MR imaging of pontine and extrapontine myelinolysis

Two cases of pontine and extrapontine myelinolysis following electrolyte derangements are presented. One case showed only extrapontine myelinolytic lesions on magnetic resonance (MR) imaging, although both pontine and extrapontine myelinolysis were confirmed at postmortem. Another case made full recovery clinically with resolution of extrapontine lesions on MR imaging.     

Unusual progression of osmotic demyelination after liver transplantation on MRI brain

Osmotic demyelination syndrome, comprised of central pontine and extrapontine myelinolysis, is an important and potentially fatal complication primarily related to rapid overcorrection of serum sodium leading to devastating neurological symptoms. While traditionally presenting in the pons, we report the case of a 43-year-old female patient who recently underwent a liver transplant and developed extrapontine myelinolysis and subsequently central pontine myelinolysis resulting in irreversible spastic quadriparesis. This rare case highlights the variability of presentation of osmotic demyelination syndrome on imaging.     

Magnetic resonance imaging of extrapontine lesions in central pontine myelinolysis.

A rare case of central pontine myelinolysis and associated extrapontine myelinolysis is presented. The MR findings confirmed the observations reported in recent papers.     

桥脑中央髓鞘溶解的MRI诊断(附2例分析)

目的:探讨桥脑中央髓鞘溶解症(central pontine Myelinolysis CPM)的MRI特征。方法:分析CPM患者的MRI表现,总结了CPM的最佳MR影像诊断与鉴别诊断要点。结果:MRI表现为:(1)病灶位于桥脑上部;(2)T1WI病灶呈低或略低信号强度,T2WI呈高信号或略高信号;(3)静脉注入GD-DTPA后,病灶中央呈明显均匀强化,及轻度强化,边缘清晰锐利。结论:MRI是CPM的最好检查方法,当有上述表现时高度提示CPM的可能。     

Symmetrical lesions of the middle cerebellar peduncle: MR imaging and differential diagnosis.

The purpose of this paper is to show several diseases that manifest symmetrical hyperintense lesions on the middle cerebellar peduncles, the largest connecting peduncles between the brainstem and the cerebellum, in conventional magnetic resonance (MR) images. We retrospectively reviewed cranial MR images obtained with 0.3-, 0.5-, 1.0-, and 1.5-Tesla scanners. We found symmetrical middle cerebellar peduncular lesions in patients with Wilson's disease; hepatic encephalopathy; extrapontine myelinolysis; acute disseminated encephalomyelitis; wallerian degeneration of the pontocerebellar tracts after either pontine infarction, pontine hemorrhage, or central pontine myelinolysis; leukodystrophy; olivopontocerebellar atrophy; and toluene abuse. Definitive diagnosis of these diseases can be made relatively easily on the basis of clinical data; however, examination of associated brainstem or supratentorial lesions in MR images is also important.     

Early diagnosis of central pontine myelinolysis with diffusion-weighted imaging

Central pontine myelinolysis (CPM) occurs in the setting of rapidly corrected hyponatremia, especially in chronically debilitated patients. Conventional CT and MR imaging findings lag the clinical manifestations of CPM. We present a case in which restricted diffusion was identified within the central pons by using MR diffusion-weighted imaging within 24 hours of onset of patient tetraplegia and before findings were conspicuous with conventional MR imaging sequences (T1, T2, and fluid-attenuated inversion recovery).     

Temporal changes of MR findings in central pontine myelinolysis.

We report central pontine myelinolysis in orthotopic liver transplant patients. Sequential MR imaging of these patients with central pontine myelinolysis shows progressive decrease of T2-weighted MR signal in the pons, which may not resolve despite complete neurologic recovery.     

MR imaging of white matter lesions in uncomplicated chronic alcoholism

Chronic alcoholics may have CNS lesions, such as microvasculitis or glial, neural, and myelin degeneration, as documented in postmortem studies on subjects who had Wernicke encephalopathy, corpus callosum degeneration, or central pontine myelinolysis. One may also expect the presence of early white matter disease in patients who do not have neurologic complications of alcoholism. Thirty-five chronic alcoholics (Diagnostic and Statistical Manual III criteria) and 35 normal control subjects were studied by means of magnetic resonance (MR) imaging. Subjects greater than 60 years old, or those with CNS involvement, or clinically evident systemic disorders were excluded. Of the remaining asymptomatic alcoholics, MR detected multiple round hyperintense areas in the white matter of 14 patients, in addition to aspecific corticosubcortical and cerebellar atrophies. None of the normal control subjects showed such a finding. These results suggest an early involvement of the brain in asymptomatic alcoholic patients.     

MRI findings in osmotic myelinolysis

OBJECTIVES: Osmotic myelinolysis is a distinctive clinical syndrome with characteristic CT and MR features. This study was undertaken to determine the MR appearance of these lesions on T1 and T2-weighted, and diffusion-weighted imaging (DWI) sequences with apparent diffusion coefficient (ADC) mapping. MATERIALS AND METHODS: We describe six patients who presented with deranged serum sodium levels and subsequently developed osmotic myelinolysis. CT and MRI scans were retrospectively reviewed, including the advanced functional MR sequence of DWI with ADC mapping. RESULTS: Both cerebral white matter and pontine lesions were typically hypo and hyper-intense on T1 and T2W sequences respectively. Lesions were mildly hyperintense on isotropic DWI images with elevation of the ADC. CONCLUSION: MRI is superior to CT in depicting lesions in osmotic myelinolysis. DWI with ADC mapping suggests that osmotic myelinolysis is not simply a demyelinating disorder but has similarities to multiple sclerosis.     

MELAS syndrome: imaging and proton MR spectroscopic findings.

PURPOSETo evaluate imaging findings in MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, strokes) syndrome for the presence and location of infarctions and the presence of lactate.METHODSEight patients were studied with MR (n = 8) and CT (n = 2). One patient underwent single-photon emission CT with technetium 99m hexamethyl-propyleneamine oxime and one patient had conventional catheter angiography. One fixed brain was studied with MR imaging. Five patients underwent single volume proton MR spectroscopy. Imaging studies were evaluated for atrophy, edema, and infarctions. Proton MR spectroscopy was visually analyzed for presence or absence of lactate.RESULTSOne patient showed a cerebral infarction, and later a second distant infarction developed. One patient showed a transient area of cortical edema. Two patients had small nonspecific periventricular white matter abnormalities and one patient had diffuse white matter hyperintensities. Two patients had nonspecific MR abnormalities (probably age-related changes), and two had normal MR findings. None had basal ganglia involvement. Proton MR spectroscopy showed presence of lactate in one case with transient cortical edema; in two cases with nonspecific (probably age-related) brain findings; and in two patients with normal MR findings.CONCLUSIONSPatients with MELAS have a variety of MR findings. The fact that proton MR spectroscopy showed lactate in all five cases studied, regardless of MR findings, indicates that proton MR spectroscopy may be more sensitive in the detection of MELAS-associated abnormalities than MR imaging.     

Acute intermittent porphyria with central pontine myelinolysis and cortical laminar necrosis

Acute intermittent porphyria (AIP) is an autosomal-dominant disease caused by a deficiency of porphobilinogen (PBG) deaminase. Patients with AIP present with neurological syndromes such as autonomic neuropathy, peripheral axonal neuropathy or central nervous system dysfunction. We report serial MRI of a patient with AIP who had cortical and subcortical cerebral changes. A 29-year-old woman with a 6-month history of AIP had an attack with severe hyponatraemia and generalised convulsions, treated with haem arginate and supportive therapy. MRI showed central pontine and extrapontine myelinolysis and cortical laminar necrosis. These are not common in AIP, but are likely to have been caused by rapid correction of hyponatraemia and by vasospasm, which could be induced by AIP. Received: 14 October 1998 Accepted: 8 February 1999     

Central pontine myelinolysis: correlation between CT and electrophysiologic data

Because of the nature and location of the lesion in central pontine myelinolysis, considerable difficulties in diagnosis may arise. Computed tomography (CT) and brainstem auditory-evoked potentials are useful in following the spread and regression of the pontine lesion. The correlation between clinical evolution, serial CT scans, and brainstem auditory-evoked potentials is considered in a patient with central pontine myelinolysis and subsequent complete recovery with special emphasis on the evolution of the CT scan after recovery.     

Evaluation of central nervous system involvement in nasal lymphomas

OBJECTIVES: To clarify the usefulness of evaluating central nervous system (CNS) involvement in patients with nasal lymphomas at the initial staging procedure, and of CNS prophylaxis for patients with clinical stage I/II. PATIENTS AND METHODS: We retrospectively reviewed 43 patients with nasal lymphomas who had been treated from 1973 through 1999. The staging procedure included mainly computed tomography (CT), ultrasonography, gallium scintigraphy, upper gastrointestinal study, magnetic resonance (MR) imaging, and bone marrow biopsy. Forty-two patients received radiotherapy, and 25 patients received chemotherapy. All 38 patients with stage I/II were not subjected to CNS prophylaxis. RESULTS: Four patients demonstrated CNS involvement at the staging procedure. MR imaging demonstrated the tumor had directly infiltrated the skull base in 3 patients, but CT demonstrated CNS infiltration in only one patient. In another patient, cerebrospinal fluid (CSF) cytologic analyses demonstrated CNS involvement, but MR imaging and CT did not. These 4 patients complained of frontonasal pain and/or cerebral nerve dysfunction. No patient with stage I/II developed CNS relapse. CONCLUSIONS: MR imaging and CSF cytologic analyses should be performed at the initial staging of nasal lymphomas, especially in patients with frontonasal pain and/or cerebral nerve dysfunction. Patients with stage I/II might not need CNS prophylaxis.     

99mTc-TRODAT-1 and 123I-IBZM SPECT studies in a patient with extrapontine myelinolysis with parkinsonian features

Osmotic demyelination syndrome can result from the rapid correction of hyponatremia, and is categorized by central pontine myelinolysis and extrapontine myelinolysis (EPM). Magnetic resonance imaging (MRI) is currently the most useful modality for visualizing EPM lesions. However, MRI is unable to delineate the severity of involvement in the nigrostriatal dopaminergic pathway. The authors describe the case of a 48-year-old woman who developed isolated EPM with predominantly right-sided parkinsonian symptoms after rapid correction of hyponatremia. MRI revealed symmetrical demyelinating lesions in the bilateral striatum without central pontine involvement. ^99mTc-TRODAT-1 and ¹²³I-iodobenzamide (¹²³I-IBZM) single-photon emission computed tomography (SPECT) images showed unequally decreased uptake in the bilateral striatum. Treatment with carbidopa/levodopa improved the clinical parkinsonian symptoms. ^99mT_C-TRODAT-1 and ¹²³I-IBZM SPECT images provide presynaptic and postsynaptic molecular information of the nigrostriatal dopaminergic pathway. The lesions demonstrated in the ^99mT_C-TRODAT-1 and ¹²³I-IBZM SPECT images show higher correlation with the severity of clinical features in EPM than MRI, and the modalities may be useful in the evaluation of patients with parkinsonian symptoms.     

Decreased diffusion in central pontine myelinolysis

Two patients with central pontine myelinolysis (CPM) were studied with diffusion-weighted MR imaging 1 week after onset of tetraplegia. In both patients, affected white matter showed hyperintensity on diffusion-weighted images associated with a decrease in apparent diffusion coefficient (ADC) values. In one patient studied serially, ADC values normalized by 3 weeks after tetraplegia. Early in the clinical course, diagnosis of CPM can sometimes be difficult. Hyperintensity on diffusion-weighted images may therefore have diagnostic utility. Decreased lesional ADC values support the notion that CPM is a consequence of relative intracellular hypotonicity.     

Neurobrucellosis: clinical and neuroimaging correlation

BACKGROUND AND PURPOSE: Manifestation of nervous system involvement by neurobrucellosis, a treatable infection, is not well documented. We investigated patterns of nervous system involvement and determined if neuroimaging abnormalities correlated with clinical manifestations of neurobrucellosis. METHODS: We reviewed 23 MR imaging studies (17 of brain, six of spine) and seven CT scans of brain in 23 patients (14 male and nine female patients; age range 17-71 years) with positive Brucella titers in their serum and CSF. RESULTS: Twelve patients had central nervous system (CNS) involvement, four had peripheral nervous system (PNS) involvement, two had combined PNS and CNS involvement, and five had isolated hearing loss. Imaging findings were variable: five of seven brain CT studies were normal, and 10 of 23 MR studies were normal (eight brain, one thoracic, one lumbar). One brain CT study showed subthalamic hemorrhage, mild perivascular enhancement, left caudate lacunae, and diffuse white matter changes. One other brain CT study showed enhancement of the tentorium in addition to white matter changes. Abnormal MR findings were basal meningeal enhancement (n = 3), lumbar nerve root enhancement (n = 3), granuloma of the suprasellar region (n = 1), diffuse white matter changes (n = 7), and spinal cord atrophy (n = 1). All patients improved after treatment with three antimicrobial drugs for 3-12 months. Seven patients had follow-up imaging; the enhancement disappeared but the white matter and ischemic changes persisted despite almost complete clinical recovery. CONCLUSION: Clinical-radiologic correlation in neurobrucellosis varies from a normal imaging study despite positive clinical findings, to a variety of imaging abnormalities that reflect either an inflammatory process, an immune-mediated process, or a vascular insult.     

Parsonage-Turner syndrome: MR imaging findings and clinical information of 27 patients

PURPOSE: To review retrospectively the magnetic resonance (MR) imaging findings and clinical information of patients with Parsonage-Turner syndrome (PTS). MATERIALS AND METHODS: The institutional review board did not require its formal approval or informed patient consent at the time of the study. However, the study was HIPAA compliant. The information in a computerized database of 2875 consecutive shoulder MR examinations was retrospectively reviewed. With use of key terms, the database software identified 81 examinations potentially associated with PTS. Both authors together reviewed the 81 imaging reports and the corresponding patients' medical records. In consensus, they made the diagnosis of PTS in 21 patients (two with bilateral involvement) on the basis of MR findings, electromyographic results, and clinical data. They also examined the data of an additional six patients (one with bilateral involvement) obtained from outside facilities. Ultimately, 30 shoulders of 27 patients (18 male, nine female; age range, 12-81 years; mean age, 41 years) were evaluated. The MR findings and clinical information (ie, regarding atrophy, pain, weakness, electromyographic results, neck and spine history, trauma, excessive overhead activity, recent surgery, vaccination, and illness) of all patients with PTS were reviewed. MR findings of diffuse high T2 signal intensity abnormality and fatty atrophy of muscles were evaluated to assess the pattern of nerve involvement. Structural causes (eg, ganglion cyst or other mass) of neurogenic high T2 signal intensity abnormality were excluded at MR imaging. RESULTS: Twenty-nine (97%) of 30 shoulders had suprascapular nerve involvement; in 15 (50%) shoulders, the involvement was limited to this nerve. Fifteen (50%) shoulders had axillary nerve involvement; in only one (3%) shoulder, the involvement was limited to this nerve. One shoulder (3%) had subscapular nerve involvement. Nine (30%) shoulders demonstrated focal muscular atrophy. Eleven (41%) of 27 patients also underwent electromyography; all of these patients demonstrated neuropathies that matched the patterns of neurogenic high T2 signal intensity abnormality seen at MR imaging. CONCLUSION: The suprascapular nerve was almost invariably involved (in 97% of shoulders) in patients with PTS. Axillary nerve involvement also was commonly observed (in 50% of shoulders). Subscapular nerve involvement was uncommon (in 3% of shoulders).     

脑桥中央髓鞘溶解症的MR影像诊断(附三例分析)

目的研究脑桥中央髓鞘溶解症（ｃｅｎｔｒａｌｐｏｎｔｉｎｅｍｙｅｌｉｎｏｌｙｓｉｓ,ＣＰＭ）的ＭＲＩ特征。方法回顾性分析３例ＣＰＭ患者的ＭＲＩ表现,总结ＭＲＩ诊断与鉴别诊断要点。结果ＣＰＭ的ＭＲＩ特征表现为：（１）病变位于脑桥中央部位,主要累及桥横纤维的髓鞘,皮质脊髓束的轴索保持完好;（２）病灶多表现为环形或蝴蝶样,边缘模糊;（３）Ｔ１ＷＩ病灶呈低信号强度影,Ｔ２ＷＩ则为高信号影;（４）病变的早期阶段可见病灶内有斑点样高信号强度影;（５）静脉注入造影剂ＧｄＤＴＰＡ后,可见病灶边缘轻度增强。结论ＭＲＩ是ＣＰＭ的最好检查方法,当有上述表现时高度提示ＣＰＭ的可能     

Central pontine myelinolysis with clinical recovery: MR documentation

Magnetic resonance (MR) features of a patient with profound hyponatremia and clinical findings of central pontine myelinolysis are presented. Resolution of the MR findings paralleled the clinical recovery.     

Angiosarcoma of the spleen: imaging characteristics in 12 patients

PURPOSE: To retrospectively review clinical, pathologic, and imaging features of angiosarcoma of the spleen in 12 patients. MATERIALS AND METHODS: Institutional review board approval was obtained, and informed consent was not required. Records of 12 cases of proved angiosarcoma of the spleen were accessed from the files of the Armed Forces Institute of Pathology. Clinical, pathologic, and imaging findings were reviewed. Presenting signs and symptoms were recorded, and the pathologist confirmed the diagnosis and determined gross and microscopic morphologic findings in each spleen. Radiologists reviewed available images to determine the size of the spleen and mass, amount of splenic involvement by the tumor (if enhanced at computed tomography [CT] and magnetic resonance [MR] imaging), and amount of nonviable tumor determined as decreased echogenicity at ultrasonography (US) and lack of enhancement at CT and MR imaging. Imaging and pathologic findings were compared. Five US, 10 CT, three MR, and two angiographic images were reviewed by two experienced abdominal radiologists. RESULTS: There were seven men and five women (age range, 36-86 years; mean, 55 years). The most common symptom was upper abdominal pain in eight (67%) patients: Pain was acute for 24 hours prior to admission in one patient and chronic (range, 1-6 months) in seven patients. At imaging, the spleen was enlarged (>12 cm in length) in nine patients. The most common finding, seen in seven (58%) patients, was a complex mass or masses in an enlarged spleen. Four of these patients had evidence of metastases and one had intraperitoneal hemorrhage. Two patients had solitary hypervascular tumors and liver metastases. One patient had a normal-sized spleen with multiple lesions that ranged 2-3 cm in size, as well as metastases to the spine. The 11th patient had two small lesions, with small calcifications in the periphery of one lesion. The 12th patient had intraabdominal hemorrhage around the spleen and no obvious mass at CT. Tumor necrosis was confirmed at histologic evaluation in nine patients. CONCLUSION: The most common clinical finding was upper abdominal pain. Angiosarcoma of the spleen could be suggested in the majority of cases (83%) by using the imaging features of splenic mass with evidence of metastatic disease.