E Klemm’s research while affiliated with University of Bonn - Medical Center and other places

To analyze the role of selective middle cerebral artery (MCA) Wada tests in the presurgical workup of patients with drug-resistant focal epilepsies. Twenty MCA Wada test procedures were performed to identify eloquent cortex (a) in nine patients with hemispheric lesions involving the motor cortex (connatal MCA infarct, n = 5; unilateral cortical dysplasia, n = 3; Rasmussen encephalitis, n = 1), (b) five patients with circumscribed neoplastic or nonneoplastic lesions adjacent to the motor cortex or classic language areas, and (c) for purely electrophysiologic reasons, in two patients with electrical status epilepticus in sleep (ESES). Sodium amobarbital and [99mTc]-HMPAO were simultaneously injected via a microcatheter into the distal M1 segment (n = 7), the inferior MCA trunk (n = 3), or into MCA branches (n = 10). Co-registered single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI;n = 18) showed that sodium amobarbital did not reach the target area in three procedures. Temporary neurologic deficits occurred in 12 procedures. Eleven patients were operated on with the following surgical approaches: functional hemispherectomy, n = 3; partial or extended lesionectomy, n = 4; anterior temporal lobectomy, n = 1; and multiple subpial transsections, n = 3. Seizure freedom (Engel class I) was achieved in five patients. Selective MCA Wada tests can contribute to risk assessment concerning postsurgical motor deficits before functional hemispherectomy. Other indications are less clear: The identification of language areas is targeted primarily by electrical-stimulation mapping after subdural grid implantations, and selective MCA Wada tests in ESES patients yet have to be validated in larger patient groups.

In light of the competition between microneurosurgery and alternative methods such as stereotactic radiosurgery, we tested the hypothesis that changes in the cerebral circulation after microneurosurgery are common among patients without evidence of cerebrovascular or neoplastic disease. Blood flow velocities (BFVs) were recorded with transcranial Doppler ultrasonography, before surgery and every other day after surgery, for a group of 50 patients who underwent transsylvian selective amygdalohippocampectomies for treatment of hippocampal sclerosis. Hexamethylpropylene amine oxime-single-photon emission computed tomographic testing, including acetazolamide testing of cerebrovascular reactivity, was performed during the second postoperative week for 20 of the 50 patients. BFVs in basal arteries ipsilateral to the surgical approach increased significantly (P < 0.001) from preoperative baseline values of approximately 52 +/- 13 cm/s (mean +/- standard deviation) to values of approximately 86 +/- 27 cm/s on postoperative Day 3 and reached their maximal values of approximately 115 +/- 37 cm/s after a median of 7 days. BFVs in contralateral vessels exhibited a similar but somewhat attenuated pattern. Hexamethylpropylene amine oxime-single-photon emission computed tomography demonstrated ipsilateral regions of hypoperfusion in 100.0% of the cases and contralateral hypoperfusion in 80.0%. Cerebrovascular reactivity was impaired in 83.3% of the cases ipsilaterally and in 33.3% contralaterally. A significant proportion of patients who undergo microneurosurgical procedures develop bilateral alterations of their cerebral circulation. The elevations in mean BFV values represent cerebral vasospasm. Because these changes remain asymptomatic for the majority of patients, the transsylvian approach can be considered "minimally invasive" but not "atraumatic." Alternative surgical routes and alternative treatment modalities should be investigated in a similar manner.

OBJECTIVE : In light of the competition between microneurosurgery and alternative methods such as stereotactic radiosurgery, we tested the hypothesis that changes in the cerebral circulation after microneurosurgery are common among patients without evidence of cerebrovascular or neoplastic disease. METHODS : Blood flow velocities (BFVs) were recorded with transcranial Doppler ultrasonography, before surgery and every other day after surgery, for a group of 50 patients who underwent transsylvian selective amygdalohippocampectomies for treatment of hippocampal sclerosis. Hexamethylpropylene amine oxime-single-photon emission computed tomographic testing, including acetazolamide testing of cerebrovascular reactivity, was performed during the second postoperative week for 20 of the 50 patients. RESULTS : BFVs in basal arteries ipsilateral to the surgical approach increased significantly (P < 0.001) from preoperative baseline values of approximately 52 ± 13 cm/s (mean ± standard deviation) to values of approximately 86 ± 27 cm/s on postoperative Day 3 and reached their maximal values of approximately 115 ± 37 cm/s after a median of 7 days. BFVs in contralateral vessels exhibited a similar but somewhat attenuated pattern. Hexamethylpropylene amine oxime-single-photon emission computed tomography demonstrated ipsilateral regions of hypoperfusion in 100.0% of the cases and contralateral hypoperfusion in 80.0%. Cerebrovascular reactivity was impaired in 83.3% of the cases ipsilaterally and in 33.3% contralaterally. CONCLUSION : A significant proportion of patients who undergo microneurosurgical procedures develop bilateral alterations of their cerebral circulation. The elevations in mean BFV values represent cerebral vasospasm. Because these changes remain asymptomatic for the majority of patients, the transsylvian approach can be considered “minimally invasive” but not “atraumatic.” Alternative surgical routes and alternative treatment modalities should be investigated in a similar manner.

Focussing on regional cerebral hypoperfusion during hemodynamically stable, but borderline hypotensive, sustained ventricular tachycardia (VT) experimental studies show (1) a reduction of cerebral blood flow (CBF) during tachyarrhythmias in contrast to the concept of CBF autoregulation, (2) a mediation of hypoperfusion by neuronal and humoral mechanisms, and (3) an involvment of microcirculation due to an ischemic stress response of the cerebral tissue. The clinical relevance of these observations remains still unclear. Two patients with coronary artery disease, left ventricular dysfunction and sustained monomorphic VT underwent electrophysiological study. VT was induced and the tracer (99m)Tc-HMPAO was injected after 3 minutes of ongoing VT. Regional CBF during this life threatening arrhythmia was determined with brain SPECT. A scanning protocol was performed after termination of VT. The measurements were repeated at baseline during normofrequent sinus rhythm (SR) one week later. CBF during SR was significantly reduced in the temporal lobe in comparison to the conditions during stable VT, particularly in the left hippocampus. The reduction of hippocampal CBF due to cerebrovascular vasoconstriction and neuronal reflex mechanism previously observed in experiments during stable, sustained VT can be confirmed in a clinical scenario by high resolution (99m)Tc-HMPAO brain SPECT. This supports the hypothesis that repetitive stable VT can play a role in the pathophysiology of cerebrovascular insufficiency. Further clinical studies are needed to analyze the impact of tachyarrhythmias on cognitive and mnemic function.

Inadequate sodium amytal delivery to the posterior hippocampus during the intracarotid Wada test has led to development of selective tests. Our purpose was to show the sodium amytal distribution in the posterior cerebral artery (PCA) Wada test and to relate it to functional deficits during the test. We simultaneously injected 80 mg sodium amytal and 14.8 MBq 99mTc-hexamethylpropyleneamine oxime (HMPAO) into the P2-segment of the PCA in 14 patients with temporal lobe epilepsy. To show the skull, we injected 116 MBq 99mTc-HDP intravenously. Sodium amytal distribution was determined by high-resolution single-photon emission computed tomography (SPECT). In all patients, HMPAO was distributed throughout the parahippocampal gyrus and hippocampus; it was also seen in the occipital lobe in all cases and in the thalamus in 11. Eleven patients were awake and cooperative; one was slightly uncooperative due to speech comprehension difficulties and perseveration. All patients showed contralateral hemianopia during the test. Four patients had nominal dysphasia for 1-3 min. None developed motor deficits or had permanent neurological deficits. Neurological deficits due to inactivation of extrahippocampal areas thus do not grossly interfere with neuropsychological testing during the test.

Idiopathic dystonia with onset in the first year of life has been described as a transient movement disorder, in contrast to other forms of idiopathic dystonia We report on a girl who showed, from her 5th month, episodes of dystonic postures of her neck and arm, which lasted for seconds and occurred several times a day. Neurologic findings and the psychomotor development were and remained normal. Neurometabolic screening tests and cerebral magnetic resonance imaging showed normal results. Functional cerebral imaging showed decreased perfusion of the basal ganglia and the left temperomesial cortex using single photon emission computed tomography (SPECT with technetium 99m hexamethylpropyleneamine oxime [99mTc-HMPAO]) and decreased glucose metabolism in the basal ganglia and the cerebellum using positron emission tomography (PET with [18F]fluorodeoxyglucose [18FDG]). Follow-up revealed that the episodes disappeared at the age of 16 months. The findings of PET and SPECT give evidence of an alteration in basal ganglia function but also in functions of other central nervous system regions, which may, however, be temporary.