[Long-term monitoring]. / Long-Term Monitoring.

The electroencephalography (EEG) keeps its essential role in the differential diagnosis of epileptic and non-epileptic seizure disorders and in the classification of the different types of epilepsies and epileptic seizures, mainly due to its unique capability to directly show epileptic malfunction. The routine EEG usually records the EEG between seizures (interictal EEG) and remains a cost effective, highly specific, but not very sensitive method in epileptology. However, a diagnosis based on clinical data and routine EEG alone if often difficult and 20-30% of patients referred to an epilepsy centre due to medical refractory seizures do not have epilepsy. The different methods of long-term monitoring (cable and radio telemetry, ambulatory EEG monitoring) can continuously record EEG and other biosignals for many hours up to several days and allow a direct assessment of seizures (ictal EEG). In combination with the video-recorded symptomatology, these methods establish a precise diagnosis and follow-up of uncertain seizure disorders in the majority of cases. Although technical and personnel investment is relatively high the method used in expert hands is efficient, accepted and cost effective.

From clinical observation to long-term monitoring: diagnostic developments in conservative epileptology.

The diagnostic goals in nonsurgical (conservative) epileptology differ from presurgical diagnostic aims. The resulting development of diagnostic methods in a tertiary-level epilepsy center is shown and the major technical and organizational consequences of this difference for diagnostic long-term monitoring (LTM) as opposed to presurgical LTM are investigated. A total of 133 consecutive daytime LTM investigations using radio telemetry were reviewed and seizure parameters such as type, duration, method of seizure detection, and need of mobility were evaluated and compared to presurgical LTM. Compared to presurgical LTM, partial seizures were relatively rare (17.8%) and short epileptic or nonepileptic motor events lasting <1 s, such as myoclonic, atonic, short tonic seizures, spasms, tics, or startle reactions, are frequent (34.9%). Of all seizures, 23% had no or minor ictal EEG changes, subtle symptomatology without signaling by a patient or accompanying person, and could be detected only by continuous online surveillance by an experienced EEG technician. Due to the nature of the patient population in diagnostic LTM, there is an increased need for ictal and interictal mobility (radio telemetry). LTM in conservative epileptology requires more intense human surveillance for seizure detection and increased patient mobility compared to presurgical LTM.

Twenty years of ictal EEG-EMG.

This study aimed to evaluate the use of ictal EEG recordings combined with simultaneous surface EMG in the diagnosis and analysis of motor events, both epileptic and nonepileptic. All ictal registrations were performed utilizing radio/cable telemetry. Routine recordings consisted of 18-channel EEG plus 8-channels bipolar surface EMG in freely moving patients. Combined ictal EEG-EMG recordings in freely moving patients enabled us to identify and define the following pathomechanisms of epileptic drop seizures, epileptic axial spasms, atonic, myoclonic-atonic, and akinetic seizures. Precise differentiation could be made between tonic and nontonic postural seizures and between startle-induced reflex seizures and hyperekplexia. The findings from telemetered ictal recordings in freely moving patients with combined EEG and surface EMG offer the only means of identifying, defining, and differentiating motor events, both epileptic and nonepileptic, of a short duration that cannot be properly differentiated by clinical examination alone.