Katrin Druschky

Differentiation of Parkinson's disease and multiple system atrophy in early disease stages by means of I-123-MIBG-SPECT

BACKGROUND Differential diagnosis between idiopathic Parkinsons disease (PD) and multiple system atrophy (MSA) is often difficult in early disease stages. Since MSA is misdiagnosed as PD in more than 20% of the early stages, there is need for methods refining the differentiation of the two disease entities. In PD postganglionic involvement of the autonomic nervous system (ANS) predominates whereas in MSA the ANS is mainly affected in its preganglionic structures. The functional integrity of postganglionic cardiac sympathetic neurons can be investigated using I-123-metaiodobenzylguanidine-single photon emission computed tomography (MIBG-SPECT). OBJECTIVES We investigated whether I-123-MIBG-SPECT allows to differentiate between early stages of PD and MSA in patients not yet requiring L-dopa therapy. METHODS Thirty patients (10 PD and 20 MSA patients) underwent MIBG-SPECT and evaluation of heart rate variability (HRV). Patients on any medication interfering with MIBG-accumulation were excluded from the study. Cardiac perfusion was evaluated by myocardial scintigraphy. RESULTS The median cardiac MIBG uptake was significantly decreased in PD as well as MSA patients compared to controls (P<0.001). However, in the PD group MIBG uptake was significantly lower than in MSA (P=0.03). Even in PD patients without clinical signs of autonomic failure, MIBG uptake was significantly lower than in MSA patients (P=0.03). Analysis of heart rate parameters did not differentiate between PD and MSA patients. The median coefficient of variation was significantly smaller in PD and MSA patients compared to control subjects. CONCLUSIONS Our study shows that MIBG-SPECT identifies autonomic cardiac dysfunction in very early stages of both, PD and MSA. More importantly, the technique facilitates differentiation of MSA and PD in the early stages. The different pathology with prominent peripheral, postganglionic sympathetic dysfunction in PD and primarily central and preganglionic lesions in MSA accounts for a lower MIBG uptake in PD compared to MSA patients.

Alteration of the somatosensory cortical map in peripheral mononeuropathy due to carpal tunnel syndrome.

Substantial plasticity of the mature mammalian somatosensory cortex was demonstrated after deprivation of sensory input produced by amputation or somatosensory deafferentation. Following transection of the median nerve, adult owl and squirrel monkeys exhibit extensive reorganization in the cortical representation of the hand in areas 3b and 1. In the present study we investigated the possible effect of incomplete median nerve damage on sensory cortex somatotopy in a patient with unilateral carpal tunnel syndrome. We assessed interhemispheric differences of the hand representation in SI by means of magnetic source imaging. Additional intersubject data comparison was performed for specific results on the basis of available normal data from the literature and from own investigations in five healthy volunteers. Our results demonstrated a decreased extension of the cortical zone representing the injured median nerve and suggested invasion of the deprived area by cortical sectors receiving inputs from the little finger (supplied by the ulnar nerve) and from the dorsum of the thumb (innervated by the radial nerve). The study indicates topographic rearrangement of the hand representational zone in the human primary somatosensory cortex in a case of chronic median nerve injury.

Outcome of epilepsy surgery correlates with sympathetic modulation and neuroimaging of the heart.

Temporal lobe epilepsy (TLE) is frequently associated with sympathetic over-activity. Single photon emission computed tomography (SPECT) with 123iodine-meta-iodobenzylguanidine (MIBG), a norepinephrine analogue, showed reduced tracer uptake in cardiac sympathetic nerve endings, indicating myocardial catecholamine disturbance. We investigated whether outcome of epilepsy surgery correlates with cardiac autonomic function in TLE patients. We studied 16 TLE patients before and after epilepsy surgery. We recorded heart rate (HR) and determined sympathetic and parasympathetic cardiac modulation as powers of low (LF, 0.04-0.15 Hz) and high frequency (HF, 0.15-0.5 Hz) heart rate oscillations. The LF/HF-ratio was calculated as index of sympathovagal balance. Cardiac MIBG uptake was assessed with MIBG-SPECT and compared to control data. After surgery, eight patients were seizure-free and eight had persistent seizures. Sympathetic LF-power and LF/HF-ratio were higher in patients who had persistent seizures than in patients who became seizure-free. After surgery, both parameters decreased in seizure-free patients but increased in patients with persistent seizures. MIBG uptake was lower in patients than controls and even lower in the patient subgroup who had persistent seizures. In this subgroup, MIBG uptake further decreased after surgery (P<0.05). Sympathetic cardiac modulation decreased in TLE patients after successful surgery, but further increased if seizures persisted. Reduction of cardiac MIBG uptake progressed after surgery in patients with persistent seizures. Interference of epileptogenic discharges with autonomic neuronal transmission might account for sympathetic cardiac over-stimulation and reduced MIBG uptake. Both findings are possible risk factors for sudden unexplained death and might be relevant for risk stratification in epilepsy patients.

CT, MRI and SPECT neuroimaging in status epilepticus with simple partial and complex partial seizures: case report

SummaryA 35-year-old female patient suffering from epilepsy was examined during status epilepticus with simple partial and complex partial seizures by means of EEG, CT, MRI and ictal SPECT. All these examinations showed focal abnormalities with identical location due to oedema and hypervascularisation; these were, however, absent during examinations carried out before and after status epilepticus.

Fatal complications after myelography with meglumine diatrizoate

SummaryA case of inadvertent intrathecal injection of diatrizoate meglumine is presented. After myelography with 10 ml i.e. 6.5 g Angiografin, a 76-year-old man rapidly developed myoclonus, drowsiness and excessive metabolic acidosis. He died only a few hours later. Postmortem showed non-specific brain edema. RP-HPL-Chromatography confirmed high concentration of the contrast medium in CSF (6 mg/ml) which must have induced refractory central nervous dysregulation. The lethal effects of the misapplication of this agent on the nervous system are discussed.

Somatotopic Organization of the Ventral and Dorsal Finger Surface Representations in Human Primary Sensory Cortex Evaluated by Magnetoencephalography

Cortical reorganization of the subtly differentiated hand map after peripheral nerve injury might be better understood if there was a topographic conception of the homuncular representation of the dorsal finger surfaces in humans, in addition to the well-established sequential rostrocaudal array of the ventral finger aspects in cortical area 3b. In the present magnetoencephalographic study, tactile pneumatic stimulation was delivered to the fingertip and to the ventral and dorsal proximal phalanx of each digit of the dominant hand in 20 right-handed volunteers. Source localization of equivalent current dipoles underlying the recorded somatosensory evoked magnetic field was performed using a Cartesian coordinate system established by the anatomical landmarks nasion and preauricular points. Of the first major peak of each somatosensory evoked field, the region with the maximum field power (root-mean-square across channels) was selected for source reconstruction. Analysis of variance for repeated measures yielded significant results with respect to the arrangement of digits along the vertical coordinate axis, demonstrating a sequential array from the most inferiorly located D1 to the most superiorly located D5 for all different stimulus positions. This is the first study providing evidence for a sequential topographical arrangement of not only the ventral but also the dorsal surface representations of the individual digits in the human somatosensory cortex. The study contributes to a better understanding of the somatosensory hand representation in human primary cortex and provides useful information with regard to cortical plasticity studies in patients with peripheral nerve injuries at the upper extremity.

Chronic parvovirus B-19 meningoencephalitis with additional detection of Epstein-Barr virus DNA in the cerebrospinal fluid of an immunocompetent patient.

Parvovirus B19 DNA was detected by polymerase chain reaction in the brain biopsy specimen from a 67-year-old immunocompetent woman with severe chronic lymphocytic meningoencephalitis. In addition to parvovirus B19, Epstein-Barr virus DNA was identified in the CSF. Genomic material from Epstein-Barr virus was absent in the brain tissue. Clinical symptoms and CSF pleocytosis improved under long-term corticosteroid-treatment. The aetio-pathogenetic role of parvovirus B19 and the possible meaning of the additionally detected Epstein-Barr virus DNA are discussed.

Pain-related somatosensory evoked magnetic fields induced by controlled ballistic mechanical impacts.

Summary The purpose of this study was to investigate cortical processing of painful compared with tactile mechanical stimulation by means of magnetoencephalography (MEG) using the novel technique of mechanical impact loading. A light, hard projectile is accelerated pneumatically in a guiding barrel and elicits a brief sensation of pain when hitting the skin in free flight. Controllable noxious and innocuous impact velocities facilitate the generation of different, predetermined stimulus intensities. The authors applied painful as well as tactile mechanical impacts to the dorsum of the second, third, and fourth digit of the nondominant hand. Pain-related somatosensory evoked magnetic fields (SSEFs) were compared with those following tactile stimulation in seven healthy volunteers. Contralateral primary sensory cortical area activation was observed within the first 70 msec after tactile as well as painful stimulus intensities. Only painful impacts elicited SSEF responses assigned to the bilateral secondary sensory cortical regions and to the middle part of the contralateral cingulate gyrus, which were active at latency ranges of 55 to 155 msec and 90 to 220 msec respectively. Additional long-latency responses occurred in these cortical areas as long as 280 msec after painful stimulation in three subjects. In contrast to tactile stimulation, painful mechanical impacts elicited SSEF responses in cortical areas demonstrated to be involved in central pain processing by previous MEG and neuroimaging studies. Because of its similarity to natural noxious stimuli and the possibility of adjustable painful and tactile impact velocities, the technique of mechanical impact loading provides a useful method for the neurophysiologic evaluation of cortical pain perception.

Severe neurological complications of ulcerative colitis

A 37 year old man presented with a 15 year history of ulcerative colitis. On examination he had weakness of the right arm, slurred speech and progressive confusion, followed by a rapid deterioration of consciousness and motor functions resulting in coma, tetraparesis and bilateral Babinski responses. Magnetic resonance imaging of the brain and spinal cord revealed multiple hyper- and hypointense white matter lesions. Clinical symptoms, history and neuroradiological findings led to the diagnosis of an ulcerative colitis-associated CNS disorder. An autoimmune vasculitic process may have played an important pathophysiological role, considering the vasculitic changes observed by skin biopsy as well as the rapid clinical improvement following immunosuppressive therapy with corticosteroids and azathioprine. During a follow up period of more than one year we observed continuous and complete recovery of neurologic symptoms.

Cardiac sympathetic denervation in Ross syndrome demonstrated by MIBG-SPECT

We investigated cardiac sympathetic innervation by metaiodobenzylguanidine (MIBG) imaging in a patient with tonic pupils, loss of tendon reflexes, and segmental anhidrosis (Ross syndrome). Despite normal cardiovascular reflex tests, we observed a reduced global myocardial MIBG uptake as well as a regional uptake defect over the posterolateral cardiac territory indicating left ventricular peripheral sympathetic denervation. MIBG imaging seems to be a useful noninvasive diagnostic method for detection of early--possibly subclinical--cardiac autonomic impairment in Ross syndrome and provides further evidence of injury to postganglionic autonomic neurons as the underlying pathological mechanism of the disease.