E. R. Flotte
MD, 2009
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Movement
Disorders
·
Reviews:
Rezai AR N2/08S - VIDEO
Targets
·
Subthalamic
Nucleus (STN): 12mm lateral to midline, 3mm posterior to MC, 6mm below AC/PC
plane
·
VIM
nucleus thalamus: 11mm from lateral wall 3rd ventricle, few mm
anterior to PC, in AC/PC plane
·
GPi (globus
pallidum interna): 19-21
lateral from midline, 2mm anterior to MC (3-4mm anterior to IC), 5mm below
AC/PC plane (2mm above optic tract)
Parkinson’s Disease
·
Etiology unknown. Decreased neurons in
SNpc (normally inhibits GPi,
which itself inhibits thalamus), DMN vagus &
locus ceruleus. Path: Lewy
bodies (eosinophilic intracytoplasmic
inclusions with halo).
·
Symptoms:
resting (pill-rolling) tremor, bradykinesia,
cogwheel rigidity. Also: micrographia, decreased
blink, masked facies, festinating gain, pain in 50%,
GI problems, dysautonomia, weight loss. Symptoms
usually asymmetric. 20% have dementia. Diagnosis is clinical – 2 cardinal signs
and response to levodopa.
·
Parkinson’s Plus syndromes: DBS is ineffective, even when responsive to levodopa.
o Parkinsonism:
80% due to Parkinsons disease, 10% Parkinsons-Plus (MSA, PSP, CBGD, diffuse lewy body dz), 10% secondary.
(drugs: neuroleptics, reserpine,
Ca-channel blockers, lithium)
o Multisystem atrophy (MSA): Younger. Path: α-synuclein
positive glial cytoplasmic
inclusions, no Lewy bodies.
Poor response to dopamine. Includes:
·
Striatonigral
degeneration: syncope, stridor. Putamen atrophy
·
Olivopontocerebellar
atrophy: AD, Chr 6, 15yo,
LE ataxia, atrophy middle cerebral peduncle
·
Shy-Drager:
autonomic probs, impotence, no lewy
bodies(?); loss in putamen, SN, & interomediolateral horn cells
o
Progressive Supranuclear
Palsy (PSP): downgaze palsy, pseudobulbar, gait palsy, eyelid freezing, no tremor,
symmetric. MR: atrophy of midbrain & tectum.
70yos. No treatment.
o Corticalbasal
Degeneration (CBD): Parkinsonism, cortical signs (apraxia, myoclonus) and alien limb. No treatment.
Treatment:
Medical:
·
Sinemet: Dopamine + carbidopa
(a dopa decarboxylase
inhibitor). SE: N/V, orthostatis, arrythmias,
on-off periods, dyskinesias (Tx
B6). Contraindicated with Monamine Oxidase Inhibitors (MAOIs).
·
benztropin (Cogentin)/
Artane: anticholinergics.
·
Amantadine: Releases dopamine. Loses effect with
time.
·
Bromocriptine/ pergolide:
Stimulates D2 receptors. SE: vasoconstriction, fibrosis (bromocriptine
is used for prolactinoma, pergolide
isn’t).
·
Selegiline/ Eldypryl:
MAOI. Slows progression. deprenyl: MAOBI.
Surgery
Modalities
·
Lesioning:
GPi, STN (VIM thalamus)
·
Deep Brain Stimulation (DBS):
of STN, (also GPi, Vim thalamus.).
Up to 35% of patients develop tolerance
(for tremor)
o
DBS may be used in patients with
cardiac pacemakers
·
Radiosurgery:
only Vim Thalamus. 130Gy margin dose.
One 4mm collimator. Success: 82% good response. Onset 2mos. SE: Dysarthria.
·
Experimental surgeries: Fetal mesencephalic transplantation into SN caused dyskinesias, some improvement <60yo. Adrenal medullary transplant abandoned.
·
Historical: Ligation of anterior
choroidal artery
Locations
1.
Pallidotomy: posteromedial GPi (6mm lesion)
Usually done unilaterally only due to cognitive risk.
Indications:
refractory to meds, dopa-induced dyskinesia
(90% success), rigidity (75%), bradykinesia (85%),
on-off, dystonia (tremor only 57% success).
SE: field cut 3%,
dysarthria 8%, hemiparesis, cognitive probs if bilateral.
CI: dementia (
cognitive probs), ipsilateral hemianopsia, >85yo,
2°
parkinsonism.
Withold
meds day of surgery. Avoid IC (medial), optic tract
(inferior). Can last >5yrs.
2.
STN stimulation: May be done bilaterally. FDA
approved 2003.
Effective
for bradykinesia, tremor, rigidity.
Medication reduced or eliminated (rarely with pallidotomy
– overall results better, however more expensive $36K vs
$12K).
Improved gait
usually requires bilateral stimulation.
Appears
to be 10% more effective than GPi stimulation.
STN can be seen on
T2 low bandwidth. Position variable enough that
microelectrode recording is needed. (JN3/04)
Usually done with
microelectrode recording
SE: cognitive
decline, depression, hypophonia. Effect declines with
time. Mechanism unknown. Also
effective in essential tremor.
Stimulation SE:
Hypothalamus (anterior): flushing, perspiration. Coticobulbar
tract (lateral): dysarthria. Medial lemniscus
(posterior): paresthesias. CNIII (inferior/anterior): diplopia.
Internal capsule/ Corticospinal
tract (laterally): tonic contraction. Optic tract (inferior with GPi): visual changes. Blepharospam
indicates effective STN stimulation.
·
Reviews:
Starr
PA N11/03 (Operative Nuances)
·
Videos: Starr PA N11/03
3. Thalamotomy or VIM DBS: VL: tremor/rigidity. VIM/VOP:
tremor.
Complications:
confusion, speech abnormality (
w/ bilateral).
Done under local
with MRI guidance
Thalamotomy
– RF lesion at 75°. Bilateral not recommended.
VIM DBS – can be
done bilaterally
Essential
Tremor
·
Occurs in elderly. Familial: Autosomal dominant with variable penetrance,
60% of cases. Sporadic in 40%.
·
Bilateral action
(not rest) tremor of hand/arms or head. No other neurologic signs. Relieved
with alcohol.
·
Treatment: Propanolol,
primadone.
·
VIM thalamotomy
or STN stimulation. (Neurologist 9/04)
Dystonia
·
Sustained muscle contractions causing twisting,
repetitive movements. Can be local or generalized, primary (idiopathic) or
secondary to brain insult.
·
Primary: 30% have autosomal
dominant DYT1 mutation
·
Treatment:
o
Medical, IT baclofen:
often ineffective.
o
Pallidotomy or GPi DBS equally effective in primary and cervical dystonia.
·
Neither effective in secondary dystonia
or patients with any MRI basal ganglia abnormality (although single center
trial showed benefit DBS – Pretto TE JN9/08 - VIDEO).
Torticollis
·
Treatment: CN11 neurectomy
& upper cervical ventral rhizotomies (97%
success), thalamotomy (66% success), MVD of CN11 (70%
success), DCS, Botox
o
Selective peripheral denervation (Bertrand procedure): denervation
and/or myotomy of sternocleidomastoid and/or levator scapulae and unilateral or bilateral ramisectomy
Hemifacial spasm
·
Intermittent, painless. Begins ocular,
goes caudally. Persists during sleep. Females. Facial weakness may occur with
advanced HFS.
o
Dx:
MRI (no angio).
o
DDx: Blepharospasm
(bilateral), focal seizures (can check EEG).
o
Atypical
spasm begins in buccal muscles, usually dorsal-rostral surface, harder to treat or preserve hearing.
·
Treatment:
o
Botox – injections q3-4mos for life (Tegretol, Baclofen).
o MVD:
·
34%
AICA, 31% PICA, 31% both, 4% basilar. Vessel usually contacts ventrocaudal surface of CN VII. May be on pontine surface or pontomedullary
sulcus (Campos-Benitez M
JN9/08)
·
Dissect
DREZ only, not distal.
·
Intraop
BAERS (Peak V latency delay: 0.6ms = warning, 1.0ms = critical). (Not used by
all – see Dannenbaum M JN9/08)
·
SE:
deafness (3-10%) > facial weakness (1%). Check contralateral hearing preop
(audiogram).
·
Success
94%, 10% recurrence, 86% at 1mo.
·
Some
use papaverine intraop.
·
HFS
may persist for up to 3 months postop.
Idiopathic
Intracranial Hypertension (IIH, Pseudotumor Cerebri):
·
Dandy criteria: symptomatic, no
localizing findings (except CN6, 7 palsy), alert, normal CT/MRI, ICP >25.
·
Obese women most common, 20-45yo.
Usually self-limited.
o
Usually transient during pregnancy –
do not give Diamox 1st trimester.
·
Sxs:
Headaches in nearly all – worse in am, with Valsalva.
Also transient visual changes.
o
Papilledema
in almost all (rarely absent – not necessary for diagnosis).
·
Ventricles may be normal or slit.
Empty sella and enlarged optic n. sheath in 50%.
·
LP: Some asymptomatic obese women may
have ICP > 25. CSF normal.
·
Associated with vitamin A & retinoids, antibiotics (tetracycline), hormones, steroid
withdrawal, lithium. Stop meds if possible (stopping OCPs not necessary). Also
associated with lupus, uremia, etc.
·
Blindness most significant sequelae – occurs in 25%. Can be rapid. Follow visual
fields.
·
Treatment:
Weight loss. Diamox (SR 500mg BID, teratogenic) ±
Decadron (for acute blindness). Surgery for progressive
visual loss or severe symptoms despite medical treatment:
1.
Serial LPs: cumbersome
2.
Subtemporal decompression: historical
3.
Optic nerve fenestration: 90% successful. Unilateral fenestration appears to
lower ICP, improves vision bilaterally and CN deficits, help HAs (debated). 2%
risk of blindness.
4.
LP shunt: Use horizontal (high pressure) – vertical (medium) valve.
Complications: failure 55% in 1 year, overdrainage
15%, lumbar radiculopathy 5%, infection 1%, acquired Chiari and syringomyelia.
5.
VP shunt: for repeated LP failure. Consider using stereotactic guidance for
catheter placement with slit ventricles.
o
Debated whether ONSF or LP shunt is
best. Have equivalent efficacy.
Empty
Sella syndrome
·
1° (incompetent diaphragm) or 2°
(surgery, stroke, etc).
·
Sxs:
HA, CSF rhinorrhea, visual loss, amenorrhea-galactorrhea.
·
Surgery only for CSF rhinorrhea – transsphenoidal repair ±
lumbar drain. Shunt may cause pneumocephalus
·
Sheehans
syndrome: ischemic necrosis 2°
to intrapartum shock
Intracranial hypotension
·
Causes
dural enhancement on MRI/CT.
o Differential diagnosis of diffuse dural enhancement
·
Causes include
shunts, CSF leaks. Spontaneous (SIH) usually result of rupture of spinal nerve
root cyst into epidural space.
·
May
occur with abducent palsy, tinnitus, and other
symptoms.
·
Most resolve
spontaneously. May be treated with blood
patches
“Brain Sag”: cause of
postoperative deterioration with lumbar CSF drainage. Reversed by the Trendelenberg
position
·
Due to sinonasal
encephalocoeles (congenital or acquired), agenesis
of the anterior fossa, empty sella, sinus infection,
tumor.
·
See traumatic CSF leak for management.
Spontaneous spinal
CSF leaks
·
May
be due to osteophytes, dural tears, absent nerve root sheaths. Connective tissue disorders may predispose.
·
Causes
postural headaches.
·
MRI:
dural enhancement, downward displacement of cerebrum. Diagnosis: Myelogram.
(Low opening pressure on LP).
·
Treatment:
Most resolve spontaneously. Bedrest, blood patch,
surgical repair. (JN11/03)
·
Air
in the intracranial compartment
·
Due
to communication with air sinuses or atmosphere
·
Due
to bony and dural disruption
·
May
be: traumatic (e.g. skull
fracture), post-surgical (e.g. transsphenoidal), or spontaneous (due to CSF leak – sinus infection, tumor etc)
·
If asymptomatic – no treatment
necessary, will resolve
·
Tension pneumocephalus:
symptomatic mass effect due to pneumocephalus
o Can
evacuate with a spinal needle thru burr hole. Avoid N2O.
Normal Pressure Hydrocephalus (NPH)
·
Term
coined by Hakim 1964. Idiopathic cases may be caused by unrecognized SAH,
meningitis, etc.
·
“Guidelines”:
Marmarou et al. Neurosurgery 9/05 Supplement.
(Not universally accepted).
·
Symptoms: triad of dementia, gait instability, and
incontinence. Usually occurs in the elderly.
·
Diagnosis:
o
Primarily
clinical based on symptoms, however triad has PPV only 65% and NPV 82%. No test sufficiently predictive (see JN 12/06). No RCTs exist.
o
Role
of confirmatory tests versus shunt placement based on symptoms alone
controversial: see JN12/06.
·
Some
authors have suggested that the only
reliable means of validating a diagnosis of INPH is to document a positive
response to shunt placement (Ojemann RG JN69)
o
DDX:
·
Parkinsons – tremor, shuffling
gait, late dementia, late incontinence. Improves with levodopa.
·
Dementias:
Alzheimer’s, Multi-infarct (step-wise decline), Depression (Pseudo-dementia),
Picks – all generally lack gait disturbance and late incontinence.
·
May
also mimic chronic unrecognized communicating hydrocephlus
(SAH, trauma)
·
In
RCT shunting for Alzheimers showed no benefit (Silverberg Neurology 2008)
o
CT/MRI:
Communicating hydrocephalus.
·
Marmarou: “it is clear that the prognostic value of CT/MRI scans is
limited”
o
High-volume
LP: remove 40-50cc (Marmarou)
and look for clinical improvement. OP usually normal. Consider ambulatory
lumbar drain trial. If positive then highly predicative, negative response is
unreliable.
·
Marmarou: “A positive response to a 40- to 50-ml tap test has a
higher degree of certainty for a favorable response to shunt placement than can
be obtained by clinical examination. However, the tap test cannot be used as an
exclusionary test because of its low sensitivity (26–61%). Determination of the
CSF outflow resistance via an infusion test carries a higher sensitivity
(57–100%) compared with the tap test and a similar positive predictive value of
75 to 92%. Prolonged external lumbar drainage in excess of 300 ml is associated
with high sensitivity (50–100%) and high positive predictive value” (80–100%).
o
Radionuclide
Cisternography:
·
Reflux
into the ventricular system (and Sylvian fissures)
with no ascent to the cerebral convexities within 24hrs. Ventricular activity
persisting >48hrs implies good response to shunting.
·
Positive
and negative predictive value only 50% - not recommended by some but commonly
used.
·
Treatment:
o
CSF
Shunt: 66% improve.
·
VP,
LP shunts used.
·
Fixed
and adjustable pressure valves used as a matter of preference.
o
Incontinence
improves first.
o
Endoscopic
third ventriculostomy has been used (N7/04)
o
Better
outcome seen with minimal change in ventricular size than in patients with a
marked decrease
Spasticity:
·
Upper motor neuron lesion – cortex to
spinal cord. Increased muscle tone, resistance to movement, hyperreflexia.
·
Graded by Ashworth score
·
Treatment:
o
Medical: Valium, Baclofen,
Dantrolene
o
Botox – local only; lasts 3mo.
o Introthecal Baclofen
pump: Use for potentially ambulatory patients. Test doses given to assess
response (50µg then 100µg).
·
IT
Baclofen Overdose: stop pump, IV physostigmine,
move to ICU for possible intubation, remove 30ml from side-port or by LP (some
say last is ineffective)
·
IT
Baclofen Withdrawal: fever, tachycardia, HTN,
spasticity. Give baclofen – oral or via LP – and fix
pump/catheter.
o Selective dorsal rhizotomies:
intraoperative EMG to preserve “useful” spasticity. Preserves ambulation.
o Also: percutaneous
radiofrequency foraminal rhizotomies,
neurectomies, myelotomies
(midline “T”)
Intrathecal
Pumps
·
Used
for spasticity (baclofen), pain (morphine)
·
Can
check CSF via side port
·
Catheter-Tip Granulomas
may form – require discontinuation of therapy or removal
·
Programmable
Pumps: Medtronic Synchromed II
Facial
Palsy: can anastamose CN12, 11, or 9 to CN7 (Campero A N9/07)
Psychosurgery
OCD (Obsessive-Compulsive disorder)
Treatment:
·
Bilateral anterior cingulotomy.
Only 6-30% permanently respond (MGH reports 50%
success). Many relapse within 1yr – may need repeat
procedure. Also used for major depression. Target: 2.5cm posterior to tip of
frontal horn.
·
Bilateral anterior capsulotomy
(anterior limb of internal capsule)
·
Limbic leucotomy.
·
Above may be done stereotactically
or with SRS.
Depression
·
Vagal
nerve stimulation was approved for treatment of major depression in 2005
Cancer
Pain
·
IT pump for life expectancy over 3-6 mos, otherwise destructive procedures
Neurostimulation
for Pain
·
Neurostimulation
for pain review: Coffey RJ JN8/06. NF12/06.
Deep
Brain Stimulation for Pain
·
Periacqueductal
grey (PAG). SE: diplopia, anxiety.
·
Periventricular
grey (PVG): Safest.
·
VPL/VPM
·
Not FDA approved
Motor Cortex Stimulation for Pain
·
MCS is unlabeled for any indication in
the US. No RCTs.
·
For constant neuropathic pain –
anesthesia dolorosa, thalamic stroke
·
Occipital nerve stimulation for
headache: No RCTs
·
Reviews: Fontaine D JN2/09
·
Videos:
CNS
University of Neurosurgery
Spinal
Cord Stimulator (Dorsal
column stimulator)
·
Placed epidurally. Works when placed
ventrally also (for unknown reasons).
·
Lead tips C3-C6 for UE, T10-T11 for
LE.
·
Done awake w/propofol & local anesthesia. May be done percutaneously of via laminectomy, with RF-controlled
receiver or IPG.
·
Permanent implantation preceded by trial
·
Psychological screening used
preoperatively
·
Results: Few RCTs.
o
Metaanalysis
(n=3679), success rates: SCI, failed-back, phantom limb = 60%, peripheral
neuropathy = 70%, ischemic limb pain (PVD), angina pectoris, postherpetic neuralgia, CPRS = 80%.
o
Poor for root avulsion, or cancer.
o
In RSD response may be predicted by
sympathetic blockade.
o
Used
commonly for angina in
o
25 to 50% of patients in whom a preimplantation trial is successful report loss of
analgesia within 12 to 24 months (Doleys DM NF 12/06)
·
MRI
with DCS has been reported (Sha
RV 04)
·
SCS hardware infection: remove
everything.
·
SCS manufacturers: Medtronic,
ANS, Boston
Scientific
·
Videos: CNS University of Neurosurgery
Destructive Procedures for Pain
·
Review: Cetas JS JN9/08
Cingulotomy: must be
bilateral; recurs 3mo; SE: 10-30% flat affect
Medial
Thalamotomy: head/neck pain.
SE: 20-70% cognitive probs,
aphasia. Controversial – rarely used.
Mesencephalotomy: head/neck
pain. Stereotactic. Diplopia.
Preferred.
Hypophysectomy
·
For severe bone pain in breast or
prostate cancer
·
Done with radiosurgery, open
resection, or alcohol ablation
Cordotomy
·
Unilateral
pain below nipple, terminal patients, aching, deafferentiation
pain
·
Open:
C1/2 or thoracic laminotomies; Cut contralateral spinothalamic tract, start anterior to dentate, 5mm deep;
Check PFTs, diaphragm function preop
·
Percutaneous:
For patients with pain at or below C5 with limited life expectancy. Done awake,
use stimulation. Done at C1/2 (contralateral side). Use fluoroscopy.
·
Success:
94% initial; 60% 1yr; 40% 2yr. SE: paresis, incontinence, Ondine’s
curse
Commisural Myelotomy:
bilateral pain, thoracic & below. Laminectomy 3 levels above –
Penfield #4 (or similar) inserted in midline sulcus
to central canal, sectioned from T10 to 2 levels above conus (avoid bladder
dysfunction); 60% success
Punctate midline myelotomy:
for pelvic and visceral pain
DREZ
lesion (myelotomy/rhizotomy):
good (50-70%) for nerve root/ brachial plexus avulsion
for patients with no return of function. Not generally for cancer pain.
·
Prone. Laminectomy.
Find roots above/below to locate DREZ. RF or bipolar lesioning,
4-5mm deep (substantia gelatinosa/Lissauers tract)
·
Reviews:
Kanpolat Y ON3/08 (Operative Nuances)
·
Videos: Kanoplat Y ON3/08
Intrathecal pumps:
For nociceptive cancer pain above C5. Suggest IT
trial 1st
·
IT morphine overdose: stop pump, move
to ICU for possible intubation, IV naloxone, remove
CSF via side port
Complex
Regional Pain Syndrome (CRPS)
·
Type I = Reflex Sympathetic Dystrophy (RSD),
no nerve injury.
·
Type II = Causalgia,
due to incomplete major nerve injury (ie GSW).
·
Both types can be sympathetically
maintained pain (SMP) or sympathetically independent pain (SIP).
·
Etiology unknown (epiphatic
transmission discredited). Most have onset <24hrs, usually within 1mo.
·
Sxs:
Hyperesthesia (not hypesthesia) Triad: burning
pain, autonomic dysfunction (
or ¯
sweating & hair, vasoconstriction or dilation), trophic
changes. Sudeks atrophy (skin, bone, etc – not
nerve).
·
Dx:
Sympathetic block: Stellate for UE, lumbar for LE.
Confirmed by 1ºC increased
temperature. Questionable – failed RCT.
·
Treatment:
o
TCA (Elavil),
Neurontin, Tegretol, reserpine
o
Guanethidine
sympathetic block (18-25% success, repeatable)
o
Spinal Cord Stimulator
o
Intrathecal
opiates (often with clonidine or bupivicaine)
o
Sympathectomy
(T2-3): evidence is scant. (Warm, reddish extremity and Horners
for UE confirm successful sympathectomy)
o
Nerve surgery, other ablative
treatment (DREZ lesioning, cordotomy)
ineffective
Deafferentiation Pain
·
DREZ coagulation may be effective
·
Reinnervation
Pain treated medically only; usually resolves
Sympathectomy
·
Used for hyperhidrosis,
Raynauds, angina, RSD/CRPS, peripheral vascular
disease.
·
Resect 2nd ±
3rd thoracic ganglia for palmar. Add 4th for axillary hyperhidrosis. (leave T1
to prevent Horners), 2nd & 3rd (±L1)
for LE
·
Approaches: supraclavicular,
transaxillary, midline posterior costotransversectomy,
thoracoscopic, percutaneous
radiofrequency.
·
Success: hyperhidrosis
>90%.
·
Complications: Thoracic: bradycardia (usually asymptomatic). Recurrent hyperhydrosis common (JN:S2/05).
Lumbar: retrograde ejaculation.
·
Lumbar sympathectomy
for RSD: 2nd & 3rd lumbar sympathetic ganglion
resected via retroperitoneal approach
Otalgia
·
May come from CN 5,7,9,
or 10. Give trial of TGN meds. Intractable: explore CNs – MVD vs sectioning (nervus intermedius, 9, upper 2 roots of 10)
Trigeminal neuralgia
·
Criteria: Sharp, lacinating,
intermittent pain. Unilateral. No neurologic deficits. Sensory trigger common.
·
Due to epiphatic
transmission.
·
More common on right. V2&V3>
V2> V3> V1&2> V1. Bilateral or V1 think MS.
·
Onset >50yo.
·
Diagnosis:
MRI if atypical (young, bilateral, V1) or considering surgery. Response to tegretol
predictive.
o
DDx: herpes zoster (shingles) or post-herpetic neuralgia if resolved (continuous pain),
dental pain, TMJ pain, temporal arteritis.
§ Look
for vesicles on TM (Ramay-Hunt)
·
Secondary TN:
due to multiple sclerosis, tumors, etc. Much less responsive to treatment
·
Atypical facial pain:
constant, dull, without trigger or otherwise atypical for trigeminal neuralgia.
Treatment
·
Medical: Tegretol
> dilantin > baclofen, neurontin, elavil, Lyrica.
o
Tegretol:
200mg TID, to 1600mg/day. May cause leucopenia, hepatitis. No levels – titrate
to side effects.
·
Surgical (see JN2/05):
o
Success (2-year): MVD 90%, balloon
compression 80%, RFR and glycerol 65%, SRS 60%. 3 year: balloon 70%, RFR 62%,
Glycerol 55%.
o
Complications (trigeminal neuropathy):
RFR = 30%, glycerol = 25%, BC = 15%, SRS = 10%
·
Microvascular
Decompression (MVD):
o
In 80% compression is by SCA (also
AICA, persistent primitive trigeminal artery). In 5% of cases compression is
primarily venous (transverse pontine & trigeminal
veins) (N8/04)
o
Indications: >5yr survival,
<65yo, failed PTR, V1 (less risk of keratitis than
PTR).
o
85-95% initial success, 70% at 10yrs.
§ MVD
more successful for lacinating (vs. constant) pain (Miller
JP JN4/09)
o
Preoperative
imaging: Miller J JN3/08.
3T
MRI used.
o
Complications: hearing loss (check contralateral
hearing preop, audiogram)
§
Mortality 0.3%, neurologic morbidity
2% (higher in redos, vertebrobasilar dolichoectasia).
§
Less risk of facial numbness than PTR.
No anesthesia dolorosa. Small pontine infarctions
occur on MRI in 24%.
·
Percutaneous
Trigeminal Rhizotomy (PTR):
o
Lesioning
methods: Radiofrequency (RFR), ballon compression
(BC), glycerol injection.
o
Bradycardia,
HTN may occur (consider atropine preop).
o
Look for ICA on preop imaging
o
Straight or curved electode
(5mm 1div, 7.5mm 2 div, 10mm 3div).
Place needle 3cm lateral to oral commissure.
Aim 3cm anterior to EAM, medial pupillary line.
Palpate intraorally. Patient winces when entering
foramen ovale. Obtain CSF (in trigeminal cistern). Stimulate to reproduce pain
before lesioning.
o
SE: Numbness in 100%. Paresthesias/ dysesthesias 20%, anaesthesia dolorosa 4%, masseter
weakness, ¯
hearing (tensor tympani), EOM paresis, neuroparalytic
keratitis (2%).
§ Aneathesia
dolorosa treatment: Meds (TCAs), trigeminal tractotomy/nucleotomy, open (Sjoquist) or percutaneous trigeminal DREZ lesion, motor
cortex stimulation
o
See
N4/04. Glycerol: JN2/05
·
Radiosurgery:
o
Success: 70% have >50% improvement
at 3yrs, 55% no pain with meds, 35% pain-free.
§ 58%
response for secondary TN, 0% for atypical. Several reports show good response
in TN 2° to multiple sclerosis
§ 13%
relapse (at avg 15mos).
§ Not
as good as initial MVD, but as good for second procedure.
§ Subsequent
MVD is no more difficult after SRS (JN1/05S).
§ Right-side
statistically significant higher success rate (JN3/05).
o
SE: 10% facial numbness, 12% other
complications.
§ New
facial numbness correlates with treatment response (JN3/05)
o
Takes days to 3 months to work. All
improvement occurs by 1 year, most by 6 mos.
o
80 (70-90) Gy. One 4-5mm isocenter. Two isocenters and
doses >85Gy also used (JN12/06S). Brainstem surface at 30% isodose line, center at DREZ
§ For
repeat SRS: 50-60Gy, anterior to 1st target. (see JN12/06S)
o
See JN3/05.
·
Also: peripheral neurectomy
(supraorbital, infrorbital,
inf. dental nerves only; nonoperative candidates); Intradural neurectomy (failed PTR
w/ preexisting CN5 anaesthesia. V1 superior, V3
inferior. Cut lower ½)
·
Raeders syndrome: V1 & V2
pain with oculosympathetic paralysis – ptosis and miosis (no anhydrosis-pseudoHorners); due to
·
Tic
convulsive:
TGN w/hemifacial spasm
Glossopharyngeal neuralgia
·
Pain in ear, tongue, tonsil, and angle
of jaw. 10% have vagal bradycardia/
asystole.
·
Dx:
cocanization of tonsillar
fossa relieves the pain.
·
DDx:
primary ear/throat disorder, Ramsay-Hunt (check TM for vesicles)
·
Eagle’s syndrome:
enlongated styloid process
causes compression of CN9
·
Treatment:
1.
MVD (PICA)
2.
Rhizotomy
(9 & top 2 roots of 10). 11% risk of hoarseness/dysphagia
(also facial paresis). Significant dysphagia is rare.
Cardiac instability may occur intraop, give atropine before manipulating nerve.
Monitoring CN9-10 not helpful. (N4/04)
Geniculate neuralgia:
otalgia, prosopalgia (deep
facial structures). Treatment: symptomatic
Postherpetic
neuralgia:
Persists >1-3mos after zoster. Lidocaine patch, TCAs (Elavil), Neurontin, IT lidocaine,
Zostrix. Surgery
controversial.
·
Thoracic ganglionectomy:
Extended foraminotomy. Cut/clip ganglion in foramen. 3 levels – 1 above and
below. Diagnose levels with lidocaine blocks.
Neurogenic hypertension: Basilar
artery on left rostral ventrolateral
medulla (RVLM), responds to MVD;
may also be due to basilar impression & responsive to odontoidectomy.
Intercostal neuralgia: Tx:
intercostals nerve blocks
Occipital
neuralgia: Occipital nerve stimulation, Block, TENS.
·
Upper cervical ganglionectomy
(C2 & C3), neurolysis/decompression, neurectomy (recurs)
Neuropathic
pain: Neurontin, TCAs, other AEDS, lidocaine gel/ patch, capsacin
Cluster
Headache: Radiosurgery of the trigeminal nerve has been
used for chronic refractory cases, but its efficacy is unclear (N12/06)
Microvascular Decompression (MVD)
·
Used for trigeminal neuralgia, hemifacial spasm, glossopharyngeal
neuralgia. Also reported for torticollis
- Refractory
essential hypertension: decompression of the left rostral anteromedial medulla. Janetta
reported 75% success.
·
Check contralateral hearing preop (may
cause ipsilateral hearing loss)
·
Intraop BAERS (Peak V latency delay: 0.6ms =
warning, 1.0ms = critical).
·
Janetta
stresses avoiding cerebellar retraction, use CSF
drainage. 2mm retractor used, arachnoid dissected on cerebellar
side only to protect CN. Dissect vessels off DREZ only (not distal? Others say
whole nerve must be dissected (vs HFS) – N12/03).
Place insulating sponge on vessel.
·
Superior petrosal
veins may be cut and divided when multiple veins exist and it is not the single
main drainer. Dandy’s vein (petrosal vein) must be
watched for.
·
Pexy
stitch on petrosal surface may be used to keep vessel
off nerve with 8-0 nylon, or Teflon and fibrin glue.
Facial Nerve Reanimation
·
Primary anastamosis
or cable graft if transected – 10-0 Nurolon
·
Facial-hypoglossal anastamosis:
some wait 6-9mos Postop following EMG
o May use partial anastamosis (hemihypoglossal) to avoid tongue atrophy
o Intratemporal: Donzelli R N12/03
Revised
6/1/09
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