Injury of the cortico-ponto-cerebellar tract in a patient with mild traumatic brain injury: A case report

RATIONALE

We report on a patient with injury of the cortico-ponto-cerebellar tract (CPCT) following mild traumatic brain injury (TBI), diagnosed by diffusion tensor tractography (DTT).

PATIENT CONCERNS

A 53-year-old female patient was injured in a car crash. While under treatment at a local medical center for headache, mild motor weakness, and cognitive impairment that developed following the car crash, she fell, hitting her head on the ground, about six weeks after the car crash.

DIAGNOSES

Approximately three months after the car crash, she began to show tremor on both hands and mild truncal ataxia. Twenty months after the car crash, when she underwent neurological evaluation at the rehabilitation department of a university hospital, she presented with mild resting and intentional tremor on both hands, and mild truncal ataxia.

INTERVENTIONS

N/A.

OUTCOMES

On 20-month DTT, the left CPCT showed tearing at the level of the subcortical white matter and pons, and discontinuation at the cerebellar portion. However, the integrity of the DRTT was well-preserved in both hemispheres.

LESSONS

Using DTT, injury of the CPCT was demonstrated in a patient with ataxia and tremor following mild TBI.

Selective lesioning of nucleus incertus with corticotropin releasing factor-saporin conjugate

The nucleus incertus (NI), a brainstem nucleus found in the pontine periventricular grey, is the primary source of the neuropeptide relaxin-3 in the mammalian brain. The NI neurons have also been previously reported to express several receptors and neurotransmitters, including corticotropin releasing hormone receptor 1 (CRF₁) and gamma-aminobutyric acid (GABA). The NI projects widely to putative neural correlates of stress, anxiety, depression, feeding behaviour, arousal and cognition leading to speculation that it might be involved in several neuropsychiatric conditions. On the premise that relaxin-3 expressing neurons in the NI predominantly co-express CRF₁ receptors, a novel method for selective ablation of the rat brain NI neurons using corticotropin releasing factor (CRF)-saporin conjugate is described. In addition to a behavioural deficit in the fear conditioning paradigm, reverse transcriptase polymerase chain reaction (RT-PCR), western blotting (WB) and immunofluorescence labelling (IF) techniques were used to confirm the NI lesion. We observed a selective and significant loss of CRF₁ expressing cells, together with a consistent decrease in relaxin-3 and GAD65 expression. The significant ablation of relaxin-3 positive neurons of the NI achieved by this lesioning approach is a promising model to explore the neuropsychopharmacological implications of NI/relaxin-3 in behavioural neuroscience.

Lateral parabrachial nucleus mediates shortening of expiration and increase of inspiratory drive during hypercapnia

We have previously shown that unilateral or bilateral lesions of the lateral parabrachial nucleus (LPBN) in anesthetized, vagotomized rats markedly and selectively attenuate the shortening of expiratory duration (T(E)) during hypoxia without appreciably affecting all other hypoxic response components. Here, we report that unilateral LPBN lesion by kainic acid in the same group of animals not only abolished normal T(E)-shortening during central chemoreceptors activation by hyperoxic hypercapnia, but led to paradoxical T(E)-prolongation and corresponding decrease of respiratory frequency. Furthermore, LPBN lesion significantly attenuated the increase in phrenic activity during hyperoxic hypercapnia, without appreciably affecting the corresponding shortening of inspiratory duration (T(I)). These findings provide the first evidence indicating that central chemoafferent inputs are organized in parallel and segregated pathways that separately modulate inspiratory drive, T(I), and T(E) in conjunction with similar parallel and segregated central processing of peripheral chemoafferent inputs reported previously [Young, D.L., Eldridge, F.L., Poon, C.S., 2003. Integration-differentiation and gating of carotid afferent traffic that shapes the respiratory pattern. J. Appl. Physiol. 94, 1213-1229].

Lateral parabrachial nucleus mediates shortening of expiration during hypoxia

Acute hypoxia elicits complex time-dependent responses including rapid augmentation of inspiratory drive, shortening of inspiratory and expiratory durations (T(I), T(E)), and short-term potentiation and depression. The central pathways mediating these varied effects are largely unknown. Here, we show that the lateral parabrachial nucleus (LPBN) of the dorsolateral pons specifically mediates T(E)-shortening during hypoxia and not other hypoxic response components. Twelve urethane-anesthetized and vagotomized adult Sprague-Dawley rats were exposed to 1-min poikilocapnic hypoxia before and after unilateral kainic acid or bilateral electrolytic lesioning of the LPBN. Bilateral lesions resulted in a significant increase in baseline T(E) under hyperoxia. After unilateral or bilateral lesions, the decrease in T(E) during hypoxia was markedly attenuated without appreciable changes in all other hypoxic response components. These findings add to the mounting evidence that the central processing of peripheral chemoafferent inputs is segregated into parallel integrator and differentiator (low-pass and high-pass filter) pathways that separately modulate inspiratory drive, T(I), T(E) and resultant short-term potentiation and depression.

Horizontal Smooth Pursuit Adaptation in Macaques After Muscimol Inactivation of the Dorsolateral Pontine Nucleus (DLPN)

The smooth pursuit (SP) system can adapt its response to developmental changes, injury, and behavioral context. Previous lesion and single-unit recording studies show that the macaque cerebellum plays a role in SP initiation, maintenance, and adaptation. The aim of this study was to determine the potential role of the DLPN in SP adaptation. The DLPN receives inputs from the cortical SP system and delivers eye and visual motion information to the dorsal/ventral paraflocculus and vermis of the cerebellum. We studied SP adaptation in two juvenile rhesus monkeys ( Macaca mulatta), using double steps of target speed that step- up (10–30°/s) or step-down (25–5°/s). We used microinjection of muscimol (≤2%; 0.15 μl) to reversibly inactivate the DLPN, unilaterally. After DLPN inactivation, initial ipsilesional SP acceleration (first 100 ms) was significantly reduced by 47–74% ( P < 0.01; unpaired t-test) of control values in the single-speed step-ramp paradigm. Similarly, ipsilesional steady-state SP velocity was also reduced by 59–78% ( P < 0.01; unpaired t-test) of control values. Contralesional SP was not impaired after DLPN inactivation. Control testing showed significant adaptive changes of initial SP eye acceleration after 100 trials in either step-up or step-down paradigms. After inactivation, during ipsilesional SP, adaptation was impaired in the step-up but not in the step-down paradigm. In contrast, during contralesional tracking, adaptive capability remained in the step-down but not in the step-up paradigm. Therefore SP adaptation could depend, in part, on direction sensitive eye/visual motion information provided by DLPN neurons to cerebellum.

cerebellar atrophy after moderate-to-severe pediatric traumatic brain injury

BACKGROUND AND PURPOSE

Although the cerebellum has not attracted the same degree of attention as cortical areas and the hippocampus in traumatic brain injury (TBI) literature, there is limited structural and functional imaging evidence that the cerebellum is also vulnerable to insult. The cerebellum is emerging as part of a frontocerebellar system that, when disrupted, results in significant cognitive and behavioral consequences. We hypothesized that cerebellar volume would be reduced in children following TBI and wished to examine the relation between the cerebellum and known sites of projection, including the prefrontal cortex, thalamus, and pons.

MATERIALS AND METHODS

Quantitative MR imaging was used to measure cerebellar white and gray matter and lesion volumes 1-10 years following TBI in 16 children 9-16 years of age and 16 demographically matched typically developing children 9-16 years of age. Cerebellar volumes were also compared with volumetric data from other brain regions to which the cerebellum projects.

RESULTS

A significant group difference was found in cerebellar white and gray matter volume, with children in the TBI group consistently exhibiting smaller volumes. Repeating the analysis after excluding children with focal cerebellar lesions revealed that significant group differences still remained for cerebellar white matter (WM). We also found a relation between the cerebellum and projection areas, including the dorsolateral prefrontal cortex, thalamus, and pons in 1 or both groups.

CONCLUSION

Our finding of reduced cerebellar WM volume in children with TBI is consistent with evidence from experimental studies suggesting that the cerebellum and its related projection areas are highly vulnerable to fiber degeneration following traumatic insult.

Posttraumatic locked-in syndrome with an unusual three day delay in the appearance

We report a rare case of posttraumatic locked-in syndrome (LIS) that appeared after an unusual three day delay. LIS was diagnosed according to clinical status and diagnostic methods (roentgenograms, computerized tomography, transcranial Doppler, electroencephalography, magnetic resonance imaging). A fourteen-year-old girl had a cervical spine injury during floor exercises that provoked LIS 72 hours after trauma. A rapid diagnosis of basilar thrombosis followed by antioedema and continuous anticoagulant therapy significantly improved the neurological status. In conclusion, posttraumatic locked-in syndrome can have sometimes a prolonged three-day delay in the clinical appearance.

A critical role for the parabrachial nucleus in generating central nervous system responses elicited by a systemic immune challenge

Using Fos immunolabelling as a marker of neuronal activation, we investigated the role of the parabrachial nucleus in generating central neuronal responses to the systemic administration of the proinflammatory cytokine interleukin-1beta (1 microg/kg, i.a.). Relative to intact animals, parabrachial nucleus lesions significantly reduced the number of Fos-positive cells observed in the central amygdala (CeA), the bed nucleus of the stria terminalis (BNST), and the ventrolateral medulla (VLM) after systemic interleukin-1beta. In a subsequent experiment in which animals received parabrachial-directed deposits of a retrograde tracer, it was found that many neurons located in the nucleus tractus solitarius (NTS) and the VLM neurons were both retrogradely labelled and Fos-positive after interleukin-1beta administration. These results suggest that the parabrachial nucleus plays a critical role in interleukin-1beta-induced Fos expression in CeA, BNST and VLM neurons and that neurons of the NTS and VLM may serve to trigger or at least influence changes in parabrachial nucleus activity that follows systemic interleukin-1beta administration.

Effects of hypocretin2-saporin and antidopamine-beta-hydroxylase-saporin neurotoxic lesions of the dorsolateral pons on sleep and muscle tone

The hypocretin neurons have been implicated in regulating sleep-wake states as they are lost in patients with the sleep disorder narcolepsy. Hypocretin (HCRT) neurons are located only in the perifornical region of the posterior hypothalamus and heavily innervate pontine brainstem neurons, such as the locus coeruleus (LC), which have traditionally been implicated in promoting arousal. It is not known how the hypocretin innervation of the pons regulates sleep-wake states as pontine lesions have never been shown to increase sleep. It is likely that in previous studies specific neurons were not lesioned. Therefore, in this study, we applied saporin-based neurotoxins to the dorsolateral pons and monitored sleep in rats. Anti-dopamine-beta-hydroxylase-saporin killed the LC neurons but sleep was affected only during a two hour light-dark transition period. Application of hypocretin2-saporin killed fewer LC neurons relative to other adjacent neurons. This occurred because the LC neurons possess the hypocretin receptor 1 but the ligand hypocretin 2 binds to this receptor with less affinity relative to the hypocretin receptor 2. The hypocretin2-saporin lesioned rats compared to controls had increased sleep during the dark period and displayed increased limb movements during REM sleep. None of the lesioned rats had sleep onset REM sleep periods or cataplexy. We conclude that the hypocretin innervation to the pons functions to awaken the animal when the lights turn off (via its innervation of the LC), sustains arousal and represses sleep during the rest of the night (via a wider innervation of other pontine neurons), and modulates muscle tone.

Excitotoxic lesions of the lateral parabrachial nucleus do not prevent cholecystokinin-induced suppression of milk intake in rats

We examined the effect of lateral (visceral) and medial (gustatory) parabrachial nucleus (PBN) lesions on the suppression of milk intake induced with cholecystokinin (CCK) in 24 h food-deprived rats. Irrespective of CCK dose, each type of PBN lesion significantly elevated the consumption of milk. Neither medial nor lateral PBN lesions had any discernible influence on the anorectic action of CCK, however. In combination with the results from a previous study using the same rats (Brain Res. 894 (2001) 288), the present results support the view that the role of the lateral PBN in CCK-induced anorexia depends on the nature of the food used at test.

Semiquantitative analysis of corpus callosum injury using magnetic resonance imaging indicates clinical severity in patients with diffuse axonal injury

OBJECTIVE

To evaluate the hypothesis that the extent of corpus callosum injury indicates the depth of shearing lesions in the central brain structure and therefore relates to the clinical severity of diffuse axonal injury.

METHODS

A simple and objective procedure for semiquantitative analysis of magnetic resonance images (MRI)-the maximum signal intensity ratio (MSIR)-was employed prospectively in 21 patients with diffuse axonal injury but without apparent injury to the ventral pons. All were diagnosed using serial combination MRI scans of fluid attenuated inversion recovery (FLAIR) and T2* weighted gradient echo imaging during the initial two weeks after the injury. The signal intensity ratio between the two regions of interest-the corpus callosum and the normal appearing ventral pons-was calculated serially in mid-sagittal and parasagittal FLAIR image sections in each patient. The MSIR during the study period was determined as a semiquantitative index of corpus callosum injury in each patient. The correlations between MSIR and the duration of unconsciousness, Glasgow outcome scale at six months, and the presence of apparent midbrain injury were investigated.

RESULTS

The mean (SD) MSIR value was 1.12 (0.18) at 7.4 (3.1) days after the injury (n = 21). MSIR correlated strongly with the duration of unconsciousness (n = 19, R(2) = 0.74, p < 0.0001), and was higher in patients with both an unfavourable GOS outcome (p = 0.020) and apparent midbrain injury (p < 0.001).

CONCLUSIONS

MSIR, which is a simple and objective procedure for semiquantitative analysis of corpus callosum damage in diffuse axonal injury, correlated with clinical severity. A high MSIR value may indicate the presence of concomitant midbrain injury.

Effects of excitotoxic median raphe lesion on working memory deficits produced by the dorsal hippocampal muscarinic receptor blockade in the inhibitory avoidance in rats

The experiments investigated the interactions between median raphe nucleus (MRN) serotonergic and septo-hippocampal muscarinic cholinergic systems in the modulation of forming and storing performances of working memory. Rats with ibotenic acid-induced MRN-lesion bilaterally received scopolamine (2-4 microg/each side) infusion into the dentate gyrus of the dorsal hippocampus and were tested in a single trial step-through inhibitory avoidance. Initial preference to the dark compartment (escape latency) was taken as the measure of non-mnemonic behaviours and response latency to enter the dark compartment immediately after the foot-shock was used to measure working memory. The high-dose scopolamine infusion 10 min before the training decreased escape latencies in the sham-lesioned rats, whereas had no effect in the MRN-lesioned rats. Although MRN lesion per se did not alter response latency, it alleviated pre-training scopolamine-induced decrease, but aggravated post-training scopolamine-induced reduction in this parameter. These results suggest that the antagonistic interactive processes between MRN-serotonergic and hippocampal cholinergic systems modulate non-mnemonic component of working memory formation, whereas the storing performance of working memory is modulated by the synergistic interactions between these systems in the hippocampus, mainly in the dentate gyrus.

Transorbital penetrating injury by a chopstick--case report

A one-year-old boy presented with orbitocranial penetrating injury by a chopstick. Neurological examination did not reveal abnormal findings. Skull radiography did not reveal any sign of fracture and there were no abnormal findings. Initially, computed tomography (CT) of the head did not reveal any intracranial lesions. However, bone window CT showed a well-defined low-density abnormality measuring 2.5 cm in length in the right orbit and parasellar region. Magnetic resonance imaging clearly revealed a low-intensity structure extending from the orbit to the prepontine area. Surgical exploration was emergently performed and the wooden fragment was removed. The postoperative course was uneventful. Transorbital penetrating injury by a wooden foreign body is relatively rare. The wound may be superficial and trivial. Major neurological deficit does not usually manifest immediately, so the penetrating injury may be overlooked. If the foreign body is retained in the orbit and cranium, severe infectious complications may occur later.

Bilateral internuclear ophthalmoplegia following mild head injury

A 7-year-old child presented with bilateral internuclear ophthalmoplegia (INO) following a trivial head injury. CT was normal. MRI revealed a pontine lesion. Two months after the injury the patient was neurologically normal. INO following head injury is rare. Rarer still is INO following mild head injury. To date, only four cases of INO had been reported following mild head injury; the present case is the fifth and the first in which the lesion was documented using MRI. The relevant literature is reviewed.

Pontine axonal injury after brain trauma and nontraumatic hypoxic-ischemic brain damage

Experimental studies have shown that diffuse axonal injury is usually induced by positive or negative acceleration mechanisms. In order to determine the reliability of axonal injury (AI) as a marker of this type of traumatic insult, we compared cases of trauma-induced focal cortical hemorrhage without dural involvement (n = 67) with cases of trauma-induced subdural bleeding without cortical hemorrhage (n = 26). Both groups exhibited a wide range of post-traumatic survival times. The injuries in the first group were caused mainly by direct impact to the head, those in the second by acceleration/deceleration mechanisms. The investigations were based primarily on immunohistochemical demonstration of antibodies targeted to beta-amyloid precursor protein (beta-APP) in the pons as a marker of AI and the results were assessed semiquantitatively. No significant differences were found between the two groups. In both groups AI was detected in 80-100% of cases with survival times of more than 3 h and two thirds of all positive cases showed pronounced positivity. Additional comparison of cases of brain death due to mechanical trauma (n = 14) with cases of brain death due to non-mechanical trauma (n = 18) also disclosed no significant intergroup differences. Finally, investigations of the pons in cases of non-traumatic death due to cerebral hypoxia/ischemia (n = 51) demonstrated AI with the same frequency as in the other groups, although the expression tended to be less pronounced. Our results confirm that beta-APP expression in the pons is a reliable indicator of AI but does not discriminate between injuries caused by traumatic strain or shearing mechanisms and secondary damage due to cerebral hypoxia/ischemia or edema. In the large majority of cases with prolonged post-traumatic survival, it can therefore be assumed that AI in the pons is the consequence of primary and/or secondary events or a combination of both, as is common in non-missile head injury survived for more than 90-120 min. Therefore, positive differentiation of the type of biomechanical event based on this criterion alone is not possible.

Peripheral facial palsy: etiology, diagnosis and treatment

Treatment options for peripheral facial palsy (PFP) are an often discussed problem in neurologic practice. Following a short description of the complex anatomy of the seventh cranial nerve we therefore review possible etiologies in the context of leading clinical signs, with idiopathic PFP or Bell's palsy (BP) being most frequent. A rather typical clinical course of BP allows to focus differential diagnostic workup predominantly on the rapid identification of treatable infections such as with Herpes zoster or Borrelia burgdorferi. Neuroimaging studies are needed only in case of trauma, with slowly developing PFP or in the presence of associated signs and symptoms. As BP is characterized by an overall high rate of spontaneous recovery, major emphasis has to be put on avoiding complications by protecting the eye. Meta-analysis of four randomized controlled studies suggests a marginal benefit of steroids concerning eventual achievement of complete recovery. Beneficial effects of a combination of acyclovir and prednisone have also been claimed. While such therapies may be considered in patients with a presumptive bad prognosis, more general recommendations on medical treatment of BP will have to await further trials.

Frontal syndrome as a consequence of lesions in the pedunculopontine tegmental nucleus: a short theoretical review

In this review, it is argued that the consequence of bilateral damage to the pedunculopontine tegmental nucleus (PPTg) in experimental animals is the production of a form of frontal syndrome. Frontal syndrome is a term used to describe the behavioural consequences of damage to the frontal lobes in human patients. These behavioural changes can be classified as disinhibition of behaviour (a release of behavioural control), the production of inappropriate behaviour (which in patients can be either inappropriate actions or verbal behaviour), and the production of perseverative behaviour (the maintenance of an action beyond the point at which it should have been terminated). The psychological changes which underlie these behavioural changes are thought to involve executive functions, which include such things as the prospective planning of sequences of actions, attentional shifting and working memory. In this review, I attempt to demonstrate two things: first, that there are significant anatomical connections from frontostriatal systems to the PPTg. The motor cortex projects directly to the PPTg while the prefrontal cortex contacts it via striatal circuitry, forming clear routes by which the frontal lobes can communicate with the PPTg. Second, having established the existence of connections between frontostriatal systems and the PPTg, behavioural data are described. Experimental animals bearing bilateral lesions of the PPTg have been examined in a wide variety of tasks. Animals bearing such lesions are not impaired in basic processes of feeding, drinking, locomotion, or grooming and simple observation of lesioned rats' normal behaviour reveals no obvious gross impairment in function. However, the results of more subtle tests reveal a wide variety of deficits in various tasks. The outcome of these experiments are in many ways contradictory, but in the vast majority of cases, the changes can be described as involving disinhibition of behaviour, the release of inappropriate behaviour, and the production of perseverative behaviour. Anatomical and behavioural data support the conclusion that there are functional connections between frontal systems and the PPTg. This review also discusses what psychological processes might be served by such connections.

Brain stem contusion due to tentorial coup injury: case report and pathomechanical analysis from normal cadavers

This report is in two parts. First, a case report on a 20-year-old man with a localized brain stem contusion. Second, in order to elucidate the mechanism of this injury, an anatomical study was performed. Ten cadaver heads were analysed to reveal the variations of spatial anatomy around the tentorial incisura. The lateral tentorial incisura (lateral to brain stem) was situated at the level of pontomesencephalic junction and nearest to the brain stem along its course. The shortest distance between them averaged 1.0 mm (0-4 mm). Based on these findings, primary brain stem injury caused by tentorial incisura occurs at its lateral portion due to the shortest distance to the brain stem and near the level of pontomesencephalic junction. In patients with a tentorial incisura closely related to or touching the brain stem, tentorial coup injury to the brain stem may occur even with a relatively minor injury. In our case, repeated CT and MRI proved that the location of contusion was at the pontomesencephalic junction, coinciding with the level of the tentorial edge. The injury started at the surface of brain stem. The tentorial edge was close to brain stem in this case. These radiological findings support the hypothesis that the brain stem contusion was caused by a tentorial coup injury.

Hyperthermia in brain hemorrhage

Hemorrhage in the midbrain and/or pons in patients is often associated with increased metabolism, resulting in hyperthermia. We have recently reported that hyperthermia develops in anesthetized rats following prepontine knife-cuts or procaine microinjections into the midbrain or upper pontine region. It was concluded that the hyperthermia in the animals was caused by the removal of a tonic inhibitor mechanism of heat production that exists in the lower midbrain. The present paper proposes a new hypothesis that the hyperthermia in patients with brainstem hemorrhage is caused by disinhibition of heat production due to the release of such a lower-midbrain mechanism.

Traumatic ponto-medullary tear: a case report

The aim of this report is to demonstrate the correlation between an extremely short time acting but strong force leading to incomplete rupture of the ponto-medullary junction (PMJ) accompanied by rupture of the basilar artery. Potential mechanisms involved in a combined hyperextension and axial torsion of the head followed by characteristic lesions at the PMJ are discussed. A 33-year-old male suffered a blunt head injury following a blow to the head, i.e. a head-butt. Resuscitation was performed for 45 min without success. At post mortem, there was a superficial periorbital haematoma on the right and a deep soft tissue bruise in the right fronto-parieto-temporal area, but no evidence of skull or dens axis fracture. A deep tear at the ponto-medullary junction was identified with rupture of the basilar artery, whereas at the tip of the tear, i.e. the floor of the IVth ventricle, only a thin tissue layer of about 2 mm remained intact. In contrast to the severity of these lesions, only mild subarachnoid hemorrhage was observed, but the ventricular system was filled with blood clot resulting from the retrograde flow of subarachnoid hemorrhage.

Pontomedullary rent. A specific type of primary brainstem traumatic injury

Pontomedullary rent is a primary injury to the brainstem that may occur in high-speed accidents. We present a series of 13 autopsies with complete or partial pontomedullary rent documented over a 12-year period. Of the 13 cases, seven had associated basal skull fractures and three had fractures of the cervical spine. In five patients, the rent was an isolated traumatic lesion of the brain. While pontomedullary rents are mostly caused by traumatic craniocervical hyperextension, some authors feel that these rents could be a form of diffuse axonal injury caused by angular acceleration of the head. In this study, two patients had documented features of diffuse axonal injury. More than one mechanism of injury could therefore be involved. Pontomedullary rents could be underdiagnosed, as partial rent is compatible with survival and, when there are no associated fractures, these tears may be attributed to artifactual damage occurring during removal of the brain at autopsy.

Persistence of distal motor control in the locked in syndrome. Review of 11 patients

We report 11 patients with the locked in syndrome (LIS). The functional outcome was good in four patients with notable motor recovery, but motor deficit remained seriously disturbed in seven patients. All of the patients regained some distal control of finger and toe movements, often allowing functional use of a digital switch. The independence thereby gained is worthwhile, in some patients allowing environment control, communication by means of a computer, and electric wheelchair ambulation. When motor recovery occurs, the progression is disto-proximal with dramatic axial hypotonia. In five patients clinical insomnia was noted and polysomnography showed a reduction of REM sleep. The implications of systems other than the pyramidal tracts in the physiopathology of LIS are discussed.

Posttraumatic primary brainstem haematoma

Nine cases of posttraumatic primary brain stem haematoma are described. All cases presented ocular and vegetative symptoms. Hyperextension was regarded as the most likely mechanism of injury. All patients were treated conservatively; half of them with a good outcome.

Effect of ambient temperature on sleep-waking cycle in cats with electrolytic dorsolateral pontine tegmental lesions

The effects of ambient temperature on the sleep-waking cycle were studied in intact cats and those with bilateral electrolytic lesions in the pontine tegmentum. At a room temperature of 23 degrees C, the percentage of time spent in paradoxical sleep was significantly lower in the lesioned cats than in intact animals. The mean duration of paradoxical sleep episodes was also decreased in the lesioned animals. The reduction in slow-wave sleep was not significant. At a slightly warmer ambient temperature of 30 degrees C, both the mean duration of paradoxical sleep episodes and the total duration of paradoxical sleep in the lesioned animals were increased toward normal values. Slow-wave sleep increased slightly but not significantly. At a higher ambient temperature of 35 degrees C, as well as at colder ambient temperatures of 15 and 7 degrees C, the durations of both paradoxical sleep and slow-wave sleep were significantly reduced. Under these thermal loads, the reduction in the duration of sleep was significantly greater in the lesioned cats than in the intact animals. The results suggest that: (i) pontine lesions alter the sleep cycle of cats and ambient temperature influences this alteration; (ii) the effects of thermal loads on the sleep cycle are more severe in the lesioned cats; and (iii) a moderately warm ambient temperature (30 degrees C) improves the sleep of pontine-lesioned cats.

Altered striatal dopaminergic metabolism 36 hours after unilateral trauma to the human mesencephalon

Markers of dopaminergic synaptic activity and choline acetyltransferase (CAT) were measured in the putamen and caudate nucleus of a patient who lived 36 hours after a unilateral mechanical lesion of the mesencephalon. After cessation of impulse flow along the nigrostriatal tract, dopamine was elevated, dihydroxyphenylacetic acid was diminished, and CAT and tyrosine hydroxylase activity were enhanced in the putamen ipsilateral to the lesion. [3H]-spiperone binding indicated an increase in D2-dopamine receptor density in the caudate nucleus. These findings indicate that the changes predicted from experimental neurochemical models occur in human nigrostriatal systems.

Cochlear nucleus lesions in the adult gerbil: effects on neurone responses in the contralateral inferior colliculus

Unilateral cochlea ablation in neonatal gerbils has previously been shown to result in transneuronal degeneration of the ventral cochlear nucleus (CN) and enhanced responses of neurones in the contralateral inferior colliculus (IC) to ipsilateral stimulation of the non-ablated ear. Neither effect occurs in adult-ablated animals. To determine whether the lack of physiological change in the adult is due to the persistence of the ventral CN we lesioned the left CN of adult gerbils and recorded neurone responses in the right IC to stimulation of the right ear. Neurone thresholds, latency and intensity/response functions were unaffected by the lesion. The proportion of recording loci in the IC at which excitatory responses were obtained was also unaffected. A transient increase was observed in the maximum unit discharge level. The findings suggest that CN lesions in adults do not produce either the range or degree of neuronal changes resulting from neonatal cochlea ablation and the subsequent transneuronal degeneration of the CN. Thus, the effects of cochlea ablation are age-dependent.

Prolonged survival after severe traumatic injury limited to the brainstem

It has been suggested that primary traumatic lesions of the brainstem do not occur in the absence of widespread injury to other parts of the brain. We describe a patient who suffered a severe head injury that left him with paralysis of three extremities and weakness in the fourth. Intellectual function was entirely preserved. Neuropathological examination 39 years after the injury disclosed the presence of a cavitary lesion within the basis pontis. There was no pathological evidence of traumatic injury to any other part of the central nervous system.

Gunshot wound to the pons with functional neuroanatomical and electrophysiological correlation

We describe a patient with a gunshot wound to the brain that traversed the left cerebellar hemisphere and terminated in the left lateral midpons. The clinical findings, operative course, neuroradiographic features, and evoked potential data are correlated with the functional anatomy of the pons. It is possible to demonstrate that a local lesion in the lateral pons causes a hemiparesis, worse in the upper extremity, thus suggesting a somatotopic localization of the pontine corticospinal tract not previously described.

Traumatic brain stem haematoma without prolonged loss of consciousness

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Superior oblique paresis and contralateral Horner's syndrome

A superior oblique paresis with contralateral oculosympathetic paresis may occur with a lesion at the dorsolateral pontomesencephalic junction.

Ponto-medullary avulsion associated with cervical hyperextension

19 cases of partial or complete ponto-medullary avulsion are reported. This type of damage seems to be produced by severe hyperextension of the head on the neck with or without an additional rotational component.

Survival after ponto-medullary junction trauma

Four cases with partial avulsions of the ponto-medullary junction resulting from a head injury with survival from 8 to 26 days are reported. Such lesions are not necessarily immediately fatal and they must be looked for specifically postmortem.

Auditory dysfunction following a gunshot wound of the pons

A patient with a gunshot wound penetrating the right side of the brainstem at the level of the pons was given a test battery to evaluate peripheral hearing function and central auditory processing abilities. A month later, the left ear had a loss of sensitivity for high frequency tones, decreased speech discrimination, and excess tone decay. Two years later these deficits had resolved. However, a central auditory impairment remained, affecting the right ear score on Binaural Fusion and left ear scores on dichotic tasks and tonal pattern sequences.

Breathing alterations in head injured patients

Breathing abnormalities in patients affected by acute cerebral damage are herein studied as neurological signs of localizing value for the neurological diagnosis of the level of the lesion. Incidence and types of abnormal breathing pattern correlate with neurological syndromes, and in a given neurological syndrome the presence of these alterations entails a more severe outcome. Tachypnea shows the most significant correlations from a diagnostic and prognostic point of view.

Survival after traumatic ponto-medullary tear

Two children (aged 10 and 12 years) were admitted unconscious to the neurosurgical department after traffic accidents. Both developed a 6th nerve paralysis on the next day. One patient was able to communicate from the 2nd day and died on the 8th day in an anuric state without major neurological deficit. The second patient remained deeply comatose, tetraplegic, and required intermittent artificial respiration: She died of pneumonia on the 26th day. Neuropathological examination revealed a ponto-medullary rent in each case: additionally there was avulsion of small arteries over the pyramids, haemorrhage and small focal infarcts in the distribution of perforating arteries in the medulla and pons, and abundant retraction balls in longitudinal fibre tracts of the brain stem. The cases show for the first time that traumatic ponto-medullary tears are not always rapidly fatal, and demonstrate that primary focal brain stem trauma may occur in the absence of diffuse trauma of the white substance.

Pontine gaze paresis due to traumatic craniocervical hyperextension. Report of two cases

Pontine gaze paresis is frequently due to tumor of the brain stem. Occasionally it may be caused by inflammation or ischemia. Two cases are reported, each with pontine gaze paresis and other signs of lower brain-stem injury, basal skull fractures, and second cervical vertebra fractures. This pattern of injuries is believed to be the result of craniocervical hyperextension with stretch injury to the brain stem at the junction of the medulla and pons.

Traumatic lesions of pontomedullary junction

An autopsied series of 162 consecutive fatal head injuries was analyzed for location and type of primary brain stem injury. Of 41 cases with primary brain stem injury, 24 (59%) demonstrated 22 tears and 2 complete transections at the level of the pontomedullary junction. Three cases are presented in detail to illustrate the range of structural and functional damage seen with trauma at this level of the brain stem. A pathologically verified case of traumatic "locked-in" syndrome is reported, including serial brain stem auditory evoked responses that are correlated with the neuropathological findings. In addition, two cases of primary traumatic damage at the pontomedullary junction (one tear and one total transection) are described; these were associated with instantaneous death at the time of injury. Pathophysiologically, the tearing or disruption occurring at this level results from rapid hyperextension, which produces stretching at the pontomedullary junction.

Unilateral gunshot wound of the pons: clinical, electrophysiologic, and neuroradiologic correlates

Following a gunshot wound to the face, a 17-year-old male patient experienced a right trigeminal and abducens paralysis, dysarthria, right-sided ataxia, left-sided weakness of the lower part of the face and limbs, and left-sided sensory loss from his neck down. Brainstem auditory evoked potentials showed a decreased P5/P1 amplitude ratio for left ear presentation, and inconsistent replication of P2 and P3 on the right and, to a lesser extent, on left ear click presentations. A computerized tomography scan showed right pontine atrophy. These findings point to a unilateral lesion of the right pons.

Blink reflexes in severe traumatic coma

Blink reflexes were studied in 21 patients in coma after severe head injury. Our observations suggest that blink reflexes are a simple, objective, neurophysiological test to evaluate brainstem function. Correlations between these reflexes and the anatomoclinical stanges of coma and the Glasgow coma scale have been established. Presence of the early R1 component shows the integrity of at least a part of the pontine structures. The appearance of the late R2 component is correlated with a better chance of recovery from coma.