following CHI begins immediately following trauma and resolves within 2 weeks. After 14 days degenerative change occurs in the cortex, as detected by specific gravity measurements which signifies the onset of the atrophic process and subsequent post traumatic ventricular dilatation.

Contribution of vasogenic and cellular edema to traumatic brain swelling measured by diffusion-weighted imaging

The contribution of brain edema to brain swelling in cases of traumatic brain injury remains a critical problem. The authors believe that cellular edema, the result of complex neurotoxic events, is the major contributor to brain swelling and that vasogenic edema, secondary to blood-brain barrier compromise, may be overemphasized. The objective of this study, therefore, was to quantify temporal water content changes and document the type of edema that forms during the acute and late stages of edema development following closed head injury (CHI). The measurement of brain water content was based on magnetic resonance imaging-determined values of tissue longitudinal relaxation time (T1-weighted imaging) and their subsequent conversion to percentage of water, whereas the differentiation of edema formation (cellular vs. vasogenic) was based on the measurement of the apparent diffusion coefficient (ADC) by diffusion-weighted imaging. A new impact-acceleration model was used to induce CHI. Thirty-six adult Sprague-Dawley rats were separated into two groups: Group I, control (six animals); and Group II, trauma (30 animals). Fast ADC measurements (localized, single-voxel) were obtained sequentially (every minute) up to 1 hour postinjury. The T1-weighted images, used for water content determination, and the diffusion-weighted images (ADC measurement with conventional diffusion-weighted imaging) were obtained at the end of the 1st hour postinjury and on Days 1, 3, 7, 14, 28, and 42 in animals from the trauma and control groups. In the animals subjected to trauma, the authors found a significant increase in ADC (10 +/- 5%) and brain water content (1.3 +/- 0.9%) during the first 60 minutes postinjury. This is consistent with an increase in the volume of extracellular fluid and vasogenic edema formation as a result of blood-brain barrier compromise. This transient increase, however, was followed by a continuing decrease in ADC that began 40 to 60 minutes postinjury and reached a minimum value on Days 7 to 14 (10 +/- 3% reduction). Because the water content of the brain continued to increase during the first 24 hours postinjury (1.9 +/- 0.9%), it is suggested that the decreased ADC indicated cellular edema formation, which started to develop soon after injury and became dominant between 1 and 2 weeks postinjury. The study provides supportive evidence that cellular edema is the major contributor to posttraumatic swelling in diffuse CHI and defines the onset and duration of the increase in cellular volume.

Effect of CP101,606, a novel NR2B subunit antagonist of the N-methyl-D-aspartate receptor, on the volume of ischemic brain damage off cytotoxic brain edema after middle cerebral artery occlusion in the feline brain

BACKGROUND AND PURPOSE

The purpose of this study was to test the hypothesis that the neuroprotective compound CP101,606 will ameliorate the increase in lactate, retard the development of cytotoxic edema, and decrease the infarct volume after ischemic stroke.

METHODS

Seventeen adult cats were allocated to control (n = 7) and CP101,606-treated groups (n = 10). Transorbital middle cerebral artery occlusion was performed under anesthesia. Extracellular fluid lactate by microdialysis as well as infarct volume measurement by triphenyltetrazolium chloride (TTC)-stained section, with and without neuroprotective agents, was used to determine the value of these potential "surrogate markers" of ischemic damage.

RESULTS

The control group showed an increased dialysate lactate (15.5% increase) at 30 minutes and a peak (332.0% increase) in dialysate lactate at 1 hour after middle cerebral artery occlusion compared with the drug-treated group. Significant differences between control and drug-treated groups were seen in the rate of fall of the apparent diffusion coefficient at both 1 and 5 hours. A close correlation was seen between the 1- and 5-hour apparent diffusion coefficient maps and the TTC-stained sections. There was a significantly smaller lesion in the CP101,606-treated group (62.9% reduction in infarct size compared with the control group; P < .001).

CONCLUSIONS

CP101,606 ranks very highly among the current neuroprotection candidates for clinical trials, and its excellent safety record in both animals and phase II studies in conscious, moderate head injury patients suggests that it will be highly effective in human occlusive stroke.

Magnetic resonance imaging-monitored acute blood-brain barrier changes in experimental traumatic brain injury

The authors posit that cellular edema is the major contributor to brain swelling in diffuse head injury and that the contribution of vasogenic edema may be overemphasized. The objective of this study was to determine the early time course of blood-brain barrier (BBB) changes in diffuse closed head injury and to what extent barrier permeability is affected by the secondary insults of hypoxia and hypotension. The BBB disruption was quantified and visualized using T1-weighted magnetic resonance (MR) imaging following intravenous administration of the MR contrast agent gadolinium-diethylenetriamine pentaacetic acid. To avoid the effect of blood volume changes, the maximum signal intensity (SI) enhancement was used to calculate the difference in BBB disruption. A new impact-acceleration model was used to induce closed head injury. Forty-five adult Sprague-Dawley rats were separated into four groups: Group I, sham operated (four animals), Group II, hypoxia and hypotension (four animals), Group III, trauma only (23 animals), and Group IV, trauma coupled with hypoxia and hypotension (14 animals). After trauma was induced, a 30-minute insult of hypoxia (PaO2 40 mm Hg) and hypotension (mean arterial blood pressure 30 mm Hg) was imposed, after which the animals were resuscitated. In the trauma-induced animals, the SI increased dramatically immediately after impact. By 15 minutes permeability decreased exponentially and by 30 minutes it was equal to that of control animals. When trauma was coupled with secondary insult, the SI enhancement was lower after the trauma, consistent with reduced blood pressure and blood flow. However, the SI increased dramatically on reperfusion and was equal to that of control by 60 minutes after the combined insult. In conclusion, the authors suggest that closed head injury is associated with a rapid and transient BBB opening that begins at the time of the trauma and lasts no more than 30 minutes. It has also been shown that addition of posttraumatic secondary insult-hypoxia and hypotension-prolongs the time of BBB breakdown after closed head injury. The authors further conclude that MR imaging is an excellent technique to follow (time resolution 1-1.5 minutes) the evolution of trauma-induced BBB damage noninvasively from as early as a few minutes up to hours or even longer after the trauma occurs.

Characterization of edema by diffusion-weighted imaging in experimental traumatic brain injury

The objective of this study was to use diffusion-weighted magnetic resonance imaging (DWI) to help detect the type of edema that develops after experimental trauma and trauma coupled with hypotension and hypoxia (THH). Reduction in the apparent diffusion coefficients (ADCs) is thought to represent cytotoxic edema. In a preliminary series of experiments, the infusion edema model and middle cerebral artery occlusion models were used to confirm the direction of ADC change in response to purely extracellular and cytotoxic edema, respectively. The ADCs increased (p<0.05) in the case of extracellular edema and decreased (p<0.001) in cytotoxic edema. Following these initial experiments, a new impact acceleration model was used to induce traumatic brain injury. Thirty-six adult Sprague-Dawley rats were separated into four groups; sham, trauma alone, hypoxia and hypotension (HH), and THH. Following trauma, a 30-minute insult of hypoxia (PaO2 of 40 mm Hg) and hypotension (mean arterial blood pressure (MABP) of 30 mm Hg) were imposed and the animals were resuscitated. The DWI was carried out at four 1-hour intervals postinjury, and MABP, intracranial pressure (ICP), cerebral perfusion pressure (CPP), and cerebral blood flow (CBF) were monitored. The ADCs in the control and HH groups remained unchanged. The ADCs in the THH group rapidly decreased from a control level of 0.68 +/- 0.05 x 10(-3) mm2/second to 0.37 +/- 0.09 x 10(-3) mm2/second by 3 hours posttrauma (p < 0.001). In this group, the decreased CBF and CPP during secondary insult remained low despite resuscitation, with the ICP increasing to 56 +/- 7 mm Hg by 3 hours. In the trauma alone group, the rise in ICP reached a maximum value (28 +/- 3 mm Hg) at 30 minutes with a significant and sustained increase in CBF despite a gradual decrease in CPP. The ADCs in this group were not significantly reduced. The data lead the authors to suggest that the rise in ICP following severe trauma coupled with secondary insult in this model is predominately caused by cytotoxic edema and that ischemia plays a major role in the development of brain edema after head injury.

Ultra-early evaluation of regional cerebral blood flow in severely head-injured patients using xenon-enhanced computerized tomography

The role of cerebral ischemia in the pathophysiology of traumatic brain injury is unclear. Cerebral blood flow (CBF) measurements with 133Xe have thus far revealed ischemia in a substantial number of patients only when performed between 4 and 12 hours postinjury. But these studies cannot be performed sooner after injury, they cannot be done in patients with intracranial hematomas still in place, and they cannot detect focal ischemia. Therefore, the authors performed CBF measurements in 35 comatose head-injured patients using stable xenon-enhanced computerized tomography (CT), simultaneously with the initial CT scan (at a mean (+/- standard error of the mean) interval of 3.1 +/- 2.1 hours after injury). Seven patients with diffuse cerebral swelling had significantly lower flows in all brain regions measured as compared to patients without swelling or with focal contusions; in four of the seven, cerebral ischemia (CBF less than or equal to 18 ml/100 gm.min-1) was present. Acute intracranial hematomas were associated with decreased CBF and regional ischemia in the ipsilateral hemisphere, but did not disproportionately impair brain-stem blood flow. Overall, global or regional ischemia was found in 11 patients (31.4%). There was no correlation between the presence of hypoxia or hypertension before resuscitation and the occurrence of ischemia, neither could ischemia be attributed to low pCO2. Ischemia was significantly associated with early mortality (p less than 0.02), whereas normal or high CBF values were not predictive of favorable short-term outcome. These data support the hypothesis that ischemia is an important secondary injury mechanism after traumatic brain injury, and that trauma may share pathophysiological mechanisms with stroke in a large number of cases; this may have important implications for the use of hyperventilation and antihypertensive drugs in the acute management of severely head-injured patients, and may lead to testing of drugs that are effective or have shown promise in the treatment of ischemic stroke.

In vivo measurement of brain water by MRI

A new method for determining brain tissue water using MRI, developed in the laboratory, has been tested and applied to the clinical setting. To evaluate the accuracy of the technique, samples of human brain tissue were harvested from patients scheduled to undergo surgical removal of tumour and in whom biopsies were required for clinical management. MR determined values from imaging water maps compared favourably with gravimetric measures of samples. From these data, we conclude that accurate non-invasive measures of brain oedema in man are now possible.

Intracellular myocardial pH measured in vivo with sustained and reperfused coronary occlusion

Intracellular pH provides an important measure of the adequacy of local tissue perfusion. The purpose of this study was to measure regional intracellular myocardial pH (impH) in the ischemic zone in vivo during experimental canine coronary occlusion, with and without coronary reperfusion. Twenty adult dogs were studied. Ten dogs underwent permanent ligation of the proximal anterior left descending coronary artery (group L), five dogs had coronary reperfusion after 1 hour of total coronary occlusion (group R), and five dogs did not undergo ligation and served as controls (group C). Intracellular myocardial pH was measured by 31phosphorus nuclear magnetic resonance spectroscopy at baseline and then at 15-minute intervals for 6 hours after coronary occlusion (or after sham occlusion in group C). Baseline impH did not differ among groups (group C, 7.22 +/- 0.12 mean +/- standard error of mean; group L, 7.17 +/- 0.07; group R, 7.22 +/- 0.09). During hour 1 of total occlusion, the impH of both groups L (6.58 +/- 0.05) and R (6.55 +/- 0.08) was significantly reduced as compared with the impH of group C (7.3 +/- 0.12; p less than 0.05). At 0 to 1, 1 to 3, and 3 to 5 hours of reperfusion, the impH of group R (7.34 +/- 0.08, 7.27 +/- 0.07, and 7.29 +/- 0.06, respectively for these times) did not differ from group C (7.26 +/- 0.11, 7.21 +/- 0.07, and 7.25 +/- 0.10). At these same times, the impH of group L (6.47 +/- 0.05, 6.57 +/- 0.04, and 6.75 +/- 0.04) was significantly reduced as compared with both groups R and C (p less than 0.05). Thus a severe, persistent regional intracellular myocardial acidosis occurs in the ischemic zone with coronary occlusion but is rapidly corrected by reperfusion within 1 hour.

Exposure to magnetic resonance imaging does not produce taste aversion in rats

A taste aversion test was used to evaluate possible toxic effects of magnetic resonance imaging (MRI). Thirty male Sprague-Dawley rats were randomly assigned to four groups: Group One (n = 10) received 30 minutes exposure inside the MRI scanner; Group Two (n = 10) received a sham exposure to the MRI scanner; Group Three (n = 5) was injected with 0.15 M lithium chloride; and Group Four (n = 5) was injected with vehicle. All groups were given 10 minutes access to a 0.1% saccharin solution immediately prior to their respective treatment. The rats treated with lithium chloride displayed a taste aversion to the saccharin solution upon subsequent testing over an eight day period. The two control groups (Two and Four) and the rats exposed to MRI did not display any aversion to the saccharin solution. These results are compared to other studies that have shown that magnetic fields can influence biological systems.

Clinical comparison of conventional and rare earth screen-film systems for cephalometric radiographs

This study compared cephalometric and P-A skull films taken with conventional (CaWO4) screens and rare earth screens. Patient exposure was reduced by 17 to 55 percent on two different x-ray machines by the use of rare earth screens. Results from 130 clinical evaluations showed that the diagnostic quality of radiographs taken with either system was roughly comparable. This presents a persuasive argument for the use of rare earth screens since the diagnostic quality of the films can be maintained while significantly reducing the patient's exposure to radiation.

The relationship between resolution and speed of x-ray intensifying screens

Two important physical characteristics of x-ray intensifying screens, speed and resolution, are inversely related. However, the exact mathematical relationship, if any, between them is not known. To investigate this matter, a simple model is considered, which predicts that the product of the equivalent passband Ne and the square root of the speed is constant for a given phosphor material and given film. This relationship is found to be in excellent agreement with experimental data. The papper concludes with a discussion of the generalized validity of this relationship.