Clinical diagnostic exome sequencing in dystonia: Genetic testing challenges for complex conditions.

Patients with dystonia are particularly appropriate for diagnostic exome sequencing (DES), due to the complex, diverse features and genetic heterogeneity. Personal and family history data were collected from test requisition forms and medical records from 189 patients with reported dystonia and available family members received for clinical DES. Of them, 20.2% patients had a positive genetic finding associated with dystonia. Detection rates for cases with isolated and combined dystonia were 22.4% and 25.0%, respectively. 71.4% of the cohort had co-occurring non-movement-related findings and a detection rate of 24.4%. Patients with childhood-onset dystonia trended toward higher detection rates (31.8%) compared to infancy (23.6%), adolescence (12.5%), and early-adulthood onset (16%). Uncharacterized gene findings were found in 6.7% (8/119) of cases that underwent analysis for genes without an established disease relationship. Patients with intellectual disability/developmental delay, seizures/epilepsy and/or multifocal dystonia were more likely to have positive findings (P = .0093, .0397, .0006). Four (2.1%) patients had findings in two genes, and seven (3.7%) had reclassification after the original report due to new literature, new clinical information or reanalysis request. Pediatric patients were more likely to have positive findings (P = .0180). Our observations show utility of family-based DES in patients with dystonia and illustrate the complexity of testing.

Haemophilus influenzae type b carriage and novel bacterial population structure among children in urban Kathmandu, Nepal.

Haemophilus influenzae type b (Hib) is a major cause of invasive bacterial infection in children that can be prevented by a vaccine, but there is still uncertainty about its relative importance in Asia. This study investigated the age-specific prevalence of Hib carriage and its molecular epidemiology in carriage and disease in Nepal. Oropharyngeal swabs were collected from children in Kathmandu, Nepal, from 3 different settings: a hospital outpatient department (OPD), schools, and children's homes. Hib was isolated using Hib antiserum agar plates, and serotyping was performed with latex agglutination. Hib isolates from children with invasive disease were obtained during active microbiological surveillance at Patan Hospital, Kathmandu, Nepal. Genotyping of disease and carriage isolates was undertaken using multilocus sequence typing (MLST). Swabs were taken from 2,195 children, including 1,311 children at an OPD, 647 children attending schools, and 237 children in homes. Overall, Hib was identified in 5.0% (110/2,195; 95% confidence interval [95% CI], 3.9% to 6.4%). MLST was performed on 108 Hib isolates from children carrying Hib isolates and 15 isolates from children with invasive disease. Thirty-one sequence types (STs) were identified, and 20 of these were novel STs. The most common ST isolates were sequence type 6 (ST6) and the novel ST722. There was marked heterogeneity among the STs from children with disease and children carrying Hib. STs identified from invasive infections were those commonly identified in carriage. This study provides evidence of Hib carriage among children in urban Nepal with genetically diverse strains prior to introduction of universal vaccination. The Hib carriage rate in Nepal was similar to the rates observed in other populations with documented high disease rates prior to vaccination, supporting implementation of Hib vaccine in Nepal in 2009.

The supraorbital approach for recurrent or residual suprasellar tumors.

BACKGROUND: Suprasellar tumors can be removed through a variety of approaches including conventional frontotemporal craniotomies, the transsphenoidal route, or the supraorbital (SO) eyebrow craniotomy. Herein we assess the utility of the SO route for recurrent or residual suprasellar tumors previously treated by an alternative route. MATERIAL AND METHODS: A retrospective analysis of all consecutive patients who underwent an SO approach for removal of a recurrent/residual tumor was undertaken. RESULTS: Between December 2007 and February 2010, 11 patients underwent an SO craniotomy for a recurrent or growing residual tuberculum sellae meningioma (n=7) or craniopharyngioma (n=4). All 11 patients had prior craniotomies, 5 had transsphenoidal surgery, 6 had radiation treatment, and 1 had chemotherapy. In the last 5 cases, the endoscope was used in addition to the microscope for intraoperative visualization. 3 patients underwent decompression of multicystic craniopharyngiomas and the remaining 8 patients had tumor debulking, all achieving 70% or more tumor removal. Of 9 patients with preoperative visual deterioration, 6 (67%) had improvement and no patient had visual worsening. No new adenohypophysis or neurohypophysis dysfunction was noted. One patient had a postoperative CSF leak requiring reoperation. CONCLUSION: The SO approach should be considered as a safe and effective alternative route for recurrent or residual suprasellar tumors previously treated by conventional craniotomy or TS surgery. It typically offers a simplified trajectory that minimizes scar tissue from prior approaches and provides excellent access for optic apparatus decompression. Endoscopy is helpful to visualize hidden tumor remnants and maximize safe tumor removal.

Vidian nerve neurofibroma removed via a transpterygoid approach.

BACKGROUND: Lesions originating in the vidian canal are extremely rare. Most frequently, they are extensions from contiguous carcinomas. We present a rare case of a vidian nerve neurofibroma and discuss its surgical management. CASE REPORT: A 62-year-old woman with a history of a basal cell skin cancer was evaluated for bilateral tinnitus. Imaging revealed a left-sided lesion at the medial aspect of the pterygoid process base, over the vidian canal. Under image-guidance, an endonasal endoscopic transpterygoid approach was performed. The histopathological examination supported the diagnosis of neurofibroma. CONCLUSION: Benign nerve sheath tumors of the vidian nerve should be considered in the differential diagnosis of a vidian canal lesion. Given the propensity of more aggressive tumors, a tissue diagnosis should be warranted in order to coordinate appropriate subsequent treatment. The expanded endonasal transpterygoid approach offers a safe, less invasive, and effective route to perform the excisional biopsy of such a lesion.

Clinical profile of invasive pneumococcal diseases in Patan Hospital, Nepal.

BACKGROUND: Pneumococcal infection is one of the leading causes of pneumonia, meningitis and septicemia in developing countries. It accounts for one million deaths each year in children. OBJECTIVES: The objective of this study is to see the clinical profile of invasive pneumococcal disease, antibiotics sensitivity pattern and prevalent serotypes in children admitted at Patan Hospital. METHODS: This is a retrospective analytical study conducted in the department of Paediatrics, Patan hospital. The lab data of those children who grew pneumococci in their blood, cerebrospinal fluid or body fluids over a period of 3 years (January 2007 to Dec 2009) were collected and the case files were then studied. RESULTS: Out of 42 cases of invasive pneumococcal diseases studied admitted diagnoses included pneumonia, febrile seizure, bacteremia or septicemia, meningitis, acute gastroenteritis and glomerulonephritis. Twenty seven of them were children under five. The male to female ratio was 1.7:1. On investigation 64%, 52% and 5% of the patients had leucocytosis, anaemia, and leucopenia respectively. Twenty six of them had radiological changes suggestive of pneumonia. Streptococcus pneumoniae grew in 38 blood samples, 5 cerebrospinal fluid and 3 pleural fluids. Almost all of these isolates were sensitive to penicillin, cefotaxime, amoxycillin, choloramphenicol, erythromycin and ofloxacin and resistant to cotrimoxazole and gentamicin. Pneumococcal serotypes found in our study were 1, 14, 5, 23B, 6B, 8, 9A, 9V, 10A, 15 and 23F (11 serotypes). CONCLUSIONS: Penicillin is still the most effective antibiotic for streptococcal infection in our study. Of the pneumococcal serotypes identified; 36% were covered by the 7-valent pneumococcal conjugate vaccine, 54% each by PCV-10 and PCV-13, and 72% by the e 23 valent vaccines.

Clinical validity assessment of genes for inclusion in multi-gene panel testing: A systematic approach.

BACKGROUND: Advances in sequencing technology have led to expanded use of multi-gene panel tests (MGPTs) for clinical diagnostics. Well-designed MGPTs must balance increased detection of clinically significant findings while mitigating the increase in variants of uncertain significance (VUS). To maximize clinical utililty, design of such panels should include comprehensive gene vetting using a standardized clinical validity (CV) scoring system. METHODS: To assess the impact of CV-based gene vetting on MGPT results, data from MGPTs for cardiovascular indications were retrospectively analyzed. Using our CV scoring system, genes were categorized as having definitive, strong, moderate, or limited evidence. The rates of reported pathogenic or likely pathogenic variants and VUS were then determined for each CV category. RESULTS: Of 106 total genes, 42% had definitive, 17% had strong, 29% had moderate, and 12% had limited CV. The detection rate of variants classified as pathogenic or likely pathogenic was higher for genes with greater CV, while the VUS rate showed an inverse relationship with CV score. No pathogenic or likely pathogenic findings were observed in genes with a limited CV. CONCLUSION: These results demonstrate the importance of a standardized, evidence-based vetting process to establish CV for genes on MGPTs. Using our proposed system may help to increase the detection rate while mitigating higher VUS rates.

Investigating the effect of AS03 adjuvant on the plasma cell repertoire following pH1N1 influenza vaccination.

Influenza pandemics require rapid deployment of effective vaccines for control. Adjuvants such as AS03 improve vaccine immunogenicity, but this mechanism is poorly understood. We used high-throughput B cell receptor sequencing of plasma cells produced following AS03-adjuvanted and non-adjuvanted 2009 pandemic H1N1 vaccination, as well as pre-pandemic seasonal influenza vaccination to elucidate the effect of the adjuvant on the humoral immune response. By analyzing mutation levels, it was possible to distinguish sequences from cells that were recently activated from naïve B cells from those that were activated by memory recall. We show that the adjuvant functions through two mechanisms. First, the adjuvant stimulates increased activation of naïve B cells, thus reducing immune interference with previous vaccine responses. Second, the adjuvant is able to increase the adaptability of the recalled cells to give improved specificity to the new vaccine antigen. We thus show how AS03 enhances pH1N1 immune responses, and reduces immune interference.

Neuropathological findings in cats with clinically suspect but histologically unconfirmed feline spongiform encephalopathy.

Central nervous system (CNS) tissues from 192 cats with neurological signs were examined histologically, and tissues from 173 of them were later examined immunohistochemically as part of a survey to determine the prevalence of feline spongiform encephalopathy (FSE). One of the cats was from Norway and the others were from Great Britain. The most commonly recorded clinical signs were ataxia, behavioural changes and epilepsy, but none of the cats had histopathological evidence of FSE. The most common organic CNS lesions were non-suppurative encephalomyelitis in 28 per cent, neoplasia in 15 per cent and a heterogeneous group of degenerative encephalopathies in 9 per cent of the cats. A range of minor histological lesions of uncertain significance was also observed. No histological lesions were observed in the tissues of 63 (33 per cent) of the cats. Disease-specific prion protein (PrP(Sc)) was observed in only one of the 173 cats examined by immunohistochemistry.

The effect of fluorine substitution on the hepatotoxicity and metabolism of paracetamol in the mouse.

The widely used analgesic paracetamol (P) produces fulminant hepatocellular necrosis in humans when taken in overdose. The toxicity is mediated by drug oxidation and depletion of hepatic glutathione. We have, therefore, explored the effects of fluorine substitution on the hepatotoxicity of P in female CD1 mice. 3-Fluoro-4-hydroxyacetanilide (1FPO), 3,5-difluoro-4-hydroxyacetanilide (2FPO), 2,6-difluoro-4-hydroxyacetanilide (2FPN) and 2,3,5,6-tetrafluoro-4-hydroxyacetanilide (4FP) were synthesized, characterized and investigated for their potential to cause hepatotoxicity in the mouse. Introduction of fluorine into P increases the oxidation potential of the drug. The oxidation potentials of paracetamol and its fluorinated analogues were measured by cyclic voltametry and found to increase in the order P < 1FPO < 2FPO < 2FPN < 4FP. Serum transaminase (ALT) and hepatic glutathione were measured 24 and 6 hr, respectively, after administration of a single dose (2.65 mmol/kg) of each compound to female CD1 mice. There was significant elevation of ALT in mice given P, 1FPO and 2FPO, but not in those which received either 2FPN or 4FP. Hepatic glutathione was reduced significantly by administration of P and IFP, but not after administration of 2FPO, 2FPN or 4FP. Accordingly, glucuronide and sulphate conjugates, but not thioether metabolites, were detected in urine after administration of 14C-labelled 2FPO, 2FPN and 4FP. These data indicate that introduction of fluorine into the 2 and 6 positions increases the oxidation potential of paracetamol which in turn reduces the propensity of the molecule to undergo oxidative bioactivation, and thereby reduces the in vivo toxicity of the molecule.

Alcohol and head injury: an issue revisited.

The pathophysiologic changes associated with acute and chronic alcohol exposure in the setting of traumatic brain injury are complex. Experimental data indicate that ethanol intoxication can exacerbate brain injury through several mechanisms including hemodynamic and respiratory depression, blood-brain barrier disruption, and derangements in hemostasis. Alcohol, however, is also a potent inhibitor of N-methyl-D-aspartate (NMDA) receptor-mediated excitotoxicity, and thus is neuroprotective. In contrast to the effects of acute intoxication, chronic alcohol exposure appears to result in upregulation of NMDA receptor activity and downregulation of gamma-aminobutyric acid (GABA) receptor function. This imbalance, it is hypothesized, can result in a surge of excitotoxicity following alcohol withdrawal. Trauma-related excitotoxic cell damage may be significantly potentiated by this alcohol-induced receptor imbalance that is unmasked as withdrawal occurs. Clinical and epidemiologic investigations of alcohol and outcome after head injury have not consistently demonstrated a measurable effect from either acute or chronic alcohol use. Multiple factors including the timing of intoxication in relation to time of injury, the degree and chronicity of intoxication, as well as the influence of other secondary injury processes appear to determine the net effect of alcohol in a given individual. Further clinical and experimental investigations aimed at defining the impact of alcohol use on outcome after head injury are warranted.

Ethanol reduces metabolic uncoupling following experimental head injury.

Previous investigations have shown that ethanol is neuroprotective following experimental traumatic brain injury (TBI). This study sought to determine if the neuroprotective effects of ethanol in a controlled cortical impact (CCI) injury model are related to its effects on cerebral glucose metabolism and blood flow. Adult rats were given ethanol (1.0 g/kg) or saline by intraperitoneal injection followed 40 min later by injury. Regional cerebral blood flow (CBF) and cerebral metabolic rates of glucose (CMRglc) were determined immediately, and at 3, 6, 12, 24, and 72 h postinjury using quantitative autoradiography. Immediately after injury, CMRglc in the contusion core and penumbra was reduced in the ethanol group compared to the saline group: (core CMRglc: 52.2 +/- 16.0 versus 94.2 +/- 14.1 micromol/100 g/min, respectively,p < 0.001; penumbral CMRglc: 58.2 +/- 12.8 versus 82.8 +/-19.7 micromol/100 g/min, respectively; p < 0.05) However, at 24 and 72 h postinjury, penumbral CMRglc in the ethanol group was increased compared to the saline group (p < 0.05 and p < 0.001, respectively). Regarding CBF, contusion core values in the ethanol group were elevated compared to the saline group immediately postinjury, (70.4 +/- 17.1 versus 31.5 +/- 27.8 mL/100 g/min, respectively (p < .05), and at 6, 12, and 24 h postinjury (p < 0.05). Penumbral CBF was also higher at 6 and 72 h in the ethanol group compared to the saline group (p < 0.05). These results indicate that low-dose ethanol is associated with a marked attenuation of immediate postinjury hyperglycolysis and with more normal glucose metabolism in the injury penumbra over the ensuing 3 days. Simultaneously, the reduction in CBF typically seen within the contusion core and penumbra after CCI is less severe when ethanol is present. The net effect of these changes is a decreased degree of uncoupling between glucose metabolism and CBF that otherwise occurs in the absence of ethanol. These changes may likely explain the neuroprotective effect of ethanol.

Dissociation of cerebral glucose metabolism and level of consciousness during the period of metabolic depression following human traumatic brain injury.

Utilizing [18F]fluorodeoxyglucose positron emission tomography (FDG-PET), we studied the correlation between CMRglc and the level of consciousness within the first month following human traumatic brain injury. Forty-three FDG-PET scans obtained on 42 mild to severely head-injured patients were quantitatively analyzed for the determination of regional cerebral metabolic rate of glucose (CMRglc). Reduction of cerebral glucose utilization, defined as a CMRglc of < or =4.9 mg/100 g/min, was present regionally in 88% of the studies. The prevalence of global cortical CMRglc reduction was higher in severely head-injured patients (86% versus 67% mild-moderate), although the absolute magnitude was similar across the injury severity spectrum (mean CMRglc 3.9 +/- 0.6 mg/100 g/min). The level of consciousness, as measured by the Glasgow Coma Scale, correlated poorly with the global cortical CMRglc value (r = 0.08; p = 0.63). With regards to severity of head injury, this correlation was worst for the severely injured (r = -0.11; p = 0.58) and better for the mildly injured patients (r = 0.50; p = 0.07). In most cases, intraparenchymal hemorrhagic lesions were associated with either focal CMRglc reduction or elevation. It is concluded that the etiologies of CMRglc reduction are likely multifactorial given the complex nature of traumatic brain injury and that the reduction of CMRglc represents a fundamental pathobiologic state following head injury that is not tightly coupled to level of consciousness.

Fatal phenytoin-related toxic epidermal necrolysis: case report.

Toxic epidermal necrolysis is a rare but often fatal hypersensitivity reaction to numerous agents, including most anticonvulsants. The authors present a case of fatal phenytoin-related toxic epidermal necrolysis in a patient who was given prophylactic anticonvulsant therapy after he sustained a moderately severe closed head injury. The typical course and current management of toxic epidermal necrolysis are reviewed, as are the indications for the prophylaxis of posttraumatic epilepsy.

Collagen sponge repair of small cerebrospinal fluid leaks obviates tissue grafts and cerebrospinal fluid diversion after pituitary surgery.

OBJECTIVE: Repair of a cerebrospinal fluid (CSF) leak created at the time of transsphenoidal surgery typically involves placement of a fat, fascial, or muscle graft and sellar floor reconstruction. In this report, a simplified repair for small, "weeping" CSF leaks using collagen sponge is described. METHODS: All patients underwent an endonasal transsphenoidal procedure using the operating microscope. At the completion of tumor removal, if a small CSF leak was noted but no obvious large arachnoidal defect was present, a piece of collagen sponge was fashioned to cover the exposed diaphragma sellae. Titanium mesh was then wedged into the intrasellar, extradural space and a larger piece of collagen was placed over the reconstructed sellar floor. Nasal packing was removed within 24 hours. RESULTS: During an 18-month period, 62 consecutive transsphenoidal procedures were performed for tumor removal. Of 20 patients with a small CSF leak (18 pituitary adenomas, 1 Rathke's cleft cyst, and 1 chordoma), all had successful repair with collagen sponge. At follow-up examinations at 1 to 18 months, no patient had required a lumbar drain or had developed meningitis. One other patient had a large intraoperative arachnoidal defect that was unsuccessfully repaired with the collagen sponge technique; in this patient, a second operation was required with a fat graft, sellar floor reconstruction, and lumbar drainage. CONCLUSION: A simplified repair of small CSF leaks after transsphenoidal surgery using a two-layered collagen sponge technique with sellar floor reinforcement is thought to be safe and effective and obviates the need for tissue grafts, fibrin glue, or lumbar drain placement.

Delayed hyponatremia after transsphenoidal surgery for pituitary adenoma. Report of nine cases.

Hyponatremia, usually attributed to the syndrome of inappropriate secretion of antidiuretic hormone, typically occurs in a delayed fashion following transsphenoidal removal of a pituitary adenoma. In a series of 99 consecutive patients who underwent transsphenoidal surgery for pituitary adenoma, nine patients developed delayed hyponatremia, seven of whom were symptomatic. Of these seven patients, four had been discharged from the hospital and required readmission on postoperative Day 7 to 9. In the nine patients who developed hyponatremia, on the average, serum sodium levels began to fall on Day 4 and reached a nadir on Day 7 (mean serum sodium nadir 123 mmol/L). The development of delayed hyponatremia was associated with the presence of a macroadenoma in eight of the nine patients. Seven of the nine patients had serum sodium levels less than 130 mmol/L and required treatment. One patient was treated with fluid restriction alone and six were treated with both fluid restriction and intravenous urea therapy. Twenty-four and 48 hours after urea administration, serum sodium levels rose by an average of 6 and 10 mmol/L, respectively, and at discharge, levels averaged 136 mmol/L. Intravenous administration of urea provides a rapid yet safe means of correcting symptomatic hyponatremia when fluid restriction alone is inadequate. In this article, the authors discuss the pathogenesis of delayed hyponatremia.

Paradoxical effects of acute ethanolism in experimental brain injury.

Acute ethanol intoxication is a frequent complicating factor in human head injury, yet its impact on neurological outcome remains poorly defined. This study was undertaken to assess the effect of varying levels of preinjury ethanol on early postinjury mortality, recovery of motor function, and degree of neural degeneration after cortical contusion injury in the rat. Adult rats were pretrained on a beam-walking task, then randomized to one of five groups: low-dose ethanol and injury (1 g/kg, 16 animals); moderate-dose ethanol and injury (2.5 g/kg, 11 animals); high-dose ethanol and injury (3 g/kg, 17 animals); no ethanol and injury (nine animals); or ethanol and sham injury (seven animals). Forty minutes after intraperitoneal injection of ethanol or saline, the rats received a pneumatic piston-induced contusion injury of the left primary motor cortex. Their beam-walking ability was assessed daily for the next 7 days. At 4 weeks postinjury, the brains were sectioned and the dimensions of the cortical lesions were determined. Preinjury ethanol administration was associated with an acute postinjury mortality rate of 29.5% (p < 0.05); the highest mortality rate (47.1%) occurred in the high-dose ethanol group, whereas no deaths occurred in the animals in the no ethanol or sham-injured groups (p < 0.01). However, injured animals receiving low- and moderate-dose ethanol had significantly less severe beam-walking impairment initially, and a more rapid return to normal beam-walking ability, compared to the no and high-dose ethanol groups (p < 0.05). Additionally, the mean lesion volumes were significantly smaller in the low- and moderate-dose ethanol treatment groups compared to the no and high-dose ethanol groups (23.2 +/- 8 mm3 and 29 +/- 6.7 mm3 vs. 52 +/- 8.8 mm3 and 53.7 +/- 10.9 mm3, respectively, p < 0.01). In this cortical contusion model, the presence of ethanol before injury appears to exert a potent neuroprotective effect when administered in low or moderate doses. This action is postulated to result from ethanol-induced inhibition of N-methyl-D-aspartate receptor-mediated excitotoxicity. The loss of neuroprotection and increased mortality rates observed with high-dose ethanol may be related to ethanol-induced hemodynamic and respiratory depression.

Hypopituitarism following traumatic brain injury and aneurysmal subarachnoid hemorrhage: a preliminary report.

OBJECT: Recognition of pituitary hormonal insufficiencies after head injury and aneurysmal subarachnoid hemorrhage (SAH) may be important, especially given that hypopituitarism-related neurobehavioral problems are typically alleviated by hormone replacement. In this prospective study the authors sought to determine the rate and risk factors of pituitary dysfunction after head injury and SAH in patients at least 3 months after insult. METHODS: Patients underwent dynamic anterior and posterior pituitary function testing. Results of the tests were compared with those of 18 age-, sex-, and body mass index-matched healthy volunteers. The 22 head-injured patients included 18 men and four women (mean age 28+/-10 years at the time of injury) with initial Glasgow Coma Scale (GCS) scores of 3 to 15. Eight patients (36.4%) had a subnormal response in at least one hormonal axis. Four were growth hormone (GH) deficient. Five patients (four men, all with normal testosterone levels, and one woman with a low estradiol level) exhibited an inadequate gonadotroph response. One patient had both GH and thyrotroph deficiency and another had both GH deficiency and borderline cortisol deficiency. At the time of injury, all eight patients with pituitary dysfunction had an initial GCS score of 10 or less and, compared with the 14 patients without dysfunction, were more likely to have had diffuse swelling, seen on initial computerized tomography scans (p < 0.05), and to have sustained a hypotensive or hypoxic insult (p = 0.07). Of two patients with SAH who were studied (Hunt and Hess Grade IV) both had GH deficiency. CONCLUSIONS: From this preliminary study, some degree of hypopituitarism appears to occur in approximately 40% of patients with moderate or severe head injury, with GH and gonadotroph deficiencies being most common. A high degree of injury severity and secondary cerebral insults are likely risk factors for hypopituitarism. Pituitary dysfunction also occurs in patients with poor-grade aneurysms. Postacute pituitary function testing may be warranted in most patients with moderate or severe head injury, particularly those with diffuse brain swelling and those sustaining hypotensive or hypoxic insults. The neurobehavioral effects of GH replacement in patients suffering from head injury or SAH warrant further study.

Cerebral blood flow as a predictor of outcome following traumatic brain injury.

As part of a prospective study of the cerebrovascular effects of head injury, 54 moderate and severely injured patients underwent 184 133Xe-cerebral blood flow (CBF) studies to determine the relationship between the period of maximum blood flow and outcome. The lowest blood flows were observed on the day of injury (Day 0) and the highest CBFs were documented on postinjury Days 1 to 5. Patients were divided into three groups based on CBF values obtained during this period of maximum flow: Group 1 (seven patients), CBF less than 33 ml/100 g/minute on all determinations; Group 2 (13 patients), CBF both less than and greater than or equal to 33 ml/100 g/minute; and Group 3 (34 patients), CBF greater than or equal to 33 ml/100 g/minute on all measurements. For Groups 1, 2, and 3, mean CBF during Days 1 to 5 postinjury was 25.7 +/- 4, 36.5 +/- 4.2, and 49.4 +/- 9.3 ml/100 g/minute, respectively, and PaCO2 at the time of the CBF study was 31.4 +/- 6, 32.7 +/- 2.9, and 33.4 +/- 4.7 mm Hg, respectively. There were significant differences across Groups 1, 2, and 3 regarding mean age, percentage of individuals younger than 35 years of age (42.9%, 23.1%, and 76.5%, respectively), incidence of patients requiring evacuation of intradural hematomas (57.1%, 38.5%, and 17.6%, respectively) and incidence of abnormal pupils (57.1%, 61.5%, and 32.4%, respectively). Favorable neurological outcome at 6 months postinjury in Groups 1, 2, and 3 was 0%, 46.2%, and 58.8%, respectively (p < 0.05). Further analysis of patients in Group 3 revealed that of 14 with poor outcomes, six had one or more episodes of hyperemia-associated intracranial hypertension (simultaneous CBF > 55 ml/100 g/minute and ICP > 20 mm Hg). These six patients were unique in having the highest CBFs for postinjury Days 1 to 5 (mean 59.8 ml/100 g/minute) and the most severe degree of intracranial hypertension and reduced cerebral perfusion pressure (p < 0.0001). These results indicate that a phasic elevation in CBF acutely after head injury is a necessary condition for achieving functional recovery. It is postulated that for the majority of patients, this rise in blood flow results from an increase in metabolic demands in the setting of intact vasoreactivity. In a minority of individuals, however, the constellation of supranormal CBF, severe intracranial hypertension, and poor outcome indicates a state of grossly impaired vasoreactivity with uncoupling between blood flow and metabolism.

Carbon dioxide reactivity, pressure autoregulation, and metabolic suppression reactivity after head injury: a transcranial Doppler study.

OBJECT: Contemporary management of head-injured patients is based on assumptions about CO2 reactivity, pressure autoregulation (PA), and vascular reactivity to pharmacological metabolic suppression. In this study, serial assessments of vasoreactivity of the middle cerebral artery (MCA) were performed using bilateral transcranial Doppler (TCD) ultrasonography. METHODS: Twenty-eight patients (mean age 33 +/- 13 years, median Glasgow Coma Scale score of 7) underwent a total of 61 testing sessions during postinjury Days 0 to 13. The CO2 reactivity (58 studies in 28 patients), PA (51 studies in 23 patients), and metabolic suppression reactivity (35 studies in 16 patients) were quantified for each cerebral hemisphere by measuring changes in MCA velocity in response to transient hyperventilation, arterial blood pressure elevation, or propofol-induced burst suppression, respectively. One or both hemispheres registered below normal vasoreactivity scores in 40%, 69%, and 97% of study sessions for CO2 reactivity, PA, and metabolic suppression reactivity (p < 0.0001), respectively. Intracranial hypertension, classified as intracranial pressure (ICP) greater than 20 mm Hg at the time of testing, was associated with global impairment of CO2 reactivity, PA, and metabolic suppression reactivity (p < 0.05). A low baseline cerebral perfusion pressure (CPP) was also predictive of impaired CO2 reactivity and PA (p < 0.01). Early postinjury hypotension or hypoxia was also associated with impaired CO2 reactivity (p < 0.05), and hemorrhagic brain lesions in or overlying the MCA territory were predictive of impaired metabolic suppression reactivity (p < 0.01). The 6-month Glasgow Outcome Scale score correlated with the overall degree of impaired vasoreactivity (p < 0.05). CONCLUSIONS: During the first 2 weeks after moderate or severe head injury, CO2 reactivity remains relatively intact, PA is variably impaired, and metabolic suppression reactivity remains severely impaired. Elevated ICP appears to affect all three components of vasoreactivity that were tested, whereas other clinical factors such as CPP, hypotensive and hypoxic insults, and hemorrhagic brain lesions have distinctly different impacts on the state of vasoreactivity. Incorporation of TCD ultrasonography-derived vasoreactivity data may facilitate more injury- and time-specific therapies for head-injured patients.

Hyperemia following traumatic brain injury: relationship to intracranial hypertension and outcome.

The role of posttraumatic hyperemia in the development of raised intracranial pressure (ICP) has important pathophysiological and therapeutic implications. To determine the relationship between hyperemia (cerebral blood flow (CBF) > 55 ml/100 g/minute), intracranial hypertension (ICP > 20 mm Hg), and neurological outcome, 193 simultaneous measurements of ICP and CBF (xenon-133 method) were obtained in 59 patients with moderate and severe head injury. Hyperemia was associated with an increased incidence of simultaneous intracranial hypertension compared to nonhyperemic CBF measurements (32.2% vs. 21.6%, respectively; p < 0.059). However, in 78% of blood flow studies in which ICP was greater than 20 mm Hg, CBF was less than or equal to 55 ml/100 g/minute. At least one episode of hyperemia was documented in 34% of patients, all of whom had a Glasgow Coma Scale (GCS) score of 9 or below. In 12 individuals with hyperemia without simultaneous intracranial hypertension, ICP was greater than 20 mm Hg for an average of 11 +/- 16 hours and favorable outcomes were seen in 75% of patients. In contrast, in eight individuals with hyperemia and at least one episode of hyperemia-associated intracranial hypertension, ICP was greater than 20 mm Hg for an average of 148 +/- 84 hours (p < 0.001), and a favorable outcome was seen in only one patient (p < 0.001). Compared to the remainder of the cohort, patients with hyperemia-associated intracranial hypertension were distinctive in being the youngest, exhibiting the lowest GCS scores (all < or = 6), and having the highest incidence of effaced basilar cisterns and intractable intracranial hypertension. In the majority of individuals with hyperemia-associated intracranial hypertension, their clinical profile suggests the occurrence of a severe initial insult with resultant gross impairment of metabolic vasoreactivity and pressure autoregulation. In a minority of these patients, however, high CBF may be coupled to a hypermetabolic state, given their responsiveness to metabolic suppressive therapy. In patients with hyperemia but without intracranial hypertension, elevated CBF is also likely to be a manifestation of appropriate coupling to increased metabolic demand consistent with a generally favorable outcome. This study supports the concept that there are multiple etiologies of both elevated blood flow and intracranial hypertension after head injury.