Alessandro Cianfoni

Motor Cortex Plasticity Predicts Recovery in Acute Stroke

Repetitive transcranial magnetic stimulation of the brain given as intermittent theta burst stimulation (iTBS) can induce long-term potentiation (LTP)-like changes in the stimulated hemisphere and long-term depression (LTD)-like changes in the opposite hemisphere. We evaluated whether LTP- and LTD-like changes produced by iTBS in acute stroke correlate with outcome at 6 months. We evaluated the excitability of affected hemisphere (AH) and unaffected hemisphere (UH) by measuring motor threshold and motor-evoked potential (MEP) amplitude under baseline conditions and after iTBS of AH in 17 patients with acute ischemic stroke. Baseline amplitude of MEPs elicited from AH was significantly smaller than that of MEPs elicited from UH, and baseline motor threshold was higher for the AH. Higher baseline MEP values in UH correlated with poor prognosis. iTBS produced a significant increase in MEP amplitude for AH that was significantly correlated with recovery. A nonsignificant decrease in MEP amplitude was observed for the UH. When the decrease in the amplitude of UH MEPs was added to the regression model, the correlation was even higher. Functional recovery is directly correlated with LTP-like changes in AH and LTD-like changes in UH and inversely correlated with the baseline excitability of UH.

Modulating cortical excitability in acute stroke: A repetitive TMS study

OBJECTIVE Changes in cerebral cortex excitability have been demonstrated after a stroke and are considered relevant for recovery. Repetitive transcranial magnetic stimulation (rTMS) of the brain can modulate cerebral cortex excitability and, when rTMS is given as theta burst stimulation (TBS), LTP- or LTD-like changes can be induced. The aim of present study was to evaluate the effects of TBS on cortical excitability in acute stroke. METHODS In 12 acute stroke patients, we explored the effects of facilitatory TBS of the affected hemisphere and of inhibitory TBS of the unaffected hemisphere on cortical excitability to single-pulse transcranial magnetic stimulation (TMS) on both sides. The effects produced by TBS in patients were compared with those observed in a control group of age-matched healthy individuals. RESULTS In patients, both the facilitatory TBS of the affected motor cortex and the inhibitory TBS of the unaffected motor cortex produced a significant increase of the amplitude of MEPs evoked by stimulation of the affected hemisphere. The effects observed in patients were comparable to those observed in controls. CONCLUSIONS Facilitatory TBS over the stroke hemisphere and inhibitory TBS over the intact hemisphere in acute phase enhance the excitability of the lesioned motor cortex. SIGNIFICANCE TBS might be useful to promote cortical plasticity in stroke patients.

Lumbar spondylolysis: a review

Spondylolysis is an osseous defect of the pars interarticularis, thought to be a developmental or acquired stress fracture secondary to chronic low-grade trauma. It is encountered most frequently in adolescents, most commonly involving the lower lumbar spine, with particularly high prevalence among athletes involved in certain sports or activities. Spondylolysis can be asymptomatic or can be a cause of spine instability, back pain, and radiculopathy. The biomechanics and pathophysiology of spondylolysis are complex and debated. Imaging is utilized to detect spondylolysis, distinguish acute and active lesions from chronic inactive non-union, help establish prognosis, guide treatment, and to assess bony healing. Radiography with satisfactory technical quality can often demonstrate a pars defect. Multislice CT with multiplanar reformats is the most accurate modality for detecting the bony defect and may also be used for assessment of osseous healing; however, as with radiographs, it is not sensitive for detection of the early edematous stress response without a fracture line and exposes the patient to ionizing radiation. Magnetic resonance (MR) imaging should be used as the primary investigation for adolescents with back pain and suspected stress reactions of the lumbar pars interarticularis. Several imaging pitfalls render MR imaging less sensitive than CT for directly visualizing the pars defects (regional degenerative changes and sclerosis). Nevertheless, the presence of bone marrow edema on fluid-sensitive images is an important early finding that may suggest stress response without a visible fracture line. Moreover, MR is the imaging modality of choice for identifying associated nerve root compression. Single-photon emission computed tomography (SPECT) use is limited by a high rate of false-positive and false-negative results and by considerable ionizing radiation exposure. In this article, we provide a review of the current concepts regarding spondylolysis, its epidemiology, pathogenesis, and general treatment guidelines, as well as a detailed review and discussion of the imaging principles for the diagnosis and follow-up of this condition.

Seizure-induced brain lesions: a wide spectrum of variably reversible MRI abnormalities.

Introduction MRI abnormalities in the postictal period might represent the effect of the seizure activity, rather than its structural cause. Material and Methods Retrospective review of clinical and neuroimaging charts of 26 patients diagnosed with seizure-related MR-signal changes. All patients underwent brain-MRI (1.5-Tesla, standard pre- and post-contrast brain imaging, including DWI-ADC in 19/26) within 7 days from a seizure and at least one follow-up MRI, showing partial or complete reversibility of the MR-signal changes. Extensive clinical work-up and follow-up, ranging from 3 months to 5 years, ruled out infection or other possible causes of brain damage. Seizure-induced brain-MRI abnormalities remained a diagnosis of exclusion. Site, characteristics and reversibility of MRI changes, and association with characteristics of seizures were determined. Results MRI showed unilateral (13/26) and bilateral abnormalities, with high (24/26) and low (2/26) T2-signal, leptomeningeal contrast-enhancement (2/26), restricted diffusion (9/19). Location of abnormality was cortical/subcortical, basal ganglia, white matter, corpus callosum, cerebellum. Hippocampus was involved in 10/26 patients. Reversibility of MRI changes was complete in 15, and with residual gliosis or focal atrophy in 11 patients. Reversibility was noted between 15 and 150 days (average, 62 days). Partial simple and complex seizures were associated with hippocampal involvement (p=0.015), status epilepticus with incomplete reversibility of MRI abnormalities (p=0.041). Conclusions Seizure or epileptic status can induce transient, variably reversible MRI brain abnormalities. Partial seizures are frequently associated with hippocampal involvement and status epilepticus with incompletely reversible lesions. These seizure-induced MRI abnormalities pose a broad differential diagnosis; increased awareness may reduce the risk of misdiagnosis and unnecessary intervention.

Magnetic resonance imaging findings in sudden sensorineural hearing loss.

OBJECTIVE To investigate the role of magnetic resonance imaging (MRI) in the diagnosis of sudden sensorineural hearing loss (SSNHL). METHODS Fifty-four consecutive patients affected by SSNHL were investigated using brain MRI. MRI was performed with an eight-channel phased-array head coil to study the entire audiovestibular pathway and the whole brain. The protocol study consisted of a high-resolution study of the temporal bone, internal auditory canal (IAC), cerebellopontine angle (CPA), and brainstem combining 2 mm thin-slice axial T(2)-weighted two-dimensional fast spin echo (FSE) and fluid-attenuated inversion recovery (FLAIR) sequences, pre- and postcontrast (gadolinium-diethylenetriamine pentaacetic acid) administration fat-suppressed axial T(1)-weighted two-dimensional FSE sequences, and a T(2)*-weighted three-dimensional Fourier transformation-constructive interference in steady state sequence (FT-CISS) , with 0.4 mm ultrathin partitions. The rest of the brain was studied with a 4 mm axial T(2)-weighted FLAIR sequence. RESULTS Thirty-one of 54 (57%) cases of SSNHL presented with MRI abnormalities. In 6 of 54 cases, the detected abnormality was directly correlated to the clinical picture (2 labyrinthine hemorrhage, 1 cochlear inflammation, 1 acoustic neuroma, 1 arachnoid cyst of the CPA, and 1 case of white matter lesions in the pons, compatible with demyelinating plaques along the central audiovestibular nervous pathway, as the first expression of multiple sclerosis). CONCLUSIONS An extensive MRI study of the audiovestibular nervous pathway and of the whole brain, pre- and postparamagnetic contrast administration, is recommended to rule out the wide spectrum of abnormalities that can cause SSNHL.

Brain perfusion CT: Principles, technique and clinical applications

The imaging of brain haemodynamics and its applications are generating growing interest. By providing quantitative measurements of cerebral blood flow (CBF) and cerebral blood volume (CBV), dynamic perfusion computed tomography (p-CT) allows visualisation of cerebral autoregulation mechanisms and represents a fast, available and reliable imaging option for assessing cerebral perfusion. Thanks to its feasibility in emergency settings, p-CT is considered most useful, in combination with CT angiography, in acute ischaemic patients, as it is able to provide a fast and noninvasive assessment of cerebral perfusion impairment. In addition, p-CT can play a diagnostic role in other types of cerebrovascular disease to assess functional reserve, and in intracranial neoplasms, where it has a role in diagnosis, grading, biopsy guidance, and follow-up during treatment. This article illustrates the principles, technique and clinical applications of p-CT cerebral perfusion studies.RiassuntoLo studio dell’emodinamica cerebrale, ottenuto con le metodiche di imaging, con le sue varie ed attuali applicazioni, genera interesse crescente. La TC perfusione dinamica (p-TC) permette una valutazione quantitativa del flusso cerebrale ematico (CBF) e del volume cerebrale ematico (CBV), offrendo così una visualizzazione diretta dei meccanismi di autoregolazione cerebrale, e si pone come una valida alternativa ad altre modalità di misurazione della perfusione cerebrale, rispetto alle quali ha il maggior vantaggio di essere una tecnica prontamente disponibile ed accessibile, in condizioni di emergenza, nella maggior parte dei centri medici. Per tale ragione la p-TC è utile soprattutto nell’ischemia cerebrale acuta, condizione in cui, associata all’angio-TC, offre in maniera rapida e non-invasiva, la valutazione eziologica dell’ipoperfusione, nonché delle sue ripercussioni emodinamiche e fisiopatologiche sul parenchima cerebrale. Inoltre la p-TC trova utile impiego in pazienti con altre patologie cerebro-vascolari e per la diagnosi, il grading, la guida alle procedure bioptiche, ed il controllo durante la terapia, dei tumori intra-cranici. Questo articolo si propone di riassumere i principi, la tecnica e le principali applicazioni cliniche degli studi di perfusione cerebrale basati sulla metodica TC.

Perfusion CT compared to H215O/O15O PET in patients with chronic cervical carotid artery occlusion

IntroductionThe purpose of this study was to compare the results of perfusion computed tomography (PCT) with those of 15O2/H215O positron emission tomography (PET) in a subset of Carotid Occlusion Surgery Study (COSS) patients.Materials and methodsSix patients enrolled in the COSS underwent a standard-of-care PCT in addition to the 15O2/H215O PET study used for selection for extracranial–intracranial bypass surgery. PCT and PET studies were coregistered and then processed separately by different radiologists. Relative measurement of cerebral blood flow (CBF) and oxygen extraction fraction (OEF) were calculated from PET. PCT datasets were processed using different arterial input functions (AIF). Relative PCT and PET CBF values from matching regions of interest were compared using linear regression model to determine the most appropriate arterial input function for PCT. Also, PCT measurements using the most accurate AIF were evaluated for linear regression with respect to relative PET OEF values.ResultsThe most accurate PCT relative CBF maps with respect to the gold standard PET CBF were obtained when CBF values for each arterial territory are calculated using a dedicated AIF for each territory (R2 = 0.796, p < 0.001). PCT mean transit time (MTT) is the parameter that showed the best correlation with the count-based PET OEF ratios (R2 = 0.590, p < 0.001).ConclusionPCT relative CBF compares favorably to PET relative CBF in patients with chronic carotid occlusion when processed using a dedicated AIF for each territory. The PCT MTT parameter correlated best with PET relative OEF.

Quantitative measurement of blood-brain barrier permeability using perfusion-CT in extra-axial brain tumors

Non-invasive assessment of vascular permeability is of main importance in the diagnosis, treatment and follow-up of intracranial tumors. Perfusion-CT is one of the imaging options available, which affords quantitative assessment of cerebral blood volume and blood-brain barrier permeability. Herein we report two cases of extra-axial tumors studied with perfusion-CT. Comparison with perfusion-MRI was available in one case. High permeability values, as measured by perfusion-CT, reflected the absence of blood-brain barrier in these extra-axial tumors.

Sleep disordered breathing in facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is one of the most frequent forms of muscular dystrophy. The aims of this study were: 1) to evaluate the prevalence of sleep disordered breathing (SDB) in patients with FSHD; 2) to define the sleep-related respiratory patterns in FSHD patients with SDB; and 3) to find the clinical predictors of SDB. Fifty-one consecutive FSHD patients were enrolled, 23 women, mean age 45.7+/-12.3 years (range: 26-72). The diagnosis of FSHD was confirmed by genetic tests. All patients underwent medical and neurological evaluations, subjective evaluation of sleep and full-night laboratory-based polysomnography. Twenty patients presented SDB: 13 presented obstructive apneas, four presented REM related oxygen desaturations and three showed a mixed pattern. Three patients needed positive airways pressure. SDB was not related to the severity of the disease. Body mass index, neck circumference and daytime sleepiness did not allow prediction of SDB. In conclusion, the results suggest a high prevalence of SDB in patients with FSHD. The presence of SDB does not depend on the clinical severity of the disease. SDB is often asymptomatic, and no clinical or physical measure can reliably predict its occurrence. A screening of SDB should be included in the clinical assessment of FSHD.

Correlation between Cerebral Blood Volume Measurements by Perfusion-Weighted Magnetic Resonance Imaging and Two-Year Progression-Free Survival in Gliomas

Our goal was to determine whether relative cerebral blood volume (rCBV) can serve as an adjunct to histopathologic grading in the assessment of gliomas, with the hypothesis that rCBV can predict two-year survival. We evaluated 29 newly diagnosed gliomas (13 WHO grade II, seven grade III, nine grade TV; 17 astrocytomas, 12 oligodendroglial tumors). Dynamic susceptibility-weighted contrast-enhanced perfusion MR images and CBV maps were obtained. rCBVmax measurements (maximum tumor CBV/contralateral normal tissue CBV) and progression-free survival (PFS) were recorded. Receiver operating characteristic curves and Kaplan-Meier survival curves were calculated for rCBVmax and histologic grade. rCBVmax measurements differed between gliomas without (2.38 +/− 1.22) and with progression (5.57 +/− 2.84) over two years. The optimal rCBVmax cut-off value to predict progression was 2.95. rCBVmax < 2.95 was a significant predictor of two-year PFS, almost as accurate as WHO grade IT In the pure astrocytoma subgroup, the optimal rCBVmax cut-off value to predict progression was 2.85. In this group rCBVmax < 2.85 was a significant predictor of two-year PFS, an even better predictor of two-year PFS than WHO grade IT rCBVmax can be used to predict two-year PFS in patients with gliomas, independent of pathologic findings, especially in tumors without oligodendroglial components.