FUNCTIONAL AND PAIN NEUROSURGERY

I. PARKINSONISM

A. Treatment

1. Thalamotomy—ventral intermediate thalamic nucleus (VIM) to treat tremor

2. Pallidotomy—globus pallidus interna (GPi) lesion to treat rigidity or bradykinesia. Also useful for levodopa-induced dyskinesias and on–off problems

3. Stimulation—of thalamus, globus pallidus, or subthalamic nucleus

4. Surgery—avoid if the patient has dementia, a coagulation disorder, contralateral hemianopsia, or secondary parkinsonism

5. Remember to create a lesion contralateral to the symptomatic side

a. 80% of patients are improved.

b. Microelectrode recording helps determine the location of the radiofrequency (RF) lesion.

6. Complications—visual field cut, hemiparesis, blood clot, and dysarthria (especially if bilateral)

II. SPASTICITY

A. Treatment

1. Medical

b. Valium

c. Baclofen

d. Dantrolene

2. Surgical

a. Intrathecal (IT) baclofen

b. Neurectomy or blocks

c. RF rhizotomy or open selective dorsal rhizotomies—electromyogram (EMG) intraop

d. Midline thoracic myelotomy with T11–L1 laminectomy—cut the T12–S1 cord to spare the S2–4 bladder reflex 4 mm deep

III. TORTICOLLIS

A. Cause—dystonia by spasm of the sternocleidomastoid muscle

B. Evaluation—rule out C1–2 rotatory subluxation, 11th nerve compression, infection, or tumor

C. Treatment—physical therapy, transcutaneous electrical nerve stimulation (TENS) unit, spinal cord stimulator, Botox injection, section spinal accessory nerve (XI), or microvascular decompression of XI from the vertebral artery

IV. HEMIFACIAL SPASM

A. Cause—compression of VII by the anterior inferior cerebellar artery (AICA) at the root entry zone (REZ)

1. Compression of VIII causes tinnitus.

2. Brainstem glioma or multiple sclerosis can cause facial myokymia (continuous facial spasm).

3. Blepharospasm is bilateral eyelid spasms.

B. Treatment—Botox injections or a microvascular decompression

A. Evaluation—rule out hyperthyroidism, diabetes, pheochromocytoma, Parkinson disease, and menopause.

B. Treatment—antiperspirants, anticholinesterases, or sympathectomy

VI. SYMPATHECTOMY—used to treat hyperhidrosis, Raynaud syndrome, angina, or reflex sympathetic dystrophy (RSD)

A. For upper extremity symptoms—remove the sympathetic ganglia at T2 (to avoid Horner syndrome) via an open midline T3 costotransversectomy or thorascopic approach.

VII. CHRONIC PAIN

A. Conservative management options—physical therapy, oral medications (nonsteroidal antiinflammatory drugs [NSAIDs], steroids, Elavil, Neurontin, narcotics), and epidural steroid injections

B. Deep brain stimulation (DBS)—placed in the periaqueductal or periventricular gray

C. Spinal cord stimulator—for RSD, failed back syndrome, arachnoiditis, and refractory angina

1. Place the electrodes percutaneously or open and connect to an internal pulse generator

D. Intrathecal pumps

1. May use subcutaneous (SQ) reservoir or pump (if > 3-month survival)

2. Test with 2 mg cerebrospinal fluid (CSF) injection

a. Watch for decreased breathing < 10/min and have Narcan 0.4 mg ready (1 A [ampule])

i.  IT dose—1/10 the epidural dose, 1/100 the intravenous (IV) dose, and 1/300 the oral dose

ii. Bolus 0.4 mg postop

3. 90% have significantly improved pain control.

1. Performed on the side contralateral to the pain because the crossed lateral spinothalamic tract is severed.

2. C1–2 percutaneous method usually used with fluoroscopic guidance.

3. Needle should be anterior to the dentate ligament.

4. Open procedure may be done in the thoracic spine.

5. Complications—ipsilateral weakness, urinary incontinence, and On-dine curse (failure of involuntary respiration with bilateral cervical procedures)

F. Midline myelotomy—for bilateral pain below the thoracic region

1. After laminectomy, the midline sulcus is penetrated with a Penfield #4 down to the central canal extending from T10 to two levels above the conus (to avoid bladder dysfunction).

G. Hypophysectomy—for severe bone pain related to breast or prostate cancer

1. May be performed with radiosurgery, open resection, or insertion of alcohol

H. Cingulotomy—for diffuse pain; a last resort

I. Dorsal root entry zone (DREZ) lesion—for deafferentation pain due to nerve root avulsion.

VIII. REFLEX SYMPATHETIC DYSTROPHY (COMPLEX REGIONAL PAIN SYNDROME, CAUSALGIA)

A. Cause—unknown

B. Signs/Symptoms

1. Burning pain—usually in the median, ulnar, and sciatic nerves

2. Vasomotor changes—pink or cold and with increased or decreased sweating

3. Trophic changes—dry and thin skin, stiff joints, possibly due to immobility

D. Treatment

1. Physical therapy—most useful option, with muscle stretching

2. Elavil, Neurontin, phentolamine IV

3. Stellate ganglion block—better at T2 to avoid Horner syndrome

4. Lumbar sympathetic blocks

5. Surgical sympathectomy

6. Spinal cord stimulator