neuropathic pain Flashcards
pain flow chart
* neuropathic vs nocioceptive
* forms?
episodic neuropathic pains
a. Trigeminal neuralgia
b. Glossopharyngeal neuralgia
c. Occipital neuralgia
d. Nervus intermedius neuralgia
continuous neuropathic pains
a. Persistent idiopathic facial pain
b. Painful post-traumatic trigeminal neuropathy
c. Trigeminal post-herpetic neuralgia
d. Burning mouth syndrome
e. Occlusal dysesthesia (phantom bite/occlusion
Superficial
somatic pains
a. Cutaneous pain
b. Muco-gingival pain
Deep somatic
pains
a. Muscoluskeletal pain
b. Visceral pain
Neuropathic Pain
Definition:
Pain initiated or caused by a primary lesion or dysfunction in the nervous system (1
Dysesthesia-
an unpleasant abnormal sensation, whether spontaneous or evoked (1
is neuropathic pain often diagnosed
Often misdiagnosed & mistreated by
doing multiple unnecessary dental
procedures (i.e. multiple root canals,
extractions
Neuropathic Pain
Dysfunction may be caused by:
- virus (i.e. herpes zoster, shingles)
- demyelinating disease (i.e. multiple sclerosis)
- trauma, injury, surgery
- dental extractions, root canal therapy, dental implant placement, restorative procedures
- Idiopathic
Inferior Alveolar Nerve (IAN) Injury incidence varies from?
most commonly injured nerve ?
Lingual nerve injury incidences is?
Inferior Alveolar Nerve (IAN) Injury incidence varies from 0-40%
IAN is the most commonly injured nerve 64.4%
Lingual nerve injury incidences is 28.8%
Etiologies of nn injury with dentistry
IAN injury due to traumatic local anesthesia injection
- % of the long beveled needles were barbed at their tips after the procedure
- % of the patients got an “electric shock type” sensation on IAN block
- % of the % suffer from prolonged neuropathy
- 78% of the long beveled needles were barbed at their tips after the procedure
- 1.3 – 8.6% of the patients got an “electric shock type” sensation on IAN block
- 57% of the 1.3-8.6% suffer from prolonged neuropathy
IAN injury due traumatic local anesthesia injection
- Local anesthetics safety for pain?
- Lidocaine, articaine, mepivicaine and bupivicaine irritation
IAN injury due traumatic local anesthesia injection
- Local anesthetics represent the safest and most effective
drugs in all medicine for the prevention and
management of pain
- Lidocaine being the least irritant followed by articaine,
mepivicaine and bupivicaine
IAN injury by implant drill
hematoma formation can occur as well impinging the nn
Neuropathic pain variable presentation
- can vary widely in clinical presentation in regard to pain quality and location
neuropathic pain can be caused by lesions where?
can be caused by either central
nervous system dysfunction
and/or by peripheral nerve
lesions
neuropathic pain may not repsond to what drugs? could respond to?
somewhat less responsive to
opioids and more likely to respond
to other drugs, such as
anticonvulsants (among others)
is neuropathic pain dependent on stimuli
can be stimulus-evoked or
stimulus-independent
(spontaneous).
CENTRAL CAUSES OF FACIAL PAIN
– Anesthesia dolorosa (pain in an area that is anesthetic)
– Central post-stroke pain
– Facial pain attributed to multiple sclerosis
– Persistent idiopathic facial pain
– Burning mouth syndrome
– Multiple sclerosis
NEURALGIAS – as a cause of a facial pain
NEURALGIAS – follows distribution of a nerve(s)
– Trigeminal neuralgia Geniculate neuralgia (Ramsay Hunt/Nervus
– Post-herpetic neuralgia intermediate neuralgia)- sensory of CN VII with lancinating pain
– in the auditory canal/middle ear
– Traumatic neuralgia Auriculotemporal neuralgia
– Glossopharyngeal neuralgia
– Occipital neuralgia
OTHER CAUSES of facial pain
– Cancer pain
– Dental pain
– Post-traumatic and post-surgical pain
– Primary headache
– Temporomandibular joint syndrome
Neuralgia
Definition:
“Paroxysmal or constant pain typically with sharp, stabbing,
itching, or burning character in the distribution of a nerve “
Neuralgia
* a form of neuropathic pain that is characterized by the following features:
1. timing, distribution?
2. neurologic deficit present?
3. Attacks can be provoked by?
4. refactory period?
- Paroxysmal, brief (seconds to a few minutes), shock-like or lightning-like pain that follows a peripheral or cranial nerve distribution and can spread to adjacent areas in the
course of the attack - Typically, there is no objective neurologic deficit in the distribution of the affected nerve
- Attacks can be provoked by non-painful stimulation (allodynia) of trigger zones (i.e. flossing elicits gingivalm pain)
- A refractory period follows attacks; the duration of the refractory period shortens as the disease progresses
Pre-trigeminal neuralgia
description
Dull, continuous, aching or burning pain in the oral cavity or teeth or jaw
evolving eventually into trigeminal neuralgia (TN)
Pre-trigeminal
neuralgia
Pain duration
Pain duration varies widely from hours to month
Pain may go into remission
Pre-trigeminal
neuralgia origin?
This brief, milder pain is
sometimes suspected to
have a dental origin and
unnecessary dental
procedures have been
performed in many cases
Trigeminal neuralgia (TN) defined
TN as sudden, usually unilateral, severe, brief, stabbing or lancinating, recurrent episodes of pain in the distribution of one or more branches of the fifth cranial
(trigeminal) nerve
CN V neuralgia EPIDEMIOLOGY
* The annual incidence of TN is?
* ? new cases occur in the US each year.
* TN is one of the most frequently seen neuralgias in what population?
* incidence increases with?
* Onset after age ?, although may occur in?
* male to female ratio?
- The annual incidence of TN is 4 to 13 per 100,000
people - 15,000 new cases occur in the US each year.
- TN is one of the most frequently seen neuralgias in the
elderly. - incidence increases with age
- Onset after age 50, although may occur in the second
and third decades or, rarely, in children. - male to female ratio is about 1:1.5
TN Pathophysiology
- Most cases of trigeminal neuralgia (TN) are caused by compression of the trigeminal nerve root, usually within a few millimeters of entry into the pons
- Compression by an aberrant loop of an artery or vein is thought to account for 80 to 90 percent of cases.
superior cerebellar aa
Other causes of nerve compression in TN include
- vestibular schwannoma (acoustic neuroma)
- Meningioma
- epidermoid or other cyst,
- saccular aneurysm or AV malformation
Neuropathic Pain
Pathophysiology-Ephaptic
Transmission
Focal Demyelination of TN
loss of Aa elasticity with age cause friction rub leading to demyleination
CLINICAL FEATURES of TN
* The pain of TN tends to occur in ? when is it worst?
* The pain sensation?
* sleep?
* duration?
* refractory period?
* may also be a co-existing?
*more invovled branches?
* unilateral/bilateral?
* Facial muscles?
- The pain of TN tends to occur in paroxysms and is maximal at or near onset.
- The pain
- “electric shock-like” or “stabbing“
- typically does not awaken patients at night.
- lasts from several seconds to minutes, but may occur repetitively
- A refractory period of several minutes during which a paroxysm cannot be provoked is common due to nerve repolarization
- may also be a co-existing continuous, deep, dull pain.
- V2 and/or V3 are involved more frequently than V1
- unilateral in most cases
- Facial muscle spasms can be seen with severe pain especially the masseter muscle
Clinical Features of TN
TN can be precipitated by?
Trigger zones?
Triggers can be?
Episodes may last? followed by?
Recurrence?
TN can be precipitated by dental procedures (i.e. root
canal therapy, dental extraction)
Trigger zones may be present
Triggers can be light touching, chewing, talking,
brushing teeth, cold air, smiling, shaving, washing face
and/or grimacing, brushing or flossing teeth.
Episodes may last weeks or months, followed by pain-
free intervals or remission of pain for years.
Recurrence is common
Classical trigeminal neuralgia diagnostic features
A. At least how many episodes of?
B. In divisions of trigeminal nerve? with no?
C. Pain has ≥3 of the following 4 characteristics:
1. recurring?
2. intensity?
3. pain feeling?
4. precipitated by?
D. No clinically evident?
E. Not better accounted for by?
A. At least 3 attacks of unilateral facial pain fulfilling criteria B and C
B. In ≥1 divisions of trigeminal nerve, with no radiation beyond trigeminal distribution
C. Pain has ≥3 of the following 4 characteristics:
1. recurring in paroxysmal attacks lasting from a fraction of a second to 2 minutes
2. severe intensity
3. electric shock-like, shooting, stabbing or sharp in quality
4. precipitated by innocuous stimuli to affected side of face
D. No clinically evident neurological deficit
E. Not better accounted for by another ICHD-3 diagnosis
Differential diagnosis of TN
- Short-lasting unilateral neuralgiform headache with conjunctival injection and tearing (SUNCT)
- Cluster-tic syndrome
- Giant Cell Arteritis
- Multiple sclerosis
- Other neuralgias
Imaging studies to
rule out brain
pathology
who should get this?
Magnetic resonance imaging (MRI) or magnetic resonance angiography (MRA) of the brain
* MRI should be obtained in the following groups to rule out a mass lesion or multiple sclerosis:
* Patients with sensory loss
* Young patients (under the age of 40)
* Patients with bilateral symptoms
* Patients who do not respond to conservative therap
Medication Management for
Neuropathic Pain
preffered/adjunct?
carb is classic but has CBC implications so oxcarb preffered, baclofen is adjunct
SURGICAL THERAPY FOR TN
Microvascular decompression
Radiofrequency rhizotomy
Glycerol rhizolysis
Balloon compression
Gamma knife radiosurgery – NON-INVASIVE
Peripheral neurectomy (not recommended)
Gamma Knife Radiation-
better for?
Gamma Knife Radiation-
better for elderly
Use of mri to located nn and aa compressing it before measuring head contours for neuroablative procedure
Gamma Knife Radiation mechanism:
Neuroablative Procedure: non-invasive
Destroys portions of the nervous system to block transmission of nociceptive information.
Pathophysiology - Microvascular
Compression theory
Compression of the trigeminal nerve root at or near the dorsal root entry
zone by a blood vessel (usually the superior cerebellar artery)
Segmental demyelination of A-beta and A-delta fibers at the site of vascular compression
Generation of ectopic impulses and spreading of these impulses to adjacent neurons through ephaptic transmission (cross-talk)
microvascular decompression sx
Microvascular Decompression
Surgery can improve Trigeminal
Neuralgia pain
HZ (shingles) features:
inflam caused by?
skin?
Occurs in cutaneous areas supplied by?
Pain?
acute inflammation caused by varicella zoster virus (chickenpox)
Multiple, painful vesicular skin or mucosal eruptions
Occurs in cutaneous areas supplied by the cranial or spinal nerve ganglia inflamed by the virus causing necrosis & hemorrhage
Pain subsides within weeks typically but can last months to years then classified as Post-herpetic neuralgia
Herpes Zoster (HZ)
Commonly affects:
areas
torso if spinal nerves involved
2. trigeminal nerve(V1) if cranial nerves involved and may cause blindness and palsies affecting CN III, IV, VI.
3. facial nerve (VII) causing facial weakness, hearing loss, tinnitus.
4. C2 & C3 causing pain over posterior head 1.
herpes zoster tx
anti-virals and steroids as soon as possible. Pain medications to manage pain.
Vaccine for Shingles Prevention
* (CDC) recommends that ?
* preffered vax?
- (CDC) recommends that appropriate adults 50 or older get vaccinated to help prevent Shingles.
- Shingrix (recombinant zoster vaccine) the preferred vaccine over ZOSTAVAX to help reduce your risk of getting Shingles in the future
POST-HERPETIC NEURALGIA (PHN)
* typeof pain
* increased risk with? % affected?
* defined? duration?
a common form of** chronic neuropathic pain**
Risk of developing PHN increases with age & affects 60% of patients > 60 years old
A pain developed during the acute phase of HZ and recurring or persisting for more than 3 months after the onset of the HZ
POST-HERPETIC NEURALGIA
(PHN) risk factors
Risk factors: age, female, prodrome, etc.
a genetic component may contribute to the varied susceptibility of some patients to developing PHN after an attack of HZ.
Post-Herpetic Neuralgia
Clinical Characteristics:
pain quality?
May be superimposed by?
a constant, deep, aching/burning pain; a brief, intense shooting pain with hyperalgesia (an increased response to a stimulus that is normally painful) or allodynia (pain due to a
stimulus that does not normally provoke pain) ( with light touch producing pain (80-90%).
May be superimposed brief stabbing exacerbations of pain
PHN pathophys
affected dermatomes?
degen changes?
central/perihpheral
sensory deficits in the affected dermatomes as well as pigmentary changes and scarring.
Major degenerative changes occur in afferent pathways with loss of axons and myelin in peripheral sensory nerves.
Both peripheral and central mechanisms are involved in PHN
options for Management of PHN PAIN
systemic and topical
Management of PHN PAIN
Systemic
a SNRI/TCAs, such as amitriptyline/nortriptyline
Gabapentin/pregabalin may be as effective as TCAs with fewer contraindications
** Lyrica**
Opioids
Steroids
NSAIDs
Management of PHN PAIN
topical
5% lidocaine patches
NSAID gel or cream – Diclofenac
Sodium topical gel 1%
Shingles gel:
Amitriptyline (2%)
Ketoprofen (10%)
Tetracaine (4%)
Deoxy d-glucose
Persistent idiopathic facial pain (PIFP) diagnositc criteria
A. Facial and/or oral pain?
B. Recurring for?
C. Pain has both of the following characteristics:
1. location?
2. dquality?
D. Clinical neurological examination?
E. Dental cause?
F. Not better accounted for by/
Persistent idiopathic
facial pain (PIFP)
A. Facial and/or oral pain fulfilling criteria B and C
B. Recurring daily for >2 h per day for >3 mo
C. Pain has both of the following characteristics:
1. poorly localized, and not following distribution of a
peripheral nerve
2. dull, aching or nagging quality
D. Clinical neurological examination is normal
E. Dental cause excluded by appropriate investigations
F. Not better accounted for by another ICHD-3 diagnosis
Persistent Idiopathic Facial Pain (trigeminal deafferentation pain)
* PIFP is best defined as?
* Affects women in?
* Previously called?
- PIFP is best defined as persistent pain in apparently normal teeth or adjacent oral tissues
- (phantom tooth pain, idiopathic toothache, idiopathic odontalgia, facial migraine, atypical facial neuralgia, and atypical facial pain have been used in the past)
- Affects women in the fourth or fifth decade (peri- menopausal or menopausal)
- Previously called Atypical Toothache
Persistent Idiopathic Facial Pain
(trigeminal deafferentation pain)
* Precipitating factors:
- traumatic injury
- various routine dental procedures such as endodontic therapy, apicoectomy, tooth extraction, periodontal surgery, or implants.
- can even follow seemingly innocuous dental procedures such as crown preparation, drilling of dentin and periodontal scaling
AO is more likely to develop in a tooth that was painful when relative to any dental procedure?
AO is more likely to develop in a tooth that was painful
immediately prior to any dental intervention
Differential Diagnosis of
PIFP
Odontogenic toothache
Myofascial trigger point pain
Pre-Trigeminal neuralgia
Neurovascular toothache (facial or midface migraine, cluster headache)
Maxillary sinusitis
Neuritic toothache
Temporomandibular disorder (TMD)
Diagnostic Workup of PIFP
Obtain a?
eliminate any ?
R/O ?
PIFP frequently arises ? and is not? However, the tooth may be?
Obtain a thorough history
eliminate any odontogenic cause
R/O a myofascial trigger point, trigeminal neuralgia,
neurovascular toothache due to facial or midface
migraine or cluster headache(episodic and throbbing or
pulsating), tooth pain from a maxillary sinusitis /
neuritic toothache/
PIFP frequently arises spontaneously and is not related
to functional demands. However, the tooth may be
sensitive to pressure and a patient may complain of pain
on eating
Neurosensory Testing
Clinical photographs of a patient undergoing various tests. A. The
intraoral cotton swab test. B. The intraoral pinprick test. C. The intraoral
spatula test using hot or cold.
Central Sensitization with nn trauma
role of chemical mediators in cnetral sensitization
Persistent Idiopathic Facial Pain Treatments
acting on nn membrane
anti epileptic can stabilize nn membrane
central acting rx for Persistent Idiopathic Facial Pain Treatment
topical meds of PIFP
Viscous Lidocaine
Topical Ketamine
** Zostrix (OTC) – contains capsaicin- depletes substance P**
NOTE: These medications may be combined & used in a stent as a medication delivery system.
Stent covers sensitive gingival tissue.
Burning Mouth Syndrome
* characterized by ?
- characterized by an intraoral burning sensation for which no medical or
dental cause can be foun
associated conditons of burning mouth:
psychiatric disorders?
– xerostomia from?
– nutritional ?
– allergic ?
– tongue?
– infection with>?
– endocrine?
– denture-related?
– thyroid?
– female related cause?
psychiatric disorders such as depression
– xerostomia (from drugs, connective tissue disease, or age)
– nutritional deficiencies (vitamin B12, iron, folate, zinc, vitamin B6) so blood tests needed first to rule out vitamin deficiency
– allergic contact stomatitis- (i.e. denture acrylic or nickel clasps)
– geographic tongue
– candidiasis
– diabetes
– denture-related pain
– thyroid abnormalities
– menopause
Epidemiology of burning mouth syndrome
predominantly affects women
especially post-menopausal due to
decreased estrogen
tx of burning mouth syndrome
30 - 50 % improve spontaneously
The frequency of burning mouth syndrome are unknown
Topical amitriptyline troches (4mg) dissolve in mouth up to 3x/day
Klonopin (clonazepam) (sedating)
IHS Diagnostic Criteria Beta III
13.10 Burning mouth syndrome (BMS)
A. Oral pain fulfilling?
B. Recurring ?
C. Pain has both of the following characteristics:
D. Oral mucosa appearance and clinical examination?
E. Not better accounted for by ?
A. Oral pain fulfilling criteria B and C
B. Recurring daily for >2 h per day for >3 mo
C. Pain has both of the following characteristics:
1. burning quality
2. felt superficially in the oral mucosa
D. Oral mucosa is of normal appearance and clinical examination including sensory testing is normal
E. Not better accounted for by another ICHD-3 diagnosis
Site of Oral Burning
cardinal symptom of BMS
pain described as?
Distribution of the burning sensation is?
Most common site is ?
Oral pain represents the cardinal symptom of BMS
Type of pain is a prolonged “burning” sensation
Distribution of the burning sensation is nearly always bilateral but it does not follow anatomical landmarks
Most common site is anterior two-thirds and tip of the tongue.
Site of Oral Burning
regions that are also affected?
areas rarely involved?
Many patients complain of ?
Anterior hard palate, mucosal aspect of lower lip, and mandibular alveolar regions are
also affected.
Buccal mucosa and floor of mouth rarely involved.
Many patients complain of burning in more than one intraoral area at the same time
Oral Burning
Onset :
Gradual with no known precipitating factors
Sudden and linked to a preceding dental procedure (tooth cleaning, filling or a new denture), upper respiratory infection or a course of antibiotics
oral burning timing of the symptoms
The timing of the symptoms is variable.
Some patients complain of continuous discomfort throughout the day
Others find that it gradually increases during the day and reaches maximum intensity by evening
Pain usually remits nightly during sleep
Management oral burning
medication only:
Clonazepam (“topical”)
Alpha-lipoic acid
Tricyclic anti- depressants: (Amitriptyline) oral or as a troche 4mg tid
Gabapentin
Pregablin
Glossopharyngeal
Neuralgia
presents as?
uni/bilat?
demo?
Triggered by?
Due to a lesion in?
Branches of carotid artery can trigger?
Severe paroxysmal, lancinating pain that radiates to the throat, ear, teeth and
tongue
Rare, unilateral condition
Affects males > age 50 years
Triggered by movement in the tonsillar region by swallowing or coughing
Due to a lesion in the petrosal and jugular ganglion of CN IX
Branches of carotid artery can trigger a vasovagal response (i.e. BP, cardiac output, altered respiration)
Geniculate Neuralgia
Known as?
defined?
Causes pain where?
Treatment:
Known as nervus intermedius neuralgia, Ramsay Hunt’s syndrome
Painful disturbance of the sensory portion of the Facial nerve - CN VII
Causes lancinating pain in the middle ear and the auditory canal
Treatment: Methyl prednisone (10mg) start with 80mg dose, then taper by 10 mg every 3 days until 20 mg dose. Maintain pt on 20mg for 14 days then taper off.
Eagle’s syndrome
defined?
Symptoms:
Pain may occur with ?
unilat/bilat? symptoms?
Exam:
Radiograph: reveal?
Refer to?
Elongation or ossification of the stylohyoid ligament
Symptoms: sore throat, dysphagia, otalgia, glossodynia, headache or vague pain in the neck
Pain may occur with swallowing, talking, chewing, turning the head to the contralateral side, yawning
Usually unilateral, constant, deep, throbbing or aching
Exam: includes palpation of the stylohyoid area to attempt to reproduce pain & turning head to side
Radiograph: reveals elongated stylohyoid process
Refer to Ear, Nose & Throat (ENT) specialis
