Vertical supranuclear gaze palsy induced by deep brain stimulation: report of two cases

Deep Brain Stimulation in Three Related Cases of North Sea Progressive Myoclonic Epilepsy from South Africa

We report on a white Afrikaans family from eastern South Africa with three members affected with North Sea progressive myoclonus epilepsy, resulting from a homozygous founder GOSR2 mutation (c.430G>T, p.Gly144Trp). The mutation was identified by exomic sequencing in a research study investigating childhood onset ataxias. All three subjects presented with ataxia, tremor, early gait difficulties, and myoclonic and generalized tonic clonic (GTC) epilepsy. Each patient underwent deep brain stimulation of the caudal Zona Incerta before coming to the attention of the authors. In each case there was a reduction in GTC seizures, and two patients exhibited a reduction in involuntary movements, as evaluated during long-term follow-up. In one case there was an improvement in gait and stance when assessed while the stimulation was on.

What You See Is What You Get: Lead Location Within Deep Brain Structures Is Accurately Depicted by Stereotactic Magnetic Resonance Imaging

BACKGROUND

Magnetic resonance imaging (MRI)-verified deep brain stimulation relies on the correct interpretation of stereotactic imaging documenting lead location in relation to visible anatomic target. However, it has been suggested that local signal distortion from the lead itself renders its depiction on MRI unreliable.

OBJECTIVE

To compare lead location on stereotactic MRI with subsequent location of its brain track after removal.

METHODS

Patients underwent deep brain stimulation with the use of MRI-guided and MRI-verified Leksell frame approach. Infection or suboptimal efficacy required lead removal and subsequent reimplantation by using the same technique. Postimplantation stereotactic MR images were analyzed. Lateral (x) and anteroposterior (y) distances from midcommissural point to center of the lead hypointensity were recorded at the anterior commissure-posterior commissure plane (pallidal electrode) or z = -4 (subthalamic electrode). Stereotactic MRI before the second procedure, x and y distances from the center of the visible lead track hypointensity to midcommissural point were independently recorded. Vectorial distance from center of the lead hypointensity to the center of its track was calculated.

RESULTS

Sixteen electrode tracks were studied in 10 patients. Mean differences between lead artifact location and lead track location were: x coordinate 0.4 mm ± 0.2; y coordinate 0.6 mm ± 0.3. Mean vectorial distance was 0.7 mm ± 0.2.

CONCLUSION

Stereotactic distance between lead location and subsequent brain track location on MRI was small. The mean discrepancy was approximately half the deep brain stimulation lead width. This suggests that lead hypointensity seen on postimplantation MRI is indeed an accurate representation of its real location within deep brain structures.