脑桥中央髓鞘溶解症和脑桥外髓鞘溶解症5例临床分析

目的　探讨脑桥中央髓鞘溶解症 (CPM)和 /或脑桥外髓鞘溶解症 (EPM)的发病机制及早期预防和诊治原则。方法　对 5例CPM/EPM患者的临床表现、影像学资料及治疗转归进行分析。结果　临床观察发现 :(1)5例患者均存在严重的基础疾病 ,特别是严重的电解质紊乱 (低钠血症 ) ,不同程度的意识障碍 ,吞咽困难 ,构音障碍。 (2 ) 3例有四肢瘫 ,锥体束征阳性 ;1例表现为帕金森综合征。 (3) 5例头颅MRI均阳性。 (4) 5例均临床好转出院 ,生活自理。结论　 (1)CPM和 /或EPM的发生与低钠血症及快速纠正低钠血症有关。 (2 )CPM和 /或EPM并非致死性疾病 ,无论病情多严重 ,均不应放弃治疗。     

Magnetic resonance imaging in central pontine myelinolysis.

Magnetic resonance imaging (MRI) was performed in two patients in whom a clinical diagnosis of central pontine myelinolysis (CPM) had been made. MRI showed lesions in the pons in both cases about 2 years after the illness, at a time when the spastic quadriparesis and pseudobulbar palsy had recovered. The persisting abnormal signals in CPM are likely to be due to fibrillary gliosis. Persistence of lesions on MRI means that the diagnosis of CPM may be electively, after the acute illness has resolved.     

Central pontine myelinolysis, an update

Central pontine myelinolysis (CPM) can be regarded as one of the demyelinating syndromes. First described by Adams et al. in 1959 in their chronic alcoholic patients, it has now been described in the malnourished, the chronically debilitated, the renal, the hepatic and the transplant patient among others. Pathologically, it is defined as a symmetric area of myelin disruption in the center of the basis pontis, although similar symmetric lesions have also been described occurring with CPM as well as independently in other brain areas (extrapontine myelinolysis or EPM) including the cerebellar and neocortical white/gray junctional areas, thalamus and striatum. Possible mechanisms include a hyperosmotically induced demyelination process resulting from rapid intracellular/ extracellular to intravascular water shifts producing relative glial dehydration and myelin degradation and/or oligodendroglial apoptosis. The process most often occurs during rapid rebalancing of the electrolyte parameters in the hyponatremic patient. Avoidance of CPM/EPM is dependent upon recognizing those patients with conditions pre-disposing them to osmotic myelinolysis and then moderating the rate of normalization of the electrolyte imbalance. The morbidity and mortality of CPM/EPM has been greatly reduced by recognition of pre-disposing conditions, increased understanding of the pathophysiology, intensive treatment, and rapid diagnosis and monitoring with advanced neuroimaging.     

Belly dancer's syndrome following central pontine and extrapontine myelinolysis.

We report on a woman with delayed-onset of belly dancer's syndrome 5 months after central pontine and extrapontine myelinolysis (CPM/EPM) and severe hyponatriemia. This case demonstrates that basal ganglia lesions in EPM can be the underlying pathoanatomic substrate for the rarely observed belly dancer's syndrome. The sequential appearance of extrapyramidal symptoms might reflect an ongoing but ineffective or deficient remyelination process. The presence of CPM/EPM should be considered in patients with involuntary dyskinesias of the abdominal wall.     

A case of alcoholic with vitamin B12 deficiency presenting central pontine and extrapontine myelinolysis on MRI]

A 55-year-old man with chronic alcoholism was first referred to us in 1992 because of spastic quadriparesis. T2-weighted images of MRI showed pontine and extracapsule lesions as central pontine and extrapontine myelinolysis (CPM/EPM). He had macrocytic anemia with normal serum level of vitamin B12 (B12). Gait disturbance was progressively worsened from the end of 2004 and dysuria appeared from June, 2005. Neurological examination on admission in November, 2005, showed mild impairment of recent memory, spastic paraparesis with hyperreflexia in all limbs, loss of deep sensations in lower limbs and urinary disturbance. The low serum level of B12 with marked macrocytic anemia was noted. On MRI. the pontine lesion extended to the midbrain but no abnormality was found in the spinal cord. We intramuscularly administered B12, resulting in marked improvement of both anemia and neurological symptoms. The brainstem lesion on MRI, however, was unchanged. We assume that B12 deficiency was involved in the formation of CPM/EPM and the neurological symptoms in our patient.     

Symptomatic hyponatraemia: can myelinolysis be prevented by treatment?

The treatment of hyponatraemia is controversial because of the risk of causing central or extrapontine myelinolysis (EPM). Rapid correction with hypertonic saline to a low normal sodium level has its proponents; others feel that slow correction to below normal sodium values is preventative. Most investigators feel that overcorrection should be avoided. It is not known whether the magnitude of serum sodium change is more important than the actual rate of correction. We present three patients with hyponatraemia ranging from 103 to 105 mmol/l who were corrected slowly with normal saline, corrected quickly with hypertonic saline, or rapidly overcorrected with hypertonic saline. All became comatose and died; all had EPM with or without central pontine myelinolysis (CPM). The rate of correction, the solution used, or the magnitude of correction did not seem to protect against demyelination. In a review of 67 reported CPM cases since 1983, no patients documented as having CPM or EPM by radiological studies or necropsy were treated with water restriction only. A group of 27 hyponatraemic patients treated only with water restriction and 35 with diuretic cessation alone did not develop CPM or EPM. This may be a reasonable approach to patients with symptomatic hyponatraemia and normal renal function.     

Sequential observation of movement disorders and brain images in the case of central pontine myelinolysis and extrapontine myelinolysis

Central pontine myelinolysis (CPM) and extrapontine myelinolysis (EPM) are well recognized syndromes related to rapid correction of hyponatremia and have been reported to show a variety of movement disorders. However, sequential observation of movement disorders as well as brain images has seldom been reported. We report a case of CPM and EPM presenting with various sequential changes in movement disorders including delayed choreic movement over 11 months; we present sequential brain magnetic resonance images showing increased T1 and decreased fat-suppression T1 signal intensity. We suggest that delayed low signal intensity, in the fat-suppression T1-weighted images, is a result of the destruction of myelin and by products. Damage to the myelin may cause various movement disorders in a delayed manner.     

Atypical forms of the osmotic demyelination syndrome

Osmotic demyelination syndrome (ODS) is the damage over the central nervous system caused by several electrolytes, metabolic and toxic disorders. We aimed to describe cases of unusual forms of ODS. In a 9-year period, 25 consecutive patients with ODS (15 men; mean age 42 years) were registered in our referral institution, among them, four (16 %) with atypical neuroimaging findings were abstracted for this communication. None of them presented cardiorespiratory arrest, head trauma, seizures, neuromyelitis optica spectrum or contact with toxic chemicals. Case 1 was a 33-year-old alcoholic man without hypertension or electrolyte imbalance, who presented a classic central pontine myelinolysis (CPM) and a hemorrhage within the pons. Case 2 was a 34-year-old alcoholic man with hypoglycemia and hyponatremia who presented CPM and diffuse bihemispheric extrapontine myelinolysis (EPM) after correction of serum sodium. Case 3 was a 52-year-old woman with mild hypokalemia and hyponatremia (inadequately corrected), who presented a peduncular and cerebellar EPM. Case 4 was a 67-year-old woman who had a suicidal attempt with antidepressants and carbamazepine without impaired consciousness, who complicated with mild hyponatremia associated with a classical CPM and a spinal cord EPM. Case 2 died and the rest remained with variable neurological impairments at last follow-up visit. With modern neuroimaging, the so-called atypical forms of ODS may not be as rare as previously thought; however, they could have a more adverse outcome than the classical ODS.     

渗透性脱髓鞘综合征的临床分析

摘 要： 目的了解渗透性脱髓鞘综合征（ODS）的发病机制、诊断、治疗和预防方法。方法报告11例ODS患者，并结合文献进行分析。结果10例患者有明显低钠血症；发病诱因包括药源性3例，营养不良3例，肝移植术后、脑挫裂伤、垂体微腺瘤、糖尿病肾病和妊娠剧吐各1例。存在严重呕吐或进食量极少的患者7例。神经系统表现包括不同程度意识障碍，假性球麻痹，四肢瘫痪，眼球活动障碍，闭锁综合征，精神症状，震颤或手足徐动等不自主运动，肌张力齿轮样增高等帕金森样症状等。头颅MRI显示桥脑或双侧豆状核、尾状核头、丘脑等桥外部位脱髓鞘。单纯CPM 3例，单纯EPM 2例，CPM合并EPM 6例。治疗后10例好转，1例病情获稳定。结论ODS的发病与脑内渗透压平衡失调有关，各种原因引起的低钠血症及其快速纠正容易诱发，临床表现可为单纯CPM、EPM或二者合并存在。随着头颅MRI的应用，可使该病早期诊断，其预后明显改善。避免快速纠正低钠血症是预防的主要措施。     

Morel's laminar necrosis like findings on MRI in a case of extra-pontine myelinolysis

A 39-year-old man developed disturbance of consciousness with hyponatremia during the treatment of schizophrenia in another hospital. He became alert after the correction of hyponatremia. But his consciousness deteriorated one day later in spite of normal serum sodium level, then he was referred to our hospital. The disturbance of consciousness, quadriparesis and rigidity were persisted even 4 months later. MRI (T2WI) showed well defined high intensity areas along the deep layer of the cerebral cortex and in the bilateral basal ganglia. But there were no lesions in the pons on MRI. Therefore, the diagnosis was made as extra-pontine myelinolysis (EPM) without apparent central pontine myelinolysis (CPM) according to the MRI findings. Recently, the EPM without CPM has been reported in 3 patients. Two cases were examined pathologically, findings of which were characterized by Morel's laminar necrosis at the deep layer of the cerebral cortex. But there is no report in the literature describing the detection of Morel's laminar necrosis on antemortem MRI. It seemed that the MRI findings of our case indicated Morel's laminar necrosis. Our case is suggestive in relation to the pathogenesis of EPM and CPM.     

Evolving spectrum of movement disorders in extrapontine and central pontine myelinolysis

Extrapontine (EPM) and central pontine myelinolysis (CPM) are rare and frequently related to rapid correction of hyponatremia. We describe a 60-year-old woman who developed an unusual evolving spectrum of movement disorders secondary to EPM and CPM following intravenous sodium replacement therapy for severe hyponatremia. She presented initially with confusion, generalized coarse postural limb tremor, myoclonic jerks and quadriparesis. Subsequently her mental state improved and her tremor and weakness resolved. Over the following months, she developed progressive painful dystonia of her facial musculature and lower limbs. This gradually became generalized and associated with choreoathethosis in her limbs. In addition, she had increasing bradykinesia and rigidity, which responded poorly to levodopa treatment. Our case illustrates that while the myelin destruction occurs during the initial insult of the osmotic demyelinating process, its delayed clinical effects resulting from ineffective reorganization of neuronal structures may be progressive, evolve with time, and difficult to treat.     

Diffusion-weighted MR findings of central pontine and extrapontine myelinolysis

Diffusion-weighted MR (DWI) can detect changes in water diffusion associated with cellular dysfunction, which enables the differentiation of cytotoxic edema from vasogenic edema. In this study on DWI findings in central pontine (CPM) and extrapontine myelinolysis (EPM), DWI showed high signal intensities in the bilateral pons, midbrain, and genu of the corpus callosum. The corresponding apparent diffusion coefficient values were rather low. This suggests that cytotoxic edema does in fact exist in CPM and EPM and that DWI can be useful in the rapid diagnosis and prediction of the various types of edema occurring in active demyelinating diseases.     

Central pontine myelinolysis presenting as isolated sixth nerve palsy in third trimester of pregnancy

A 30-year-old primigravida presented with isolated left sixth nerve palsy at 38 weeks gestation. Her MRI showed a lesion consistent with central pontine myelinolysis (CPM). Extensive investigations did not reveal any secondary cause for the CPM. She recovered spontaneously in 2 weeks with complete resolution of her MRI changes. To our knowledge, this is the first report of CPM occurring in third trimester in the absence of identifiable secondary causes and of CPM presenting as an isolated sixth nerve palsy. We discuss the reported causes of CPM in pregnancy, possible pathophysiologic mechanisms involved and the anatomic basis of the unique clinical presentation of sixth nerve palsy in our case.     

Central and extrapontine myelinolysis: then...and now

In this review, we emphasize neuropathologic and neurobehavioral aspects of central pontine and extrapontine myelinolysis (CPM/EPM), also known as the osmotic demyelination syndrome. The literature is reviewed from the time of the initial report in 1959 and from key developments that have occurred more recently. Particular consideration is given to pathogenic mechanisms as revealed by recent animal studies. The role of white matter pathology in neurobehavioral dysfunction is also considered. The "then" and "now" of CPM and EPM tell 2 different stories. Yet, in many respects, this expansion of information over the past nearly 50 years simply represents a continuum, as well as recognition, of the vast gaps that still persist in our understanding of this disorder.     

Central pontine and extrapontine myelinolysis: a report of 58 cases

In 58 cases with central pontine myelinolysis (CPM) and/or extrapontine myelinolysis, systematic examination of the central nervous system was performed. The demyelinating disease occurred in three subtypes: (1) CPM, in which the lesion was confined to the pons, (2) CPM combined with extrapontine myelinolysis and (3) exclusively extrapontine myelinolysis. Type (1) was found in 27 cases, (2) in 18 cases and (3) in 13 cases. Cerebellum and lateral geniculate body were the most frequently affected extrapontine regions. One case with an extreme extension of the lesions is described in detail. Extrapontine lesions seem to be more frequent and widespread than has been hitherto reported in the literature.     

Extrapontine myelinolysis caused by electrolyte imbalance during the management of suprasellar germ cell tumors Report of two cases

Extrapontine myelinolysis (EPM) is caused by marked fluctuation of the serum electrolyte level. Patients with suprasellar germ cell tumors frequently present with diabetes insipidus, which is often aggravated by administration of steroid hormone. In addition, cisplatin-based chemotherapy is sometimes accompanied by marked serum electrolyte fluctuation because it needs massive hydration to prevent renal damage. Two children with suprasellar germ cell tumors in whom EPM developed secondary to profound hyponatremia and was rapidly corrected are described. The central pons was spared in both cases. Clinically the children showed transient neurological deficits including confusion, pseudobulbar palsy, and deterioration of consciousness. MRI demonstrated bilateral symmetrical, high-signal-intensity (HSI) lesions on T2-weighted images (T2WI) at the basal ganglia and adjacent cerebral cortex. Follow-up T1WI a few months later revealed newly developed HSI lesions in the basal ganglia. The patients gradually improved, but the neurological deficits did not completely disappear. During the perioperative management of suprasellar germ cell tumors, EPM should be considered when a patient has a significant electrolyte imbalance and neurological deficits, especially confusion and pseudobulbar palsy. Received: 19 September 1997 Revised: 16 December 1997     

Overlapping features of extrapontine myelinolysis and acquired chronic (non-Wilsonian) hepatocerebral degeneration

Central pontine myelinolysis (CPM, osmotic demyelination syndrome) and acquired chronic hepatocerebral degeneration (ACHD) both occur in patients with liver failure, but are not thought to be caused by similar etiopathogenic mechanisms despite the fact that occasional patients exhibit both disorders. In our autopsy practice we have recently encountered three patients with the pontine lesions of acute or subacute osmotic demyelination syndrome, coupled with superimposed non-Wilsonian ACHD. All three patients had well-documented rapid elevations in serum sodium proximate to their demise, as well as terminal liver failure. A close intermingling and juxtaposition of lesions with severe demyelination and macrophage breakdown [thought to represent extrapontine myelinolysis (EPM)] to those with vacuolization of myelin but no cellular reaction or myelin loss (ACHD) was noted within some of the same anatomic areas. Particular overlap was seen in lesions at the cerebral cortical gray–white junction and in pencil fibers of the striatum. In these areas it was difficult to be certain whether the lesions were due to EPM or ACHD. We concluded that there was a synergism between the two disorders and raise the possibility that there may be factors common to both disorders that lead to similar anatomic sites for involvement.Presented (in abstract format) at XVIth International Congress of Neuropathology, San Francisco, Sept 10–15, 2006.     

Central pontine myelinolysis after hepatic transplantation]

We report two cases of central pontine myelinolysis (CPM) following liver transplantation. The incidence may well be underestimated as in the past the diagnosis of CPM was based on postmortem findings. Malnutrition, poor clinical condition, encephalopathy are common features of transplanted patients developing CPM. The clinical course is characterized by a biphasic pattern; after normal recovery from anesthesia, there is a subsequent and gradual deterioration in the neurological state. The complex syndrome associates loss of consciousness, flaccid quadriplegia and pseudobulbar palsy. Among the many factors suspected of inducing CPM, a rapid correction of natremia (> 12 mmole/l/day) seems most probable. With regards to liver transplantation, CPM presents rather specific problems. Delaying transplantation to correct hyponatremia carries a risk of severe hepatic encephalopathy. On the other hand, the intraoperative compensation of blood losses with high sodium content blood products tends to induce an abrupt rise in sodium serum concentration. Moreover, renal capacity to excrete sodium is often impaired, due to hepatic insufficiency and surgical procedure. Transplantation should not be delayed, but as infusion of large amounts of sodium cannot be avoided (fresh frozen plasma, human albumin, red blood cells), natremia may be controlled by continuous veno-venous hemofiltration with low sodium content substitution fluids.     

EXTENSIVE EXTRAPONTINE AND CENTRAL PONTINE MYELINOLYSIS ASSOCIATED WITH CORRECTION OF PROFOUND HYPONATRAEMIA

The relationship between correction of hyponatraemia and the development of central pontine myelinolysis (CPM) remains controversial. A case of CPM associated with extensive extrapontine demyelination is described. Profound hyponatraemia and its subsequent correction are documented. It is suggested that the extent of demyelination reflects the degree of hyponatraemia noted prior to correction, supporting current hypotheses regarding the role of hyponatraemia in CPM. This case is unusual in that other recognized risk factors for the development of CPM are absent.     

Central pontine myelinolysis.

Central pontine myelinolysis (CPM) is a demyelinating disease of the pons often associated with demyelination of other areas of the central nervous system (CNS). The term 'osmotic demyelinization syndrome' is used for pontine and extrapontine myelinolysis. In this paper, we are concerned with CPM although the extrapontine one is based on the same pathogenesis. Both share the diagnostic methods, and their prevention and therapy are the same. The etiology and pathogenesis of this disorder are unclear and will be discussed. However, almost all cases of CPM are related to severe diseases. Chronic alcoholism is still the most common underlying condition of CPM patients. In the literature, 174 cases of CPM have been reported in alcoholics since 1986, which is equivalent to an incidence of 39.4%. Likewise, 95 cases of CPM following the correction of hyponatremia have been documented since 1986 (21.5%). The role of hyponatremia and its correction will be outlined in the discussion of the pathogenesis of CPM. The third largest group of CPM cases are liver transplant patients (17.4%), with the development of CPM being attributed to the immunosuppressive agent cyclosporine in particular. Depending on the involvement of other CNS structures, the clinical picture can vary considerably. The large-scale introduction of magnetic resonance imaging has increasingly facilitated the antemortem diagnosis of CPM, although the radiological findings lag behind and do not necessarily correlate with the clinical picture. As yet, there is no specific therapy of choice. A number of therapeutic approaches have been tested and although they have not been compared with regard to their rate of success, they have all led to a substantial improvement in the prognosis of CPM.