Neurophysiological assessment of alpha pattern coma.

Somatosensory evoked potentials, blink reflexes, and H wave reflexes, were recorded on several days from three patients with alpha pattern coma. Coma was secondary to cardiac arrest in two cases and to brainstem infarction in one. Results are compatible with damage to the brainstem reticular formation with sparing of thalamo-cortical circuits as the main physiopathological characteristic of alpha pattern coma. This condition should not be regarded as a discrete entity when establishing the prognosis of patients in coma, since they only differ from other patients in coma from the point view of the EEG record.     

Early outcome prediction in severe head injury: comparison between children and adults

The prognostic value in 49 children and 56 adults of the following parameters recorded on admission was analyzed: oculocephalic and light reflexes, posturing, Glasgow Coma Scale (GCS), the need for ventilatory support, and the presence of associated injuries. All patients had been in coma for at least 6 h. The presence of intracranial hematoma and the duration of coma were recorded and the relative risk of poor outcome calculated. There was poor outcome in 51% of the children and 61% of the adults. Oculocephalic and light reflexes, posturing, GCS, need for ventilatory support, and duration of coma were significantly related to the outcome in children. Only oculocephalic and light reflexes, and posturing were significantly related to the outcome in adults. Some parameters appeared to have different prognostic value in children and in adults: the simultaneous evaluation of oculocephalic reflex and need for ventilation was the best prognostic guide in children, the light reflex was the best prognostic indicator in adults.     

Correlation between facial involuntary movements and abnormalities of blink and corneal reflexes in Huntington's chorea

Blink and corneal reflexes were studied in 11 patients with Huntington's chorea and the results compared with the severity of the disease. The latency of the R2 component of the blink reflex was delayed and the duration of R2 and of the corneal reflex (CR) prolonged. A greater habituation of the R2 component was found in the patients with involuntary movements in the face, and in some patients a long-lasting depression of R2 was present. A correlation was found between: (a) severity of involuntary face movements and R2 and CR latency and (b) severity of involuntary movements in the neck and latency of R2.     

The corneal reflex and the R2 component of the blink reflex

A reflex contraction of the human orbicularis oculi muscles can be evoked by stimulation of either the supraorbital region ("blink reflex") or the cornea ("corneal reflex"). We found that the latency of the corneal reflex was longer, and the duration was longer than the R2 component of the blink reflex. The absolute refractory period of the R2 component of the blink reflex was longer after supraorbital than after corneal conditioning stimulation. When the R2 component of the blink reflex was habituated by repetitive stimuli, stimulation of the cornea still evoked a reflex, but supraorbital stimulation produced only a depressed R2 response. These findings suggest that the two reflexes do not have identical neural connections.     

Reversible coma with prolonged absence of pupillary and brainstem reflexes: an unusual response to a hypoxic-ischemic event in MS

A quadriparetic man with multiple sclerosis became comatose with absent pupillary and brainstem reflexes for 48 hours following a respiratory arrest. A periodic electroencephalographic pattern was recorded 12 hours after arrest suggesting a poor prognosis. Despite the poor prognostic signs, clinical recovery to baseline occurred within 2 weeks. Reversible coma with absent pupillary and brainstem reflexes may occur in MS patients for prolonged periods and lead to potential errors in prognosis if not recognized.     

External ophthalmoplegia, alpha and spindle coma in imipramine overdose: case report and review of the literature

A 13-year-old boy with imipramine overdose developed seizures, respiratory arrest, and coma. Abnormalities of oculovestibular reflexes, electroencephalograms, and brainstem auditory evoked potentials were monitored in relation to measurements of drug levels. An alpha-coma electroencephalographic pattern evolved into one evidencing spindle coma and eventually into a normal pattern. Prolonged brainstem auditory evoked potentials also normalized as coma and oculocephalic reflex abnormalities resolved. In spite of the history that suggested hypoxic damage, the absence of reflex eye movements in a comatose patient and the presence of alpha- and spindle-coma electroencephalographic patterns, even with prolonged brainstem auditory evoked potentials, are not reliable prognostic indicators in tricyclic drug overdose.     

Familial hemifacial spasm

We present a family in which hemifacial spasm involving in all cases the left side of the face occurred in five persons in three generations. Blink reflexes recorded in two cases demonstrated an unexpected R1 component on the affected side during stimulation of the contralateral side.     

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.     

When is “brainstem death” brain death? The case for ancillary testing in primary infratentorial brain lesion

The widely accepted concept of brain death (BD) comprises the demonstration of irreversible coma in combination with the loss of brainstem reflexes and irreversible apnea. In some countries the combined clinical finding of coma, apnea, and loss of all tested brainstem reflexes (“brainstem death”) is sufficient for diagnosing BD irrespective of the primary location of brain lesion. The present article aims to substantiate the need for ancillary testing in patients with primary infratentorial brain lesions. Anatomically, the “brainstem-death” syndrome can theoretically occur without relevant lesion of the mesopontine tegmental reticular formation (MPT-RF). Thus, a brainstem lesion may cause an apneic total locked-in syndrome, a rare syndrome with preserved capability for consciousness, mimicking “brainstem death”. Findings in animals and humans have shown that alpha- or alpha/theta- EEG patterns in case of isolated brainstem lesion indicate intactness of relevant parts of the MPT-RF. In such patients the presence of irreversible coma has to be doubted, and the potential capacity for some degree of consciousness cannot be excluded as long as the EEG activity persists. Consequently the demonstration of either ancillary finding, electro-cortical inactivity or, preferably, cerebral circulatory arrest, is mandatory for diagnosing BD in patients with a primary infratentorial brain lesion.     

Levetiracetam suppresses long-loop reflexes at the cortical level

Posthypoxic coma is often associated with cortical and brainstem hyperexcitability. Five months following cardiopulmonary resuscitation after myocardial infarction and ventricular arrhythmia, a 47-year-old man presented with posthypoxic cerebral dysfunction, minimal responsiveness, severe spastic-dystonic tetraparesis, and stimulus-sensitive muscle spasms upon acoustic and sensory stimulation. Neurophysiological examination revealed increased long-loop reflexes in abductor pollicis brevis muscle following median nerve stimulation at the wrist, consistent with cortical hyperexcitability. Exaggerated startle responses provided evidence of concomitant brainstem disinhibition. Levetiracetam up to 3,000 mg per day suppressed transcortical long-loop reflexes in a dose-dependent manner without concomitant suppression of the H-reflex and only mild attenuation of the startle response. The present findings suggest a suppressive effect of levetiracetam on cortical neurons in the absence of a spinal effect on monosynaptic reflexes, and thus support the drug's efficacy in posthypoxic cortical hyperexcitability.     

The diagnostic value of three common primitive reflexes

Systematic attempts were made to elicit the snout, palmomental and corneomandibular reflexes in 50 young patients with prolonged traumatic coma, 50 elderly hemiplegics soon after their first cerebrovascular accident and in 100 normal age-matched controls. None was found significantly more frequently alone in brain-damaged patients than in age-matched controls. Only combinations of two or three reflexes showed diagnostic value in distinguishing between neurologically damaged patients and normal age-matched controls. Only the combination of all three was completely absent in the normal controls; this combination was found in 13% of the brain-damaged subjects.     

Glabella tap sign: Is it due to a lack of R2-habituation?

In 30 patients with Parkinson's disease, 55 patients with other neurological disorders and 25 normal subjects, both upper eyelid movements and orbicularis oculi reflexes to repetitive glabella taps were simultaneously recorded using a newly devised apparatus for the measurement of eyelid movement. Upper lid movement during the blink reflex has been thought to correspond to the late component of the two components of the orbicularis oculi reflex, and failure of habituation of the late component to repetitive stimuli has been considered to be responsible for the glabella tap sign. However, the present study showed that the eyelid lowered after the early component (R1), and habituation of the late component (R2) was recognized in 31% of subjects with the glabella tap sign. This shows that there is no direct causual relationship between the glabella tap sign and lack of the habituation of the late component.     

Neurologic status and prognosis after cardiopulmonary arrest: I. A retrospective study

A retrospective survey of survivors of cardiorespiratory arrest included 34 patients. Twenty-one had a good outcome neurologically and 13 were seriously impaired. Depth and duration of postarrest coma correlated significantly with poor neurologic function. Seventy percent of the seriously impaired patients never regained consciousness and none emerged from coma within 5 days; 90 percent of patients with good outcome were alert within 18 hours after resuscitation. Coma motor unresponsiveness, absent pupillary light reflexes, and absent oculocephalic responses were closely associated with dismal prognosis for neurologic functioning. This retrospective study cannot provide a basis for discontinuation of life support at any specific time.     

Re-evaluation of short latency somatosensory evoked potentials (P13, P14 and N18) for brainstem function in children who once suffered from deep coma

One of the major clinical features of brain death is deep coma. Therefore, we re-evaluated retrospectively electrophysiological examinations of brainstem function in about 31 children who had once suffered from deep coma in order to reveal its pathophysiological characteristics. The patient age at coma ranged from 1 month to 10 years (mean 2 years 1 month). The electrophysiological examinations were performed, including any of short-latency somatosensory evoked potential (SSEP), brainstem auditory evoked potential (BAEP) and blink reflexes. We first compared results between the fair and poor prognostic groups, and then re-evaluated SSEP results on a few severely impaired patients with persistent vegetative state (PVS). Subsequently, SSEP clarified more specific findings for a deep coma condition than BAEP and blink reflex. A lack of P14, N18 and N20, and an amplitude reduction or vagueness of P13 in SSEP in these children strongly suggested high risk in their future neurological prognosis. In conclusion, electrophysiological examinations, especially SSEP (P13, P14 and N18), might be very useful in obtaining a long-term neurological prognosis after deep coma in children.     

Different responses to auditory and somaesthetic stimulation in patients with an excessive startle: a report of pediatric experience.

OBJECTIVES: Children with cerebral injury often exhibit brief muscle contraction to a variety of stimuli. However, it remains to be determined whether or not the pattern of the reaction is stereotypical irrespective of the site stimulated. To answer this question, we studied electromyographic (EMG) responses to three types of stimuli in children. METHODS: The EMG responses of cranial and limb muscles were recorded after acoustic or somaesthetic stimulation in 6 patients and 23 control subjects. RESULTS: Acoustic stimuli evoked patterned motor activity with a rostrocaudal progression. Nose-tapping stimuli elicited reflex EMG activity in the VIIth cranial muscles that was similar to the R1 component of the electrical blink reflex. Sternum-tap stimuli evoked motor activity in the sternocleidomastoid and arm muscles, and this reflex was probably mediated through the cervical cord (H-reflex). Moreover, late reflexes were evoked following these early reflexes in the patients. In particular, atypical forms of myoclonic jerks were evoked on sternum-tap stimuli. CONCLUSIONS: Many types of primitive reflexes were evoked following three types of stimuli. These reflexes included startle reflex, trigeminomotor reflex, H-reflex and atypical forms of myoclonus, and they were enhanced in the patient group. There are many startle-mimicking reflexes.     

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.     

Blink reflexes and the silent period in tetanus

Abnormalities of the silent period (SP) and blink reflexes occur in diseases that interfere with inhibitory pathways, such as tetanus and stiff-person syndrome (SPS). The SP is abnormal in tetanus but not in SPS. Studies of the blink reflex in tetanus are limited. In this report, a patient with generalized tetanus is described. The masseteric-and mixed-nerve SP was absent or truncated. In contrast to SPS, blink reflex studies revealed no bilateral R1 component, and a discrete R3 was only present ipsilateral to right supraorbital stimulation. This reflects the distinct inhibitory pathways underlying these disorders.     

Semiologic aspects of traumatic coma (author's transl)

After studying 85 patients with severe traumatic coma and reviewing the published literature, the authors propose a simple clinical procedure for the diagnostic of such cases. This classification is based on signs without any ambiguity, easily recognized by different physicians, and of pathognomonic significance. These include reaction to pain, testing four reflexes integrated at different levels in the brain stem, pupil morphology, and spontaneous ocular movements. The clinical features corresponding to different levels of dysfunction in the brain are described and their characteristics outlined. The importance of motor reactivity to pain associated to the brain stem reflexes (fronto-orbicular, photomotor, horizontal and vertical oculo-encephalic) is stressed.     

Acute aortic dissection mimicking basilar artery occlusion in a patient presenting with sudden coma

A 77-year-old female suddenly became comatose. Examination at the emergency room revealed stable vital signs and bilateral positive plantar reflexes but absent brainstem reflexes. Basilar artery occlusion was initially diagnosed and recombinant tissue plasminogen activator was administered. However, her blood pressure dropped after thrombolysis. A chest CT scan showed aortic dissection extending to the bilateral common carotid arteries. Her follow-up brain CT scan disclosed infarctions over bilateral carotid territories without brainstem involvement. Aortic dissection should be listed as a possible diagnosis in a patient who presents with a sudden coma mimicking basilar artery occlusion. Detailed clinical examination and discussion might lead to the correct diagnosis and avoid inadvertent thrombolysis in the emergency room.