Sometimes it can seem as if the emergency department is the neurology waiting room. Many new technologies are being applied to neurologic disorders, but they may result in complications and an ED visit for the patient. Deep brain stimulation is one of them.
Deep brain stimulation (DBS) consists of the implantation of electrodes that block electrical signals in certain target regions (subthalamic nucleus, the internal segment of the globus pallidus, or the ventral intermediate nucleus of the thalamus) that can dramatically alleviate symptoms such as tremor, slowed movement or bradykinesia, and altered muscle tone or dystonia. (Annu Rev Neurosci 2006;29:229.) DBS has proven to be remarkably successful in treating movement disorders such as Parkinson's disease (PD) or essential tremor over the past 25 years. The application of DBS in other neurologic and neuropsychiatric conditions like neuropathic pain, depression, and Tourette's syndrome has become the object of extensive research in recent years. (Front Hum Neurosci 2017;11:177; Ann Transl Med 2017;5[Suppl 1]:S1; Lancet Neurol 2017;16:610.) The physiological mechanisms behind the varied uses of this treatment remain uncertain, but its use continues to increase. (Annu Rev Neurosci 2006;29:229.)
The most extended use of DBS is, by far, in movement disorders such as PD. DBS has been proven to enable a significant reduction in dopaminergic medications and their side effects. (Annu Rev Neurosci 2006;29:229.) This is advantageous for patients, but we should expect to see some associated complications and understand how to identify them correctly.
These conditions can be divided into perioperative and postoperative. The main perioperative complications are intracranial hemorrhage (including intracerebral, intraventricular, subdural, subarachnoid, and epidural), venous infarction, and air embolus. (Parkinsonism Relat Disord 2010;16:153.) Symptoms of intracranial hemorrhage can include epileptic seizure, hemiparesis, or a reduced level of consciousness, and may be a consequence of venous infarction. Venous infarction may present progressively hours to days after surgery, and manifest with confusion and focal neurological symptoms. Air embolus is caused by the entry of air into the venous system during surgery, and usually has a benign clinical course. (Curr Neurol Neurosci Rep 2017;17:51.)
Postoperative complications can appear at any stage from the immediate perioperative phase to weeks or months after surgery. They can include neuroleptic-like malignant syndrome, dyskinetic storm, psychiatric complications (acute behavioral and cognitive changes, suicide attempt or ideation), and hardware-related complications (hardware infection, failure, accidental on/off), among others. All of them may present in the emergency department.
Neuroleptic-like malignant syndrome, though rare in clinical practice, can be a consequence of postoperative withdrawal of dopaminergic agents used to evaluate the success of the procedure. It is defined by parkinsonism, high fever, rhabdomyolysis, and myoglobinuria. Treatment measures typically include hydration and respiratory support. (Curr Neurol Neurosci Rep 2017;17:51.)
Postoperative dyskinesias, in which a patient presents with involuntary movement, can sometimes acutely progress to dyskinetic storm, in which a patient presents with severe, uncontrollable, and often violent involuntary movement that can manifest with dyspnea and rhabdomyolysis in severe cases. (Parkinsonism Relat Disord 2010;16:153.) Careful dose reduction of dopaminergic medications and administration of sedatives may help; ICU care is sometimes necessary. (Curr Neurol Neurosci Rep 2017;17:51.)
Psychiatric or neuropsychiatric complications such as cognitive and behavioral changes are common adverse events after DBS surgery. Though usually self-limited, these changes may become permanent in patients with cognitive alterations pre-surgery. Confusion and alterations in verbal fluency are the most common manifestations. Underlying causes such as hemorrhage or urinary tract infection can contribute to psychiatric changes. (Parkinsonism Relat Disord 2010;16:153.) Suicide attempt or ideation may be more prevalent in DBS patients than in the general population, but not when compared with the PD population. (Neurology 2004;63:2170.) Screening for suicide ideation following DBS and inpatient psychiatric treatment if suicidal thoughts are identified are recommended. (Parkinsonism Relat Disord 2010;16:153.)
Hardware complications can include infection, malfunction, and accidental on/off, among others. Infection following surgery is not uncommon, and can present with focal neurological deficits and fever. Abscess drainage and removal of infected pieces of hardware, along with antibiotics, are the main components of adequate treatment. (Parkinsonism Relat Disord 2010;16:153.) Sudden loss of function in a previously satisfactory clinical course post-DBS might be due to hardware malfunction or accidental on/off. Adequate patient information, use of the DBS programming/interrogation device, and referral to a DBS specialist may be of help in these cases. (Curr Neurol Neurosci Rep 2017;17:51.)
Keeping these complications in mind when presented with a patient who has used DBS is key. A thorough patient history and physical examination, including a complete neurological examination, as well as careful listing of the patients' medications with special attention to past or present use of dopaminergic agents can point us in the right direction.