Introduction
Deep Brain Stimulation (DBS) is a revolutionary neurosurgical procedure that has transformed the treatment landscape for various neurological disorders. This comprehensive guide delves into the intricacies of DBS surgery, covering patient selection, surgical technique, anesthetic management, and the management of perioperative complications.
Patient Selection for DBS
Multidisciplinary Approach: The journey begins with a multidisciplinary evaluation involving neurosurgeons, neurologists, and neuropsychiatrists. This collaborative effort is essential to assess patient suitability for DBS.
Disease-Related Concerns
- Aspiration Risk: Patients, particularly those with Parkinson’s disease, may have impaired swallowing, increasing the risk of aspiration.
- Respiratory System: Neurological conditions can impact respiratory function, necessitating vigilant monitoring during surgery.
- Autonomic Dysfunction: Orthostatic hypotension and autonomic instability should be considered.
Procedure-Related Concerns
- Stereotactic Head Frame: The use of a stereotactic head frame can complicate airway management. Strategies for proper positioning are crucial.
- Semi-Sitting Position: Patients are often placed semi-sitting during DBS, which heightens the risk of venous air embolism.
- Lengthy Procedures: Prolonged surgeries require careful pain management and monitoring.
- Interference with Microelectrode Recordings: Anesthetic agents must not hinder microelectrode recordings used for precise electrode placement.
Surgical Technique of DBS
DBS surgery involves two key stages: electrode insertion into deep brain nuclei and lead and pulse generator internalization.
Stage 1: Insertion of Electrodes
- Neurophysiological Localization: This technique involves frame-based imaging, microelectrode recordings (MER), and macrostimulation testing to pinpoint electrode placement accurately.
- Real-time Interventional MRI (iMRI) Guidance: An alternative to the traditional approach, iMRI navigation offers real-time confirmation of electrode placement without the need for a stereotactic head frame.
Stage 2: Lead and Pulse Generator Internalization
- Tunneling Electrodes: Electrodes are tunneled subcutaneously from the scalp to an infraclavicular area or abdomen, where they connect to the impulse generator.
Anesthetic Management of DBS
Effective anesthetic management is essential for patient comfort and safety throughout DBS procedures.
Airway Management
- Comprehensive Assessment: Airway assessment and planning are critical due to the restricted access caused by the stereotactic head frame.
- Semi-Sitting Position: The semi-sitting position and the presence of the stereotactic frame require careful airway planning and positioning.
- Communication: Effective communication with the surgical team is vital for determining the need to transition the patient to a supine position for airway management.
Monitoring and Positioning
- Monitoring: Standard monitoring includes oxygen saturation, ECG, noninvasive blood pressure, and end-tidal CO2. Invasive blood pressure monitoring may be necessary.
- Proper Positioning: Ensuring patient comfort, cooperation, and optimal surgical exposure are essential elements of positioning.
Pharmacological Considerations
- Choice of Agents: Anesthetic agents should be selected to minimize interference with microelectrode recordings (MER) and macrostimulation testing.
- Propofol: While commonly used, propofol must be administered cautiously to avoid excessive suppression of deep brain nuclei activity.
- Dexmedetomidine: This alternative offers minimal interference with MER.
- Opioids: Fentanyl or remifentanil can be used but require careful titration to prevent respiratory depression.
Anesthetic Techniques for DBS Stage I
- Options: Monitored Anesthesia Care (MAC), conscious sedation, and general anesthesia are available techniques.
- Local Anesthesia: Local anesthetics are employed for scalp blocks and pain control during head frame placement.
- Pain Management: Adequate pain control, temperature regulation, and judicious fluid administration contribute to patient comfort.
General Anesthesia
- Suitable Patients: General anesthesia is considered for patients who cannot tolerate conscious sedation.
- Maintenance: Low-dose inhalation anesthesia, opioids, and propofol maintain controlled light anesthesia during microelectrode recordings (MER).
Perioperative Complications in DBS Procedures
Intraoperative complications are not uncommon during DBS procedures, occurring in approximately 12% to 16% of patients. These complications encompass a range of issues, both anesthetic and surgical, that can impact the outcome of the procedure. Below, we outline the incidence of common perioperative complications associated with DBS, along with strategies for their management.
Table 1: Perioperative Complications of DBS
| Complications | Incidence (%) |
|---|---|
| Agitation and Confusion | 2.8 – 5.8 |
| Airway Obstruction | 0.03 – 1.1 |
| Respiratory Distress | 0.02 – 1.1 |
| Hypertension | 3.9 – 0.4 |
| Nausea and Vomiting | 0.02 – 1.7 |
| Seizures | 0.8 – 4.5 |
| Intracranial Hemorrhage | 0.8 – 2.8 |
Source: Chui J et al. Can J Neurol Sci. 2017;110:1–8; Venkatraghavan L et al. J Neurosurg Anesthesiol. 2006;18(1):64–7; Khatib R et al. J Neurosurg Anesthesiol. 2008;20(1):36–40.
Airway and Respiratory Complications
Airway compromise can arise due to over-sedation or secondary to other complications, such as seizures or intracranial hemorrhage. Limited airway access is often attributed to the stereotactic head frame used in DBS procedures. Additionally, patients may gradually shift their position during surgery, potentially leading to airway obstruction or awkward postures that further complicate management. Intraoperative arterial desaturation or respiratory failure occurs in approximately 1.6% to 2.2% of patients.
Patients with Parkinson’s disease may exhibit an obstructive ventilatory pattern and pulmonary comorbidities, further reducing respiratory reserves. Prompt management of acute desaturation or upper airway obstruction is crucial. Communication with the surgical team is essential to decide whether intracranial electrodes and the stereotactic headframe need removal, transitioning the patient to a supine position for airway management.
Cardiovascular Complications
Hypertension is a common intraoperative complication, with an incidence of up to 37% in some cohorts. Intraoperative hypertension has been linked to intracerebral hemorrhages, emphasizing its significance. Effective management typically involves the administration of labetalol and/or hydralazine through bolus or infusion, with the occasional use of nitroglycerine or sodium nitroprusside if necessary.
It’s important to note that DBS can sometimes induce arrhythmias, typically due to electrode manipulation. Thus, continuous ECG monitoring is essential.
Seizures and Intracranial Hemorrhage
Seizures can occur during DBS electrode placement. The reported incidence varies, with some studies suggesting rates as high as 5.8%. Prevention and management often involve the use of antiepileptic drugs, such as levetiracetam.
Intracranial hemorrhage is a severe complication associated with DBS surgery. Although it is relatively rare, occurring in approximately 2.8% of cases, its consequences can be devastating. Timely recognition, discontinuation of anticoagulants if applicable, and consultation with a neurosurgeon for possible evacuation are crucial.
Conclusion
Deep Brain Stimulation (DBS) surgery has revolutionized the treatment of various neurological disorders. Successful outcomes depend on meticulous patient selection, surgical precision, and effective anesthetic management. Understanding disease and procedure-related concerns, mastering airway management, and selecting appropriate pharmacological agents are paramount. Moreover, being vigilant about perioperative complications and their management is vital for ensuring the safety and efficacy of DBS procedures. The choice between conscious sedation and general anesthesia should align with individual patient factors and the center’s capabilities.