Brainstem reflex circuits revisited

Our current understanding of brainstem reflex physiology comes chiefly from the classic anatomical-functional correlation studies that traced the central circuits underlying brainstem reflexes and establishing reflex abnormalities as markers for specific areas of lesion. These studies nevertheless had the disadvantage of deriving from post-mortem findings in only a few patients. We developed a voxel-based model of the human brainstem designed to import and normalize MRIs, select groups of patients with or without a given dysfunction, compare their MRIs statistically, and construct three-plane maps showing the statistical probability of lesion. Using this method, we studied 180 patients with…

P25. Sensitivity of imaging and electrophysiological brainstem testing in the diagnosis of acute vertebrobasilar ischemia

The course of corticofacial projections in the human brainstem.

Transcranial magnetic stimulation was used to investigate the corticofacial projections in 53 patients with (n = 28) and without (n = 25) central facial paresis due to unifocal ischaemic lesions at different brainstem levels. Lesion topography documented by MRI studies was correlated with the electrophysiological findings. In the majority of patients the corticofacial fibres travel within the ventromedial base of the pons and cross the midline at the level of the facial nucleus. In some individuals, however, we found evidence that corticolingual fibres form an 'aberrant bundle' in a paralemniscal position at the dorsal edge of the pontine base. In other patients the corticofacial fibres loo…

Topodiagnostic implications of hemiataxia: An MRI-based brainstem mapping analysis

The topodiagnostic implications of hemiataxia following lesions of the human brainstem are only incompletely understood. We performed a voxel-based statistical analysis of lesions documented on standardised MRI in 49 prospectively recruited patients with acute hemiataxia due to isolated unilateral brainstem infarction. For statistical analysis individual MRI lesions were normalised and imported in a three-dimensional voxel-based anatomical model of the human brainstem. Statistical analysis revealed hemiataxia to be associated with lesions of three distinct brainstem areas. The strongest correlation referred to ipsilateral rostral and dorsolateral medullary infarcts affecting the inferior ce…

L�sionsverteilung von Hirnstamminfarkten im MRT

Seit langer Zeit sind typische Hirnstammsyndrome bekannt. Eines der haufigsten ist das Wallenberg- Syndrom bei dorsolateralem Medulla-oblongata-Infarkt. Ursache ist hier meist ein Verschluss der ipsilateralen PICA. Die Vielzahl der Syndrome auf der einen Seite sowie die Klassifikation der Hirnstamminfarkte in Gruppen andererseits konnen als Hinweis darauf angesehen werden, dass die Hirnstamminfarkte regelmasig bestimmte Territorien und Gebiete bevorzugen. Inwieweit diese Hypothese zutrifft, sollte an einem Patientenklientel mit akuten Hirnstamminfarkten untersucht werden. Ziel unserer Arbeit war die Darstellung typischer Lasionsverteilungen bei Patienten mit akutem Hirnstamminfarkt. Bei 117…

Topodiagnostic significance of hemiataxia: An MRI based mapping analysis

Abolished laser-evoked potentials and normal blink reflex in midlateral medullary infarction.

We investigated two patients presenting with the rare finding of almost isolated hemianalgesia with a sensory level on the contralateral side sparing the face. Clinical findings, electrophysiological studies (absent laser-evoked pain-related somatosensory potentials, normal electrically evoked somatosensory potentials, magnetically evoked potentials, and blink reflexes), and magnetic resonance imaging showed the ventrolateral medullar tegmentum containing the spinothalamic tract to be affected by lacunar infarction. The blink reflex R2 component was unimpaired in both patients.

Seventh nerve palsies may be the only clinical sign of small pontine infarctions in diabetic and hypertensive patients

Backgroud: Small brainstem infarctions are increasingly recognized as a cause of isolated ocular motor and vestibular nerve palsies in diabetic and/or hypertensive patients. This raises the question whether there are also isolated 7th nerve palsies due to pontine infarctions in patients with such risk factors for the development of cerebrovascular diseases. Methods: Over an 11-year-period, we retrospectively identified 10 diabetic and/or hypertensive patients with isolated 7th nerve palsies and electrophysiological abnormalities indicating pontine dysfunction. All patients had examinations of masseter and blink reflexes, brainstem auditory evoked potentials, direct current electro-oculograp…

An educational multimedia campaign improves stroke knowledge and risk perception in different stroke risk groups.

Background and purpose:  Stroke risk factor knowledge and individual risk perception are low in the general public. Our study aimed at identifying the educational effects of a multimedia campaign on stroke knowledge and risk perception in several subgroups at increased risk of stroke. Methods:  Telephone surveys were administered in a random sample of 500 members of the general public, before and immediately after an intense 3 months educational campaign using various mass and print media. Results:  A total of 32.7% of respondents considered themselves as being at risk of stroke before, and 41.9% (P < 0.01) after the intervention. Evaluation of stroke risk increased with number of appreciat…

A new method to investigate brain stem structural-functional correlations using digital post-processing MRI - reliability in ischemic internuclear ophthalmoplegia

We investigated the reliability of a new digital post-processing magnetic resonance imaging (MRI) technique in ischemic brain stem lesions to identify relations of the lesion to anatomical brain stem structures. The target was a medial longitudinal fasciculus (MLF) lesion, which was evident from ipsilateral internuclear ophthalmoplegia (INO). Sixteen patients with acute unilateral INO and an isolated acute brain stem lesion in T2- and EPI-diffusion weighted MRI within 2 days after the onset of symptoms were studied. The MRI slice direction was parallel and perpendicular to a slice selection of a stereotactic anatomical atlas. The individual slices were normalized and projected in the digita…

Blink reflex R2 changes and localisation of lesions in the lower brainstem (Wallenberg's syndrome): an electrophysiological and MRI study

OBJECTIVES—Pathways of late blink reflexes are detected by high resolution MRI. Electronically matched stroke lesions superimposed to an anatomical atlas show the suspected course. METHODS—Fifteen patients with infarction of the lower brainstem, MRI lesions and electrically elicited blink reflexes were examined. The involved structures in patients with R2 and R2c blink reflex changes were identified by biplane high resolution MRI with individual slices matched to an anatomical atlas at 10 different levels using digital postprocessing methods. RESULTS—The blink reflexes were normal in five of 15 patients (33%) and showed loss or delay of R2 and R2c to stimulation ipsilaterally to lesion (R2-…

3.4. Functional brainstem infarction studies: Previous results and new ways of lesion coregistration

A novel SP-1 site in the human interleukin-1β promoter confers preferential transcriptional activity in keratinocytes

To investigate the mechanisms of transcriptional activation of interleukin-1beta (IL-1beta) in non-monocytic cells, we constructed a series of reporter plasmids with the bacterial chloramphenicol acetyltransferase gene linked to various parts of the human IL-1beta promoter and performed transient transfection experiments. We identified a promoter segment that activates transcription most efficiently in keratinocytes. Electrophoretic mobility shift assays (EMSA) with a 43-mer oligonucleotide derived from the functionally identified cis-acting element revealed specific complexes. By competition analysis with transcription factor consensus sequence oligonucleotides and by immunosupershift, tra…

Diffusionsgewichtetes MRT bei vertebrobasil�ren Isch�mien

The aim of this study was to evaluate the applicability, sensitivity, and predictive power of diffusion-weighted MR imaging (DWI) in the diagnosis of vertebrobasilar infarction. From 1997 to 2002, we prospectively recruited 268 patients with acute signs and symptoms suspective of vertebrobasilar ischemia. The patients underwent biplanar EPI-T2 and EPI DWI within 24 h after onset of symptoms and high-resolution MRI as a control within 7 days. One hundred twenty-one patients had additional CT scanning. The DWI revealed acute vertebrobasilar infarction in 71.0%. The mean time exposure of DWI was 8 min and thus no more than that of CT imaging. It showed significantly more acute lesions than CT …

16. Increasing clinical variety of brainstem infarcts

Electrophysiological brain stem investigations in idiopathic narcolepsy.

Narcolepsy is associated with various rapid eye movement (REM) sleep abnormalities. Distinct brain stem areas seem to play a prominent role in REM sleep regulation. Recent magnetic resonance imaging (MRI) studies have led to conflicting findings concerning the presence of structural brain stem lesions in patients with idiopathic narcoleptic syndrome. However, multimodal electrophysiological brain stem investigations may reveal functional brain stem abnormalities even in the absence of MRI abnormality. Therefore we investigated brain stem function in 12 idiopathic narcoleptic patients by systematically studying tegmental brain stem pathways. All of the patients met the diagnostic criteria of…

A topodiagnostic investigation on body lateropulsion in medullary infarcts.

Body lateropulsion may occur without signs of vestibular dysfunction and vestibular nucleus involvement. The authors examined 10 such patients with three-dimensional brainstem mapping. Body lateropulsion without limb ataxia reflected an impairment of vestibulospinal postural control caused by a lesion of the descending lateral vestibulospinal tract, whereas body lateropulsion with limb ataxia was probably the consequence of impaired or absent proprioceptive information caused by a lesion of the ascending dorsal spino-cerebellar tract.

Diffusion weighted magnetic resonance imaging in the diagnosis of reversible ischaemic deficits of the brainstem

Objectives: To evaluate the sensitivity of diffusion weighted magnetic resonance imaging (MRI) for the diagnosis of clinically suspected reversible ischaemic deficits of the brainstem. Methods: A total of 158 consecutive patients presenting with acute signs of brainstem dysfunction were investigated using EPI diffusion weighted MRI within 24 hours of the onset of symptoms. High resolution T1 and T2 weighted imaging was performed as a follow up after a median of six days Results: Fourteen of the 158 patients had a complete clinical recovery within 24 hours (transitory ischaemic attack (TIA)), and 19 patients recovered in less than one week (prolonged reversible neurological deficit (RIND)). …

Isolated voluntary facial paresis due to pontine ischemia

We describe a patient withpatientwith isolated voluntary facial paresis due to a unilateral lacunar lesion in the contralateral mediodorsal middle base of the pons. Transcranial magnetic stimulation confirmed the involvement of supranuclear corticofacial tract fibers and sparing of the corticolin-gual and corticospinal connections. This observation demonstrates that the fibers conveying voluntary orofacial activation descend mediodorsally at the level of the middle pons and that the fibers conveying emotional activation may be assumed to converge below this level.

Mechanisms and predictors of chronic facial pain in lateral medullary infarction

The purpose of this study was to identify clinical predictors and anatomical structures involved in patients with pain after dorsolateral medullary infarction. Eight out of 12 patients (67%) developed poststroke pain within 12 days to 24 months after infarction. The pain occurred in the ipsilateral face (6 patients) and/or the contralateral limbs and trunk (5 patients, 3 of whom also had facial pain). Ipsilateral facial pain was significantly correlated with lower medullary lesions, including those of the spinal trigeminal tract and/or nucleus, as documented by magnetic resonance imaging. The R2 blink reflex component was abnormal only in patients with facial pain. Likewise, pain and temper…

FMRI of the Cerebellum: Rostral Paravermal Activation in Tongue and Lip

We investigated with fMRI the cerebellar representation of articulatory vertical movements of the tongue and orofacial muscles in healthy volunteers and its correspondence to the area known to be affected in cerebellar dysarthria. fMRI stimulation is mainly unilateral in agreement with the frequent occurrence of dysarthria in unilateral infarction.

P14. Impaired balance with brain stem infarcts

17. Masseter reflex abnormalities with meso-diencephalic lesions

different papers and some eponyms used to characterize a certain neurological state differ from the original description. Except for Wallenberg‘s syndrome, classical brainstem syndromes are rarely seen in clinical practice. Lacunar brainstem syndromes are the consequence of infarcts, which involve long tracts and spare intra-axial cranial nerve segments. This group includes pure motor or pure sensory stroke, dysarthriaclumsy hand syndrome, or ataxic hemiparesis. Such infarcts may also cause body lateropulsion with or without limb ataxia, internuclear ophthalmoplgia, skew-torsion sign, or ocular tilt reaction. Small deep infarcts, which solely affect certain nuclei, may be followed by horizo…

1.2. 3-D brainstem mapping

Therapy of Early Poststroke Depression With Venlafaxine: Safety, Tolerability, and Efficacy as Determined in an Open, Uncontrolled Clinical Trial

To the Editor: The development of persistent depressive symptoms is a severe and frequent complication of ischemic or hemorrhagic stroke.1 The etiology of poststroke depression is not well understood. Only few placebo-controlled, double-blind studies have been carried out, all reporting various degrees of superiority of standard antidepressants over placebos.1 2 On the other hand, serious side effects have been reported.3 4 In most of these studies, patients were examined whose stroke had occurred several weeks to several months before the antidepressive therapy was started. Antidepressive therapy in the first weeks after stroke has not yet been attempted in studies. Drug-induced improvemen…

Medullary infarcts may cause ipsilateral masseter reflex abnormalities.

There is a suprasegmental influence on the masseter reflex (MassR) in animals, which is mediated via the fifth nerve spinal nucleus (5SpN). Corresponding data in humans are lacking. Out of 268 prospectively recruited patients with clinical signs of acute brainstem infarctions, we identified 38 with magnetic resonance imaging (MRI)-documented unilateral infarcts caudal to the levels of the fifth nerve motor and main sensory nuclei. All had biplanar T2- and echo planar diffusion-weighted MRI and MassR testing. Five patients (13%) had ipsilateral MassR abnormalities. In all, the infarcts involved the region of the 5SpN. Patients with medullary infarcts involving the region of the 5SpN may thus…

An Artificial Neural Network for 3D Localization of Brainstem Functional Lesions

The human brainstem is a highly complex structure where even small lesions can give rise to a variety of symptoms and signs. Localizing the area of dysfunction within the brainstem is often a difficult task.To make localization easier, we have developed a neural net system, which uses 72 clinical and neurophysiological data inputs and displays it (using 5268 voxels) on a three-dimensional model of the human brainstem. The net was trained by means of a back-propagation algorithm, over a pool of 580 example-cases. Assessed on 200 test-cases, the net correctly localized 83.6% of the target voxels; furthermore the net correctly localized the lesion in 31/37 patients. Because our computer-assist…

Ipsilateral facial weakness in upper medullary infarction-supranuclear or infranuclear origin?

We describe two patients with upper medullary infarctions showing ipsilateral facial weakness and relative sparing of the upper facial muscles. Electrophysiological follow-up using transcranial magnetic stimulation of the motor cortex in combination with stimulation of the peripheral facial nerve disclosed a supranuclear (corticofacial) tract lesion in one patient and a partial nuclear/infranuclear intra-axial facial nerve lesion in another.

Chapter 15 Pain and itch in Wallenberg's syndrome: anatomical–functional correlations

Publisher Summary The Wallenberg syndrome or dorso-lateral medullary infarction is the most common vascular syndrome of the medulla oblongata. Its clinical features include an ipsilateral Horner's syndrome, an ipsilateral limb ataxia, and mostly an ipsilateral but sometimes also a contralateral or bilateral decrease of pain and temperature sensibility of the face. Patients with Wallenberg's syndrome and with morphological (lesion) or functional (ipsilateral sensory deficit and delayed late blink reflex responses) show evidence of damage to the trigeminal tract and nucleus with sparing of the nucleus caudalis would develop facial pain. The trigeminal trophic syndrome (TTS), a very rare compl…

Long term follow up after percutaneous closure of PFO in 357 patients with paradoxical embolism: Difference in occlusion systems and influence of atrial septum aneurysm

Abstract Background Percutaneous transcatheter closure of patent foramen ovale (PFO) in cryptogenic stroke or TIA is an alternative to medical therapy especially in patients with atrial septal aneurysm (ASA). The differences in time to complete occlusion for various closure devices in PFO alone and PFO plus ASA are of natural interest. Methods and results Between January, 1st 1998 and November, 30th 2006 percutaneous PFO closure was performed in 357 patients with a history of ≥1 paradoxical embolism using three different devices: Amplatzer PFO-( n =199), Starflex-( n =48) and Helex Occluder ( n =110). All patients were assigned to a post-interventional protocol with contrast-enhanced transe…

P24. Classical brain stem syndromes: Myth or reality?