UpToDate: Combined Unilateral Posteroventral Pallidotomy and Ventral Intermediate Nucleus Thalamotomy

Combined Unilateral Posteroventral Pallidotomy and Ventral Intermediate Nucleus Thalamotomy

Patients with tremor predominant Parkinson’s disease (PD) achieve more improvement in tremor control after combined unilateral posteroventral pallidotomy and ventral intermediate nucleus thalamotomy 1)2).

Case series

Twenty-four patients with tremor-dominant PD were included in a study of Fayed et al. from the Department of Neurosurgery, Faculty of Medicine, Ain Shams University, CairoEgypt.

Twelve patients received unilateral PVP contralateral to the most affected side. The other 12 patients received simultaneous unilateral PVP and VIM thalamotomy contralateral to the most affected side. Assessment of results in both groups was achieved using both UPDRS “off” motor scores and UPDRS rest tremor subscores.

The mean UPDRS off motor score improved in the pallidotomy group from 61.3 preoperatively to 36.8 at 12 months. In the combined group, it improved from 59.6 to 35.2 at 12 months, with no statistically significant difference between both groups. On the other hand, while the mean tremor subscore in the pallidotomy group improved from a mean of 2.3-0.8, the tremors were abolished in all of the patients in the combined group except for 1 patient who showed slight infrequent tremors at 12 months 3).


Iacono et al. from the Division of Neurosurgery, Loma Linda University Medical Center, combined Vim/VOp junction thalamotomy and PVP in 29 patients with severe tremorrigidity, and bradykinesia. Patients underwent unilateral Vim thalamotomy followed at the same sitting by PVP. The distinct physiological consequences of each procedure were documented by intraoperative electromyography (EMG) and video recording, revealing the effects on both tremor and agonist/antagonist co-contraction. Lack of reciprocal inhibition of antagonistic muscle groups often remained following thalamotomy but was eliminated by subsequent PVP. The complementary therapeutic effects of PVP and Vim thalamotomy may be due to the interruption of different neuronal circuits by the two procedures. The effect of Vim thalamotomy has been attributed to the interruption of the rubrothalamocortical loop. PVP interrupts the outflow of the globus pallidus internus (GPi), which may cause disinhibition of locomotor centers in the mesencephalon and spinal cord. There is no direct interruption of the rubrothalamocortical loop by PVP, explaining why this procedure sometimes exacerbates tremor in certain patients 4).

References

1) , 3)

Fayed ZY, Radwan H, Aziz M, Eid M, Mansour AH, Nosseir M, Anwer H, Elserry T, Abdel Ghany WA. Combined Unilateral Posteroventral Pallidotomy and Ventral Intermediate Nucleus Thalamotomy in Tremor-Dominant Parkinson's Disease versus Posteroventral Pallidotomy Alone: A Prospective Comparative Study. Stereotact Funct Neurosurg. 2018 Sep 18;96(4):1-6. doi: 10.1159/000492229. [Epub ahead of print] PubMed PMID: 30227440.

2) , 4)

Iacono RP, Henderson JM, Lonser RR. Combined stereotactic thalamotomy and posteroventral pallidotomy for Parkinson’s disease. J Image Guid Surg. 1995;1(3):133-40. PubMed PMID: 9079438.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.

WhatsApp WhatsApp us