Douglas I. Katz

The minimally conscious state: Definition and diagnostic criteria

ObjectiveTo establish consensus recommendations among health care specialties for defining and establishing diagnostic criteria for the minimally conscious state (MCS). BackgroundThere is a subgroup of patients with severe alteration in consciousness who do not meet diagnostic criteria for coma or the vegetative state (VS). These patients demonstrate inconsistent but discernible evidence of consciousness. It is important to distinguish patients in MCS from those in coma and VS because preliminary findings suggest that there are meaningful differences in outcome. MethodsAn evidence-based literature review of disorders of consciousness was completed to define MCS, develop diagnostic criteria for entry into MCS, and identify markers for emergence to higher levels of cognitive function. ResultsThere were insufficient data to establish evidence-based guidelines for diagnosis, prognosis, and management of MCS. Therefore, a consensus-based case definition with behaviorally referenced diagnostic criteria was formulated to facilitate future empirical investigation. ConclusionsMCS is characterized by inconsistent but clearly discernible behavioral evidence of consciousness and can be distinguished from coma and VS by documenting the presence of specific behavioral features not found in either of these conditions. Patients may evolve to MCS from coma or VS after acute brain injury. MCS may also result from degenerative or congenital nervous system disorders. This condition is often transient but may also exist as a permanent outcome. Defining MCS should promote further research on its epidemiology, neuropathology, natural history, and management.

Update of neuropathology and neurological recovery after traumatic brain injury.

This review focuses on the potential for traumatic brain injury to evoke both focal and diffuse changes within the brain parenchyma, while considering the cellular constituents involved and the subcellular perturbations that contribute to their dysfunction. New insight is provided on the pathobiology of traumatically induced cell body injury and diffuse axonal damage. The consequences of axonal damage in terms of subsequent deafferentation and any potential retrograde cell death and atrophy are addressed. The regional and global metabolic sequelae are also considered. This detailed presentation of the neuropathological consequences of traumatic brain injury is used to set the stage for better appreciating the neurological recovery occurring after traumatic injury. Although the pathological and clinical effects of focal and diffuse damage are usually intermingled, the different clinical manifestations of recovery patterns associated with focal versus diffuse injuries are presented. The recognizable patterns of recovery, involving unconsciousness, posttraumatic confusion/amnesia, and postconfusional restoration, that typically occur across the full spectrum of diffuse injury are described, recognizing that the patients long-term recovery may involve more idiosyncratic combinations of dysfunction. The review highlights the relationship of focal lesions to localizing syndromes that may be embedded in the evolving natural history of diffuse pathology. It is noted that injuries with primarily focal pathology do not necessarily follow a comparable pattern of recovery with distinct phases. Potential linkages of these recovery patterns to the known neuropathological sequelae of injury and various reparative mechanisms are considered and it is proposed that potential biological markers and newer imaging technologies will better define these linkages.

Stroop performance in focal lesion patients: dissociation of processes and frontal lobe lesion location

There were three primary objectives: to examine the usefulness of the Stroop interference effect as a measure of frontal lobe function; to investigate the possibility of distinct lesion effects for word reading or color naming; and to specifically determine the brain regions necessary for the performance of the incongruent condition. Fifty-one patients with single focal brain lesions in frontal and non-frontal regions and 26 normal control subjects (CTL) were administered the word reading, color naming and incongruent conditions of the Stroop task. Only frontal lesions produced significant impairment. Patients with posterior lesions were not significantly deficient in any condition. Damage to the left dorsolateral frontal lobe resulted in increased errors and slowness in response speed for color naming. Contrary to Perret (Neuropsychology, 1974; 12: 323-330), lesions of the left frontal lobe did not result in a selective interference deficit on the Stroop incongruent condition. Rather, bilateral superior medial frontal damage was associated with increased errors and slowness in response time for the incongruent condition. This result is interpreted as failure of maintenance of consistent activation of the intended response in the incongruent Stroop condition. The results and conclusion are compatible with the prevalent theories of both the Stroop effect and the role of the superior medial frontal regions. The role of the anterior cingulate cortex on performance of the Stroop task is likely related to task and patient context.

The trail making test : a study in focal lesion patients

The relationship of the Trail Making Test (TMT) to the frontal lobes was tested by comparing patients with damage to the frontal and nonfrontal regions to control participants. Although the analysis of time measurements, both raw and transformed, showed notable slowing of frontal groups, error analysis proved to be a more useful method of categorizing performance. Analysis of errors on Part B indicated that all patients who made more than 1 error had frontal lesions. Dividing the frontal damaged patients into subgroups on the basis of the number of errors yielded specificity of brain-behavior relations within the frontal lobes. Patients with damage in dorsolateral frontal areas were most impaired. Those with inferior medial damage to the frontal lobes were not significantly affected in TMT Part B performance.

Assessment Scales for Disorders of Consciousness: Evidence-Based Recommendations for Clinical Practice and Research

OBJECTIVES To conduct a systematic review of behavioral assessment scales for disorders of consciousness (DOC); provide evidence-based recommendations for clinical use based on their content validity, reliability, diagnostic validity, and ability to predict functional outcomes; and provide research recommendations on DOC scale development and validation. DATA SOURCES Articles published through March 31, 2009, using MEDLINE, CINAHL, Psychology and Behavioral Sciences Collection, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Cochrane Central Register of Controlled Trials, Biomedical Reference Collection, and PsycINFO. Thirteen primary terms that defined DOC were paired with 30 secondary terms that defined aspects of measurement. Scale names, abbreviations, and authors were also used as search terms. Task force members identified additional articles by using personal knowledge and examination of references in reviewed articles. STUDY SELECTION Primary criteria included the following: (1) provided reliability, diagnostic validity, and/or prognostic validity data; (2) examined a cohort, case control, or case series sample of persons with DOC who were age older than or equal to 18 years; and (3) assessed in an acute care or rehabilitation setting. Articles were excluded if peer review was not conducted, original data were not reported, or an English language article was not available. The initial search yielded 580 articles. After paired rater review of study abstracts, guideline development was based on 37 articles representing 13 DOC scales. DATA EXTRACTION Rater pairs classified studies addressing diagnostic and prognostic validity by using the American Academy of Neurology 4-tier level of evidence scheme, and reliability by using a task force-developed 3-tier evidence scheme. An independent quality review of ratings was conducted, and corrections were made. DATA SYNTHESIS The Coma Recovery Scale-Revised (CRS-R), Sensory Stimulation Assessment Measure (SSAM), Wessex Head Injury Matrix (WHIM), Western Neuro Sensory Stimulation Profile (WNSSP), Sensory Modality Assessment Technique (SMART), Disorders of Consciousness Scale (DOCS), and Coma/Near-Coma Scale (CNC) have acceptable standardized administration and scoring procedures. The CRS-R has excellent content validity and is the only scale to address all Aspen Workgroup criteria. The SMART, SSAM, WHIM, and WNSSP demonstrate good content validity, containing items that could distinguish persons who are in a vegetative state, are in a minimally conscious state (MCS), or have emerged from MCS. The Full Outline of UnResponsiveness Score (FOUR), WNSSP, CRS-R, Comprehensive Levels of Consciousness Scale (CLOCS), and Innsbruck Coma Scale (INNS) showed substantial evidence of internal consistency. The FOUR and the CRS-R showed substantial evidence of good interrater reliability. Evidence of diagnostic validity and prognostic validity in brain injury survivor samples had very high levels of potential bias because of methodologic issues such as lack of rater masking. CONCLUSIONS The CRS-R may be used to assess DOC with minor reservations, and the SMART, WNSSP, SSAM, WHIM, and DOCS may be used to assess DOC with moderate reservations. The CNC may be used to assess DOC with major reservations. The FOUR, INNS, Glasgow-Liege Coma Scale, Swedish Reaction Level Scale-1985, Loewenstein Communication Scale, and CLOCS are not recommended at this time for bedside behavioral assessment of DOC because of a lack of content validity, lack of standardization, and/or unproven reliability.

Multiple frontal systems controlling response speed

This study evaluated a model of attention that postulates several distinct component processes, each mediated by specific neural systems in the human frontal lobes. A series of reaction time (RT) tests (simple, choice, and prepare) examined the hypothesis that different attentional processes are related to distinct regions within the frontal lobes. These tests were given to 38 patients with frontal lesions and 38 age-matched control subjects. Lesions were localized both by general regions (superior medial, inferior medial, left and right lateral) and by individual architectonic areas. Lesions in the superior medial (SM) frontal lobes, particularly involving areas 24 and 32 on the right, were associated with slow RT in all tests and with failure to decrease RT after a warning signal. Lesions in the right lateral (RL) frontal lobe, centred in area 9/46v, prevented the decrease in RT with increasing foreperiod that was seen in normal subjects and in patients with lesions elsewhere in the frontal lobes. The ability to energize a response for rapid RT, either generally or specifically following a warning stimulus, is sensitive to lesions of the right SM. Monitoring of stimulus occurrence and response behaviour in order to enhance the speed of response to upcoming stimuli is sensitive to RL lesions.

Dissociations between behavioural and functional magnetic resonance imaging-based evaluations of cognitive function after brain injury

Functional neuroimaging methods hold promise for the identification of cognitive function and communication capacity in some severely brain-injured patients who may not retain sufficient motor function to demonstrate their abilities. We studied seven severely brain-injured patients and a control group of 14 subjects using a novel hierarchical functional magnetic resonance imaging assessment utilizing mental imagery responses. Whereas the control group showed consistent and accurate (for communication) blood-oxygen-level-dependent responses without exception, the brain-injured subjects showed a wide variation in the correlation of blood-oxygen-level-dependent responses and overt behavioural responses. Specifically, the brain-injured subjects dissociated bedside and functional magnetic resonance imaging-based command following and communication capabilities. These observations reveal significant challenges in developing validated functional magnetic resonance imaging-based methods for clinical use and raise interesting questions about underlying brain function assayed using these methods in brain-injured subjects.

Natural history of recovery from brain injury after prolonged disorders of consciousness: outcome of patients admitted to inpatient rehabilitation with 1-4 year follow-up

UNLABELLED The natural history of recovery from brain injury typically consists of a period of impaired consciousness, a subsequent period of confusion and amnesia, followed by a period of post-confusional recovery of function. Patients with more severe injuries may have more prolonged episodes of unconsciousness or minimal consciousness and may not fully evolve through this continuum of recovery. There is limited information on the course of recovery and long-term outcome of patients with prolonged unconsciousness, particularly those with extended periods in the minimally conscious state. Further, patients with impaired consciousness are frequently denied access to hospital-based rehabilitation services because of uncertain prognosis and a perceived lack of benefit from rehabilitative interventions. METHODS A consecutive series of 36 patients with traumatic (TBI) and non-traumatic brain injury (nonTBI) in a vegetative state (VS) or minimally conscious state (MCS) on admission to a specialized, slow-to-recover brain injury program in an acute rehabilitation hospital was retrospectively reviewed to evaluate course of recovery during rehabilitation hospitalization and in follow-up, 1-4 years post-injury. Independent variables included: time to resolution of VS, MCS and confusional state/posttraumatic amnesia (CS/PTA), based on Aspen criteria, Coma Recovery Scale-Revised (CRS-R) and Galveston Orientation and Amnesia Test (GOAT) scores. Outcome measures (calculated separately for TBI, nonTBI, VS, or MCS on admission subgroups) included: proportion of patients who recover and recovery time to MCS, CS/PTA stages, household independence, and return to school or work, as well as Disability Rating Scale (DRS) scores at 1, 2, 3, and 4 years post-injury. RESULTS The majority emerged from MCS (72%) and CS/PTA (58%) by latest follow-up. It took significantly longer for patients admitted in VS (means: MCS, 16.43 weeks; CS/PTA, 30.1 weeks) than MCS (means: MCS, 7.36 weeks; CS/PTA, 11.5 weeks) to reach both milestones. Almost all who failed to clear CS/PTA by latest follow-up were patients with nonTBI or TBI with VS lasting over 8 weeks. Duration of MCS was a strong predictor of duration CS/PTA after emergence from MCS, accounting for 57% of the variance. Nearly half the patients followed at least 1 year achieved recovery to, at least, daytime independence at home and 22% returned to work or school, 17% at or near pre-injury levels. Discharge FIM score or duration of MCS, along with age, were best predictors of DRS in outcome models. DRS scores continued to improve after 2 and 3 years post-injury. CONCLUSIONS Patients in VS whose transition to MCS occurred within 8 weeks of onset are likely to continue recovering to higher levels of functioning, a substantial proportion to household independence, and productive pursuits. Patients with TBI are more likely to progress than patients with nonTBI, though significant improvement in the nonTBI group is still possible. Active, higher intensity, rehabilitation should be strongly considered for patients with severely impaired consciousness after brain injury, especially for patients with TBI who have signs of progression to the MCS.

Development of Practice Guidelines for Assessment and Management of the Vegetative and Minimally Conscious States

The Aspen Neurobehnvioml Conference was convened as a venue to consider interactions of mind and brain with regard to health and disease. The primary purpose of the conference was to provide a forum for discussion and scientific collaboration, particularly in areas marked by uncertainty and controversy, with eventual dissemination of conclusions. One of the selected topics for the inaugural session of the conference concerned the development of guidelines for evaluation and management of the vegetative and minimally conscious states. The purpose of this article is to acquaint neurorehabilitation specialists with the unique approach to consensus-based guideline development utilized at the Aspen Conference and to summarize the proceedings of the Aspen Workgroup on the Vegetative and Minimally Conscious States conducted since 1994

Botulinum toxin a in the treatment of spasticity: Functional implications and patient selection☆

OBJECTIVE To explore the range of functional indications and benefit of botulinum toxin A (BTA) in spastic patients. DESIGN Case report of a series of patients selected for BTA treatment. Clinical information was collected in a prospective fashion on each patient. SETTING Freestanding acute rehabilitation hospital. PATIENTS 39 consecutive patients with 40 limbs with acquired spasticity. INTERVENTION All 39 patients received BTA injections into muscles targeted for treatment based on functional indications. MAIN OUTCOME MEASURES Objective evaluation of outcome was measured by Ashworth Scale, goniometry, ambulation score, and brace wear scale. Subjective measures included patient self report of improvement and pain relief. RESULTS Mean BTA dose per limb was 180 units, mean number of muscles injected per limb was 2. Twenty-nine patients had subjective and/or objective improvement with treatment. Mean Ashworth Scale improvement was one point. Mean gain in active range of motion (AROM) was 17.0 degrees, and in passive range of motion (PROM) 18.4 degrees. Brace tolerance improved in 14 of 22 patients and pain relief occurred in 10 of 13 patients. There were no adverse effects, and there was no difference in duration of effect compared to dystonia patients. CONCLUSION BTA is a useful intervention in the treatment of spasticity, with the majority of patients demonstrating improvement on objective measures of tone and function, and reporting improvement on subjective measures. Careful patient selection will maximize functional benefit.