Brain parenchyma sonography

Transcranial sonography in adult patients is, without doubt, a challenging area because it raises a number of difficulties (ultrasound dampening caused by cranial bone, axial and lateral resolution of the ultrasound beam, progressive reduction of the resolution with decreasing transducer insonation frequencies, etc.). Although we recognise the scientific importance of these difficulties, linked exclusively to the physical limits of the ultrasound technique, the advent of last generation software imaging nevertheless encourages us to pursue the idea of a possible useful sonographic bi-dimensional approach to the non-ischaemic pathologies of the brain parenchyma. In general, our experience, as already quoted in several papers in the literature (1,2), shows that when a sufficient acoustic bone window is present, it is sometimes possible to detect the presence of brain expansive processes: tumours, subdural haematomas, brain haemorrhages (35). The ultrasound examination can, obviously, only arouse the suspicion of expansive pathologies, which must then be confirmed by neuroradiological examinations. Nevertheless, we must not ignore this innovative aspect of the TCCD method. Furthermore, in the follow up of patients undergoing surgery for subdural haematoma, TCCD will offer valid, non-invasive assistance in monitoring the more or less complete re-absorption of the haematoma and/or post-surgery subdural pneumo-encephalon. In addition, TCCD allows us to detect indirect signs of space-occupying masses: – third ventricle midline shift – middle cerebral artery shift (for temporal space-occupying masses) – posterior cerebral artery-shift (for hippocampal uncus space-occupying masses). While the predictive value of midline shift alone is certainly far from immediate and really very approximate, it is nonetheless true that its association with the other two elements can give us useful information. Measurement of the third ventricle width is certainly a valid clinical element which can supply us with useful indications both about the presence of possible hydrocephalus but, in particular, about the efficiency of a ventriculoperitoneal or ventricoloatrial shunt. Not only are these data are of great importance in the monitoring of intensive care unit therapy, they also enable us to detect, in a few minutes and with certainty, cerebral areas of different density and thus to optimise both the treatment of the patient and the rationalisation of the neuroradiological examinations (CT scan and MRI). The literature contains several papers, most of them by the German school, concerning the study, with ultrasound, of extrapyramidal pathologies. We are seeing increasing confirmation of the possibility of detecting echogenicity of particular anatomical structures in the course of some CNS degenerative diseases, such as the presence of substantia nigra (SN) hypecogenicity as a “subclinical marker” idiopathic Parkinson’s disease (IPD). Whether this echogenic pattern is to be related to the accumulation of iron and/or calcium at the level of the SN is debated. Recent surveys seem to exclude the involvement of calcium. On the other hand, genetic studies (6,7) showed, in patients with PD, mutations of several genes involved in iron metabolism in the brain. Mutation of the ceruloplasmin gene is often present in these patients. This picture is absent in healthy controls. Nevertheless, the literature evidence confirms that SN hyperechogenicity is present in IPD patients and not in patients with essential tremor. An SN larger than 0.20 cm is indicative of pathology. In conclusion, with regard to the relationship between parkinsonism and SN hyperechogenicity, from the literature (8) we can infer that: