Neuropathic pain and Atypical Odontalgia

Question 1

What are the different pain assessments used when investigating facial pain?

Answer 1

Physical symptoms
-> PAIN scores (McGill)

Emotional symptoms
-> Psychological scores (HAD)

QOL scores (OHIP)

Question 2

What pain assessments can be used to investigate severity of pain in children?

Answer 2

Face modified pain scales

Linear analogue scales- mark on line what level of pain you experience (10cm long)

Lego pain assessment tool

Question 3

What occurs in nociceptive pain?

Answer 3

Acute pain
- Stimulus (inflammation) causes pain to pass into CNS and be perceived

Question 4

What occurs in neuropathic pain?

Answer 4

Pain perception generated beyond nociceptor
- Pain stimulus is generated beyond nociceptor
- Damage has occurred to pathway sending pain signal to brain (dysfunction)
- Patient feels pain- but connect wrong tissue even although this has nothing wrong with it (mimics pain in other regions)

Question 5

What causes stroke pain?

Answer 5

Damage has occurred to nerve pathways in brain resulting in pain signals passing through pain nerves from damaged section leading to it being perceived as somatic pain when it is in fact damage within CNS

Question 6

What occurs in diabetic neuropathy?

Answer 6

Nerve damage due to change in vascular supply to peripheral nerve
- Patient feels pain from tissue supplied by damaged nerve even although tissue is healthy (neuropathic pain)

Question 7

What occurs in Post Herpetic Neuralgia

Answer 7

Herpetic lesions damage nerves in which it is living
- Symptoms from vesiculation in peripheral tissues is experienced due to virus
- After lesions resolve the pain continues
- Aim to limit damage at time patient presents- consequences in subsequent months can be reduced

Question 8

What are the features of neuropathic pain?

Answer 8

• Constant burning/aching- nerve damage present all the time
• Fixed intensity- damage to nerve remains the same
• Fixed location- nerve damage equates to particular tissue

Question 9

What are the genetic abnormalities that can lead to neuropathic pain?

Answer 9

Predisposed susceptibility to nerve damage

Inheritance of different types of ion channel within nerve structure

Question 10

What are the common types of neuropathic pain?

Answer 10

Diabetic peripheral neuropathy

PHN

Cancer-related pain

Spinal cord injury

Chronic regional pain syndrome

MS

Phantom limb pain

Stroke pain

HIV-associated pain

TN

Question 11

What are the causes of neuropathic pain?

Answer 11

Follows history of injury:
Facial trauma

Extractions

‘routine’ treatment without complications

Herpes Zoster (Shingles) episode
-> POST HERPETIC NEURALGIA

Can follow destructive treatment for pain

Question 12

What causes neuropathic pain to be present even when injury has healed?

Answer 12

• Nerve has been damaged and heals in a way that causes constant input of signal into CNS
• If relatively minor event that has caused initial damage- problem is likely to get worse as it would cause more damage to tissue and nerves

Question 13

What is destructive treatment in neuropathic pain, what are the drawbacks?

Answer 13

Damage nerve supplying area of pain causing numbness (no sensory input so shouldn’t get pain)

If this nerve is not fully damaged it can regenerate and heal leading to original neuralgic pain returning and neuropathic pain from damage to nerve

Question 14

What systemic medications are used to treat neuropathic pain?

Answer 14

Use gabapentin/pregabalin/TCAs- reduce pain transmission within CNS (reduce effect of signal being passed to central appreciation by slowing pain signalling in brain)

Valproate

Mirtazepine

Opioid analgesics

Question 15

What is topical treatment of neuropathic pain based off?

Answer 15

Gate hypothesis- use of peripheral stimulation
-> medication causes sensory nerve activation over area of pain which helps gate off pain signals coming from neuropathic damage

Question 16

What topical medicines are used in treatment of neuropathic pain?

Answer 16

 Capsaicin (depolarisation of peripheral nerve)
 EMLA
 Topical lignocaine- irritates surface nerves and helps gate off pain perception
 Ketamine
 Benzdamine

Question 17

What physical treatments can be helpful for neuropathic pain?

Answer 17

TENS (low frequency)- electrical stimulation of area causing the pain
-> Gates pain off by electrical modification by sensory nerves

Acupuncture- allows opioids to reduce transmission within CNS
-> Only helps for short duration

Question 18

Why is psychological treatment helpful for neuropathic pain? What can be done?

Answer 18

As pain is designed to catch attention of individual (especially if it passes through basal ganglia)
-> Training patient to distract themselves can be helpful- less intrusive if they don’t pay attention to it (behaviour change)
-> correction of abnormal illness behaviour
-> improve outlook/self esteem

Psychologists are part of pain MDT
-> May be more beneficial than pharmacological treatment

Question 19

What is Atypical Odontalgia?

Answer 19

Dental pain without dental pathology
- Patient will report information that sounds like dental pathology (acute pulpitis) but on examination you find health (can be hard if patient has heavily restored dentition)
- Follows no particular characteristics/trends

Question 20

How does atypical odontalgia differ from pulpal pain?

Answer 20

Intense unbearable pain lasts 2-3 weeks then settles spontaneously (pain free period between episodes)
-> different from pulpal pain which continues until treated (*unless pulp necroses)

Question 21

What can happen when a patient presents with dental pain which the dentist does not realise is being caused by Atypical Odontalgia?

Answer 21

Dental treatment (RCT)is carried out as the patient has described pain of an acute pulpitis then pain returns after short time
- Can lead to dentist thinking they have missed a canal or not fully removed the pulp and retreating the tooth to help settle the pain
- This may lead to extraction as patient feels pain to be unbearable
- The patient can then come back in a few weeks with pain in adjacent tooth leading to belief from patient that they took out wrong tooth (dentist may believe this)
- Same pattern occurs- many teeth may be extracted as a result of atypical odontalgia (contact oral medicine if you start to suspect it)
- As toothache settles it can feel like intervention was successful

Question 22

What checks/tests can dentists do to help diagnose Atypical Odontalgia?

Answer 22

Check for hyperocclusion- fix if present

Check radiographs for signs pf pathology

Sensibility test to see if tooth vital

Attempt Endodontics and see if pain persists

Anaesthetic tests

Question 23

What should a dentist do in primary care if they suspect AO?

Answer 23

Refer to oral medicine

Question 24

How is AO managed in OM?

Answer 24

• Reduce number of episodes
• Reduce chronic pain severity- gabapentin
• Opioids analgesics are effective for pain- high doses when needed for short burst of neuropathic pain which lasts 2 weeks
• Patient may want tooth still to be extracted as they feel like they cannot bear to continue with tooth (done by OM team)

Question 25

What is Persistent Idiopathic Facial Pain?

Answer 25

Pain which poorly fits into standard chronic pain syndromes:
Neuropathic
CRPS
TMD
Trigeminal Neuralgia
Migrainous Pain
Atypical odontalgia

Diagnosis if cause of pain is not known

Often high disability level – autonomic component

Question 26

What is unusual about where pain is felt in PIFP?

Answer 26

Felt in areas of common Embryological origin of tissue- if neuropathic/autonomic problem all the tissues of the same origin may feel pain

Question 27

How is PIFP managed?

Answer 27

Clinical psychology
-> Patients may become depressed due to pain (not depression causing pain- treating mental health will not help)

Surgery is not helpful

Monitor quality of life and disease impact
-> use of pain scores

Suggest that you are trying to improve life rather than pain (reducing pain even slightly can help them cope)
-> Be realistic with patient, let them know what would be considered a success