9. Pain

Question 1

What are the types of pain?

Answer 1

Nociceptive
- pain transmitted by noiceptors
- SOMATIC (soft tissue, bone)
- VISCERAL (less well-localised)

Neuropathic
- pain as a result of damage to the pain system

Noiciplastic
- pain as a result of a modualted pain system eg central sensitisation

Question 2

what is fibromyalgia

Answer 2

Fibromyalgia is a syndrome characterised by widespread pain throughout the body with tender points at specific anatomical sites

The exact pathophysiology is not known. Hypotheses include:
Peripheral and central hyperexcitability at spinal or brainstem level.
Altered pain perception.
Somatisation.

Question 3

epidemiology fibromyalgia

Answer 3

women are around 5 times more likely to be affected
typically presents between 30-50 years old

Question 4

features of fibromyalgia

Answer 4

chronic pain: at multiple site, sometimes ‘pain all over’
lethargy
cognitive impairment: ‘fibro fog’
sleep disturbance, headaches, dizziness are common

Symptoms are generally reported as worse in cold, humid weather and under times of stress

Question 5

diagnosis of fibromyalgia

Answer 5

clinical

may refer to American college pf rheumatology classification criteria which lists 9 pairs of tender points on the body. If a patient is tender in at least 11 of these 18 points it makes a diagnosis of fibromyalgia more likely

Question 6

management fibromyalgia

Answer 6

aerobic exercise: has the strongest evidence base

NICE advises that gabapentinoids, including pregabalin, should not be offered to people with chronic primary pain

However SIGN recommends that clinicians should consider pregabalin for people with fibromyalgia, but states that this is outwith the marketing authorization

Question 7

neuropathic pain guidance

Answer 7

first-line treatment*: amitriptyline, duloxetine, gabapentin or pregabalin

if the first-line drug treatment does not work try one of the other 3 drugs
in contrast to standard analgesics, drugs for neuropathic pain are typically used as monotherapy, i.e. if not working then drugs should be switched, not added

tramadol may be used as ‘rescue therapy’ for exacerbations of neuropathic pain

topical capsaicin may be used for localised neuropathic pain (e.g. post-herpetic neuralgia)
pain management clinics may be useful in patients with resistant problems

*please note that for some specific conditions the guidance may vary. For example carbamazepine is used first-line for trigeminal neuralgia

Question 8

causes of neuropathic pain

Answer 8

radiculopathy
Postherpetic neuralgia (post-shingles)
Trigeminal neuralgia
Nerve damage, including postoperative.
Pain because of cancer tumour infiltration.

Peripheral neuropathy:
A – Alcohol
B – B12 deficiency
C – Cancer and Chronic Kidney Disease
D – Diabetes and Drugs (e.g. amiodarone, metronidazole, cisplatin, phenytoin, isoniazid, nitrofurantoin)
E – Every vasculitis

Question 9

pathophysiology of neuropathic pain

Answer 9

Neuropathic pain may be defined as pain which arises following damage or disruption of the nervous system. It is often difficult to treat and responds poorly to standard analgesia.

Neuropathic pain is characterised by continuous or intermittent spontaneous pain, typically described as burning, aching or shooting in nature. The pain may be provoked by normally innocuous stimuli (allodynia). Neuropathic pain is also commonly associated with hyperalgesia (increased pain intensity evoked by normally painful stimuli), paraesthesia and dysaesthesia.

Question 10

causes of peripheral neuropathy

Answer 10

A – Alcohol
B – B12 deficiency
C – Cancer and Chronic Kidney Disease
D – Diabetes and Drugs (e.g. amiodarone, metronidazole, cisplatin, phenytoin, isoniazid, nitrofurantoin)
E – Every vasculitis

Question 11

Presentations different types of diabetic peripheral neuropathy

Answer 11

A-alpha/A-delta (larger sensory fibres)
- distal symmetrical sensory neuropathy
- touch, vibration and proprioception defecits

A-delta/C
- Caused by loss of small sensory fibres.
- Presents with deficits in pain and temperature sensation in a glove and stocking distribution along with episodes of burning pain.

Autonomic nerves (very small)
Autonomic Neuropathy
Presents with postural hypotension, gastroparesis, constipation, urinary retention, arrhythmias and erectile dysfunction.

Mononeuritis multiplex

Diabetic Amyotrophy
Caused by inflammation of lumbosacral plexus or cervical plexus.
Severe pain around the thighs and hips.
Proximal weakness.

Question 12

How does gastroparesis present? diabetes

Answer 12

symptoms include erratic blood glucose control, bloating and vomiting
management options include metoclopramide, domperidone or erythromycin (prokinetic agents)

Question 13

cause, pathophysiology and presentation alcoholic neuropathy

Answer 13

secondary to both direct toxic effects and reduced absorption of B vitamins
sensory symptoms typically present prior to motor symptoms

Alcoholic neuropathy is damage to the nerves that results from excessive drinking of alcohol. The damage may affect the autonomic nerves (those that regulate internal body functions) and the nerves that control movement and sensation.

Question 14

what vitamin deficiency is associated with peripheral neuropathy?

Answer 14

A lack of B12 damages the myelin sheath that surrounds and protect nerves. Without this protection, nerves cease to function properly and conditions such as peripheral neuropathy occur. Even B12 deficiency that is relatively mild may affect the nervous system and the proper functioning of the brain.

Question 15

what neuropathic pain syndorme is treated differently?

Answer 15

trigeminal neuralgia

1. Carbamazepine

Question 16

pathophysiology trigeminal nauralgia?

Answer 16

Most cases are idiopathic but compression of the trigeminal roots by tumours or vascular problems could be the cause.

Question 17

red flags trigeminal neuralgia

Answer 17

looking for non-idiopathic cause ef tumour or vascualr problems

Red flags:
Sensory changes
Deafness or other ear problems
History of skin or oral lesions that could spread perineurally
Pain only in the ophthalmic division of the trigeminal nerve (eye socket, forehead, and nose), or bilaterally
Optic neuritis
A family history of multiple sclerosis
Age of onset before 40 years

Question 18

when should you refer someone with tirgeminal neuralgia? to who?

Answer 18

Failure to respond or atypical features should prompt referral to neurology

Question 19

Presentation trigeminal neuralgia

Answer 19

Severe unilateral pain, often triggered by touching the skin, brief electric shock like pains, abrupt in onset and termination
Triggers
Light touch, washing, shaving, mocking, talking, brushing teeth. Particularly of nasolabial fold.

Question 20

what is shingles?

Answer 20

Shingles (herpes zoster infection) is an acute, unilateral, painful blistering rash caused by reactivation of the varicella-zoster virus (VZV). Following primary infection with VZV (chickenpox), the virus lies dormant in the dorsal root or cranial nerve ganglia.

Question 21

features shingles

Answer 21

Features
prodromal period
burning pain over the affected dermatome for 2-3 days
pain may be severe and interfere with sleep
around 20% of patients will experience fever, headache, lethargy
rash
initially erythematous, macular rash over the affected dermatome
quickly becomes vesicular
characteristically is well demarcated by the dermatome and does not cross the midline. However, some ‘bleeding’ into adjacent areas may be seen

Question 22

most commonly affected dermatomes shingles

Answer 22

The most commonly affected dermatomes are T1-L2.

Question 23

management shingles

Answer 23

1. remind patients they are potentially infectious
   may need to avoid pregnant women and the immunosuppressed
   should be advised that they are infectious until the vesicles have crusted over, usually 5-7 days following onset
   covering lesions reduces the risk

+ anaglgesia
paracetamol and NSAIDs are first-line
if not responding then use of neuropathic agents (e.g. amitriptyline) can be considered
oral corticosteroids may be considered in the first 2 weeks in immunocompetent adults with localized shingles if the pain is severe and not responding to the above treatments

+ antivirals
within 72 hours for the majority of patients, unless the patient is < 50 years and has a ‘mild’ truncal rash associated with mild pain and no underlying risk factors
one of the benefits of prescribing antivirals is a reduced incidence of post-herpetic neuralgia, particularly in older people
aciclovir, famciclovir, or valaciclovir are recommended

Question 24

complication shingles?

Answer 24

post-herpetic neuralgia
the most common complication
more common in older patients
affects between 5%-30% of patients depending on age
most commonly resolves with 6 months but may last longer

Question 25

what is somatisation

Answer 25

multiple physical SYMPTOMS present for at least 2 years
patient refuses to accept reassurance or negative test results

Question 26

what is illness anxiety disorder/hypochondriasis

Answer 26

persistent belief in the presence of an underlying serious DISEASE, e.g. cancer
patient again refuses to accept reassurance or negative test results

Question 27

what is conversion disorder?

Answer 27

typically involves loss of motor or sensory function
the patient doesn’t consciously feign the symptoms (factitious disorder) or seek material gain (malingering)
patients may be indifferent to their apparent disorder - la belle indifference - although this has not been backed up by some studies

Question 28

what is facticious disorder

Answer 28

also known as Munchausen’s syndrome
the intentional production of physical or psychological symptoms

Question 29

what is malingering

Answer 29

fraudulent simulation or exaggeration of symptoms with the intention of financial or other gain

Question 30

layers of meninges

Answer 30

Skin
–
Skull
(epidural space)
Dura
(subdural space)
Arachnoid
(subarachnoid space - CSF)
Pia
Brain/spinal cord

DAP

Question 31

where does a spinal/lumbar puncture go in relation to meningeal layers?

Answer 31

Subarachnoid space

Skin
–
Skull
(epidural space)
Dura
(subdural space)
Arachnoid
(subarachnoid space - CSF)
Pia
Brain/spinal cord

Question 32

side effects of spinal block

Answer 32

hypotension, sensory and motor block, nausea and urinary retention.

Question 33

benefits of epidural

Answer 33

Patient awake during procedure

Avoidance of SE associated with GA (n&v, resp depression, aspiration)

Reduces bleeding in surgical field (due to hypotension and lower HR)

Question 34

risks of an epidural?

Answer 34

High failure rate
Haematoma
May go into spinal region (subarachnoid space) and cause motor weakness in the legs
Hypotension
Nerve damage
Infection eg meningitis
Severe headache “dural tap” if dura is punctured
Morphine = nausea and itching particularly in young females

Question 35

contraindications of an epidural?

Answer 35

Patient refusal
Coagulation defects
Local infection
Raised ICP
Allergy

Question 36

what drugsa re given in an peidural?

Answer 36

Epidural medications fall into a class of drugs called local anaesthetics (examples include: bupivacaine, chloroprocaine, and lidocaine) and can be delivered in combination with narcotics (examples include: fentanyl and sufentanil) in order to decrease the required dose of local anaesthetic

Question 37

what anaesthetic technique, incombinateion with other things, may be usefyl for extensive laparoscopic abdominal procedures?

Answer 37

Transversus Abdominal Plane block (TAP)

In this technique, an ultrasound is used to identify the correct muscle plane and local anaesthetic (usually bupivicaine) is injected. The agent diffuses in the plane and blocks many of the spinal nerves.

It is an attractive technique as it provides a wide field of blockade but does not require the placement of any indwelling devices.

There is no post-operative motor impairment. For this reason, it is the preferred technique when extensive laparoscopic abdominal procedures are performed. They will then provide analgesia immediately following surgery but as they do not confine the patient to bed, the focus on enhanced recovery can begin sooner.

Question 38

What is a PCA?

Answer 38

Patient Controlled Analgesia (PCA)
Patients administer their own intravenous analgesia and titrate the dose to their own end-point of pain relief using a small microprocessor - controlled pump. Morphine is the most popular drug used.

Question 39

management pain in refractory shingles

Answer 39

prednisolone