Thalamotomy

Thalamotomy
Intervention
ICD-9-CM 01.41

First introduced in the 1950s, thalamotomy is derived from two words i.e. "thalamus" a part of the brain, and "otomy" means opening into a cavity. It is, therefore, a surgical procedure in which an opening is made into the thalamus in order to improve the overall brain function in patients. It is primarily effective for tremors such as those associated with Parkinson's disease (PD), where a selected portion of the thalamus is surgically destroyed (ablated). Neurosurgeons use specialized equipment to precisely locate an area of the thalamus, usually choosing to work on only one side (the side opposite that of the worst tremors). Bilateral procedures are poorly tolerated because of increased complication and risk, including vision and speech problems. The positive effects on tremors are immediate. Other less destructive procedures are sometimes preferred, such as subthalamic deep brain stimulation (DBS), since this procedure can also improve tremors and other symptoms of PD.[1][2][3]

Indications

Thalamotomy is a complex procedure performed by specialists of brain or neurosurgeons. It is mostly indicated in following conditions: Stroke, damage to third ventricle of brain, brain hemorrhage, accidents leading to head injury, oedema around thalamus, subdural hemorrhage and cerebrovascular accident.

Sub-thalamotomy

Sub-thalamotomy is a type of brain surgery in which the subthalamic nucleus is destroyed in attempt to help alleviate movement disorders often associated with Parkinson’s disease.[4] This surgery has been most widely researched at Cuba’s International Center for Neurological Restoration (CIREN) located in Havana. This center has assumed a leading role in developing a surgical procedure that provides significant relief for patients experiencing the slowness of movement, tremor and muscle rigidity in middle to late stages of PD. Similar to the thalamotomy, this procedure can be repeated on both sides of the brain bilaterally, but is not recommended due to a large increase in the risk of speech and cognitive problems post-surgery.[5] The aim of subthalamotomies is to reduce symptoms of PD and the uncontrolled movements that can occur in patients taking the drug levodopa for a long period of time.[6]

Surgical procedures

Frame for Stereotactic Thalamotomy on display at the Glenside Museum

Thalamotomy can be performed in an invasive or non-invasive manner. If performed invasively then prior to the operation, a neurosurgeon will use stereotactic technology to identify the exact part of the brain that needs treatment by putting in place a frame on the patient’s head with four pins to keep it still. The doctor will then take a detailed brain scan using computed tomography (CT scan) or magnetic resonance imaging (MRI) in order to identify the precise location for operation as well as a path through the brain to get to that specific spot. During the surgery the patient is awake, however, the area on the scalp where the surgical tools are inserted is numbed with an anesthetic. The surgeon makes a scalp incision (about 2 inches long), then inserts a hollow probe through a small hole drilled in the skull to the specific location. Different methods can be used to kill the brain cells, including circulating liquid nitrogen inside the probe, destroying the targeted brain tissue, or by inserting an electrode heated up to near 200 °F (93 °C) to cook the cells.[6] Although the surgery usually requires only about a 2-day hospital stay, full recovery generally takes about 6 weeks.[5] Thalamotomy can be performed without incisions by using ultrasound waves. The ultrasound waves are focused to the thalmua and thus cause thalamotomy through an intact skull. This procedure uses MRI guidance in order to localize the thalamus. The ultrasound waves cause gradual warming of the tissue until there is ablation, seen clinically as resolution of tremor. During the procedure the patient is awake. Thus if there are any adverse effects, the area of the thalamus that is treated can be adjusted before there is ablation. Favorable responses have so far been reported in Parkinson's disease patients and in essential tremor patients [7]

Complications

Some of the patients in Cuban studies developed complications from the surgery, including severe involuntary movements, but the symptoms abated (to the point where patients could tolerate them) after three to six months.[5] Most common complications include a risk of stroke, confusion, speech and/or visual problems.[8] Although there are risks with unilateral sub-thalamotomy, the risks are greatly increased with bilateral sub-thalamotomy.

Studies

One study followed 89 patients with PD who were treated with unilateral sub-thalamotomy. Sixty-eight patients were available for evaluations after 12 months, 36 after 24 months and 25 patients after 36 months. The Unified Parkinson’s Disease Rating Scale motor scores improved significantly and levodopa daily doses were significantly reduced by 45%, 36% and 28% at 12, 24 and 36 months post-surgery. Unilateral sub--thalamotomy was associated with significant motor benefit contralateral to the lesion. Further work is needed to ascertain what factors led to severe, persistent chorea-ballism in a subset of patients.[9] In an earlier study, 18 advanced PD patients received staged or simultaneous bilateral one or more sub-thalamotomy. One patient subsequently developed multiple system atrophy (MSA) signs and was excluded from further analysis. Motor improvements compared to baseline were 58% in the off state and 63% in the on state. Daily levodopa dose was reduced by a mean of 72%, with 5 patients receiving none. Three patients developed severe chorea post-operatively, which improved spontaneously at 3–6 months.[10] In a third study, microelectrode mapping (guided stereotactic surgery on the subthalamic nucleus) was performed in eight patients with PD and the findings indicated that sub-thalamotomy can ameliorate the cardinal symptoms of PD, reduce the dosage of levodopa, diminish complications of the drug therapy, and improve the quality of life.[11] Havana’s International Center for Neurological Restoration reported at the American Neurological Association meeting in October 2002 that two years after undergoing a bilateral dorsal sub-thalamotomy, 17 Cuban patients improved by an average of 50% on movement tests, and they could dramatically reduce their daily ingestion of the Parkinson’s drug levodopa.[5]

Sub-thalamotomy could be a preferred option for people with PD who have trouble affording either the medication or deep-brain stimulation needed to moderate symptoms.

References

  1. ↑ Julie A. Fields, Alexander I. Tröster, Cognitive Outcomes after Deep Brain Stimulation for Parkinson's Disease: A Review of Initial Studies and Recommendations for Future Research, Brain and Cognition, Volume 42, Issue 2, March 2000, Pages 268-293, ISSN 0278-2626, 10.1006/brcg.1999.1104.
  2. ↑ Bruce BB, Foote KD, Rosenbek J, Sapienza C, Romrell J, Crucian G, Okun MS: Aphasia and Thalamotomy: Important Issues. Stereotact Funct Neurosurg 2004;82:186-190 doi:10.1159/000082207
  3. ↑ Justin S. Cetas, Targol Saedi, and Kim J. Burchiel. Destructive procedures for the treatment of nonmalignant {}pain: a structured literature review. J Neurosurg 109:000–000, 2008
  4. ↑ Sub-thalamotomy. National Parkinson Foundation. Retrieved from http://www.parkinson.org/Parkinson-s-Disease/Treatment/Surgical-Treatment-Options/Subthalamotomy.aspx
  5. 1 2 3 4 Stix, Gary. (2003). Sustainable Surgery. Scientific American. Retrieved from http://www.scientificamerican.com/article.cfm?id=sustainable-surgery
  6. 1 2 Subthalamotomy. BootsWebMD. Retrieved from http://www.webmd.boots.com/a-to-z-guides/parkinsons-disease-subthalamotomy
  7. ↑ Schlesinger I, Eran A, Sinai A, Erikh I, Nassar M, Goldsher D, Zaaroor M. MRI Guided Focused Ultrasound Thalamotomy for Moderate-to-Severe Tremor in Parkinson's Disease. Parkinsons Dis. 2015; 2015:219149. doi: 10.1155/2015/219149. Epub 2-Sep-2015
  8. ↑ Subthalamotomy for Parkinson's Disease. (2004). National Institute for Health and Clinical Excellence. ISBN 1-84257-657-7. Retrieved from http://www.nice.org.uk/nicemedia/live/11102/31038/31038.pdf
  9. ↑ L Alvarez, R Macias, N Pavón, G López, M C Rodríguez-Oroz, R Rodríguez, M Alvarez, I Pedroso, J Teijeiro, R Fernández, E Casabona, S Salazar, C Maragoto, M Carballo, I García, J Guridi, J L Juncos, M R DeLong, J A Obeso. (2009). Therapeutic efficacy of unilateral sub-thalamotomy in Parkinson’s disease: results in 89 patients followed for up to 36 months. Journal of Neurology, Neurosurgery, and Psychiatry with Practical Neurology, Volume 80, Issue 9. Retrieved from http://jnnp.bmj.com/content/80/9/979.full
  10. ↑ L Alvarez, R Macias, G Lopez, E Alvarez, C Maragoto, JA Obeso, N.Pavon, MC Rodriguez-Oroz, J Juncos, J Guridi, ES Tolosa, W Koller, MR DeLong. (2002). Bilateral Sub-thalamotomy for PD. Movement Disorder Virtual University. Retrieved from http://www.mdvu.org/emove/article.asp?ID=531
  11. ↑ Philip C. Su, M.D., Ham-Min Tseng, M.D., Hon-Man Liu, M.D., Ruoh-Fang Yen, M.D., and Horng-Huei Liou, M.D., Ph.D. (2002). Subthalamotomy for advanced Parkinson disease. Journal of Neurosurgery, volume 97. Retrieved from http://thejns.org/doi/abs/10.3171/jns.2002.97.3.0598?journalCode=jns
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