Substantia nigra hyperechogenicity in Parkinson's disease

Transcranial brain sonography for Parkinsonian syndromes

Substantia nigra (SN) hyperechogenicity has been proved to be a characteristic finding for idiopathic Parkinson's disease (PD), occurring in more than 90% of the patients. This echofeature is owed to increased amounts of iron in the SN region and reflects a functional impairment of the nigrostriatal dopaminergic system. In a prospective blinded study in which a group of patients with early mild signs and symptoms of unclear Parkinsonism were followed until a definite clinical diagnosis of PD, the hyperechogenicity of the SN was demonstrated to be highly predictive of a final diagnosis of PD. For the diagnosis of PD in individuals with early motor symptoms, both the sensitivity and positive predictive value of SN hyperechogenicity were higher than 90% and both the specificity and negative predictive value were higher than 80%. For early differential diagnosis between PD and atypical Parkinsonian syndromes, the sensitivity and positive predictive value of SN hyperechogenicity were higher than 90%, and both the specificity and negative predictive value were higher than 80%. The diagnostic specificity is increased if combining the TCS findings of SN, lenticular nucleus and third ventricle. In asymptomatic adult subjects, SN hyperechogenicity, at least unilaterally, indicates a subclinical functional insufficiency of the nigrostriatal dopaminergic system. Recent papers revealed that SN hyperechogenicity might suggest preclinical PD. Reduced echogenicity of midbrain raphe indicates increased risk of depression in PD patients. Caudate nucleus hyperechogenicity has been associated with drug-induced psychosis, and frontal horn dilatation >20 mm with dementia. Transcranial brain sonography can be a valuable tool for managing patients with Parkinsonian signs and symptoms.

Magnetic resonance-transcranial ultrasound fusion imaging: A novel tool for brain electrode location

BACKGROUND

A combination of preoperative magnetic resonance imaging (MRI) with real-time transcranial ultrasound, known as fusion imaging, may improve postoperative control of deep brain stimulation (DBS) electrode location. Fusion imaging, however, employs a weak magnetic field for tracking the position of the ultrasound transducer and the patient's head. Here we assessed its feasibility, safety, and clinical relevance in patients with DBS.

METHODS

Eighteen imaging sessions were conducted in 15 patients (7 women; aged 52.4 ± 14.4 y) with DBS of subthalamic nucleus (n = 6), globus pallidus interna (n = 5), ventro-intermediate (n = 3), or anterior (n = 1) thalamic nucleus and clinically suspected lead displacement. Minimum distance between DBS generator and magnetic field transmitter was kept at 65 cm. The pre-implantation MRI dataset was loaded into the ultrasound system for the fusion imaging examination. The DBS lead position was rated using validated criteria. Generator DBS parameters and neurological state of patients were monitored.

RESULTS

Magnetic resonance-ultrasound fusion imaging and volume navigation were feasible in all cases and provided with real-time imaging capabilities of DBS lead and its location within the superimposed magnetic resonance images. Of 35 assessed lead locations, 30 were rated optimal, three suboptimal, and two displaced. In two cases, electrodes were re-implanted after confirming their inappropriate location on computed tomography (CT) scan. No influence of fusion imaging on clinical state of patients, or on DBS implantable pulse generator function, was found.

CONCLUSIONS

Magnetic resonance-ultrasound real-time fusion imaging of DBS electrodes is safe with distinct precautions and improves assessment of electrode location. It may lower the need for repeated CT or MRI scans in DBS patients.

Dopamine transporter imaging using 99mTc-TRODAT-1 SPECT in Parkinson's disease

Background

Although the decrease in striatal dopamine transporter (DAT) density has been described in North American, European, and Asian Parkinson’s disease (PD) patients, studies on this issue are required in the rest of the world. This study examined the diagnostic utility of DAT imaging in Brazilian PD patients.

Material/Methods

Twenty PD patients (13 males, 7 females, median age: 62 years, median age at disease onset: 56 years, median disease duration: 5 years, and median UPDRS-III score: 29) and 9 age- and sex-matched healthy subjects underwent single-photon emission computerized tomography (SPECT) using ^99mTc-TRODAT-1.

Results

PD patients showed a significant decrease in the striatum, caudate nucleus, and putamen DAT densities compared with data from healthy subjects. Striatal ^99mTc-TRODAT-1 bindings had the highest diagnostic accuracy compared to those estimates from caudate nucleus and putamen. For the diagnosis of PD, a striatal ^99mTc-TRODAT-1 binding cut-off value of 0.90 was associated with a sensitivity of 100% and a specificity of 89%. There was no significant difference between striatal ^99mTc-TRODAT-1 binding values provided by different readers, contrary to ^99mTc-TRODAT-1 binding estimates in the caudate nucleus.

Conclusions

Striatal DAT imaging using ^99mTc-TRODAT-1 can be considered a marker for differentiating PD patients from healthy individuals, with a good interobserver reproducibility.

Transcranial sonography in Parkinson's disease

Transcranial sonography has become a useful tool in the differential diagnosis of parkinsonian syndromes. This is a non-invasive, low cost procedure. The main finding on transcranial sonography in patients with idiopathic Parkinson's disease is an increased echogenicity of the mesencephalic substantia nigra region. This hyperechogenicity is present in more than 90% of cases, and reflects a dysfunction in the dopaminergic nigrostriatal pathway. This study discussed how the hyperechogenicity of the substantia nigra may facilitate the differential diagnosis of parkinsonian syndromes.

Substantia nigra echogenicity is correlated with nigrostriatal impairment in Machado-Joseph disease

BACKGROUND

Several studies have demonstrated increased substantia nigra (SN) echogenicity in Parkinson's disease (PD) and Machado-Joseph disease (MJD). Pathological substrate of PD is characterized by dopaminergic nigrostriatal cell loss, also found in MJD. Also, SN hyperechogenicity might be associated with nigrostriatal dysfunction in PD, when comparing dopamine transporter binding with SN echogenicity. The present study aimed to correlate the SN echogenic size and striatal dopamine transporter density in MJD patients.

METHODS

We performed TCS in 30 subjects and SPECT with [(99m)Tc]-TRODAT-1 in 18 subjects with MJD. Fifteen healthy subjects matched for age and gender formed a control group. TCS and [(99m)Tc]-TRODAT-1 SPECT findings from both MJD patients and control subjects were compared.

RESULTS

There were no differences regarding age (p = 0.358) or gender (p = 0.566) between groups (MJD versus control group). Mean DAT binding potentials and SN echogenicity were significantly different between groups. There was a significant negative correlation with regard to the SN echogenic size and the ipsilateral striatal TRODAT-1 uptake: the higher the SN echogenicity, the lower the DAT uptake in the ipsilateral cerebral hemisphere.

CONCLUSION

Increase in SN echogenic size likely correlates with presynaptic dopaminergic nigrostriatal dysfunction in MJD, suggesting a concurrent in vivo pathophysiological mechanism.

Achados de ultrassonografia transcraniana na doença de Parkinson e no tremor essencial: relato de casos

A ultrassonografia transcraniana tem sido objeto de investigação como ferramenta diagnóstica em neurologia nos últimos anos. Ela permite boa visualização de estruturas cerebrais situadas na linha média, sítio frequente de anormalidades nas doenças do movimento. Relatamos os casos de pacientes com a doença de Parkinson e o tremor essencial em que a ultrassonografia transcraniana foi capaz de sugerir o diagnóstico.

Sonothrombolysis for acute ischemic stroke: a systematic review of randomized controlled trials

OBJECT

Sonothrombolysis has recently been considered an emerging modality for the treatment of stroke. The purpose of the present paper was to review randomized clinical studies concerning the effects of sonothrombolysis associated with tissue plasminogen activator (tPA) on acute ischemic stroke.

METHODS

Systematic searches for literature published between January 1996 and July 2011 were performed for studies regarding sonothrombolysis combined with tPA for acute ischemic stroke. Only randomized controlled trials were included. Data extraction was based on ultrasound variables, patient characteristics, and outcome variables (rate of intracranial hemorrhages and arterial recanalization).

RESULTS

Four trials were included in this study; 2 trials evaluated the effect of transcranial Doppler (TCD) ultrasonography on sonothrombolysis, and 2 addressed transcranial color-coded duplex (TCCD) ultrasonography. The frequency of ultrasound waves varied from 1.8 to 2 MHz. The duration of thrombus exposure to ultrasound energy ranged from 60 to 120 minutes. Sample sizes were small, recanalization was evaluated at different time points (60 and 120 minutes), and inclusion criteria were heterogeneous. Sonothrombolysis combined with tPA did not lead to an increase in symptomatic intracranial hemorrhagic complications. Two studies demonstrated that patients treated with ultrasound combined with tPA had statistically significant higher rates of recanalization than patients treated with tPA alone.

CONCLUSIONS

Despite the heterogeneity and the limitations of the reviewed studies, there is evidence that sonothrombolysis associated with tPA is a safe procedure and results in an increased rate of recanalization in the setting of acute ischemic stroke when wave frequencies and energy intensities of diagnostic ultrasound systems are used.

Transcranial sonography findings in spinocerebellar ataxia type 3 (Machado-Joseph disease): a cross-sectional study

Few studies on transcranial brain sonography have been performed in hereditary and non-hereditary ataxias. The objective of the present study was to report transcranial brain sonography findings in a sample of clinically and molecularly proven Machado-Joseph disease patients and to compare these data against those of an age- and gender-matched control group. A cross-sectional study on transcranial brain sonography was conducted in 30 Machado-Joseph disease patients. Transcranial brain sonography was performed by an experienced sonographer blinded to the clinical, genetic, and neuroimaging data. The results were compared with those of a control group of 44 healthy subjects matched for age and gender. The sonographic findings were also correlated with clinical features and genetic data in Machado-Joseph disease group. A significantly higher frequency of substantia nigra and lenticular nucleus hyperechogenicity was found in the Machado-Joseph disease group compared to an age- and gender-matched healthy control group (p<0.001). The substantia nigra echogenic area proved to be the best predictor for differentiating cases from controls. Third and lateral ventricles were significantly larger in the Machado-Joseph disease patients than in the control subjects. No significant correlations were found between transcranial brain sonography findings and Machado-Joseph disease demographic/clinical data. Transcranial brain sonography findings in Machado-Joseph disease patients differed significantly to those in age- and gender-matched controls. Substantia nigra hyperechogenicity occurred frequently in Machado-Joseph disease patients and was found to be the best predictor for differentiating cases from controls. Additionally, this data describes the occurrence of brain atrophy in Machado-Joseph disease group.

Transcranial sonographic localization of deep brain stimulation electrodes is safe, reliable and predicts clinical outcome

In patients with deep brain stimulation (DBS), poor postoperative outcome or unexpected clinical change require brain imaging to check the lead location. Here, we studied safety, reliability and prognostic value of transcranial sonography (TCS) for DBS lead localization applying predefined TCS criteria. After measuring thermal effects of TCS and imaging artefact sizes of DBS lead using a skull phantom, we prospectively enrolled 34 patients with DBS of globus pallidus internus, ventro-intermediate thalamic or subthalamic nucleus. TCS had no influence on lead temperature, electrical parameters of DBS device or clinical state of patients. TCS measures of lead coordinates agreed with MRI measures in anterior-posterior and medial-lateral axis. Lead dislocation requiring reinsertion was reliably detected. Only patients with optimal lead position on TCS had favorable clinical 12-month outcome (>50% improvement), whereas unfavorable outcome (<25% improvement) was associated with suboptimal lead position. TCS may therefore become a first-choice modality to monitor lead location.