This specialised procedure is used to treat several movement disorders, ranging from dystonia to Parkinson’s disease.
With the introduction of levodopa in the treatment of Parkinson’s Disease (PD) the need for surgical intervention declined rapidly.
Long term follow up of patients on medical treatment showed increased dosing over period of time with dose related side effects in the form of dyskinesias and hallucinations.
Surgical intervention were thus again explored in patients having sub optimal benefits with medical management.
Dr. Lauri Laitinen in 1985 was the first to demonstrate the benefits of pallidotomy by performing the procedure as described by Dr. Lars Leksell.
In 1992 he published his series of 38 patients treated with pallidotomy which showed 80-90% patients showed long lasting symptom relief.
Drawing showing the relationship of the pallidal target to the internal capsule and optic tract.
The other common indication for the pallidotomy is unilateral dystonia
Patients responding to levodopa in general show a good response to pallidotomy. Symptoms like swallowing difficulty, hypophonic speech, postural instability, and freezing do not respond to pallidotomy and sometimes may worsen.
In cases of Dystonia there is approximately 70% success rate in controlling the dystonic symptoms and pain.
Secondary causes of Parkinsonism like MSA, PSP, Diffuse Lewy body disease needs to be ruled out before offering Pallidotomy. These patients don not derive benefit from the procedure and may even worsen. Bilateral pallidotomies have not been extensively studied in controlled trial but have shown both long term and short term benefits. Still Pallidotomy is performed unilaterally on the side opposite to the involved side.
We currently advocate pallidotomy for the following group of patients
The patient is evaluated by the movement disorder neurologist prior to surgery. The patient is admitted two days prior to surgery. On the preoperative day the patient undergoes UPDRS, H&Y and Schwab and England activities of daily living assessment in “off” medication condition.
A video recording is also performed at this stage. The same protocol of assessment and video recording is performed in “on” condition. Patient is observed in neurosurgical intensive care for one day after surgery and discharged on the third postoperative day. Follow up visits are scheduled at 1, 3, 6 and 12 months after surgery.
After a patient gets evaluated on outpatient basis; he / she gets admitted and is thoroughly evaluated by our team comprising of well trained doctors and nurses.
Each individual patient is put through rigorous tests and evaluation parameters which help us to further narrow down the patient’s problems and offer optimum treatment. Routine blood and radiological required for surgery are performed.
The patient is also assessed by anaesthesiologist to determine surgical fitness.
The next day patient undergoes a MRI which may or may not require anaesthesia.
On the day of the surgery the patient is taken to the operation theatre. A frame is fixed to the patients head under local anaesthesia.
Patient is taken for CT scan after frame fixation. After the patient returns from the CT scan his/her head is fixed with the help of the frame to the table. The head is cleaned thoroughly with antiseptic solution.
The appropriate surgical trajectory is identified to target the GPi. Incision is taken based on the coordinates under local anaesthesia.
A microelectrode is inserted after creating a small hole in the skull. The electrical recordings are sequentially noted followed by which macro electrode stimulation of target is done during which the patient is assessed for symptom improvement.
A lesion is then created using thermal energy at appropriate level/s. The wound is closed and patient is shifted to CT scan. Patient is subsequently shifted to his/her room.
The surgical precision and meticulousness along with proper patient selection has meant that our complications are on the lower side. Complications related to surgical techniques like hemorrhage or infarct are reported in literature with an incidence of around 4%.
Transient encephalopathy which is reversible occurs in 10% of patients in various studies.
Speech disturbances in the form of dysarthria, hypophonia and dysphasia are common in literature but not so frequent in our series of patients.
Bilateral Pallidotomies result in severe dysphagia, apathy, loss of initiative, loss of motivation and motor drive and persistent levodopa resistant gait freezing.
Pallidotomy greatly helps in sustained amelioration of contralateral dyskinesias.
This leads to improved tolerance of Levodopa and more dyskinesia free On phase. Rigidity Bradykinesia and tremors of the opposite side also improve to a great extent. Speech symptoms do not respond to pallidotomy and may even worsen. Painfull dystonia greatly decreases.
With the advent and technological advances made in the field of DBS have made Pallidotomy less opted treatment modality. Though it still remains a viable option for many patients.
Pallidotomy is a useful surgery in the armamentarium of Parkinson’s disease treatment. When performed in a carefully selected group of patients it provides a significant improvement in the quality of life. The risk of major complications and mortality is less than 2%. It is at present the most acceptable form of surgical treatment for the idiopathic dystonia. Pallidal stimulation has proven to be superior than any other treatment in primary dystonia.
