Pontine anosognosia for hemiplegia.

Four patients had anosognosia for hemiplegia (AHP) as a manifestation of pontine infarction in the mediolateral region. Patients with AHP syndrome had no mental and neuropsychologic disturbances, and all had involvement of the medial or lateral part of the pons (medial or lateral pontine reticular nuclei). Brainstem lesions, which activate frontoparietosubcortical areas, may be a critical factor in the development of AHP syndrome.     

Basilar branch pontine infarction with prominent sensory signs

We identified 10 patients with acute pontine infarction and specific sensory findings. Two patients had pure sensory symptoms, two had sensory complaints of the hand and mouth, and the other six had hemisensory loss referable to medial lemniscal or spinothalamic tract dysfunction but localized to one limb, to an arm and leg, or to the face, characteristic of stroke localized to the cerebral hemisphere. All patients had magnetic resonance imaging showing infarction of the medial or lateral pontine tegmentum and a patent basilar artery. No definite source for cardiogenic thromboembolism was found. Infarcts in the midline extending from the base of the pons posteriorly into the tegmentum suggested basilar branch occlusion, while infarcts involving only part of the tegmentum probably resulted from small penetrator branch occlusion. Vertigo, light-headedness, or cranial nerve dysfunction suggested a pontine location of neurological dysfunction in these patients, but the nature of the sensory findings did not always predict the lateral, medial, inferior, or superior extent of tegmental infarction.     

Wall-Eyed Monocular Internuclear Ophthalmoplegia (WEMINO) with Contraversive Ocular Tilt Reaction

Wall-eyed monocular internuclear ophthalmoplegia (WEMINO) with contraversive ocular tilt reaction has not been previously reported. A 71-year-old woman suddenly developed blurred vision. Examination revealed left internuclear ophthalmoplegia, left exotropia, right hypotropia, and rightward head tilt. Magnetic resonance imaging showed a tiny infarction at the area of the left medial longitudinal fasciculus in the upper pons. WEMINO with contraversive ocular tilt reaction may be caused by a paramedian pontine tegmental infarction that selectively involves the medial longitudinal fasciculus.     

A case of hemi-hyperhidrosis and non-paralytic pontine exotropia due to brainstem infarction]

A case of hemihyperhidrosis and non-paralytic pontine exotropia due to brainstem infarction is reported. A 55-year-old hypertensive man developed right hemiparesis with slight dysarthria and nausea upon awaking. The right side of his face and right upper limb and trunk to the level of the Th8-9 territory showed hyperhidrosis, which disappeared in a week. Ocular motor examination revealed that during forward gaze with the left eye fixing, the right eye deviated outward. The patient was able to adduct the right eye to midposition with the right eye fixing. Rightward gaze elicited full abduction and right-beating nystagmus of the right eye, but the left eye did not adduct. When he attempted to gaze leftward, both eyes made the full excursion, but saccades were slow in that direction. Convergence was intact. Vertical gaze was full, and he did not show Horner's sign. This ocular sign, non-paralytic pontine exotropia, disappeared three days later. T2-weighted spin echo magnetic resonance imaging disclosed a small lesion with high intensity in the inner side of the left middle pons. This hyperhidrosis was thought to be caused by destruction of inhibitory fibers thermoregulating sweating. These findings suggest that at the level of the middle pons inhibitory fibers descend along the inner side of facilitatory fibers thermoregulating sweating, which are speculated to descend the dorso-lateral part of the pontine tegmentum. These findings also suggest that lesions of non-paralytic pontine exotropia may be located in the paramedian pontine reticular formation rostral to the abducens nucleus with ipsilateral medial longitudinal fasciculus lesion, but further investigation is necessary.     

A case of brainstem and cerebellar infarctions related to basilar impression]

We report a 30-year-old man presenting with medial longitudinal fasciculus (MLF) syndrome after an afternoon nap. Magnetic resonance imaging revealed a right medial pontine tegmental infarction and right cerebellar infarctions. This patient was complicated with basilar impression detected on cervical X-ray and MRI. Three-dimensional CT angiography disclosed that the odontoid process migrated into the posterior fossa, thrusting the bilateral vertebral arteries postero-laterally. The mechanical stress on the bilateral vertebral arteries may have caused infarctions in the territories of the posterior circulation of this patient with basilar impression.     

Dissociated ipsilateral horizontal gaze palsy in one-and-a-half syndrome: a clinicopathologic study

We report a patient with a one-and-a-half syndrome due to an isolated small infarction in the left rostral part of the paramedian pontine reticular formation and the ipsilateral medial longitudinal fasciculus. Oculocephalic movements toward the left were preserved (dissociated ipsilateral horizontal conjugate gaze palsy).     

Isolated abducens nerve palsy caused by pontine infarction]

An 82-year-old hypertensive man suddenly developed diplopia during right lateral gaze. Neurological examination revealed right isolated abducens nerve palsy without any other findings. By cranial CT scan, a low density area over the posterior limb of right internal capsule and tortuosity of basilar artery were noted. 3 months later, his symptom disappeared and then he was well in next 2 years til he felt diplopia during left lateral gaze. On this time he showed left isolated abducens nerve palsy. Though cranial CT scan failed to find out new abnormality, T2-weighted cranial MRI disclosed high intensity spot over left pontine base located between medial lemniscus and pyramidal tract, which was supposed to coincide to fascicle of left abducens nerve Three months later, he recovered in the same manner as 2 years before. Hemilateral isolated abducens nerve palsy may be caused by many origins, but pontine infarct was not detected so much in pre-MRI era. Being the long-term prognosis of the lacunar infarction not satisfactory, it is important for the cases of isolated abducens palsy to ascertain whether there is pontine small infarction or not. So in these cases, precise examination including MRI should be needed.     

Jerky hemi-seesaw nystagmus and head tilt reaction combined with internuclear ophthalmoplegia from a pontine infarction

Internuclear ophthalmoplegia (INO) is a complex ocular motility disorder caused by damage to the medial longitudinal fasciculus. The occurrence of hemi-seesaw nystagmus in an INO patient has been reported rarely. This nystagmus may be caused by damage to the pathway from the contralateral vertical semicircular canal. The ocular tilt reaction is characterized by ipsilateral head and neck tilt, skew deviation, and ocular torsion. We report a patient who presented with hemi-seesaw nystagmus, ocular tilt reaction, and limb ataxia combined with an INO from a right focal pontine infarction. INO may be accompanied by a variety of ocular findings associated with the disruption of the medial longitudinal fasciculus.     

Retrograde double-labeling study of the mammillothalamic and the mammillotegmental projections in the rat

Collateral axonal branching from the medial or lateral mammillary nuclei to the anterior thalamus, Gudden's tegmental nuclei, the nucleus reticularis tegmenti pontis, and the medial pontine nucleus was studied using the fluorescent retrograde double-labeling method. One day after injection of Fast Blue into the anterior thalamic nuclei or Gudden's tegmental nuclei, Nuclear Yellow was injected into Gudden's tegmental nuclei or the nucleus reticularis tegmenti pontis and the medial pontine nucleus. Following 1 day survival, single- and double-labeled neurons were examined in the mammillary nuclei. The lateral mammillary nucleus contains neurons whose collateral fibers project to both the dorsal tegmental nucleus of Gudden and the ipsilateral or contralateral anterodorsal thalamic nucleus, to both the medial pontine nucleus and the anterodorsal thalamic nucleus, and to both the dorsal tegmental nucleus of Gudden and the medial pontine nucleus. The pars medianus and pars medialis of the medial mammillary nucleus contain neurons whose collateral fibers project to both the anteromedial thalamic nucleus and the ventral tegmental nucleus of Gudden, to both the anteromedial thalamic nucleus and the medial part of the nucleus reticularis tegmenti pontis, and to both the ventral tegmental nucleus of Gudden and the medial part of the nucleus reticularis tegmenti pontis. The dorsal half of the pars posterior of the medial mammillary nucleus contains a few neurons whose collateral fibers project to both the anteromedial thalamic nucleus and the rostral part of the ventral tegmental nucleus of Gudden, and to both the caudal part of the anteroventral thalamic nucleus and the rostral part of the ventral tegmental nucleus of Gudden, while the pars lateralis of the medial mammillary nucleus contains no double-labeled neurons and projects only to the anteroventral thalamic nucleus.     

A case of pontine infarction presenting with conjugate deviation and unilateral conjugate gaze palsy]

We reported a case of pontine infarction presenting with conjugate deviation and unilateral conjugate gaze palsy. A 75-year-old man was admitted to our hospital because of vomiting. On the day of admission, his neurological findings showed only conjugate deviation to the right without consciousness disturbance, hemispatial neglect, and hemiparesis. On day 5 after admission, the conjugate deviation to the right disappeared, but he could not gaze left with either of his eyes. The pathological lesions, therefore, were considered to be a unilateral paramedian pontine reticular formation (PPRF) and abducens nucleus. Diffusion-weighted imaging (DWI) on day 2 revealed a small high intensity lesion in the left paramedian pontine tegmentum. A diagnosis of brain infarction was made. A Holter electrocardiogram and electroencephalogram were normal. Transesophageal echocardiography disclosed ulcerated plaque in the aortic arch. This is the first case of pontine infarction presenting with conjugate deviation in which unilateral conjugate gaze palsy and DWI could confirm the pathological lesion.     

The correlation between vertebral artery asymmetry and pontine infarction--an MR angiography study]

The purpose of this study is to evaluate the correlation between variation of the vertebral artery (VA) and the incidence of pontine infarction. A total of 206 patients were examined using magnetic resonance imaging (MRI) and 3-dimension time-of-flight MR angiography (MRA) of the brain. Of these, 54 patients had pontine infarctions (23 symptomatic and 31 asymptomatic), and the majority of them were located in the pontine base. The sites of dominant lesion in the pons were right in 18 cases, left in 8 cases, and bilateral in 28 cases. The number of patients with VA asymmetry (the ratio of internal diameters 1:2 or more) were 89 (43.2%). Of these, 67 patients had small diametric VA of right side, and 22 of left side. Among the 117 patients with normal VA pattern, 19 (16.2%) had infarction, while among the 89 patients with VA asymmetry, 35 (39.3%) had infarction. The patients with small diametric VA of right side significantly had infarctions in the same side of the pons. The results of this study suggest that VA asymmetry is considered to be one of the risk factors of pontine infarction and that MRA can be useful in the examination of the cerebral artery as a valuable and non-invasive screening method.     

Neural generator of P14 far-field somatosensory evoked potential studied in a patient with a pontine lesion

Somatosensory evoked potentials (SEPs) to electrical stimulation of the right and the left median nerves were studied in a patient with a pontine lesion. At first there was mainly right medial lemniscus involvement. Four months later the left medial lemniscus was found to be also involved. SEPs to stimulation of the right median nerve had normal wave forms and latencies while N20 was lacking and P14 was abnormal after stimulation of the left median nerve in the first SEP record. N20 and P14 were absent with preservation of P9 and P11 after stimulation of both left and right median nerves in the second SEP record. Therefore the P14 component has been found abnormal, then absent, in a patient with a pontine lesion.     

后循环梗死患者的眼动及前庭功能评价

目的   评价眼动及前庭功能检查对后循环梗死（posterior circulation Infarction,PCI）患者的诊断价值。 方法  纳入22例PCI患者,收集其临床基线资料,包括性别、年龄、首发症状、高血压、糖尿病、吸烟、饮酒史及入院体征等相关指标。患者均行眼动检查：包括凝视试验（gaze test,GT）、扫视试验（saccade test,ST）、平滑跟踪试验（smooth pursuit test,SPT）、视动眼震检查（optokinetic nystagmus test,OPK）;前庭功能检查：包括自发眼震（spontaneous nystagmus,SN）、摇头试验（head shaking test,HST）、固视抑制检查,上述检查均应用眼震视图仪（videonystagmograph,VNG）进行记录。 结果  共纳入22例PCI患者,首发症状：15例（68.2%）为头晕/眩晕,7例（31.8%）为肢体无力麻木。眼动检查提示：异常19例（86.4%）,其中GT异常4例（18.2%）,ST异常11例（50.0%）,SPT异常15例（68.2%）,OPK异常12例（54.5%）。前庭功能检查提示：22例完成SN检查,其中SN阳性8例（36.4%）,包括小脑梗死4例,脑桥梗死3例,左侧延髓背外侧、双侧小脑半球及蚓部梗死1例;17例完成HST检查,其中HST阳性6例（35.3%）,包括小脑梗死2例,脑桥梗死2例,小脑及脑桥梗死1例,右侧小脑及延髓上段梗死1例;19例完成固视抑制检查,其中固视抑制失败8例（42.1%）,包括双侧小脑梗死1例,脑桥梗死4例,左侧延髓梗死1例,右侧小脑及延髓上段梗死1例,左侧延髓背外侧、双侧小脑半球及蚓部梗死1例。以头晕/眩晕为首发症状的患者与以肢体无力、麻木为首发症状的患者相比,眼动及固视抑制检查阳性率高（P分别为0.023和0.045）。 结论  小脑、延髓梗死的患者常以头晕/眩晕起病;眼动检查有助于筛查PCI患者;小脑梗死患者的病灶侧别常与自发、摇头眼震的水平成分一致;脑桥梗死患者HST后可诱发下跳眼震;脑桥、延髓梗死患者常固视抑制失败。     

Anosognosia for hemiplegia in a patient with pontine infarction]

We report a patient with anosognosia for hemiplegia associated with a right pontine infarction. A 51-year-old woman with histories of hypertension and diabetes mellitus was admitted because of weakness of her left upper and lower extremities. On neurologic examination, she was alert and oriented without dementia. Visuospatial hemineglect was not present. Hemiparesis of her left upper and lower extremities was noted. Her brain MRIs showed a large infarction in the right pons. On admission, she could recognize her illness but was indifferent to her hemiplegia, so she said that there was not well-off for her life. Two weeks after the onset, her neurological symptoms gradually improved. Simultaneously, her interest in her hemiparesis increased. We proposed that, in the present patient, anosognosia for hemiplegia was caused by the pontine infarction. Since pontine anosognosia for hemiplegia has been rarely reported to date, it is expected that the findings of the present patient will be useful to the better understanding of mechanisms underlying anosognosia.     

A case of pontine hemorrhage showing hemiasomatognosia]

We reported a case of pontine hemorrhage showing hemiasomatognosia. A 74-year-old, right-handed man was admitted to our hospital complaining of numbness of left upper and lower extremities. Neurological examination revealed marked disturbance of superficial and deep sensation of left half of his body without hemiparesis and consciousness disturbance. Neuropsychologically, he had experience of having lost the perception of his left upper limb, which was referred to "conscious hemiasomatognosia" by Frederiks. Brain CT and MRI showed a pontine hematoma involving the right medial lemniscus, the right spinothalamic tract and the right medial longitudinal fasciculus. One week after the onset, hemiasomatognosia disappeared with improvement of sensory disturbance. These indicate that this form of hemiasomatognosia may be associated with transient blockage of somesthetic input.     

Corticopontine projections from the cingulate cortex in the rhesus monkey

The corticopontine projections of the cingulate cortices were investigated in the rhesus monkey with the use of autoradiography. A well-organized topography of projections was observed with anterior cingulate cortex projecting to the medial part of the pontine gray matter and posterior cingulate cortex projecting to the lateral part. Together these projections form a circle of termination around the periphery of the pontine gray matter.     

Amygdaloid and pontine projections to the ventromedial nucleus of the hypothalamus

Amygdaloid and pontine projections to the feline ventromedial nucleus of the hypothalamus (HVM) were studied with retrograde transport of horseradish peroxidase (HRP) and anterograde transport of tritiated amino acids. Following injections of HRP into HVM, amygdaloid neurons were labeled in the ipsilateral cortical and medial nuclei and the ventral portion of the parvocellular part of the basal nucleus. In experiments in which HRP was injected into the tuberal hypothalamus following stria terminalis lesions, it was determined that amygdaloid neurons projecting to HVM by way of the stria terminalis were located in the cortical and medial nuclei while those projecting through another route, presumably the ventral amygdalofugal pathway, were found in the rostral part of the medial nucleus and the parvocellular basal nucleus. Following HRP injection into lateral hypothalamus at the level of HVM, labeled neurons were seen in the magnocellular basal nucleus. After preoptic injections, neurons containing the HRP reaction product were in cortical and medial nuclei and magnocellular and parvocellular parts of the basal nucleus. In addition to cells in the amygdala, rostral pontine neurons were labeled after HRP injections into HVM. The cells were located ipsilateral to the injection, mostly in the dorsal nucleus of the lateral lemniscus, lateral and dorsolateral to the brachium conjunctivum. The pontine cells labeled following HVM injections of HRP were different from those labeled following lateral hypothalamic and preoptic region injections. The pontine projection to HVM was confirmed using axoplasmic transport autoradiography. A mixture of tritiated leucine and tritiated proline was injected into the lateral pontine region labeled after HRP injections into HVM. Labeled axons ascending in the medial forebrain bundle terminated throughout the rostro-caudal extent of HVM.     

The pontocerebellar projection onto the paramedian lobule in the cat: an experimental study with the use of horseradish peroxidase as a tracer.

Horseradish peroxidase (HRP) was injected into cerebellar cortex of the paramedian lobule in 12 cats, and the ensuing distribution of labeled cells in the pontine nuclei was mapped in some detail. The cells in the pontine gray which give origin to fibers to the paramedian lobule lie together, in part in groups, and in part in columns. The columns are situated both medial and ventrolateral to the peduncle, as well as in the dorsolateral pontine nucleus. The projection is bilateral with a clearcut contralateral preponderance, except in the lateralmost region in the dorsolateral nucleus, which projects mainly ipsilaterally. The column medial to the peduncle projects in a topographical pattern to the paramedian lobule. The dorsal part of this column projects to the rostral folia of the paramedian lobule, while successively more ventral parts in the column project to more caudal paramedian lobules. Within the other columns only a faint sign of a topographical organization is found. The location of the pontine columns projecting onto the paramedian lobule largely corresponds to the pontine terminal areas of fibers from the sensory cerebral cortex (SmI and SmII). The corresponding topography in these parts of the corticopontine and pontocerebellar pathways is suitable for a somatotopical impulse transmission from the sensory cortex to the paramedian lobule, in agreement with the results of physiological investigations. Furthermore, a correlation of the pontine areas projecting onto the paramedian lobule with the terminal areas of pontine afferents shows that the pons may be a relay station in mediating influences from other parts of the cortex (MsI, visual and acoustic), the cerebellar nuclei and the colliculi to the paramedian lobule.     

Secondary obsessive-compulsive disorder related to diaschisis after pontine infarction, successfully treated with paroxetine

This report describes a case of secondary obsessive-compulsive disorder related to diaschisis after pontine infarction. A 71-year-old male developed obsessive images, after a pontine infarction. A brain magnetic resonance imaging scan showed a low intensity area in the right pons on T1-weighted image, while brain single photon emission computed tomography showed low cerebral blood flow in the temporal lobe as well as the pons. In this case, infarction in the pons appeared to cause dysfunction in the temporal lobe via the neural projection network, an example of so-called 'diaschisis'. This case suggests that brainstem infarction and decreased temporal lobe perfusion can lead to secondary obsessive-compulsive disorder.     

Efferent projections of the deep mesencephalic nucleus (pars medialis) in the rat

The projections of the medial part of the deep mesencephalic nucleus (DMN) were traced by autoradiography and retrograde horseradish peroxidase (HRP) techniques. No ascending projections were observed from the medial part of the DMN; however, two groups of descending fibers were observed. One group crossed the midline and coursed to the caudal part of the red nucleus. At this point, these fibers divided into two distinct bundles. One bundle of fibers passed caudally to terminate in the contralateral pontine reticular nucleus, superior olive-trapezoid body complex, gigantocellular nucleus, and upper cervical spinal cord. The other bundle entered the medial longitudinal fasciculus (MLF) and coursed through the pons and medulla without termination, to enter the cervical spinal cord where terminations were noted in the dorsal horn. The other group of fibers from the medial DMN descended through the ipsilateral pons and medulla, projecting to the pontine reticular nucleus, superior olive-trapezoid body complex, gigantocellular nucleus, and upper cervical spinal cord. These findings indicate that the medial part of the DMN is likely to be involved in complex sensorimotor events via reticulobulbar and reticulospinal connections.