Temporal Intermittent Rhythmic Delta Activity Research Articles

Temporal intermittent rhythmic theta activity (TIRTA): A marker of epileptogenicity?

To describe a novel EEG rhythm, temporal intermittent rhythmic theta activity (TIRTA), and its potential association with epilepsy. We report TIRTA on scalp EEG in a series of 12 patients, all of whom were found to have epilepsy. The clinical and electroencephalographic characteristics of each patient were reviewed. In addition, features that may distinguish TIRTA from benign EEG patterns, including rhythmic temporal theta bursts of drowsiness (RTTBD), were identified. TIRTA was unilateral in all cases. For all patients, TIRTA was seen in the awake and drowsy states. Eight patients also had TIRTA observed during N2 sleep. The average frequency of TIRTA was 5.5Hz and the average duration of a train of TIRTA was 5.25s. In seven cases the morphology was notched in appearance. Temporal intermittent rhythmic delta activity (TIRDA) was seen in seven patients on the same side as TIRTA. Eleven patients also had ipsilateral temporal sharp waves. Abnormal MRI (6/12) and or PET (5/5) findings were ipsilateral to TIRTA. In this preliminary report we suggest that TIRTA may be a novel marker of potential epileptogenicity, possibly representing a higher frequency variant of TIRDA.

Modified lateral orbitotomy approach for resection of anterior temporal cavernous malformation

Background: The lateral orbitotomy approach (LOA) provides a direct and minimally invasive corridor to orbital apex, cavernous sinus, and middle cranial fossa (MCF) lesions. Removal of the lateral orbital wall and retraction of the orbital contents, as performed with a traditional LOA, can cause diplopia and enophthalmos and affect visual acuity. The modified LOA (mLOA) preserves the lateral orbital wall to limit this morbidity.Case Description: A 58-year-old man experienced new-onset headaches and anxiety attacks that improved with anti-seizure medication. He was neurologically intact on examination. Magnetic resonance imaging demonstrated a 2-cm right anterior temporal cavernous malformation with an associated hemosiderin ring. Electroencephalogram revealed right temporal intermittent rhythmic delta activity suspicious for anterior temporal lobe epilepsy. He underwent an endoscopic-assisted keyhole mLOA for resection of the cavernoma and hemosiderin-stained brain. Key steps included a Y-shaped incision in the upper eyelid/lateral canthus, removal of a 1.5-cm segment of the lateral orbital rim, drilling of the lateral orbital wall with preservation of the medial cortex, drilling the lateral sphenoid ridge to access the anterior temporal lobe, resecting the cavernoma with endoscopic assistance for removal of all potentially epileptogenic abnormal brain, and plating the orbital rim as part of a layered closure. Postoperatively, he remained neurologically intact. He was discharged on postoperative day 4 after resolution of a cerebrospinal fluid leak with lumbar drainage. On follow-up, his anxiety attacks had completely resolved, and his incision was well-healed.Conclusion: The mLOA is an ideal keyhole technique for selected lesions of the MCF.

Electroencephalographic features associated with intermittent rhythmic delta activity

To investigate the clinical importance of intermittent rhythmic delta activity (IRDA) in terms of accompanying electrophysiological findings on EEG and their association with IRDA. We retrospectively assessed all EEG studies recorded in our institution from 2011 to 2017. Patients with intermittent rhythmic delta activity (IRDA) in EEGs were included. Clinical data were collected from charts of the patients with IRDA. We identified 69 EEGs with IRDA in 58 patients from a total of 18,625 EEG recordings. The most common IRDA type was frontal IRDA (FIRDA; 55%), followed by temporal IRDA (TIRDA; 28.9%). Unilateral (UL) distribution was present in 36.8% of FIRDAs and 95% of TIRDAs. The frequency of focal epileptiform discharges (FED) was 78.5% in UL FIRDA group and 89.4% in UL TIRDA group. Among the EEGs with FEDs, in UL FIRDA group 90.9% and in UL TIRDA group 70.5% of the FEDs were ipsilateral. Concordance of focal structural brain lesions and FEDs with UL TIRDA was 30.7%, and with UL FIRDA was 50%. UL FIRDA had a 71.4% positive predictive value for ipsilateral focal epileptic focus and UL TIRDA had 63.1%. The frequency of focal structural lesions and FEDs were significantly higher in the UL FIRDA group than bilateral FIRDA group (P=0.03; P=0.01). Among the patients with focal structural lesions, ipsilateral FED association is significantly higher in the UL FIRDA group than BL FIRDA group (P=0.03). UL FIRDA is more likely to indicate a focal lesion and a focal epileptic focus compared to bilateral FIRDA, and it had similar characteristics to UL TIRDA. It can be considered that UL FIRDA has as good a lateralizing value for ipsilateral focal epileptic focus and focal lesion as UL TIRDA.

De novo temporal intermittent rhythmic delta activity after laser interstitial thermal therapy for mesial temporal lobe epilepsy predicts poor seizure outcome

ObjectiveTo evaluate EEG abnormalities, particularly development of temporal intermittent rhythmic delta activity (TIRDA) after laser interstitial thermal therapy (LITT) and assess the role of further surgery after LITT. MethodsWe retrospectively identified consecutive cases of LITT for the prevalence of post-operative TIRDA. We assessed baseline demographics, clinical variables including age of seizure onset, age at surgery, pre-operative and post-operative EEG changes. Results40 patients underwent LITT for drug-resistant temporal lobe epilepsy (TLE), 29 met inclusion criteria. Median duration of follow-up was 15 months. Ten patients had post-LITT ipsilateral TIRDA, another two demonstrated post-operative TIRDA but they occurred contralateral to the side of ablation. None of the patients with TIRDA on their post-LITT EEG became seizure-free. Six out of 29 patients (21%) eventually required anterior temporal lobectomy (ATL), and of those 6 patients 4 (66%) had evidence of TIRDA on their post-LITT follow up EEG. The sensitivity and specificity of post-LITT TIRDA in predicting surgical failure was 57.14% and 100% respectively. ConclusionsPost-LITT TIRDA may serve as a biomarker to predict unsuccessful seizure outcome following LITT and be an early indicator for ATL. SignificanceThe presence of TIRDA following LITT should prompt early consideration for reoperation.

Temporal intermittent rhythmic delta activity and abdominal migraine

Temporal intermittent rhythmic delta activity and abdominal migraine

Late‐onset temporal lobe epilepsy in a patient with juvenile myoclonic epilepsy

We report a patient with longstanding, severe juvenile myoclonic epilepsy who subsequently developed features of temporal lobe epilepsy, which gradually became clinically dominant. Over the years, there was an electrographic evolution from the typical generalised epileptiform patterns, characteristic of juvenile myoclonic epilepsy, to the novel appearance of interictal temporal spikes immediately preceding bisynchronous discharges, and subsequently to temporal intermittent rhythmic delta activity and temporal lobe-onset seizures. In this rare case of coexistent primary generalised epilepsy and focal epilepsy, the epileptic networks of the two forms of epilepsy appear to overlap.

EEG Leading to the Diagnosis of Limbic Encephalitis

Limbic encephalitis is characterized by subacute onset of short-term memory loss, seizures, sleep disturbances, as well as psychiatric and behavioral symptoms. A subgroup is associated with voltage-gated potassium channel antibodies (VGKC-Abs). In many cases, brain magnetic resonance imaging (MRI) demonstrates hyperintense areas in the medial part of the temporal lobe. Also, pleiocytosis is frequently found. In this study, we describe a 69-year-old man with VGKC-Abs limbic encephalitis with generalized tonic-clonic seizures, increasing memory deficits, visual hallucinations, depression, and severe insomnia. Brain MRI and cerebrospinal fluid (CSF) were normal, while the electroencephalogram (EEG) showed bilateral frontal and temporal intermittent rhythmic delta activity with disorganization and slowing of background activity, ultimately leading to the diagnosis of limbic encephalitis. The patient improved markedly after starting immunosuppressive therapy, both clinically and electrophysiologically. In addition to temporal lobe involvement on the brain MRI and CSF inflammation, we propose EEG abnormalities as an additional diagnostic criterion for limbic encephalitis.

An Unexpected Abnormality on the EEG

An Unexpected Abnormality on the EEG

Temporal intermittent delta activity: A marker of juvenile absence epilepsy?

Purpose To report three cases of juvenile absence epilepsy (JAE) with temporal intermittent, asynchronous delta activity over the temporal regions. Methods Long term video-EEG using the international 10/20 system and supplementary anterior-inferior temporal electrodes. Cohort of 1123 patients included in our active file seen at least one time over one year. Results Among 23 patients with JAE (2% of our active file), temporal intermittent rhythmic delta activity (TIRDA) was observed in 3 (13%). Moreover, this activity was never observed in 80 patients with juvenile myoclonic epilepsy. None of the three patients had inadequate antiepileptic drug for idiopathic generalized epilepsy. Case 1 had no antiepileptic drug. Case 2 was treated with valproate (1000 mg/day) and case 3 with levetiracetam (1500 mg/day). These delta activities were activated by hyperventilation and drowsiness. They decreased in NREM sleep and reappeared in REM sleep. The frequency was around 3 Hz. These changes were not frequently recorded in any given patient. Conclusion The presence of TIRDA in the clinical and EEG context is very suggestive of JAE as posterior delta waves are of childhood absence epilepsy but with a more anterior location over the temporal lobe. This pattern was not described before probably because in this easily diagnosed and treated type of IGE, few patients have long-term video-EEG and also because a wrong diagnosis of focal epilepsy can be made. This pattern must be known to avoid the risk of treating this epilepsy by inappropriate antiepileptic drugs.

Temporale intermittierende Delta-Aktivität (TIRDA) und neuropsychologische Defizite bei familiärer mesialer Temporallappen-Epilepsie (FMTLE)

Die Familiäre Mesiale Temporallappenepilepsie (FMTLE) ohne Assoziation zur Hippokampussklerose oder Fieberkrämpfen geht häufig mit einem interiktal unauffälligen EEG-Befund einher. Wir beschreiben hier das Auftreten temporaler intermittierender rhythmischer Delta-Aktivität (TIRDA), welche ansonsten mit temporo-mesialen Läsionen assoziiert ist, bei einem Patienten mit FMTLE ohne bildmorphologischen Hinweis auf eine Hippokampussklerose oder temporomesiale Atrophie. Es fand sich jedoch ein rechts temporales neuropsychologisches Defizit. Somit ist die TIRDA in unserem Fall Ausdruck einer epileptogenen temporomesialen Hirnfunktionsstörung, die offensichtlich auch unabhängig von einer morphologischen temporomesialen Pathologie auftreten kann.

Localizing significance of temporal intermittent rhythmic delta activity (TIRDA) in drug-resistant focal epilepsy.

Temporal intermittent rhythmic delta activity (TIRDA) is an EEG pattern characterized by sinusoidal trains of activity, ranging from 1 to 3.5 Hz, and well localized over the temporal regions. It is considered to be an indicator of temporal lobe epilepsy (TLE), but full agreement between different authors has still not been reached. The aim of this study was therefore to assess the role of TIRDA in localizing the epileptogenic zone, which was estimated using anatomo-electro-clinical correlations obtained from non-invasive pre-surgical investigations, in a large group of patients affected by drug-resistant partial epilepsy. The occurrence of TIRDA was investigated using a prolonged Video-EEG recording of 129 patients affected by drug-resistant partial epilepsy that underwent a non-invasive pre-surgical protocol. Patients were divided into 3 groups: TLE only, extratemporal epilepsy, and multilobar epilepsy including temporal lobe. According to the epileptogenic zone identified using anatomo-clinical-radiological correlations, 3 different subgroups of TLE were identified: mesial, lateral, and mesio-lateral. Statistical analysis was performed in order to evaluate the relationship between TIRDA and the epileptogenic zone, and neuroradiological, neuropathological, EEG interictal and ictal findings. The pattern of TIRDA was observed in 52 out of the 129 (40.3%) patients studied. Significant correlations were found between TIRDA and: (i) mesial and mesio-lateral TLE; (ii) mesial temporal sclerosis; (iii) interictal epileptiform discharge localized over the anterior temporal regions; and (iv) 5-9 Hz temporal ictal discharge. Our research shows that TIRDA plays a role in localizing the epileptogenic zone, suggesting that this pattern might be considered as an EEG marker of an epileptogenesis that involves the mesial structures of the temporal lobe. However, further studies investigating the relationship between intracranial EEG monitoring and simultaneous scalp EEG recording are needed in order to confirm our findings and improve our understanding of the significance of TIRDA.

Posterior cerebral epilepsy: special considerations

Posterior cerebral epilepsy: special considerations

Significance of interictal temporal lobe delta activity for localization of the primary epileptogenic region.

Because interictal temporal lobe delta activity (TLDA) has been described in 30 to 90% of patients with temporal lobe epilepsy (TLE) but has not been investigated in patients with extratemporal epilepsy, we sought to determine the localizing significance of TLDA. We compared the presurgical interictal scalp EEG results of 47 consecutive patients who received extratemporal resection (40 frontal and 7 parietal-occipital) for intractable epilepsy with 43 consecutive patients who received anterior temporal lobectomy. We defined lateralized TLDA as runs of lower than 4-Hz waveforms that were easily distinguished from the background rhythms and were maximal at electrodes T4, F8, and T6 or T3, F7, and T5. The lateralized TLDA was subcategorized as temporal intermittent rhythmic delta activity (TIRDA) or temporal intermittent polymorphic delta activity (TIPDA). A chi-square test was used to determine the association of the lobe of the epileptogenic zone with TIRDA and TIPDA. We found TIRDA in 12 (28%) and TIPDA in 8 (19%) patients in the temporal lobe group, and TIRDA in 2 (4%) and TIPDA in 9 (19%) patients in the extratemporal group. TIRDA was strongly associated with TLE (p < 0.003), whereas TIPDA occurred at an equal rate in both groups. Similar to anterior temporal epilepsy, lateralized TIPDA is present in up to 20% of patients with extratemporal epilepsy. The presence of TIRDA strongly suggests TLE but may infrequently occur in extratemporal epilepsy. Caution should be used when using lateralized TLDA as a presurgical localizing finding.

Hippocampal temporal intermittent rhythmic delta activity (TIRDA) and positive sharp waves during intraoperative EEG recordings suggest another focus distant from a parieto-occipital lesion

Hippocampal temporal intermittent rhythmic delta activity (TIRDA) and positive sharp waves during intraoperative EEG recordings suggest another focus distant from a parieto-occipital lesion

Temporal intermittent rhythmic delta activity in electroencephalograms.

Temporal intermittent rhythmic delta activity (TIRDA) has been reported to be highly specific for diagnosing complex partial epilepsy. Of 12,198 electroencephalographic (EEG) recordings performed at the Mayo Clinic between May 1, 1990 and May 1, 1991, 33 records from 27 patients (18 women and nine men; mean age, 41.5 years; range, 13-82 years) showed TIRDA. Clinical seizures were diagnosed in all patients, and complex partial epilepsy was well documented in 23. In a control group of 100 patients without TIRDA and matched for age and sex, generalized seizures were diagnosed in 25 and partial seizures in 15. Differences between TIRDA and control groups were highly statistically significant. Focal temporal sharp waves or spikes occurred in 23 patients with EEG recordings that contained TIRDA; three of these patients also exhibited generalized atypical spike-and-wave discharges. Four patients had TIRDA but no other epileptiform activity, although earlier EEGs of three of these patients contained spikes or sharp waves. These findings confirm earlier work, and we conclude that TIRDA represents an important epileptogenic abnormality.

Temporal intermittent rhythmic delta activity (TIRDA) in the diagnosis of complex partial epilepsy: sensitivity, specificity and predictive value.

Temporal interictal rhythmic delta activity or TIRDA was found in 45 of the 127 recordings of patients with complex partial epilepsy (CPE) referred for both awake and sleep EEG. TIRDA was more abundant during drowsiness and light sleep; it occurred more characteristically as trains of 50-100 microv sinusoidal or saw-toothed 1-4Hz activity, recorded predominantly from anterior temporal regions. When occurring bilaterally and independently, TIRDA varied from side to side. TIRDA is often found in association with anterior temporal spikes or sharp waves (TS) particularly during sleep, as observed in 43 out of 45 EEGs. TIRDA can nevertheless occur as an isolated abnormality, as noted in two sleep and 12 awake study recordings. Because of its high specificity and positive predictive value over a large range of prevalence, TIRDA should be singled out as an accurate interictal indicator of CPE. In patients with isolated TIRDA, the cost of prolonged EEG recording during sleep for the purpose of activating TS has to be weighed against the yield of eventually confirming the obvious.