Cold caloric test in altered states of consciousness

Can one predict outcome of medical coma?

The combined evaluation of the motor response to stimulation and the oculovestibular (OV) reflex gives useful indicants to the outcome of medical coma. We examined 48 patients during the first 12 h and at 24 h after the onset of medical coma. We excluded patients who had ingested drugs or who had hypothermia. Motor responses to a noxious stimulus were scored on a 6 'best' and 1 'worst' scale, and the presence or absence of oculovestibular responses to icewater irrigations was recorded. Subjects were divided by outcome at three months into three groups: death or persistent vegetative state, severe disability, and moderate disability or good recovery. On the basis of the present series it was often possible to distinguish among the outcomes at or before 24 h. The patient's age and the presence or absence of pupillary responses, spontaneous eye movements and oculocephalic responses were not predictive of outcome, nor were the respiratory pattern, blood gases, blood pressure, heart rate and temperature. A minimal motor score and an absence of oculovestibular responses at 12 h always were assoicated with death. With higher motor scores, the absence of oculovestibular responses at either 12 or 24 h implied an outcome no better than severe disability. The results of the present study imply that early bedside assessments can yield accurate predictive information in medical coma.

Brainstem auditory evoked response and vestibulo-ocular reflex in severe head injury patients. A prospective study of 60 cases

Brainstem auditory evoked response (BAER) performed in 60 serious head injury patients, over the last two year period at All India Institute of Medical Sciences, New Delhi have been analysed, to correlate the findings with ultimate outcome. All patients included in this study were unconscious, not following any command at the time of initial evaluation, mostly within 48 hours of injury. Repeat studies were performed in surviving patients. Computerized cranial tomography was performed to establish the nature of the intracranial pathology. The clinical status and cold caloric responses were recorded in all. The patients were followed up for 1 to 24 months. Three patients had extradural haematoma, 2 patients had subdural haematoma and 30 patients had intracerebral contusion/haematoma. Brain oedema was recorded in 14 cases. BAER was normal in 32 patients and 26 of them had good recovery (81%). Three patients with normal BAER died. Abnormal BAER was recorded in 21 patients and only 50% of them had good recovery and 25% of them died. In 7 patients BAER was absent and only 2 (29%) had a good recovery. Thus 48 out of 60 patients (66%) had a good recovery and 11 (18%) died. When compared to cold caloric response, 87% patients with normal caloric response had a good recovery and 5 out of 6 patients with absent caloric response died and remaining 1 left in a vegetative state. Thus the caloric response is at least as good a prognostic factor as BAER.

Bilateral decerebration in head-injury patients. An analysis of sixty-two cases

The factors that contributed to recovery were reviewed in 62 head-injured patients with bilateral decerebration. The most important prognostic variables were age, mode of accident, time interval since injury, results of initial neurological evaluations, and the type of intracranial mass lesion. A higher survival rate was recorded in patients less than 20 years of age, those involved in nonvehicular accidents, those admitted within 6 hours of the accident, and where the vestibuloocular reflexes were preserved. Patients with extradural hematomas and those with nonsurgical intracerebral mass lesions also had a relatively better prognosis. In no patient was elective ventilation, steroid, or megadose barbiturate therapy utilized. Twenty patients (32%) of the 62 survived, and 11 patients had a good functional recovery.

Vestibular recruitment and decruitment

Serial Thermal Vestibulometry with the application of increasing caloric stimuli (corresponding to decreasing temperature of water at successive irrigration of the ears) was performed on normal subjects and patients with lesions in the central nervous system involving the statoacoustic subsystem. The normal values and 'slope' values (i.e.increase in degrees of velocity of slow component of nystagmus in response to each 4 degrees C change in water temperature) were computed to yield values of the normal vestibulogram. The values obtained in patients were compared with those of the Normograms and the following diagnostic patterns observed: (a) Hypograms, (b) Hypergrams, (c) Central Vestibular Decruitment. Central Vestibular Recruitment has been explained on the basis of the locus of the lesion leading to involvement of the nystagmogenic area in the lower part of the reticular formation, suprasegmental neurones in the vicinity of the vestibular nuclear complex, and partial destruction of the complex itself, each being responsible alone or in combination. Hypergrams presumably result from suprasegmental lesions, e.g. in cerebrum and stem components. Central decrittment follows neural lesions in the vestibular subsystem. Hypograms are found in vestibular nuclear pathology. Furthermore, it helps in charting a plan for therapy, viz. head and balance exercise, in particular, in the sense that his exercise is not helpful in cases with central decruitment but is in peripheral one. An explanation for this has been put forward.

[Prognostic-evolutive evaluation of patients in coma based on ocular reflexes]

The ocular reflexes (ciliospinal, photomotor, oculocephalic, vestibulo-ocular, corneal) were studied in 84 comatose patients. The scope of the investigation was the assessment of each reflex in terms of its resistance according to the degree of depth of the coma. From the statistical viewpoint it was possible to emphasize the photomotor, corneal and vestibulo-ocular as the most resistant ones. The periodic evaluation in short time intervals of these five reflexes, observing their extinction or their re-appearance, permits a better prognostic assessment in a longitudinal viewpoint of the comatose patient.

Laboratory criteria of brain death

✓ Thirty patients with the clinical signs of brain death were subjected to a series of laboratory tests reputed to be capable of confirming this state. Three new procedures, electronystagmography, RISA intrathecal studies, and brain temperature tests, are described. The authors conclude that certain bedside tests, namely, electroencephalography, echoencephalography, electronystagmography, and electrocardiographic response to atropine, have been shown to be entirely adequate for a confident diagnosis.