Neurologic aspects of traumatic brain injury

Traumatic brain injury is a common neurologic condition that can have a significant emotional and financial burden. Neurologic injury is classified on the basis of initial clinical status by the Glasgow Coma Scale, and also by the type and location of head injury. Complications in the management of these patients are reviewed, ranging from intracranial pressure management and stroke to post-traumatic epilepsy. In addition, predictive prognostic variables that can be used to predict outcome based on a patient's presentation at the time of a head trauma are discussed. Finally, interventions such as induced hypothermia that can be undertaken to try to optimize outcome, are discussed along with current data in support of or against such techniques.     

Cellular prion protein ablation impairs behavior as a function of age

Cellular prion protein (PrPc) has been associated with some physiological functions in recent reports. Here we investigate behavioral parameters in 3- and 9-month-old mice lacking PrPc protein (Prnp0/0) and in rats after intrahippocampal administration of affinity purified anti-PrPc IgG (0.09 microg/side). No differences were observed between 3-month-old animals. However, 9-month-old Prnp0/0 mice and rats infused with anti-PrPc antibody showed a clear impairment of short- and long-term memory retention of a step-down inhibitory avoidance task. A decreased locomotor activity during exploration of an open field was also observed. These results suggest that systems involved in memory formation become more susceptible to mechanisms that require PrPc between the ages of 3 and 9 months in both mice and rats.     

Uptake of serotonin by adult rat corpus callosum is partially reduced by common antidepressants

The corpus callosum (CC) is the main white matter tract involved in interhemispheric brain communication. We establish that uptake of [3H]5-hydroxytryptamine (5-HT) in CC is partially inhibited by some antidepressants. Slices of the adult rat CC had a high-affinity uptake of 5-HT. About 80% of this uptake was Na+ dependent, with a Michaelis-Menten constant, Km, of 420 +/- 80 nM and a rate of 5-HT uptake, Vmax, of 9.5 +/- 0.8 pmol/mg protein/min. The 5-HT uptake was reduced approximately 60% at pH 5 compared with that at pH 7. Fluoxetine (Prozac) inhibited only 43% of 5-HT uptake in a concentration-dependent manner, with an affinity constant, Ki, of 44.7 +/- 10.0 nM. We also studied the effects of other monoamine uptake inhibitors, all at 10 microM, and found that zimelidine, imipramine, and clomipramine inhibited 5-HT uptake in the CC by approximately 30-40%. The fluoxetine-insensitive 5-HT uptake was not altered by high concentrations of dopamine plus norepinephrine. The present data show that Na(+)-dependent 5-HT uptake occurs in the CC and optic nerve and that this uptake is partially sensitive to antidepressants and probably mediated by the serotonin transporter, which may be relevant during depression.     

Bilateral posterior agyria-pachygyria and epilepsy

We analyzed the electroclinical findings in two patients with bilateral posterior agyria-pachygyria. Both patients presented with mental retardation, mild motor deficit and epilepsy. The electroclinical findings were characterized by frequent tonic or atonic generalized seizures with occasionally simple or complex partial seizures. Interictal electroencephalography (EEG) showed occipital spikes and diffuse polyspike-wave paroxysms predominantly in the posterior region. Ictal EEG showed diffuse 10-11 Hz activity. Cerebral magnetic resonance imagings (MRIs) showed thickened cortex in the parieto-occipital lobes, bilaterally and symmetrically. The volume of underlying white matter appeared reduced, and the overlying subarachnoid spaces were enlarged. The occipital horns were dilated. These findings were compatible with agyria-pachygyria of the posterior portions of the brain.In conclusion, in patients with mental retardation, mild motor deficit and epilepsy characterized by tonic or atonic generalized seizures, interictal EEG with diffuse polyspike-wave paroxysms predominantly in posterior region, posterior focal epileptilorm abnormalities and ictal diffuse 10-11 Hz activity, bilateral parieto-occipital agyria-pachygyria should be considered as a possible etiology. Magnetic resonance image is the best neuroradiological study to identify this disorder of cortical development.     

Endoscopically placed expandable metal tracheal stents for the management of complicated tracheal stenosis

BACKGROUND: Metal stents have been advocated to manage complicated tracheal stenosis. OBJECTIVE: The purpose of this investigation is to review the effectiveness of endoscopic placement of tracheal expandable metal stents for complicated tracheal stenosis. METHODS: The charts of 6 patients who have undergone placement of metal expandable stents between 1998 and 2000 were reviewed. RESULTS: Initially, all patients enjoyed immediate palliation of symptomatic tracheal stenosis. Eventually, 4 patients developed significant granulation tissue and/or recurrent stenosis, requiring intervention within 6 months after placement of the stent. One patient required the removal of the stent and placement of a T-tube silicone stent. CONCLUSIONS: Metal stents provide temporary palliation for tracheal stenosis. Metal stents, however, are associated with a high incidence of obstruction with granulation tissue. Their use should be limited to a select group of patients with a short life expectancy (because of other comorbidities) or patients who are not good candidates for reconstructive surgery and/or who refuse or cannot tolerate a tracheotomy.     

Effect of mandibular titanium reconstructive plates on radiation dose

BACKGROUND: The effects of the mandibular titanium alloy plates on the radiation-tissue interactions are not clearly defined. Photon beam radiation may be modified after striking a metal plate used to reconstruct the mandible after oncologic surgery. The purpose of this study was to determine, in a human mandible model, the effects of a titanium alloy plate on the radiation dose received at the bone/titanium (plate and screws) interface and bone/soft tissue interface. METHODS: We used an adult male human head and neck ex vivo model. A medical grade titanium alloy 6-hole plate, 2.4 mm, was fixed in the midline of the mandible. The mandible was then irradiated using 6 MV photon beams. Thermoluminescent dosimeters were used to measure the radiation doses anterior and posterior to the mandible. The experiment was then repeated without the plate and screws. RESULTS: The difference between the average doses received by the mandible reconstructed with plate/screws and a mandible without plate/screws was +2.1% at the buccal aspect of the mandible and +3.0% at the lingual aspect; respective P values were.741 and .323. Thus, these differences were not statistically significant. CONCLUSION: In this study, we did not observe any significant influence of titanium alloy plate/screws on the radiation doses received by tissues anterior or posterior to the mandible.     

What proportion of dermatological patients receive evidence-based treatment?

OBJECTIVE: To determine the proportion of dermatological patients who are offered evidence-based therapy in the routine dermatological practice. METHODS: For every patient seen for the first time at one of our tertiary hospital setting clinics between April and May 1999, the primary diagnosis and the primary intervention were recorded. For each primary diagnosis-primary intervention combination, evidence was searched for in electronic databases from January 1966 to December 1999. The proportion of patients who were offered evidence-based interventions was calculated as the main outcome measure. RESULTS: With a study sample of 136 patients, 61 different diagnosis-treatment couples were generated and 94 queries on electronic databases were performed (to account for "primary interventions" including more than 1 drug or treatment modality). Eighty-seven (64%) of 136 patients received evidence-based interventions. Evidence from randomized controlled trials was found for 69 patients (50.7% of the sample). Controlled studies lacking randomization or double blinding or including fewer than 20 patients per treatment group dealt with treatments offered to 14 patients (10.3%). The treatments offered to 4 patients (2.9%) were judged to have self-evident validity (ie, trials unanimously judged unnecessary). Symptomatic and supportive measures accounted for most interventions lacking substantial evidence (36% of the patients), but we had to include in this class other important treatment regimens, mainly for rare conditions. CONCLUSIONS: Most of the study patients received evidence-based care. However, published trials should be carefully appraised, and relevance of clinical end points should be evaluated together with methodological issues. More accessible, clinically oriented, evidence-based information sources are needed.     

Basic auditory processing skills and specific language impairment: a new look at an old hypothesis.

PURPOSE: To explore the sensitivity of children with specific language impairment (SLI) to amplitude-modulated and durational cues that are important for perceiving suprasegmental speech rhythm and stress patterns. METHOD: Sixty-three children between 7 and 11 years of age were tested, 21 of whom had a diagnosis of SLI, 21 of whom were matched for chronological age to the SLI sample, and 21 of whom were matched for language age to the SLI sample. All children received a battery of nonspeech auditory processing tasks along with standardized measures of phonology and language. RESULTS: As many as 70%-80% of children diagnosed with SLI were found to perform below the 5th percentile of age-matched controls in auditory processing tasks measuring sensitivity to amplitude envelope rise time and sound duration. Furthermore, individual differences in sensitivity to these cues predicted unique variance in language and literacy attainment, even when age, nonverbal IQ, and task-related (attentional) factors were controlled. CONCLUSION: Many children with SLI have auditory processing difficulties, but for most children, these are not specific to brief, rapidly successive acoustic cues. Instead, sensitivity to durational and amplitude envelope cues appear to predict language and literacy outcomes more strongly. This finding now requires replication and exploration in languages other than English.