Functional and Stereotactic Neurosurgery - exam-focused guide
Functional and Stereotactic Neurosurgery covers epilepsy, movement disorders, pain and spasticity. The exam tests patient selection, targets and recognition of hardware complications.
Core rules
- Epilepsy surgery is considered for drug-resistant focal epilepsy. Presurgical evaluation seeks concordance between semiology, EEG, MRI and neuropsychology; temporal lobe epilepsy is the commonest surgical syndrome.
- Vagus nerve stimulation reduces seizure frequency but is not curative. Responsive neurostimulation and deep brain stimulation are options in selected patients.
- Parkinson disease: subthalamic nucleus or globus pallidus interna DBS improves motor fluctuations and dyskinesia. Thalamic VIM stimulation treats tremor. Atypical parkinsonism and significant cognitive impairment are contraindications.
- Essential tremor responds to VIM thalamotomy or DBS. Dystonia may respond to GPi stimulation.
- Neuropathic pain may be treated with spinal cord stimulation after failed medical therapy. Intrathecal baclofen treats severe spasticity; abrupt withdrawal can cause rebound spasticity, fever and autonomic instability.
- Selective dorsal rhizotomy is used in selected spastic diplegia.
Worked example: A 60-year-old with Parkinson disease has disabling dyskinesia and motor fluctuations despite optimized medication. Cognitive testing is normal and MRI shows no atypical features. STN DBS is offered because it improves off-time and dyskinesia; the patient is warned about infection, lead misplacement, speech worsening and the need for programming.
Traps: offering DBS to a patient with atypical parkinsonism; assuming VNS cures epilepsy; stopping intrathecal baclofen abruptly; selecting epilepsy surgery without concordant data; ignoring hardware infection.