Primary Brain Stem Lesions Research Articles

"The Brain as a Whole" Concept: Facilitating Approaches to Brain Death Understanding (Short Communication)

James Bernat claimed that "the formulation of whole-brain death provides the most congruent map for our correct understanding of death". However, the author has recently proposed the categorization of another phrase: "brain as a whole (BAAW)". This is because patients with primary brainstem lesions who otherwise meet the clinical criteria for BD may still have EEG, CBF, evoked potentials, and hypothalamic-pituitary neurosecretion.Bernat and colleagues suggested "tightening the clinical tests for brain death or loosening the whole-brain criterion of death". They emphasize that the BAAW criterion is an intermediate standard between the whole-brain and brainstem views, tolerating the irreversible cessation of critical brain functions, whereas the BD/DNC determination does not require the cessation of all brain functions or the death of every neuron.In this paper, we have revised the concept of BAAW, which is intuitive and facilitates a conceptual and practical approach, but requires further refinement to specify precisely which brain functions must cease at brain death and which may continue.

Brain Death Diagnosis in Primary Posterior Fossa Lesions.

New controversies have raised on brain death (BD) diagnosis when lesions are localized in the posterior fossa. The aim of this study was to discuss the particularities of BD diagnosis in patients with posterior fossa lesions. The author made a systematic review of literature on this topic. A supratentorial brain lesion usually produces a rostrocaudal transtentorial brain herniation, resulting in forebrain and brainstem loss of function. In secondary brain lesions (i.e., cerebral hypoxia), the brainstem is also affected like the forebrain. Nevertheless, some cases complaining posterior fossa lesions (i.e., basilar artery thrombotic infarcts, or hemorrhages of the brainstem and/or cerebellum) may retain intracranial blood flow and EEG activity. In this article, I discuss that if a posterior fossa lesion does not produce an enormous increment of intracranial pressure, a complete intracranial circulatory arrest does not occur, explaining the preservation of EEG activity, evoked potentials, and autonomic function. I also addressed Jahi McMath, who was declared braindead, but ancillary tests, performed 9 months after initial brain insult, showed conservation of intracranial structures, EEG activity, and autonomic reactivity to "Mother Talks" stimulus, rejecting the diagnosis of BD. Jahi McMath's MRI study demonstrated a huge lesion in the pons. Some authors have argued that in patients with primary brainstem lesions it might be possible to find in some cases partial recovery of consciousness, even fulfilling clinical BD criteria. This was the case in Jahi McMath.

The importance of decompressive craniectomy for the management of severe head injuries.

Neurosurgical therapy aims to minimize the secondary brain damage after a severe head injury. This includes the evacuation of an intracranial space occupying bleeding, the reduction of intracranial volumes, in hematocephalus an external ventricular drainage, and the conservative therapy in order to influence an increased intracranial pressure (ICP) and a decreased p(ti)02. When conservative treatment fails to act a decompressive craniectomy might be successful in lowering ICP. From September 1997 until August 2001 we operated on 439 patients with severe head injuries. 50 patients (11%) were treated by means of a decompressive craniectomy. The prognosis after decompression depends on the clinical signs and symptoms on admission, the patients age and the existence of major extracranial injuries. Our guidelines for an indication for decompressive craniectomy after failure of conservative interventions and evacuation of space occupying hematomas include a patients age below 50 years without multiple trauma, a patients age below 30 years in the presence of major extracranial injuries, a severe brain swelling on CT scan, the exclusion of a primary brainstem lesion or injury and the intervention before irreversible brainstem damage and secondarily while monitoring ICP and p(ti)02 in an interval up to 48 hours after the accident before irreversible brainstem damage or generalized brain damage has occurred.

Leiomyosarcomatous transformation of unknown pediatric primary brainstem lesion following radiotherapy

Primary leiomyosarcoma of the central nervous system is rare and has been described both de novo and following temporally remote radiotherapy for a different unrelated malignancy. The authors report the case of a 42-year-old man in whom 60Co radiation treatment had been performed for an unknown primary mass in the brainstem 25 years previously. He presented with progressive neurological deterioration after undergoing many years of conservative therapy. A stereotactic biopsy sampling procedure was performed, and examination of the left cerebral pedunculopontine lesion revealed a spindle cell neoplasm. Histopathological and immunohistochemical examination of the tumor obtained from definitive resection suggested leiomyosarcomatous transformation of ganglioglioma.

REM sleep behavior disorder

REM sleep is the stage associated with vivid dream mentation, desynchronous cortical EEG, and atonia of antigravitary muscles. REM sleep behavior disorder (RBD) is characterized by the intermittent loss of REM sleep atonia and by the appearance of elaborate motor activity associated with dream mentation. The animal model of REM sleep without atonia indicates that lesions to the perilocus coeruleus disrupt the excitatory connection to the nucleus reticularis magnocellularis in the descending medullary reticular formation and disable the hyperpolarization of the alpha spinal motoneurons. Extensive neurologic evaluations in humans suffering from both idiopathic and symptomatic forms have not identified specific lesions; however, findings in some patients suggest that diffuse lesions of the hemispheres, bilateral thalamic abnormalities, or primary brain-stem lesions may result in the RBD. Symptomatic RBD cases are associated with several neurologic disorders such as dementia, cerebrovascular diseases, multiple sclerosis, brain-stem neoplasm. RBD has been often documented to precede or to co-occur with neurodegenerative disorders, such as dementia, Parkinson's disease and multiple system atrophy. Most importantly, RBD is readily diagnosable and treatable. Patients and their bed partners usually report immediate improvement in sleep-related motor behavior with small doses of clonazepam.

Visuell evozierte Potentiale: Zum Einfluß primärer Hirnstammläsionen auf die Skalp-Topographie

Visual evoked potentials were examined in 24 patients (mean age: 51.1 ± 10.2 years) with primary brain stem lesion. Topographical recordings were performed within the first 3.1 ± 2.7 days after onset of disease. The results showed an increase in the signal to noise ration-(SNR) parameter and the amplitude over the occipital region in patients with unfavourable outcome. These findings seem to indicate that the VEP topography probably can be used as an additional prognostic parameter in patients with primary brain stem lesions.

Primary brain stem lesions caused by closed head injuries.

Traumatic lesions of the brain stem are of two types: primary, which are considered to be caused at the moment of impact, and secondary, associated with supratentorial mass lesion. Of the 239 patients with a serious head injury who showed a severe disturbance of consciousness upon admission and who had CT scan carried out immediately, 21 cases were considered to have a primary brain stem lesion with initial CT scan. A primary brain stem lesion was found in 21 of 239 (8.8%) of patients with serious head injury. Their injuries were caused primarily by traffic accidents. Sixteen of the 21 cases showed not only brain stem lesions but also other brain injuries such as cerebral contusion of the white and gray matter, callosal injury, intraventricular hemorrhage, and subarachnoid hemorrhage, which are considered to be caused by a diffuse shearing injury. Five cases who showed a single injury to the brain stem with no other brain lesions were considered to have a pure brain stem lesion. Primary brain stem lesions were observed on the dorsal side of the midbrain, where they can be differentiated from secondary brain stem lesions. These lesions are considered to result from the shearing mechanism in and around the brain stem very close to the tentorial edge, or to an injury of the lower brain stem by hyperextension of the cervical vertebrae. The prognosis of patients with a primary brain stem lesion was usually unfavorable, except in those with a single brain stem lesion.

Corpus callosum lesions after closed head injury in children: MRI, clinical features and outcome.

Thirty-four children who sustained moderate to severe closed head injury underwent magnetic resonance imaging (MRI). Eight (24%) had MRI evidence of corpus callosum injury, most commonly within the posterior body and splenium. In contradistinction to reports in adults, there was no definite relationship between callosal injury and lower initial Glasgow Coma Scale scores, nor was there a significantly higher incidence of primary brain-stem lesions, diffuse axonal shear injury or intraventricular hemorrhage. In none of these 8 children did the initial admission computed tomography show evidence of callosal injury. Callosal injuries on MRI are not necessarily a poor prognostic finding, the majority of the 8 children showing good functional recovery.

Central somatosensory conduction time and acoustic brainstem transmission time in post-traumatic coma.

Short-latency evoked potentials (SEPs) of the scalp and neck after median nerve stimulation and acoustic brainstem evoked potentials (BAEPs) were recorded in 85 patients in post-traumatic coma with clinical signs of brainstem impairment between days 2 and 6 after trauma. The central somatosensory conduction time (CCT), the amplitude ratio (AR) N20:N13, the interpeak latencies (IPL) I-III, III-V, I-V, and the ARs between waves I and V (I:V) and between wave I and the wave IV/V complex (I:IV/V) were calculated and related to the outcome of the patients. In cases of coma due to supratentorial lesions, CCT and ARs of SEPs were close to normal in patients with good outcome: CCT increased and ARs decreased with worsening of outcome. In cases of primary brainstem injury, a significant prolongation of CCT was also seen in patients with good recovery, whereas normal CCTs could be found in patients with severe disability and death outcome. In this case, unilateral absent scalp SEPs were frequently found. The IPLs I-III, III-V, I-V, and the ARs of BAEPs increased with worsening of outcome. Significant differences of IPL I-V and III-V (brainstem transmission time) were seen between patients with good recovery or moderate disability outcome and the patients with severe disability or death outcome. There was no difference in BAEPs between patients with primary brainstem lesion and patients with secondary brainstem lesion. Patients with bilateral absent SEPs and bilateral absent BAEPs not related to traumatic or preexisting hearing disorders died or survived severely disabled. Unilateral absence of scalp SEPs and unilateral absence of BAEPs were frequently found in patients who died or who had severe disability. Asymmetries in scalp SEPs appeared to be distributed equally to all outcome categories, but asymmetries in BAEPs increased with worsening of outcome too. In most of the patients who died or survived disabled, both SEPs and BAEPs were abnormal.

MR imaging of head trauma: review of the distribution and radiopathologic features of traumatic lesions.

The distribution and extent of traumatic lesions were prospectively evaluated with MR imaging in 40 patients with closed head injuries. Primary intraaxial lesions were classified according to their distinctive topographical distribution within the brain and were of four main types: (1) diffuse axonal injury (48.2%), (2) cortical contusion (43.7%), (3) subcortical gray-matter injury (4.5%), and (4) primary brainstem injury (3.6%). Diffuse axonal injury most commonly involved the white matter of the frontal and temporal lobes, the body and splenium of the corpus callosum, and the corona radiata. Cortical contusions most frequently involved the inferior, lateral, and anterior aspects of the frontal and temporal lobes. Primary brainstem lesions were most commonly seen in the dorsolateral aspects of the rostral brainstem. The pattern and distribution of primary lesions seen by MR were compared with those expected from previous pathologic studies and found to be quite similar. Our data and review of the literature would also indicate that MR detects a more complete spectrum of traumatic lesions than does CT. Secondary forms of injury (territorial arterial infarction, pressure necrosis from increased intracranial pressure, cerebral herniation, secondary brainstem injury) were also visible by MR in some cases. The level of consciousness was most impaired in patients with primary brainstem injury, followed by those with widespread diffuse axonal injury and subcortical gray-matter injury. The best MR imaging planes, pulse sequences, and imaging strategies for evaluating and classifying traumatic lesions were evaluated, and the mechanisms by which traumatic stresses result in injury were reviewed. MR was found to be superior to CT and to be very effective in the detection of traumatic head lesions and some secondary forms of injury. While T2-weighted images were most useful for lesion detection, T1-weighted images proved to be most useful for anatomic localization and classification.

Histopathologic criteria of primary and secondary brain stem lesions

The brain stems from 52 corpses were microscopically examined. These cases died as a result of closed head injuries, which were clinically diagnosed and/or diagnosed postmortem as primary brain stem lesions. The morphological changes in these cases were compared with morphological changes in the brain stems of corpses who died from cerebral hemorrhage with additional secondary brain stem lesions. The examinations revealed acidophilic necrosis of the vessel walls in brain stem hemorrhages with fibrin impregnation of the vessel walls. Fibrin penetration to the perivascular space was the basic morphological marker that helped to differentiate between these two groups of cases.

Traumatic Decerebracy with Preserved Consciousness and Voluntary Movement

Decerebrate rigidity is a frequent occurrence in cases of craniocerebral trauma. It is almost always accompanied by coma and usually denotes a poor prognosis. Primary focal brain stem lesions due to trauma are uncommon and may be accompanied by other diffuse cerebral lesions. This report reviews the anatomical basis and clinical findings of a unilateral brain stem lesion in a patient with traumatic decerebracy and preserved consciousness. The anatomical pathways and possible physiological mechanism are discussed, and a few comments on the prognosis of such lesions are given.

Incidence and prognostic value of spindles in post-traumatic coma

One hundred and thirty-three EEGs were analysed from 80 comatose patients with signs of brain stem impairment due to head/brain injury. Seventy EEGs were taken in acute coma on day 1 or 2 after brain injury. Sixty-three EEGs were recorded in prolonged coma 3–12 days after brain injury. Brain stem involvement was divided by neurological signs and by CT scan into secondary lesions due to supratentorial mass displacement and primary lesions due to direct violence to the brain stem. Different EEG patterns were observed, but spindle activity was of special interest. Spindles were classified as typical (easily recognizable, well organized, 12–14 c/sec activity) or atypical (hardly recognizable, distorted form, 6–11 c/sec activity). Furthermore, asymmetries of spindles were noted. The spindles and their alterations were related to different stages of outcome. Spindles were seen in 91% of the EEGs in acute coma and in 30% in prolonged coma. In acute coma due to secondary brain stem involvement a good outcome was heralded by the occurrence of typical symmetrical spindles combined with early stages of secondary brain stem impairment at neurological examination. In cases of primary brain stem involvement typical spindles also suggested a good prognosis despite the observation of serious clinical signs (decerebrate posturing). The percentage of spindle activity decreased, and distortion and asymmetry of spindles increased with the worsening of outcome. Severe intracerebral lesions (confirmed by clinical and CT scan examinations) led to distortion, asymmetry and finally disappearance of spindles. In prolonged coma spindle activity was markedly reduced regardless of the final outcome. When spindles were present atypical and asymmetric forms significantly increased in patients with bad outcome. There were no significant differences in spindle activity in the different outcome categories, if primary and secondary brain stem lesions were compared.

Frequency of primary brain stem lesions after head injuries. A CT scan analysis from 186 cases of severe head trauma.

Analysis of level of brain stem dysfunction, evolution, and CT scan profile was made on 76 cases of head injuries with prolonged unconsciousness and without hemispheric focal lesion and midline shift on CT scan. Eleven cases were considered normal on CT scan. The CT scan aspect of primary brain stem lesion was identified in 31.5% of these series, and in 14.5% of all severe head traumas (186 cases), from which this series is taken. Primary and secondary CT scan profiles were observed whatever the clinical level of dysfunction and its evolution. Pontine lesions were mainly associated with haemorrhage in the brain stem and diffuse brain swelling; but minimal signs (cortical level) and benign outcome can also be related to axial haemorrhage. These results emphasize the frequency of primary brain stem lesions and the value of CT scan in head injuries.

BRAINSTEM LESIONS DUE TO CLOSED HEAD INJURY

A characteristic patient with a primary brainstem lesion due to closed head injury would be a young male with a patch of ischæmic necrosis or a hæmorrhage in one side of the tegmentum of his undistorted midbrain. There would also be acute degeneration of neurones in his vestibular nuclei and segmental degeneration of one inferior olivary nucleus. He would have hit the back of his head, probably have a fractured skull and a contused brain, especially a contused cerebellum. He would remain unconscious from the time of his head injury to his death in under a week, probably within 12 hours.