Ventral intermediate nucleus deep brain stimulation for treatment-resistant focal aware motor seizures: illustrative case

Abstract

BACKGROUND Resection of the seizure onset zone (SOZ) is considered the gold standard for treating refractory focal aware seizures (FASs). When resective surgery is unadvisable, deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT; ANT-DBS) has been the procedure of choice. However, less than half of patients with FASs respond to ANT-DBS. The need for alternative targets to effectively treat FAS is thus evident. OBSERVATIONS The authors report the case of a 39-year-old woman presenting with pharmaco-resistant focal aware motor seizures, with the SOZ located in the primary motor cortical area. She had previously undergone unsuccessful resection of the left temporoparietal operculum elsewhere. Considering the risk of new resective surgery, she was offered combined ventral intermediate nucleus (Vim)/ANT-DBS. Vim-DBS proved to be superior to ANT-DBS for seizure control (88% vs 32%), although the association of both provided the best results (97%). LESSONS This is the first report on the use of the Vim as a target of DBS for the treatment of FAS. The excellent results were presumably obtained by modulation of the SOZ through Vim projections to the motor cortex. This opens a completely new avenue for treating FAS: chronic stimulation of specific thalamic nuclei.

A new strategy for treating drug-resistant focal aware seizures: thalamic specific nuclei deep brain stimulation. Illustrative case

“…Thalamic specific nuclei DBS has some apparent advantages over ANT DBS. First, in accordance with our present (LGN DBS) and previous (Vim DBS) results, 18 it is somewhat more efficacious than ANT DBS. Second, unlike ANT DBS, which is performed bilaterally and requires higher amplitudes, 8 , 12 , 16 , 17 it is performed unilaterally and with lower amplitudes (< 3.0 V), 18 thus significantly reducing the costs of the procedure and increasing the battery life.…”

“…Recently, Vilela-Filho et al 18 reported a new target for FAMSs, the Vim nucleus, which reduced seizure frequency by 88%. Encouraged by these results, we hypothesized that the stimulation of different thalamic specific nuclei can modulate the abnormal electrical activity of the SOZ located in their respective cortical projection areas and thus started an open clinical trial to test this hypothesis.…”

“…In keeping with that thought, Vilela-Filho et al 18 in 2023, through pure serendipity, pioneeringly demonstrated the successful use of ventral intermediate nucleus (Vim) DBS to treat a patient with drug-resistant focal aware motor seizures (FAMSs), obtaining an 88% reduction in seizure frequency. These authors attributed this result to the well-known projections of the Vim to the motor cortex, where it would modulate the abnormal electrical activity of the SOZ.…”

“…These authors attributed this result to the well-known projections of the Vim to the motor cortex, where it would modulate the abnormal electrical activity of the SOZ. 18 On the basis of this report, we hypothesized that the stimulation of different thalamic specific nuclei, that is, the Vim, ventral caudal nucleus (VC), lateral geniculate nucleus (LGN), and medial geniculate nucleus (MGN), can modulate the abnormal electrical activity in their respective cortical projection areas (i.e., motor, somesthetic, visual, and auditory cortical areas, respectively).…”

Abolition of seizures following Forel‐H‐tomy for drug‐resistant epilepsy: A case report

“…However, it is unclear whether the lesion was correctly located in the FF H, as CT and MRI were inconclusive in confirming the lesion site. It is possible that the lesion extended to the thalamus, such as the centromedian and ventrolateral nuclei, or that it also involved the cerebellothalamic tract, which has been reported to be effective for epilepsy, possibly due to lesion encroachment on the neighboring structures 16–18 . The target position of Jinnai et al is slightly lower and posterior to ours.…”