Effect of sedation with dexmedetomidine vs lorazepam on acute brain dysfunction in mechanically ventilated patients: the MENDS randomized controlled trial

CONTEXT

Lorazepam is currently recommended for sustained sedation of mechanically ventilated intensive care unit (ICU) patients, but this and other benzodiazepine drugs may contribute to acute brain dysfunction, ie, delirium and coma, associated with prolonged hospital stays, costs, and increased mortality. Dexmedetomidine induces sedation via different central nervous system receptors than the benzodiazepine drugs and may lower the risk of acute brain dysfunction.

OBJECTIVE

To determine whether dexmedetomidine reduces the duration of delirium and coma in mechanically ventilated ICU patients while providing adequate sedation as compared with lorazepam.

DESIGN, SETTING, PATIENTS, AND INTERVENTION

Double-blind, randomized controlled trial of 106 adult mechanically ventilated medical and surgical ICU patients at 2 tertiary care centers between August 2004 and April 2006. Patients were sedated with dexmedetomidine or lorazepam for as many as 120 hours. Study drugs were titrated to achieve the desired level of sedation, measured using the Richmond Agitation-Sedation Scale (RASS). Patients were monitored twice daily for delirium using the Confusion Assessment Method for the ICU (CAM-ICU).

MAIN OUTCOME MEASURES

Days alive without delirium or coma and percentage of days spent within 1 RASS point of the sedation goal.

RESULTS

Sedation with dexmedetomidine resulted in more days alive without delirium or coma (median days, 7.0 vs 3.0; P = .01) and a lower prevalence of coma (63% vs 92%; P < .001) than sedation with lorazepam. Patients sedated with dexmedetomidine spent more time within 1 RASS point of their sedation goal compared with patients sedated with lorazepam (median percentage of days, 80% vs 67%; P = .04). The 28-day mortality in the dexmedetomidine group was 17% vs 27% in the lorazepam group (P = .18) and cost of care was similar between groups. More patients in the dexmedetomidine group (42% vs 31%; P = .61) were able to complete post-ICU neuropsychological testing, with similar scores in the tests evaluating global cognitive, motor speed, and attention functions. The 12-month time to death was 363 days in the dexmedetomidine group vs 188 days in the lorazepam group (P = .48).

CONCLUSION

In mechanically ventilated ICU patients managed with individualized targeted sedation, use of a dexmedetomidine infusion resulted in more days alive without delirium or coma and more time at the targeted level of sedation than with a lorazepam infusion.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00095251.

Medical aspects of the persistent vegetative state (1)

This consensus statement of the Multi-Society Task Force summarizes current knowledge of the medical aspects of the persistent vegetative state in adults and children. The vegetative state is a clinical condition of complete unawareness of the self and the environment, accompanied by sleep-wake cycles, with either complete or partial preservation of hypothalamic and brain-stem autonomic functions. In addition, patients in a vegetative state show no evidence of sustained, reproducible, purposeful, or voluntary behavioral responses to visual, auditory, tactile, or noxious stimuli; show no evidence of language comprehension or expression; have bowel and bladder incontinence; and have variably preserved cranial-nerve and spinal reflexes. We define persistent vegetative state as a vegetative state present one month after acute traumatic or nontraumatic brain injury or lasting for at least one month in patients with degenerative or metabolic disorders or developmental malformations. The clinical course and outcome of a persistent vegetative state depend on its cause. Three categories of disorder can cause such a state: acute traumatic and non-traumatic brain injuries; degenerative and metabolic brain disorders, and severe congenital malformations of the nervous system. Recovery of consciousness from a posttraumatic persistent vegetative state is unlikely after 12 months in adults and children. Recovery from a nontraumatic persistent vegetative state after three months is exceedingly rare in both adults and children. Patients with degenerative or metabolic disorders or congenital malformations who remain in a persistent vegetative state for several months are unlikely to recover consciousness. The life span of adults and children in such a state is substantially reduced. For most such patients, life expectancy ranges from 2 to 5 years; survival beyond 10 years is unusual.

Validation of a new coma scale: The FOUR score

The Glasgow Coma Scale (GCS) has been widely adopted. Failure to assess the verbal score in intubated patients and the inability to test brainstem reflexes are shortcomings. We devised a new coma score, the FOUR (Full Outline of UnResponsiveness) score. It consists of four components (eye, motor, brainstem, and respiration), and each component has a maximal score of 4. We prospectively studied the FOUR score in 120 intensive care unit patients and compared it with the GCS score using neuroscience nurses, neurology residents, and neurointensivists. We found that the interrater reliability was excellent with the FOUR score (kappa(w) = 0.82) and good to excellent for physician rater pairs. The agreement among raters was similar with the GCS (kappa(w) = 0.82). Patients with the lowest GCS score could be further distinguished using the FOUR score. We conclude that the agreement among raters was good to excellent. The FOUR score provides greater neurological detail than the GCS, recognizes a locked-in syndrome, and is superior to the GCS due to the availability of brainstem reflexes, breathing patterns, and the ability to recognize different stages of herniation. The probability of in-hospital mortality was higher for the lowest total FOUR score when compared with the lowest total GCS score.

Assessment and prognosis of coma after head injury

The Glasgow Coma Scale, based upon eye opening, verbal and motor responses has proved a practical and consistent means of monitoring the state of head injured patients. Observations made in the early stages after injury define the depth and duration of coma and, when combined with clinical features such as a patient's age and brain stem function, have been used to predict outcome. Series of cases in comparable depths of coma in Glasgow and the Netherlands showed remarkably similar outcomes at 3 months. Based upon observations made in the first 24 hours of coma after injury, data from 255 previous cases reliably predicted outcome in the majority of 92 new patients. The exceptions were patients with potential to recover who later developed complications: no patient did significantly better than predicted.

Auditory brain stem responses in neurological disease

A sequence of seven low-amplitude (nanovolt) potentials that occur in the initial 10 msec following click signals can be recorded from scalp electrodes in human subjects using computer averaging techniques. The potentials, termed auditory brain stem responses, are thought to be the far-field reflection of electrical events originating in the auditory pathway during its course through the brain stem. We have studied auditory brain stem responses in a variety of neurological disorders and found them to be of assistance in evaluating the mechanisms of coma, the localization of midbrain and brain stem tumors, the localization of demyelination of the brain stem, and tumors, the localization of demyelination of the brain stem, and the presence of diminished brain stem circulation.

Prevalence of nonconvulsive status epilepticus in comatose patients

BACKGROUND

Nonconvulsive status epilepticus (NCSE) is a form of status epilepticus (SE) that is an often unrecognized cause of coma.

OBJECTIVE

To evaluate the presence of NCSE in comatose patients with no clinical signs of seizure activity.

METHODS

A total of 236 patients with coma and no overt clinical seizure activity were monitored with EEG as part of their coma evaluation. This study was conducted during our prospective evaluation of SE, where it has been validated that we identify over 95% of all SE cases at the Medical College of Virginia Hospitals. Only cases that were found to have no clinical signs of SE were included in this study.

RESULTS

EEG demonstrated that 8% of these patients met the criteria for the diagnosis of NCSE. The study included an age range from 1 month to 87 years.

CONCLUSION

This large-scale EEG evaluation of comatose patients without clinical signs of seizure activity found that NCSE is an underrecognized cause of coma, occurring in 8% of all comatose patients without signs of seizure activity. EEG should be included in the routine evaluation of comatose patients even if clinical seizure activity is not apparent.

Bedside detection of awareness in the vegetative state: a cohort study

BACKGROUND

Patients diagnosed as vegetative have periods of wakefulness, but seem to be unaware of themselves or their environment. Although functional MRI (fMRI) studies have shown that some of these patients are consciously aware, issues of expense and accessibility preclude the use of fMRI assessment in most of these individuals. We aimed to assess bedside detection of awareness with an electroencephalography (EEG) technique in patients in the vegetative state.

METHODS

This study was undertaken at two European centres. We recruited patients with traumatic brain injury and non-traumatic brain injury who met the Coma Recovery Scale-Revised definition of vegetative state. We developed a novel EEG task involving motor imagery to detect command-following--a universally accepted clinical indicator of awareness--in the absence of overt behaviour. Patients completed the task in which they were required to imagine movements of their right-hand and toes to command. We analysed the command-specific EEG responses of each patient for robust evidence of appropriate, consistent, and statistically reliable markers of motor imagery, similar to those noted in healthy, conscious controls.

FINDINGS

We assessed 16 patients diagnosed in the vegetative state, and 12 healthy controls. Three (19%) of 16 patients could repeatedly and reliably generate appropriate EEG responses to two distinct commands, despite being behaviourally entirely unresponsive (classification accuracy 61-78%). We noted no significant relation between patients' clinical histories (age, time since injury, cause, and behavioural score) and their ability to follow commands. When separated according to cause, two (20%) of the five traumatic and one (9%) of the 11 non-traumatic patients were able to successfully complete this task.

INTERPRETATION

Despite rigorous clinical assessment, many patients in the vegetative state are misdiagnosed. The EEG method that we developed is cheap, portable, widely available, and objective. It could allow the widespread use of this bedside technique for the rediagnosis of patients who behaviourally seem to be entirely vegetative, but who might have residual cognitive function and conscious awareness.

FUNDING

Medical Research Council, James S McDonnell Foundation, Canada Excellence Research Chairs Program, European Commission, Fonds de la Recherche Scientifique, Mind Science Foundation, Belgian French-Speaking Community Concerted Research Action, University Hospital of Liège, University of Liège.

Prediction of poor outcome within the first 3 days of postanoxic coma

OBJECTIVE

To determine the optimal timing of somatosensory evoked potential (SSEP) recordings and the additional value of clinical and biochemical variables for the prediction of poor outcome in patients who remain comatose after cardiopulmonary resuscitation (CPR).

METHODS

A prospective cohort study was conducted in 32 intensive care units including adult patients still unconscious 24 hours after CPR. Clinical, neurophysiologic, and biochemical variables were recorded 24, 48, and 72 hours after CPR and related to death or persisting unconsciousness after 1 month.

RESULTS

Of 407 included patients, 356 (87%) had a poor outcome. In 301 of 305 patients unconscious at 72 hours, at least one SSEP was recorded, and in 136 (45%), at least one recording showed bilateral absence of N20. All these patients had a poor outcome (95% CI of false positive rate 0 to 3%), irrespective of the timing of SSEP. In the same 305 patients, neuron-specific enolase (NSE) was determined at least once in 231, and all 138 (60%) with a value >33 microg/L at any time had a poor outcome (95% CI of false positive rate 0 to 3%). The test results of SSEP and NSE overlapped only partially. The performance of all clinical tests was inferior to SSEP and NSE testing, with lower prevalences of abnormal test results and wider 95% CI of false positive rates.

CONCLUSION

Poor outcome in postanoxic coma can be reliably predicted with somatosensory evoked potentials and neuron-specific enolase as early as 24 hours after cardiopulmonary resuscitation in a substantial number of patients.

Accuracy of diagnosis of persistent vegetative state

We reviewed pre-admission diagnosis in all patients referred for inpatient brain injury neurorehabilitation over a 5-year period (n = 193). All patients more than 1 month postinjury with diagnosis of coma or persistent vegetative state were selected for review (n = 49). We found that 18 (37%) of these patients were diagnosed inaccurately. Inaccurate diagnosis was more likely if the injury was more than 3 months before admission and the etiology of injury was trauma (48%). Results were statistically significant when traumatic injuries were compared with anoxic injuries (p < 0.10). Errors in diagnosis may result from confusion in terminology, lack of extended observation of patients, and lack of skill or training in the assessment of neurologically devastated patients.

Determination of Brain Death/Death by Neurologic Criteria: The World Brain Death Project

IMPORTANCE

There are inconsistencies in concept, criteria, practice, and documentation of brain death/death by neurologic criteria (BD/DNC) both internationally and within countries.

OBJECTIVE

To formulate a consensus statement of recommendations on determination of BD/DNC based on review of the literature and expert opinion of a large multidisciplinary, international panel.

PROCESS

Relevant international professional societies were recruited to develop recommendations regarding determination of BD/DNC. Literature searches of the Cochrane, Embase, and MEDLINE databases included January 1, 1992, through April 2020 identified pertinent articles for review. Because of the lack of high-quality data from randomized clinical trials or large observational studies, recommendations were formulated based on consensus of contributors and medical societies that represented relevant disciplines, including critical care, neurology, and neurosurgery.

EVIDENCE SYNTHESIS

Based on review of the literature and consensus from a large multidisciplinary, international panel, minimum clinical criteria needed to determine BD/DNC in various circumstances were developed.

RECOMMENDATIONS

Prior to evaluating a patient for BD/DNC, the patient should have an established neurologic diagnosis that can lead to the complete and irreversible loss of all brain function, and conditions that may confound the clinical examination and diseases that may mimic BD/DNC should be excluded. Determination of BD/DNC can be done with a clinical examination that demonstrates coma, brainstem areflexia, and apnea. This is seen when (1) there is no evidence of arousal or awareness to maximal external stimulation, including noxious visual, auditory, and tactile stimulation; (2) pupils are fixed in a midsize or dilated position and are nonreactive to light; (3) corneal, oculocephalic, and oculovestibular reflexes are absent; (4) there is no facial movement to noxious stimulation; (5) the gag reflex is absent to bilateral posterior pharyngeal stimulation; (6) the cough reflex is absent to deep tracheal suctioning; (7) there is no brain-mediated motor response to noxious stimulation of the limbs; and (8) spontaneous respirations are not observed when apnea test targets reach pH <7.30 and Paco2 ≥60 mm Hg. If the clinical examination cannot be completed, ancillary testing may be considered with blood flow studies or electrophysiologic testing. Special consideration is needed for children, for persons receiving extracorporeal membrane oxygenation, and for those receiving therapeutic hypothermia, as well as for factors such as religious, societal, and cultural perspectives; legal requirements; and resource availability.

CONCLUSIONS AND RELEVANCE

This report provides recommendations for the minimum clinical standards for determination of brain death/death by neurologic criteria in adults and children with clear guidance for various clinical circumstances. The recommendations have widespread international society endorsement and can serve to guide professional societies and countries in the revision or development of protocols and procedures for determination of brain death/death by neurologic criteria, leading to greater consistency within and between countries.

Outcome following severe head injuries in children

The outcome in 53 children following severe head injury is presented. All children were graded using the Glasgow Coma Scale; 90% made a good recovery or were moderately disabled, and 8% died or were left vegetative. All patients were treated with controlled ventilation and steroids; mannitol, and, if necessary, Nembutal (pentobarbital) were used to maintain the intracranial pressure below 20 torr. With this regimen, only one death occurred due to uncontrollable intracranial hypertension. All patients with a coma scale of 5 or greater recovered well. The worst prognostic sign was the presence of flaccidity: 33% of these patients died or were vegetative. Five of seven patients who were decerebrate or flaccid with bilateral fixed pupils and absent caloric responses made a good recovery or were moderately disabled. The relatively low incidence of mass lesions (23%) and high incidence of diffuse cerebral swelling (34%) suggest a different pathophysiological response of the child's brain to injury, which may play a role in the improved survival of children following severe head injury when compared to adults.

Aspects of coma after severe head injury

Features of coma during the first week after sever head injury were analysed in 700 patients. Coma is best defined as inability to obey commands, to speak, or to open the eyes. If eye opening is omitted from the definition then some less severly affected patients will be included in the early stages, the duration of coma will be overestimated, and in the later stages the distiction between coma and other unresponsive states may be blurred. Other features which correlate with responsiveness (as judged by motor response, speech, and eye opening) are pupil reactions and eye movements; respiratory abnormalities are less common and less closely related to other aspects of severity. A rigorous fefinition of coma is necessary for valid commparisons between individual patients and between different series of patients with head injury. This is essential for the assessment of alternative management regimens and for establishing predictive criteria.

Sedation confounds outcome prediction in cardiac arrest survivors treated with hypothermia

BACKGROUND

Therapeutic hypothermia is commonly used in comatose survivors' post-cardiopulmonary resuscitation (CPR). It is unknown whether outcome predictors perform accurately after hypothermia treatment.

METHODS

Post-CPR comatose survivors were prospectively enrolled. Six outcome predictors [pupillary and corneal reflexes, motor response to pain, and somatosensory-evoked potentials (SSEP) >72 h; status myoclonus, and serum neuron-specific enolase (NSE) levels <72 h] were systematically recorded. Poor outcome was defined as death or vegetative state at 3 months. Patients were considered "sedated" if they received any sedative drugs ≤ 12 h prior the 72 h neurological assessment.

RESULTS

Of 85 prospectively enrolled patients, 53 (62%) underwent hypothermia. Furthermore, 53 of the 85 patients (62%) had a poor outcome. Baseline characteristics did not differ between the hypothermia and normothermia groups. Sedative drugs at 72 h were used in 62 (73%) patients overall, and more frequently in hypothermia than in normothermia patients: 83 versus 60% (P = 0.02). Status myoclonus <72 h, absent cortical responses by SSEPs >72 h, and absent pupillary reflexes >72 h predicted poor outcome with a 100% specificity both in hypothermia and normothermia patients. In contrast, absent corneal reflexes >72 h, motor response extensor or absent >72 h, and peak NSE >33 ng/ml <72 h predicted poor outcome with 100% specificity only in non-sedated patients, irrespective of prior treatment with hypothermia.

CONCLUSIONS

Sedative medications are commonly used in proximity of the 72-h neurological examination in comatose CPR survivors and are an important prognostication confounder. Patients treated with hypothermia are more likely to receive sedation than those who are not treated with hypothermia.

Brainstem auditory and short-latency somatosensory evoked responses in brain death

Thirty-five patients who met all clinical criteria for brain death and 53 patients who did not were tested with brainstem auditory (BAER) and short-latency somatosensory (SER) evoked responses. Of the brain-dead patients, 77% had no waves present in the BAER, including wave I, whereas 69% had medullary components present in the SER. These data suggest that the SER has greater clinical utility in the brain-death setting, because it is important to have a wave present that established that the input signal has reached the central nervous system. No brain-dead patients had subsequent waves in either test. These results are correlated with neuropathologic findings and contrasted with data obtained in the comatose but not brain-dead patients.

The EEG in coma

The EEG allows insight into thalamocortical function in comatose patients when this is inaccessible clinically. A single EEG can help with broad diagnostic categorization whereas continuous or serial EEG provides monitoring for unstable and potentially treatable conditions and for monitoring the effects of therapy. The EEG plays a supplemental role in establishing the prognosis in disease states that are capable of causing neuronal death. The most prevalent and problematic of these conditions involves survivors of cardiac arrest who are initially in coma with intact brainstem reflexes. In such patients single EEGs are of 100% specificity for no possibility of recovery of consciousness only for essentially complete generalized suppression (<10 microV) after the first day of the arrest. Several other generalized patterns, including less marked suppression, burst-suppression, epileptiform activity, periodic complexes, and alpha-theta coma patterns, usually but not invariably indicate a poor outcome. Serial EEGs, continuous raw and automated "trending," testing of reactivity, and the inclusion of multiple variables hold promise for an improved role in the prognostic determination in these patients.

The JFK Coma Recovery Scale--Revised

The JFK Coma Recovery Scale (CRS) was developed to help characterise and monitor patients functioning at Rancho Levels I-IV and has been used widely in both clinical and research settings within the US and Europe. The CRS was recently revised to address a number of concerns emanating from our own clinical experience with the scale, feedback from users and researchers as well as the results of Rasch analyses. Additionally, the CRS did not include all of the behavioural criteria necessary to diagnose the minimally conscious state (MCS), thereby limiting diagnostic utility. The revised JFK Coma Recovery Scale (CRS-R) includes addition of new items, merging of items found to be statistically similar, deletion or modification of items showing poor fit with the scale's underlying construct, renaming of items, more stringent scoring criteria, and quantification of elicited behaviours to improve accuracy of rating. Psychometric properties of the CRS-R appear to meet standards for measurement and evaluation tools for use in clinical and research settings, and diagnostic application suggests that the scale is capable of discriminating patients in the minimally conscious state from those in the vegetative state.

Chronic disorders of consciousness

The vegetative state and the minimally conscious state are disorders of consciousness that can be acute and reversible or chronic and irreversible. Diffuse lesions of the thalami, cortical neurons, or the white-matter tracts that connect them cause the vegetative state, which is wakefulness without awareness. Functional imaging with PET and functional MRI shows activation of primary cortical areas with stimulation, but not of secondary areas or distributed neural networks that would indicate awareness. Vegetative state has a poor prognosis for recovery of awareness when present for more than a year in traumatic cases and for 3 months in non-traumatic cases. Patients in minimally conscious state are poorly responsive to stimuli, but show intermittent awareness behaviours. Indeed, findings of preliminary functional imaging studies suggest that some patients could have substantially intact awareness. The outcomes of minimally conscious state are variable. Stimulation treatments have been disappointing in vegetative state but occasionally improve minimally conscious state. Treatment decisions for patients in vegetative state or minimally conscious state should follow established ethical and legal principles and accepted practice guidelines of professional medical specialty societies.

Recommendations for use of uniform nomenclature pertinent to patients with severe alterations in consciousness. American Congress of Rehabilitation Medicine

There continues to be considerable confusion and controversy on the use of diagnostic and clinical terms assigned to patients with severe alterations in consciousness. This confusion results largely from the lack of a uniform classification system that is based on behaviorally defined criteria. This position paper provides recommendations for defining coma, vegetative state (including persistent and permanent vegetative state), akinetic mutism, the minimally responsive state, and locked-in syndrome based on neurobehavioral and neuropathologic features. Current controversies surrounding use of these terms also are discussed.

Observer variability in assessing impaired consciousness and coma

Head-injured patients were examined by a number of observers whose assessments were compared. Considerable discrepancies occurred when overall "levels" of consciousness and coma were used, and also with some terms which are in common use. More consistent assessments were obtained by employing the "Glasgow Coma Scale," which describes eye opening, verbal behaviour, and motor responsiveness. Nurses and general surgeons were as consistent as neurosurgeons when using this scale, and it was relatively resistant to language or cultural differences between observers. The practical reliability of the Glasgow scale enhances its value, both for monitoring individual cases and for making meaningful comparisons between series of patients with acute brain damage.

Prognostic value of myoclonus status in comatose survivors of cardiac arrest

Generalized myoclonus status is common in comatose patients after cardiac resuscitation, but its prognostic value is uncertain. We studied the clinical, radiologic, and pathologic findings in 107 consecutive patients who remained comatose after cardiac resuscitation. Myoclonus status was present in 40 patients (37%). Features more prevalent in patients with myoclonus status were burst suppression on electroencephalograms, cerebral edema or cerebral infarcts on computed tomography scans, and acute ischemic neuronal change in all cortical laminae. All patients with myoclonus status died. Of 67 patients without myoclonus, 20 awakened. We conclude that myoclonus status in postanoxic coma should be considered an agonal phenomenon that indicates devastating neocortical damage. Its presence in comatose patients after cardiac arrest must strongly influence the decision to withdraw life support.

The Wessex Head Injury Matrix (WHIM) main scale: a preliminary report on a scale to assess and monitor patient recovery after severe head injury

OBJECTIVE

To develop a behavioural assessment based on observations of patients recovering after severe head injury whereby data could be collected by observation and by testing everyday tasks.

DESIGN

A prospective observational study of a cohort of 88 consecutive hospital admissions with severe head injury.

SETTING

Two district general hospitals in the UK.

PATIENTS

Eighty-eight consecutive admissions with severe traumatic head injury. Ages ranged from 14 to 67 years, mean coma duration was 14 days and mean duration of post traumatic amnesia (PTA) was 56 days.

RESULTS

Fifty-eight items of behaviour were identified. Paired preference analysis was used to identify a sequence of recovery of these behaviours. The sequence began with arousal and led on to behaviours signalling recovery of social interaction and communication. Subsequent behaviours indicated increasing cognitive organization and return of orientation and memory. The behaviours on the scale are hierarchical and range from coma to emergence from PTA.

CONCLUSIONS

A scale to assess patients and monitor cognitive recovery after severe head injury has been developed. While individual patients will show some departures from the sequence identified, the scale helps to make explicit the earliest stages of natural recovery patterns after head injury.

Chronic intrathecal baclofen administration for control of severe spasticity

Baclofen, the most effective drug for treating spasticity, is a specific agonist of gamma-aminobutyric acid-B receptors, and is very abundant in the superficial layers of the spinal cord. Given orally, baclofen does not easily penetrate the blood-brain barrier, and is distributed equally to the brain and spinal cord. Direct intrathecal administration was given in order to change the distribution of the drug by preferentially perfusing the spinal cord. Eighteen patients presenting a severe spastic syndrome were treated with chronic intrathecal infusion of baclofen in the lumbar cerebrospinal fluid. After clinical preselection, 38 patients were implanted with a lumbar access port allowing long-term trials in order to determine the efficacy of baclofen therapy and the effective 12-hour dose. The 18 patients selected for chronic administration were implanted with a programmable pump. The pathology in these cases was: multiple sclerosis (6 cases), posttrauma spastic syndrome (eight cases), and (one case each) cerebral palsy, ischemic cerebral lesion, spinal ischemia, and transverse myelitis. The mean follow-up period was 18 months (range 4 to 43 months). The clinical results were evaluated according to muscular hypertony on Ashworth's scale (changed for occurrence of painful spasms) and functional improvement. Results were better for spastic syndrome secondary to traumatic medullary lesion than for demyelinating disease. Hypertonia was improved in all cases as confirmed by the registration of the Hoffman (H) reflex. Painful muscular spasms disappeared in 14 of the 16 affected patients. Significant functional improvement was noted in nine patients and was considerable in three. The risk of side effects secondary to overdose (such as excessive hypotonia or central depression) and the absence of a specific baclofen antagonist stresses the necessity for accurate determination of the efficient dose. After an initial titration period and adjustment of the therapeutic dose, the individual doses were from 21 to 500 micrograms/24 hrs (mean 160 micrograms/24 hrs). This new conservative method is very effective, perfectly reversible, and safe when administered in conditions favorable to its use.

Specific changes in human brain after hypoglycemic injury

BACKGROUND AND PURPOSE

Very few reports are available on serial changes in the human brain after severe hypoglycemic injury. The aim of this study was to investigate sequential neuroradiological changes in brains of patients after hypoglycemic coma compared with those after cardiac arrest previously studied with the same methods.

METHODS

We repeatedly studied CT scans and MR images obtained at 1.5 T in four vegetative patients after profound hypoglycemia associated with diabetes mellitus.

RESULTS

In all patients, consecutive CT scans showed symmetrical, persistent low-density lesions with transient enhancement in the caudate and lenticular nuclei and transient enhancement in the cerebral cortex 7 to 14 days after onset. Serial MR images consistently revealed symmetrical lesions of persistent hyperintensity and hypointensity on T1- and T2-weighted images, respectively, in the caudate and lenticular nuclei, cerebral cortex, substantia nigra, and/or hippocampus from 8 days to 12 months after onset.

CONCLUSIONS

Repeated MR images revealed specific lesions in the bilateral basal ganglia, cerebral cortex, substantia nigra, and hippocampus, which suggests the particular vulnerability of these areas to hypoglycemia in the human brain. We speculate that the localized lesions represent tissue degeneration, including some combination of selective neuronal death, proliferation of astrocytic glial cells, paramagnetic substance deposition, and/or lipid accumulation. The absence of localized hemorrhages on MR images in hypoglycemic encephalopathy is in marked contrast to the presence of regional minor hemorrhages in postischemic-anoxic encephalopathy.