Subtle Neurological Signs Predict the Severity of Subacute Cognitive and Functional Impairments After Traumatic Brain Injury

Medical records of 83 patients consecutively admitted to an acute inpatient neurorehabilitation unit following traumatic brain injury were reviewed. Inclusion criteria for this study were: clinical diagnosis of TBI by American Congress of Rehabilitation Medicine definition 6 ; nonpenetrating TBI; age 20–89 years; English as the primary language; not aphasic; Behavioral Neurology & Neuropsychiatry consultation performed, including neurological and cognitive examinations required to address the study hypotheses; and medical records containing all relevant assessment and rehabilitation outcome measures. Among participants meeting these inclusion criteria, medical records data extraction included: subject age, gender and education; mechanism of injury; presence or absence of intracranial abnormality on computed tomography (CT) or MRI of the brain; whether or not the patient was in the period of posttraumatic amnesia as assessed by the Galveston Orientation and Amnesia Test (GOAT) 7 upon rehabilitation admission and also upon Behavioral Neurology & Neuropsychiatry consultation; neurological examination findings; MMSE, and FAB scores; FIM scores at time of rehabilitation admission, proximate (±3 days) to Behavioral Neurology & Neuropsychiatry consultation, and at rehabilitation hospital discharge; and acute hospital and rehabilitation hospital lengths of stay.

A subtle neurological signs score was constructed based on the neurological examination data recorded during the Behavioral Neurology & Neuropsychiatry consultations. The elements contributing to the subtle neurological signs score included paratonia ( mitgehen and/or gegenhalten ) and primitive reflexes. Mitgehen and gegenhalten reflect impairments of volitional motor inhibition during assessment of resistance to passive manipulation (hence the designation of “paratonia”). Mitgehen (from German, “go along” or “go with”) refers to a patient’s inability to inhibit active movement of the extremity under examination despite instructions to the patient to remain passive during the examiner’s movement of that extremity. Gegenhalten (from German, “hold against” or “go against”) describes purposeless resistance by the patient against movement of the extremity by the examiner (“pull-counter-pull” phenomenon). The primitive reflexes included in the subtle neurological signs score: glabellar response, snout response, grasp response (left and right), palmomental (left and right), suck reflex, and rooting response. The examination for these findings and interpretation of primitive reflexes were performed according to the methods described in Arciniegas and Beresford. 8 One point was allocated for each abnormal finding, and missing data points were scored as 0. The subtle neurological signs score was equal to [# of primitive reflexes] + [ mitgehen ] + [ gegenhalten ], with a range of 0–10 points.

The MMSE was administered as described by Folstein et al. 3 and the FAB was administered as described by Dubois et al. 4 To correct for the effects of age and education on MMSE and FAB scores, Z-transformations were performed using normative data for these measures. 9, 10

The FIM assessments were performed by physical therapy, occupational therapy, speech language pathology, and nursing staff assigned to the acute inpatient rehabilitation unit using the method described in the Guide for Uniform Data Set for Medical Rehabilitation, Version 5.1. 5

Statistica 8.0 (StatSoft, Inc., Tulsa, Okla.) was used for all descriptive data analyses as well as for regression analyses to test the study hypotheses. Simple regression modeling was used to investigate the proportion of variance in MMSE and FAB scores (raw and Z-scores), FIM scores, and rehabilitation length of stay accounted for by subtle neurological signs score.

Paratonia was present in 30 patients (58.8%); all of these demonstrated mitgehen, and eight patients (15.7%) also demonstrated gegenhalten . Fifty patients (98%) demonstrated at least one primitive reflex; two or more primitive reflexes were present in 45 patients (88.2%), and three or more were present in 34 patients (66.7%). Glabelar response was the most common primitive reflex (82.4%), followed by snout response (74.5%), palmomental response (left 49% and right 47.1%), grasp response (left 41.2% and right 41.2%), suck reflex (19.6%), and rooting response (3.9%).

Subtle neurological signs score predicts raw FAB score (adjusted R ² =0.28, β=−0.54, p<0.00005), raw MMSE score (adjusted R ² =0.25, β=−0.51, p<0.0002), FAB Z-score (adjusted R ² =0.24, β=−0.51, p<0.0002), and MMSE Z-score (adjusted R ² =0.15, β=−0.41, p<0.003). Subtle neurological signs score also predicts total FIM score at the time of Behavioral Neurology & Neuropsychiatry consultation (adjusted R ² =0.12, β=−0.37, p<0.01) and rehabilitation discharge (adjusted R ² =0.13, β=−0.38, p<0.006). Finally, subtle neurological signs score predicts rehabilitation length of stay (adjusted R ² =0.24, β=0.51, p<0.0002).