D. Zegers de Beyl

Prognostic value of early cortical somatosensory evoked potentials after resuscitation from cardiac arrest

Short-latency somatosensory evoked potentials (SEPs) were evaluated in patients after cardiorespiratory arrest to study their pattern of recovery in the acute stage of anoxic-ischaemic coma. Fifty consecutive comatose patients were investigated within 8 h after cardiorespiratory resuscitation. In 30 patients no cortical SEPs were recorded and none of the patients recovered cognition. In 20 patients cortical SEPs were recorded and 5 recovered. The different susceptibility of frontal and parietal cortical structures to anoxia was reflected by the dissociated loss of parietal or frontal potentials in 6 patients. Post-mortem pathology in 15 patients confirmed extensive anoxic-ischaemic damage of cerebral and cerebellar cortex and thalamus in patients without cortical SEPs whereas the histological lesions were restricted to Sommers sector and Purkinje cells in those with preserved SEPs. SEPs thus reflect the extent of brain damage after cardiorespiratory resuscitation.

The somatosensory central conduction time: physiological considerations and normative data

The somatosensory central conduction time (CCT) can be measured from the peak of N13 to the peak of N20 (peak CCT) or from the onset of N11 to the onset of N20 (onset CCT). The onset and peak CCT were measured concomitantly in 40 normal subjects and the mean peak CCT was significantly shorter than the mean onset CCT. Records with different reference electrodes (linked earlobes, F3, over the ipsilateral parietal scalp, non-cephalic reference in some subjects) showed no significant latency change of the N11 onset, the N20 onset, the peak and onset CCT in contrast with the significant latency changes of the N13 and N20 peak with different montages. The onset CCT was divided by the onset of the P14 far-field in 2 parameters, the N11-P14 interval predominantly concerned with spinal conduction and the P14-N20 interval which reflected only supraspinal conduction. The onset and peak CCT, the N11-P14 and P14-N20 intervals were not correlated with height or age. Three independent recording sessions over 1 year in 16 subjects showed that the parameters were reproducible. From the physiological point of view the onset and peak CCT are different parameters and the anatomical correlates of both parameters are discussed.

Unusual pattern of somatosensory and brain-stem auditory evoked potentials after cardio-respiratory arrest.

Two patients in coma after cardio-pulmonary arrest showed bilateral absence of all brain-stem auditory evoked potentials contrasting with normal brain-stem reflexes and normal somatosensory cortical evoked potentials. In both patients pre-existing dysfunction of peripheral auditory structures could be ruled out. Subsequent neuropathological analysis showed that the anoxic-ischaemic lesions were restricted to Sommers sector and the Purkinje cells. These unusual data suggest the hypothesis that a severe hypoxic-ischaemic insult may impair cochlear function and interfere with the activation of the intact auditory pathways.

Spinal and brain-stem SEPs and H reflex during enflurane anesthesia.

Whereas cortical SEPs are altered by halogenated anesthetics, spinal and subcortical SEPs are thought to be hardly affected. In this study the spinal N13 potential (recorded with anterior neck reference) showed a significant delay with enflurane anesthesia. The P13 and P14 far-field potentials, however, remained unchanged. Our results indicate that oligosynaptic as well as polysynaptic pathways are influenced by halogenated anesthetics and that enflurane has different effects on spinal gray matter and cuneate synapses. Our data also demonstrate that earlobe reference recordings are not adequate to measure pharmacologic effects on subcortical SEPs.

Focal seizures with reversible hypodensity on the CT scan.

Sir: When a postictal abnormal computed tomographic (CT) finding corresponds anatomically to the presumed ictal focus in patients with focal seizures, the abnormality is thought to reflect the existence of a pathological process responsible for the occurrence of the seizures. The CT abnormality is usually not considered to be the result of the ictal and interictal metabolic disturbances which are known to occur in and around the seizure focus. We report a case whose transient postictal focal CT abnormality appears to have been the direct consequence of recurrent focal seizure activity. An 18-year-old right handed student was in good health until ten days prior to admission when he woke up with headache and noted he had bitten his tongue. Three days prior to admission he experienced spontaneous twitching of the right corner of the mouth and the right hand. He was unable to talk during this focal seizure which lasted several minutes. Over the next 12 hours he had four identical focal seizures. Previous medical and family history were unremarkable, blood pressure was 115/70 mm Hg, auscultation of the heart was normal. Neurological examination was normal. A CT scan on the day of admission showed a large hypodense left frontal area without displacement of the lateral ventricle or midline structures (fig). Contrast injection showed a peripheral rim of enhancement. EEG, ECG, chest radiographs, serum electrolytes and full blood count were normal. He was treated with phenobarbitone 150 mg nocte. A four vessel angiogram performed six days after admission showed no abnormalities of the aortic arch, the carotid and vertebral arteries. The intracerebral circulation was normal in the arterial, capillary and venous phases. A presumptive diagnosis of left frontral glioma was made. Three weeks after admission a stereotaxic biopsy under CT monitoring revealed two specimen of normal cerebral tissue. The hypodense area appeared less extensive and a transient right facial weakness was noted after the procedure. One month after admission a CT scan with and without contrast enhancement was normal. Anticonvulsant therapy was gradually withdrawn after twelve months. Over the next two years he remained free of seizures and the CT scan remained normal. This young mans repeated focal seizures suggested an underlying focal pathologic 187

Effects of levodopa on upper limb mobility and gait in Parkinson's disease

Background: Most clinicians rely on clinical scales such as the unified Parkinson’s disease rating scale (UDPRS) for evaluating parkinsonian patients and assessing their response to levodopa. Gait analysis is not commonly used, probably because of the equipment required and the time needed. Few data have been published on the relations between gait variables and measures of arm and hand mobility. Objectives: To evaluate the correlation between dopa induced gait improvement and upper limb motor improvement using a rapid and simple method; and to evaluate the correlation between gait improvement and UPDRS III improvement. Methods: A finger tapping test and a simple walking test were used to measure the OFF-ON variations of upper limb motor function and gait in 23 patients with Parkinson’s disease. The UPDRS motor score and the Hoehn and Yahr stage were measured in the OFF and the ON state. Results: There was no correlation between OFF-ON variation of the number of hits with the finger tapping test and OFF-ON variation in the gait variables. OFF-ON variation in the UPDRS motor score was not correlated with OFF-ON variation in the gait variables. Conclusions: There was a dissociation between the effect of levodopa on upper limb and gait. The findings suggest that simple measures like the finger tapping test and a walking test should be included in the usual evaluation of patients with Parkinson’s disease.

Audiogenic startle reflex in acute hemiplegia

The generators of the audiogenic startle reflex (ASR) are located in the bulbopontine reticular formation. We studied the influence of acute vascular supratentorial lesions on ASR. Ten patients with hemiplegia due to hemispheric cerebral infarct were studied within 5 days of stroke onset. ASR and magnetic cortical stimulation were performed the same day. A muscle response to magnetic stimulation was not elicited over the plegic side in any patient. In four of seven patients, ASR was enhanced over the plegic side. We suggest that enhanced ASR is due to the loss of a predominantly inhibitory hemispheric drive on ASR generators.

Gd-DTPA-enhanced MR in thoracic disc herniations

SummaryThe Gd-DTPA-enhanced magnetic resonance findings in two patients with herniated thoracic intervertebral discs are reported. The first patient was a 56-year-old woman with a small subligamentous T6-7 disc herniation, slightly lateralized to the right. The second patient was a 51-year-old man with a central and right posterolateral disc herniation, including a large calcified fragment, at the T8-9 level. The nonenhanced MR examination revealed the presence of an extradural mass lesion in both patients, impinging upon the dural sac and compressing and displacing the spinal cord posteriorly. The lesion was slightly hypointense on both T1- and T2-weighted spin echo sequences. Following intravenous injection of Gd-DTPA in a dosage of 0.1 mmol/kg body weight, enhancement of the posterior longitudinal ligament was noted and triangular areas of contrast uptake were seen to occur in the epidural space above and below the herniated disc. At surgery, they were found to correspond to dilated and congested epidural veins.

Painful arm and moving fingers: Clinical features of four new cases†

The syndrome of painful arm and moving fingers associates pain in one arm or hand with involuntary movement of one or several fingers. In the four cases described, an association between a central and a peripheral nervous system lesion is demonstrated or suspected. Treatment of the condition is disappointing.

Ocular bobbing and myoclonus in central pontine myelinolysis.

Ocular bobbing and myoclonus were unusual findings in a patient with central pontine myelinolysis. Pathological findings confirmed the diagnosis of pontine and extrapontine myelinolysis.