Myotonic Dystrophy (DM1) - Clinical Images for DDx

Image 1 - DDx Comparison: FSH Dystrophy (A) vs. Myotonic Dystrophy (B)

• Panel A (left): Patient with facioscapulohumeral (FSH) dystrophy - unable to purse the lips when attempting to whistle; note the preserved temporalis bulk
• Panel B (right): Patient with myotonic dystrophy type 1 - note the classic triad:
  • Frontal balding
  • Temporalis + masseter wasting (hollowed temples)
  • Ptosis + facial weakness (long, expressionless face)

Images 2 & 3 - DM1 Type 1 (58-year-old man) - Pathognomonic Features

• Panel A: Frontal balding, bilateral ptosis, temporal muscle atrophy - "hatchet face" appearance
• Panel B: Forced eye closure - note the inability to bury the eyelashes (orbicularis oculi weakness), a sign of orbicularis weakness distinct from facioscapulohumeral dystrophy where orbicularis is equally or more severely affected

DDx Key Distinguishing Features at a Glance

DDx of Vomiting - 36-Year-Old Asian Immigrant Female

STEP 1: RULE OUT FIRST (Critical & Common)

STEP 2: GASTROENTEROLOGICAL (Most Common Overall)

Acute vomiting WITHOUT significant abdominal pain

• Infectious gastroenteritis - most common single cause globally; viral (Norovirus, Rotavirus) >> bacterial
• Food poisoning (Staph aureus, Bacillus cereus, Salmonella) - immigrant status increases exposure to unfamiliar food preparation
• Hepatitis A/B/E - higher prevalence in Asia; hepatitis E especially in recent immigrants
• Medications / drug toxicity - OCPs, NSAIDs, antibiotics, herbal remedies (common in Asian cultures)
• Migraine headache - peak incidence in women aged 25-55

Acute vomiting WITH abdominal pain

• Peptic ulcer disease (PUD) / H. pylori - H. pylori seroprevalence in East/Southeast Asia is 50-80% vs ~35% in Western countries; strongly associated with nausea, epigastric pain, vomiting
• Acute cholecystitis / biliary colic - "Fat, fertile, forty, female" - Asian women are NOT exempt; common in Chinese, Japanese, Korean women
• Pancreatitis - gallstone-related predominates in Asian women
• Appendicitis - still in the age range

Chronic/Recurrent vomiting (>1 month)

• Gastroparesis - idiopathic or post-viral
• GERD / esophagitis - regurgitation may be misreported as vomiting
• Cyclic vomiting syndrome - episodic, stereotyped; associated with migraine
• Small bowel or gastric outlet obstruction - undigested food hours after eating = gastric obstruction

STEP 3: IMMIGRANT/ASIAN-SPECIFIC ELEVATED PRIORITIES

STEP 4: SYSTEMIC / NON-GI CAUSES

STEP 5: DIAGNOSTIC APPROACH FRAMEWORK

VOMITING IN THIS PATIENT
        │
        ├─ Pregnancy test (urine hCG) ──► FIRST, ALWAYS
        │
        ├─ +Abdominal pain? ──► CBC, CMP, lipase, LFTs, RUQ US, CT abdomen
        │
        ├─ Acute (<1 week)? ──► Consider infectious, medication, pregnancy
        │
        ├─ Chronic (>1 month)? ──► EGD (H. pylori + biopsy), motility studies, CT
        │
        ├─ Alarm features (weight loss, dysphagia, hematemesis)?
        │   ──► Urgent EGD (exclude gastric cancer, ulcer)
        │
        └─ Immigrant-specific workup:
            - H. pylori stool antigen / breath test
            - Stool O&P (parasites)
            - Hepatitis serologies (A, B, E)
            - TB screening (IGRA/Mantoux)
            - LFTs (herbal toxicity)

Mnemonic: "VINDICATE P" applied here

1. H. pylori gastritis/PUD (by far most probable given Asian origin)
2. Infectious gastroenteritis (viral/bacterial)
3. Biliary colic / cholecystitis
4. Medication/herbal toxicity
5. Functional nausea/vomiting with psychosocial overlay (immigration stress)

What Multiple Sexual Partners Adds to the Vomiting DDx

1. PREGNANCY - Risk Now Substantially Higher

• Intrauterine pregnancy / Morning sickness - #1 still; now even more likely
• Ectopic pregnancy - CRITICAL addition. Prior STIs (even silent ones like Chlamydia) cause subclinical salpingitis → tubal scarring → ectopic implantation. The patient may have no pelvic pain yet if the ectopic is early and unruptured. Nausea/vomiting + amenorrhea + positive hCG + adnexal tenderness on exam = ectopic until proven otherwise. This is a surgical emergency if ruptured.

Risk factors for ectopic: prior PID, multiple partners, prior STI, smoking - this patient may have several of these silently.

2. ACUTE HIV / ACUTE RETROVIRAL SYNDROME (ARS) - Must Not Miss

"The most common symptoms seen in the acute retroviral syndrome are fever, lymphadenopathy, pharyngitis, and myalgias/arthralgias - all seen in >75% of cases. Other common symptoms include non-pruritic maculopapular rash (upper body), nausea, vomiting, and diarrhea. Up to 50% of patients experience severe headaches and may have signs of meningitis or encephalitis."

• Occurs 2-4 weeks after HIV exposure
• Standard HIV ELISA/Western blot may be negative during this window - need HIV RNA PCR (viral load) or p24 antigen (4th-generation HIV combo test)
• Mimics infectious mononucleosis ("the great imitator")
• No vaginal symptoms expected - this is a systemic viremia
• High viral load = high transmissibility = public health urgency

• EBV infectious mononucleosis (monospot, EBV PCR)
• CMV mononucleosis
• Toxoplasmosis
• Secondary syphilis
• Viral hepatitis (A, B, C)
• Drug reaction (DRESS)

3. VIRAL HEPATITIS - Sexually Transmitted Forms

4. SECONDARY SYPHILIS - The "Great Imitator"

• Secondary syphilis is classically systemic: rash (palms/soles), fever, malaise, nausea, lymphadenopathy, mucous patches
• No genital symptoms required - primary chancre may have healed silently weeks earlier
• Syphilitic hepatitis can occur in secondary syphilis - causing nausea, vomiting, elevated LFTs, RUQ discomfort
• Check RPR/VDRL + TPHA/FTA-ABS

5. DISSEMINATED GONOCOCCAL INFECTION (DGI) - Silent Locally, Systemic

• Disseminated N. gonorrhoeae can occur even without urogenital symptoms or discharge in ~25% of women (the primary infection in the endocervix is often asymptomatic)
• Systemic features: fever, nausea, polyarthralgia/tenosynovitis, petechial/pustular rash
• Can cause gonococcal perihepatitis (Fitz-Hugh-Curtis syndrome) - RUQ pain + nausea + vomiting without significant lower abdominal pain
• Also seen with Chlamydia causing Fitz-Hugh-Curtis

6. FITZ-HUGH-CURTIS SYNDROME (Perihepatitis)

• Caused by Chlamydia trachomatis or N. gonorrhoeae ascending to the liver capsule
• Presents as RUQ pain + nausea/vomiting mimicking cholecystitis or hepatitis
• May have no discharge, no cervicitis, no lower abdominal pain at presentation
• "Violin-string" adhesions between liver capsule and peritoneum (visible on laparoscopy)
• Liver enzymes may be mildly elevated
• Diagnose with cervical/vaginal NAAT (nucleic acid amplification test) for Chlamydia/GC

7. MEDICATION EFFECTS FROM CONTRACEPTION / POST-EXPOSURE TREATMENT

• Emergency contraception (Plan B / levonorgestrel) - nausea and vomiting are the #1 side effects (incidence 23-50%)
• Oral contraceptive pills - nausea common, especially in first weeks
• HIV PrEP (tenofovir/emtricitabine) - nausea is a known early side effect
• HIV PEP (post-exposure prophylaxis) - if the patient recently had a risk event and started PEP, nausea/vomiting is extremely common with PEP regimens

8. PSYCHOSOCIAL / BEHAVIOURAL OVERLAY

• Shame, stigma, fear of STI diagnosis in culturally conservative Asian contexts can manifest somatically as nausea/vomiting
• Eating disorders (higher prevalence in young women with high-risk sexual behaviour contexts)
• Substance use (alcohol, recreational drugs) in some sexual risk contexts

Updated Priority DDx Given Full Context

Immediate Investigations to Add to Previous List

Previous workup + ADD:

MANDATORY:
□ urine/serum β-hCG → if positive: transvaginal ultrasound to exclude ectopic
□ 4th-gen HIV combo test (Ag/Ab) → if negative but high suspicion: HIV RNA PCR
□ HBsAg, HBcAb IgM, HCV Ab, HAV IgM
□ RPR (syphilis screen) + TPHA
□ Cervical/vaginal NAAT for Chlamydia + GC (even without symptoms)
□ LFTs (hepatitis, Fitz-Hugh-Curtis, syphilitic hepatitis)

CONSIDER:
□ Emergency contraception history (timing of last sexual encounter?)
□ RUQ ultrasound (if LFTs elevated or RUQ tenderness → Fitz-Hugh-Curtis vs cholecystitis)
□ Monospot + EBV/CMV serology (ARS mimics mono)

Headache + Vomiting, No Fever, No Visual Changes, No Pelvic Symptoms, Normal Periods

THE CLINICAL LOGIC

• Projectile (without preceding nausea in classic ICP)
• Morning-predominant (worsens lying flat overnight, ICP peaks in early morning)
• Worse with Valsalva (coughing, straining, bending forward)

PRIORITY DDx: HEADACHE + VOMITING

1. IDIOPATHIC INTRACRANIAL HYPERTENSION (IIH) / Pseudotumor Cerebri - TOP DIAGNOSIS

"Primary idiopathic intracranial hypertension occurs in obese women of childbearing age. Incidence is 19-20 per 100,000 in obese women aged 15-55."

"The most prominent symptoms include headache (84%), transient visual obscurations (68%), pulsatile tinnitus (52%). Only 32% of patients report visual loss."

• Young woman (36 years) ✓
• Asian women are also susceptible, especially with weight gain ✓
• Headache + vomiting ✓
• No visual changes - still consistent (visual obscurations and papilledema can be absent early)
• A variant without papilledema exists - diagnosed by MRI neuroimaging criteria (empty sella, posterior globe flattening, perioptic subarachnoid space distension, transverse sinus stenosis)

2. MIGRAINE - Most Common Primary Headache + Vomiting

"In primary care, <10% of patients presenting with headache >3 months without neurologic symptoms have tension-type headache; >90% have migraine."

• Headache + nausea/vomiting (cardinal symptom pair)
• No visual changes required - only migraine with aura has visual prodrome
• Photophobia, phonophobia, worse with movement
• Young woman: peak migraine incidence is 25-55 years in females
• Hormonal trigger: menstrual migraine (around menstrual cycle even with normal periods)
• Indian/Asian women have similar migraine prevalence to the general population

• ≥5 attacks lasting 4-72h
• Unilateral, pulsating, moderate-severe, worsened by routine activity
• Nausea/vomiting OR photophobia + phonophobia

3. CEREBRAL VENOUS SINUS THROMBOSIS (CVST) - Must Not Miss

• Headache is the presenting feature in >90% of CVST
• Vomiting from raised ICP
• No fever, no focal deficit required early in the course
• OCP use is the #1 risk factor in young women - and this patient is likely using contraception
• Indian women have additional risk: antiphospholipid syndrome, inherited thrombophilias (Factor V Leiden less common in Asians but protein C/S deficiency more common)
• Thunderclap or progressive subacute headache worsening over days-weeks

Red flag per Tintinalli's: "Wakens from sleep, early morning headache, progressive frequency/severity" → Elevated ICP, CVST must be excluded

4. INTRACRANIAL MASS LESION (Brain Tumor / Abscess)

• Any space-occupying lesion raises ICP → headache + vomiting
• Morning headache worsened by Valsalva is the classic pattern
• No focal neuro deficits required early
• In Indian immigrants: CNS tuberculoma is a genuine concern (TB is endemic in South Asia; CNS TB presents as ring-enhancing lesion, chronic headache, vomiting)
• Primary brain tumors (glioma, meningioma), metastases
• Brain abscess (consider given MSP - risk of bacterial endocarditis if IV drug use; or dental/ENT source)

5. SUBARACHNOID HEMORRHAGE (SAH) - Thunderclap Variant

• Classic: sudden "worst headache of life" (thunderclap)
• BUT: sentinel headaches can precede full SAH by days-weeks, presenting as recurrent moderate headaches + vomiting
• No focal deficit, no meningism required in early/small bleeds
• No fever
• Must be excluded in any new headache + vomiting pattern in a young adult
• CT head is the first-line test; if negative and suspicion remains → LP (xanthochromia)

6. CARBON MONOXIDE POISONING

"DDx includes alcoholic intoxication, cerebrovascular accident, influenza, meningitis, migraine, myocardial infarction, food poisoning."

• Cooking with gas stoves in poorly ventilated homes
• Headache + vomiting without fever is the classic presentation
• Multiple household members affected simultaneously is the clue
• Ask: does the headache improve when leaving the house/environment?

7. TENSION-TYPE HEADACHE + FUNCTIONAL VOMITING

• Least alarming
• Bilateral, band-like, not worsened by activity, no vomiting typically
• However: immigration-related chronic psychosocial stress → tension headache + functional nausea/vomiting
• Diagnosis of exclusion - never assign without ruling out structural causes first

8. MEDICATION / SUBSTANCE EFFECT

• OCP - headache is a recognized side effect; combined OCP can trigger migraines (estrogen withdrawal during pill-free week)
• Emergency contraception - headache + vomiting after levonorgestrel
• NSAID overuse headache (rebound/analgesic overuse headache)
• Herbal remedies common in Indian communities

RED FLAG FEATURES TO ACTIVELY SEEK

Prioritized DDx for This Specific Patient

Immediate Investigation Priority

STEP 1 - URGENT (exclude emergencies):
□ Non-contrast CT head → exclude SAH, mass, herniation
□ If CT negative + SAH still suspected → LP (xanthochromia)
□ MR venography if CVST suspected (young woman on OCP)

STEP 2 - TARGETED:
□ MRI brain with gadolinium → better for mass, tuberculoma, abscess, IIH signs
□ Fundoscopy (papilledema? → IIH; normal → doesn't exclude)
□ LP with opening pressure (if imaging safe) → IIH (>250 mmH₂O), meningitis

STEP 3 - SYSTEMIC:
□ CO-oximetry / carboxyhaemoglobin (if CO poisoning suspected)
□ OCP/medication history
□ Formal visual fields (IIH - visual acuity preserved until late)
□ urine hCG (periods can be present in early pregnancy)

IIH as the Most Likely Diagnosis: MRCP PACES History & Examination Guide

THE MODEL PATIENT PRESENTATION

A 34-year-old obese Indian woman presents with a 3-month history of daily generalised headache and vomiting. She has been using minocycline for acne.

PART 1: HISTORY (Hx)

SOCRATES - The Headache

PACES tip: The examiner loves "wakes from sleep" + "worse on bending/coughing" + "retro-orbital pain" - this trio strongly points to raised ICP rather than migraine or tension headache.

Asking About the "IIH Symptom Cluster"

1. Visual symptoms:
   • "Do you get brief episodes of blurred or greyed-out vision, especially when you stand up quickly or bend forward?" → Transient visual obscurations (TVOs) - almost pathognomonic for IIH
   • "Do you see double?" → Diplopia (CN VI palsy - false localising sign)
   • "Any permanent change in vision?" - Loss is late and the patient may not volunteer this
   • Note: TVOs occur in 68% but the patient may not have reported them unless asked directly - always ask
2. Pulsatile tinnitus:
   • "Do you hear a whooshing or pulsing sound in one or both ears?" - present in ~52%; synchronous with heartbeat; often louder on one side
3. Neck/back pain:
   • Referred pain from raised CSF pressure; reported in >50%
4. Cognitive/mood symptoms:
   • Brain fog, concentration difficulties in chronic IIH

Systematic Enquiry - Risk Factors to Actively Seek

Negative History (Equally Important in PACES)

• No fever → excludes meningitis, encephalitis, abscess
• No thunderclap onset → against SAH
• No focal neurological symptoms → against mass lesion, stroke
• No neck stiffness → against meningitis/SAH
• No preceding viral illness → against post-infectious causes
• No immunosuppression / HIV → against opportunistic CNS infection
• No known malignancy → against metastases
• Normal periods → pregnancy less likely (but test anyway)

PART 2: PHYSICAL EXAMINATION (PE)

General Inspection (First 10 Seconds)

"This is an obese young woman who appears well and alert with no focal neurological deficit at rest."

• BMI >30 is present in ~90% of IIH cases
• Patient looks well - not acutely unwell, no signs of systemic sepsis
• No rash (excludes meningococcaemia, secondary syphilis)

Vitals

• BP - may be normal or mildly raised (raised ICP → hypertension; Cushing response is a late/severe sign)
• Heart rate - normal (bradycardia + hypertension = Cushing triad = late, severe)
• Temperature - normal (fever → infectious/inflammatory cause)

Cranial Nerve Examination - The Key Findings

PACES pearl: When you examine the eyes, say clearly: "I would like to examine the fundus." Then describe: "On fundoscopy, I can see bilateral disc swelling with blurring of the disc margins and loss of the physiological cup, consistent with papilledema. Visual acuity is preserved."

Rest of Neurological Examination

The examiner wants to hear: "The rest of the neurological examination is entirely normal, with no focal deficits, no meningism, and no signs of herniation." This is the key phrase - IIH = raised ICP + NORMAL neuro exam (except for the optic nerve and possibly CN VI).

Systemic Examination Additions

• BP in both arms (coarctation can rarely cause IIH-like picture)
• Skin: Look for acne (→ on minocycline/isotretinoin?), moon face/striae (steroid use?)
• Neck: No lymphadenopathy (excludes infiltrative/malignant causes)
• Thyroid: Check for hypothyroidism (rare IIH trigger)
• BMI / waist circumference: Document obesity formally

PART 3: THE PACES DIAGNOSTIC SUMMARY

"My most likely diagnosis is idiopathic intracranial hypertension. This is supported by the history of progressive generalised headache worse on waking and on Valsalva, associated vomiting, transient visual obscurations, and pulsatile tinnitus, in an obese young woman who is taking [minocycline / OCP / isotretinoin]. On examination, the most important positive finding is bilateral papilledema on fundoscopy with an enlarged blind spot on confrontation visual fields, and a right-sided lateral rectus palsy as a false localising sign. Crucially, the remainder of the neurological examination is normal with no focal deficits and no meningism."

PART 4: MODIFIED DANDY CRITERIA (What the Examiner May Ask)

Without papilledema variant - diagnosed if CN VI palsy present, OR if ≥3 MRI criteria (empty sella, posterior globe flattening, perioptic subarachnoid space distension, transverse sinus stenosis).

PART 5: INVESTIGATIONS TO PRESENT

PART 6: MANAGEMENT (For Examiner Questions)

Monitoring: Serial formal visual fields + fundoscopy. Visual acuity alone is insufficient - field loss precedes acuity loss.

PACES EXAMINER'S CHECKLIST - IIH CASE

HISTORY TICK-BOXES:
✓ Progressive headache - worse on waking, Valsalva, lying flat
✓ Retro-orbital component
✓ Transient visual obscurations (ask directly)
✓ Pulsatile tinnitus (ask directly)
✓ Nausea and vomiting
✓ Neck/back pain
✓ Obesity / recent weight gain
✓ Drug history - tetracyclines, OCP, vitamin A, isotretinoin
✓ No fever, no focal deficit, no thunderclap, no meningism

EXAMINATION TICK-BOXES:
✓ Obese young woman, well-looking
✓ Afebrile, BP may be mildly elevated
✓ Bilateral papilledema on fundoscopy
✓ Enlarged blind spot on confrontation
✓ CN VI palsy (unilateral or bilateral) - false localising
✓ Visual acuity PRESERVED
✓ No focal motor/sensory/cerebellar deficit
✓ No meningeal signs
✓ Normal consciousness

DIAGNOSTIC SUMMARY:
✓ IIH (Pseudotumor cerebri)
✓ Secondary cause excluded (drug-induced vs. primary)
✓ MRI + MRV + LP for confirmation
✓ Visual fields as baseline
✓ Management: remove trigger, weight loss, acetazolamide

MRCP PACES SHORT CASE - Bilateral Symmetrical Lower Limb Weakness

STEP 1: CANDIDATE CASE PRESENTATION

"On examination of this middle-aged gentleman, the findings are as follows:

General inspection: The patient is comfortable at rest. I note [describe anything relevant - wasting, foot deformity, skin changes - if present].

Lower limbs - Motor system: Inspection reveals no obvious muscle wasting [or: distal muscle wasting bilaterally], no fasciculations at rest. Tone is reduced bilaterally - the legs are hypotonic and floppy. Power is reduced to 3/5 bilaterally, with a distal predominance - distal muscles are weaker than proximal muscles. Reflexes are diminished to absent bilaterally - the ankle jerks are absent, knee jerks are diminished. Coordination testing cannot be formally assessed due to the degree of weakness.

Lower limbs - Sensory system: There is reduced sensation in a stocking distribution, affecting all modalities [or specify: light touch and pinprick], extending to approximately [level - e.g. mid-shin]. There is no sensory level and no dermatomal pattern. Vibration sense is reduced at the toes [and at the ankles].

Negative findings: There is no spinal tenderness, no midline scar, no upper limb involvement [or: upper limbs are currently unexamined]. The upper motor neurone signs are absent - no spasticity, no hyperreflexia, no extensor plantars.

Summary and interpretation: The combination of bilateral symmetrical distal weakness, hypotonia, absent/diminished reflexes, and sensory loss in a stocking distribution - without a spinal level or UMN signs - is consistent with a peripheral polyneuropathy of predominantly distal, length-dependent pattern.

My most likely diagnosis is a sensorimotor peripheral polyneuropathy. The commonest cause in a middle-aged man in the UK would be diabetic polyneuropathy or alcohol-related neuropathy, though the full differential is broad.

I would like to complete my examination by examining the upper limbs, cranial nerves, and looking for relevant systemic clues such as signs of diabetes, chronic liver disease, or lymphadenopathy."*

STEP 2: ANATOMICAL LOCALISATION - Why Peripheral Nerve / Polyneuropathy?

STEP 3: THE COMPLETE DDx

METABOLIC

TOXIC

INFLAMMATORY / IMMUNE

HEREDITARY

Pes Cavus with Hammertoes - Charcot-Marie-Tooth (Hereditary Neuropathy)

STEP 4: MOST LIKELY DIAGNOSIS (By Probability)

STEP 5: COMPLETING THE EXAMINATION IN PACES

"To complete my examination, I would like to: 1. Examine the upper limbs for distal weakness and sensory loss (glove distribution) - suggesting more severe or generalised polyneuropathy 2. Check for pes cavus and hammertoes - hereditary neuropathy 3. Palpate peripheral nerves for thickening - CMT, leprosy, amyloid 4. Look for systemic signs: spider naevi/Dupuytren's (alcohol), acanthosis/ulcers (diabetes), lymphadenopathy (malignancy/sarcoid), cushingoid features (steroid-induced myopathy DDx) 5. Check the spine for midline tenderness and do a rectal exam if cauda equina suspected 6. Gait assessment - high-stepping gait (foot drop) in peroneal/axonal neuropathy 7. Fundoscopy - diabetic retinopathy"

STEP 6: INVESTIGATIONS TO MENTION

EXAMINER'S FAVOURITE QUESTIONS - Prepared Answers

"Distal symmetrical sensorimotor polyneuropathy - length-dependent, affecting the longest fibres first, causing stocking-and-glove sensory loss and distal > proximal weakness."

"The peripheral nerve forms the afferent and efferent limbs of the reflex arc. In polyneuropathy, damage to peripheral nerve fibres disrupts both limbs, leading to diminished or absent reflexes."

"Both cause weakness and sensory loss. Demyelinating neuropathies (GBS, CIDP, CMT-1) tend to cause more prominent reflex loss early and slowed nerve conduction velocities. Axonal neuropathies (diabetic, alcoholic) cause more prominent distal muscle wasting and reduced nerve action potential amplitudes on NCS. CIDP and GBS are important to identify as they are treatable with immunotherapy."

"Nerve conduction studies - they confirm the diagnosis of polyneuropathy, determine whether it is axonal or demyelinating, and quantify severity."

Physical Examination Findings That Point Specifically to CIDP

THE SINGLE MOST IMPORTANT DISCRIMINATING FINDING

Proximal AND Distal Weakness - The Hallmark of CIDP

"Symmetric proximal and distal weakness is the hallmark of acquired immune demyelinating polyneuropathies, both the acute form (GBS) and the chronic form (CIDP). The importance of finding symmetric proximal AND distal weakness in a patient who presents with motor and sensory symptoms cannot be overstated."

"The occurrence of symmetric weakness in both proximal and distal muscles that progressively increases for more than 2 months is the pivotal symptom in the diagnosis of CIDP."

THE FULL SET OF CIDP-POINTING EXAMINATION FINDINGS

1. Proximal + Distal Weakness (Both Upper and Lower Limbs)

Examination action: Test hip flexion (L1/2), knee extension (L3/4), shoulder abduction (C5), grip strength (C8/T1). CIDP will give you weakness at multiple levels including proximal. Diabetic neuropathy alone does not cause significant proximal weakness.

2. Upper Limb Involvement Relatively Early

3. Areflexia More Severe and Widespread Than Expected

• All four limb reflexes may be absent (arms + legs)
• Knee jerks often absent even when weakness appears mild
• Reflex loss is disproportionately severe relative to the degree of wasting

PACES tip: If you find absent knee AND ankle jerks AND absent biceps/triceps jerks in a patient with moderate (not severe) weakness, and no obvious metabolic cause staring at you (no Dupuytren's, no acanthosis) - think CIDP.

4. Large-Fibre Sensory Loss Predominates

Contrast this with diabetic small-fibre neuropathy where pain/temperature loss (burning feet, neuropathic pain, reduced pinprick) often predominates early and vibration may be relatively preserved initially.

5. Sensory Ataxia (Romberg Positive)

• Romberg's sign is positive - the patient stands steadily with eyes open but sways/falls with eyes closed
• Gait is ataxic - broad-based, stamping gait (patient cannot sense where their feet are)
• Coordination testing (heel-shin) may be impaired due to proprioceptive loss, not cerebellar disease - the key distinction is that limb ataxia disappears when visual feedback is allowed

PACES action: Perform Romberg's test and observe the gait. A positive Romberg in the context of a polyneuropathy strongly supports large-fibre demyelination = CIDP.

6. Palpably Thickened Peripheral Nerves

• Great auricular nerve - runs over the sternocleidomastoid, visible and palpable as a cord in severe cases
• Ulnar nerve - at the elbow (behind the medial epicondyle)
• Common peroneal nerve - at the fibular head
• Radial nerve - in the spiral groove
• Sural nerve - at the lateral ankle

PACES tip: Run your fingers behind the medial epicondyle bilaterally and compare. A visibly prominent great auricular nerve over the SCM is dramatic and almost always noted by the examiner. This finding is present in CIDP, CMT-1, leprosy, and amyloid - but in a PACES context without tropical disease exposure, CIDP or CMT-1 is the answer.

7. No Systemic Signs of Metabolic Cause

8. Upper Limb Signs on Completing Examination

• Reduced grip strength bilaterally (distal hand weakness)
• Absent biceps/triceps/supinator reflexes
• Sensory loss in glove distribution (not just stocking)
• Positive Romberg when tested from standing

SUMMARY TABLE: PACES DISCRIMINATING FEATURES

THE MODEL PACES CANDIDATE STATEMENT FOR CIDP

"My examination findings reveal a bilateral sensorimotor polyneuropathy. Importantly, the weakness affects both proximal and distal muscle groups symmetrically in all four limbs, which is the hallmark of an acquired immune demyelinating polyneuropathy. Reflexes are absent throughout, including upper limbs, which is disproportionate to the degree of muscle wasting. Sensory loss preferentially affects large fibre modalities - vibration and joint position sense are severely impaired with a positive Romberg's sign, indicating sensory ataxia. I also note palpably thickened ulnar nerves at the elbows bilaterally. There are no stigmata of diabetes, alcohol-related liver disease, or hereditary foot deformity.

These findings together most strongly suggest Chronic Inflammatory Demyelinating Polyneuropathy - CIDP. This is an important diagnosis to establish because it is potentially treatable with IVIg, plasma exchange, or corticosteroids. I would confirm with nerve conduction studies showing demyelinating pattern, and CSF showing elevated protein with normal cell count."

Hyperkinetic Movement Disorders - MRCP PACES Short Case Guide

STEP 1: THE MASTER CLASSIFICATION TABLE

STEP 2: HOW TO DESCRIBE MOVEMENTS TO THE EXAMINER

1. Distribution - which body parts? (face, hands, limbs, trunk, generalised)
2. Symmetry - bilateral or unilateral?
3. Relation to posture/action - present at rest, with posture, or only with movement?
4. Rhythm - regular/rhythmic vs. random/arrhythmic?
5. Speed - rapid, slow, sustained?
6. Pattern - stereotyped and repetitive vs. random and flowing?
7. Suppressibility - can the patient suppress it voluntarily?

DISORDER 1: TREMOR

Definition

Classification by Activation Condition

PACES-Relevant Tremor Causes

A. Essential Tremor (ET) - Most Common Movement Disorder

• Affects ~1% of population, 5% over age 60
• 6-10 Hz high-frequency postural/action tremor
• Bilateral, predominantly upper limbs (hands)
• Head tremor in 30%, voice in 20%
• Improved by alcohol (pathognomonic clue - ask in history)
• Worsened by stress and caffeine
• Handwriting shows large, tremulous script (contrast with PD's micrographia)
• Family history in ~50% (autosomal dominant)
• Neurological exam otherwise normal (no bradykinesia, no rigidity)
• Treatment: propranolol, primidone

• Tremor present on arms outstretched - disappears at rest
• Tremor on finger-nose test (kinetic component) - no past-pointing
• Head nod (titubation)
• Normal tone, normal gait (or mild tandem gait difficulty)
• No cogwheel rigidity, no bradykinesia

B. Parkinson's Disease Tremor

• 4-6 Hz low-frequency resting tremor
• "Pill-rolling" - thumb rolling over fingers
• Disappears with voluntary movement (opposite to ET)
• Unilateral onset, later becomes bilateral
• Associated with bradykinesia, cogwheel rigidity, micrographia, shuffling gait, hypomimia
• (This is technically a hypokinetic disorder with a resting tremor - included here for differential)

C. Cerebellar Tremor

• Intention tremor - absent at rest, minimal with posture, maximal as approaching target
• Associated cerebellar signs: ataxia, nystagmus, dysarthria (scanning speech), dysdiadochokinesia, past-pointing, hypotonia
• Causes: MS, alcohol, paraneoplastic, cerebellar stroke

D. Enhanced Physiologic Tremor

• High-frequency (10-12 Hz), fine postural tremor
• Causes: hyperthyroidism, anxiety, alcohol withdrawal, caffeine, drugs (valproate, lithium, beta-agonists, steroids)
• Look for: thyroid signs, signs of alcohol dependence, drug history

DISORDER 2: CHOREA

Definition

PACES Examination Signs

• Milkmaid's grip - when asked to squeeze your fingers, alternating contractions cause grip to vary rhythmically (cannot sustain a constant squeeze)
• Pronator sign - patient cannot keep arms supinated when outstretched; hand pronates involuntarily
• Tongue impersistence - cannot keep tongue protruded steadily; it darts in and out
• Choreic gait - irregular, irregular steps, dancing quality
• The face, hands, and limbs all show random, flowing, non-repetitive movements

DDx of Chorea - PACES Causes

Huntington's Disease MRI (for PACES viva context)

DISORDER 3: BALLISM / HEMIBALLISMUS

Definition

PACES Points

• Almost always unilateral (hemiballismus) → lesion of the contralateral subthalamic nucleus
• Most common cause: contralateral subthalamic nucleus infarct (lacunar stroke in hypertensive patient)
• Examine for: hypertension signs, contralateral signs of stroke
• Look for: Hemi-distribution (one side only), preserved consciousness, normal cognition
• Often self-limiting (resolves in weeks); treatment with tetrabenazine if disabling

DISORDER 4: DYSTONIA

Definition

Classification

PACES-Relevant Dystonia Scenarios

DISORDER 5: MYOCLONUS

Definition

PACES Key Points

• Action myoclonus - jerks appear when patient moves (e.g., reaching for a cup)
• Stimulus-sensitive myoclonus - jerks triggered by touch, sound, or light
• Cortical myoclonus - focal, often stimulus-sensitive; associated with epilepsy
• Subcortical/spinal myoclonus - more generalised

PACES-Relevant Causes

PACES tip: Asterixis (liver flap) is technically a negative myoclonus - brief lapses in sustained posture. Always look for it when you see flapping-type movements. Ask the patient to hold arms outstretched with wrists dorsiflexed. Causes: hepatic encephalopathy, uraemia, CO2 retention, drug toxicity.

DISORDER 6: TICS

Definition

PACES Points

• Patient can suppress but builds up an overwhelming urge to perform the movement
• After suppression: burst of tics when released
• Simple motor tics: eye blinking, facial grimacing, shoulder shrugging, head jerking
• Complex motor tics: jumping, touching, gesturing
• Vocal tics: throat clearing, sniffing, barking, coprolalia (in minority)

Tourette Syndrome

• Multiple motor tics + at least one vocal tic, onset <18 years, lasting >1 year
• Associated: OCD, ADHD, echolalia, coprolalia
• Worsens with stress, improves with sleep and concentration
• Examination: tics visible; otherwise neurologically normal
• Treatment: clonidine, risperidone, haloperidol, habit-reversal therapy

DISORDER 7: TARDIVE DYSKINESIA - HIGH YIELD PACES CASE

1. Lip smacking / lip pursing
2. Tongue protrusion / rolling
3. Chewing movements (buccal-masticatory syndrome)

• Long-term antipsychotic use (haloperidol, chlorpromazine, older drugs)
• Also metoclopramide (>12 weeks - FDA black box warning)
• Prochlorperazine
• Also affects trunk, limbs, and respiratory muscles in severe cases

THE PACES CANDIDATE'S APPROACH - SUMMARY FLOW

PATIENT WITH INVOLUNTARY MOVEMENTS
              │
    DESCRIBE THE MOVEMENT FIRST
    ─────────────────────────────
    Rhythmic? → TREMOR
    Random/flowing? → CHOREA
    Violent/flinging/proximal? → BALLISM (hemiballismus)
    Sustained/twisting/posturing? → DYSTONIA
    Lightning-fast jerks? → MYOCLONUS
    Stereotyped/suppressible? → TICS
    Orofacial/stereotyped on antipsychotics? → TARDIVE DYSKINESIA
              │
    THEN EXAMINE FOR CLUES TO THE CAUSE
    (See table below)

MASTER TABLE: WHAT TO LOOK FOR ON EXAMINATION

PACES PRESENTATION TEMPLATE

"On inspection of this patient, I observed [describe movement type and distribution]. The movements are [rhythmic/random/sustained/brief], affecting [body parts], present at [rest/posture/action], and [are/are not] suppressible.

This is most consistent with [tremor/chorea/dystonia/myoclonus/tics].

On examination, I additionally found [relevant positive and negative findings].

The most likely underlying diagnosis is [specific cause], because [key distinguishing features].

I would like to complete my examination by [checking tone, saccadic eye movements, fundoscopy, KF rings, cardiac auscultation, cognitive assessment] and would confirm with [genetic testing/slit-lamp/TFTs/copper studies/drug history]."

• Left leg only - UMN pattern (spasticity, hyperreflexia, reduced power) = corticospinal tract lesion
• Sensory dissociation - vibration/proprioception LOST, soft touch/pain PRESERVED = dorsal column lost, spinothalamic intact
• This combination = Brown-Séquard syndrome pattern or a hemicord/unilateral cord lesion
• Right leg completely normal

MRCP PACES - Spastic Left Leg Monoparesis with Dorsal Column Loss

STEP 1: ANATOMICAL ANALYSIS - THE CRITICAL FIRST STEP

The Findings Mapped Anatomically

The Anatomical Conclusion

• Left corticospinal tract (UMN signs left leg)
• Left dorsal column (vibration + proprioception lost left leg)
• Left spinothalamic tract is spared (pain/touch preserved)

"Brown-Séquard syndrome: ipsilateral pyramidal deficit, loss of ipsilateral tactile discrimination, position sense, and vibratory sensation, and loss of pain and temperature sensation on the contralateral aspect - one to two dermatomes below the level of injury."

PACES key insight: In a pure Brown-Séquard, you would expect right leg pain/temperature loss (contralateral spinothalamic). In this case pain/touch is preserved bilaterally - this is a partial/incomplete Brown-Séquard or an anterior-to-posterolateral cord lesion preferentially sparing the spinothalamic. This is actually the more common presentation in clinical practice.

STEP 2: WHERE IS THE LESION IN THE NEURAXIS?

1. A cord lesion (thoracic or cervical - affecting lower limb representation)
2. A parasagittal cortical/subcortical lesion (the leg area of motor homunculus lies in the parasagittal cortex - medial surface - and can give isolated leg weakness)
3. An internal capsule lesion (though this would usually involve arm + leg + face)

• Dorsal columns are ipsilateral all the way to the medulla
• Combined UMN + dorsal column loss ipsilaterally = spinal cord (most likely) or medullary lesion

STEP 3: WHAT COMPLETING THE EXAMINATION WOULD REVEAL - AND WHY IT MATTERS

STEP 4: COMPLETE DDx - PACES RELEVANT

GROUP A: SPINAL CORD LESIONS (Most Likely Given Brown-Séquard Pattern)

1. Multiple Sclerosis (MS) - TOP DIAGNOSIS in PACES

• Relative afferent pupillary defect (RAPD) - previous optic neuritis
• Internuclear ophthalmoplegia (INO) - failure of adduction on lateral gaze (brainstem plaque)
• Lhermitte's sign - electric shock down spine on neck flexion (cervical cord plaque)
• Cerebellar signs (intention tremor, nystagmus, ataxia) - "DANISH" mnemonic: Dysarthria, Ataxia, Nystagmus, Intention tremor, Scanning speech, Hypotonia
• Upper limb signs if cervical cord plaque
• Uhthoff's phenomenon (worsening in heat) - ask in history
• No systemic signs of other disease - otherwise well-appearing patient

2. Spinal Cord Compression - Extradural

• Commonest cause of spinal cord compression in adults >50
• Gradual onset, often with neck pain radiating to arm
• Examination: neck stiffness, restricted neck movements, wasting of intrinsic hand muscles (C8/T1), Lhermitte's sign
• May have lower motor neurone signs at the level of compression (wasted hand) + UMN below

• Very high PACES yield - metastatic deposits in vertebrae compressing cord
• Look for: cachexia, lymphadenopathy, clubbing (bronchial), breast mass, midline vertebral tenderness on percussion, point tenderness
• Breast, lung, prostate, renal, thyroid are the common primaries ("BLT + KT" - "Bad Luck Tumours Killing Tissue")
• Thoracic cord most commonly compressed (longest segment, poorest vascular supply)
• Acute onset if pathological fracture; gradual if slow growth

• Fever + back pain + neurological deficit = emergency
• Examination: fever, tenderness over spine, may have source of infection (IV drug use track marks, skin infection, dental procedure)
• Staphylococcus aureus most common organism

3. Intradural Extramedullary Tumours

• Middle-aged to older women (female predominance)
• Thoracic cord most common site
• Slow progressive cord compression
• Examination: no systemic signs (benign), gradual UMN + sensory level
• Look for: neurofibromatosis stigmata (NF2 - multiple meningiomas + bilateral acoustic neuromas + café-au-lait spots)

• Can compress cord asymmetrically → Brown-Séquard
• NF1: café-au-lait spots ≥6, axillary freckling, neurofibromas, Lisch nodules (iris hamartomas)
• NF2: bilateral acoustic neuromas, spinal and cranial meningiomas

4. Intramedullary Cord Lesions

• Cavity within the cord, usually cervical
• Central cord syndrome classically: dissociated sensory loss (pain/temp lost, dorsal columns preserved early) - different from this case
• But when syrinx expands laterally → Brown-Séquard-like
• Examination: cape/vest distribution of pain/temperature loss over shoulders, wasted hands (lower motor neurone at level), UMN legs, Horner's syndrome (ciliospinal centre)
• Associated: Chiari malformation (cerebellar tonsillar descent), scoliosis, pes cavus, kyphoscoliosis

• Anterior spinal artery syndrome: bilateral UMN + bilateral pain/temperature loss, dorsal columns SPARED (this case has dorsal column loss, so ASA syndrome less likely - but partial presentations occur)
• Causes: aortic aneurysm repair, aortic dissection, atherosclerosis, emboli
• Sudden onset (seconds to minutes) - key history point

5. Inflammatory/Infectious Cord Lesions

• Acute/subacute inflammatory demyelination of cord
• Bilateral more common but can be asymmetric
• Causes: post-viral, MS, NMO (neuromyelitis optica), sarcoidosis, SLE
• NMO: associated with aquaporin-4 antibodies; predilection for optic nerves + long spinal cord segments; young women; Asian patients

• Important in immigrant/at-risk patients
• Tropical spastic paraparesis (HTLV-1): bilateral spastic legs, dorsal column loss, bladder involvement
• Examination: signs of HIV (if applicable)

• Dorsal column destruction by Treponema pallidum
• Loss of vibration + proprioception + Romberg positive
• Argyll Robertson pupils (small, irregular, accommodate but don't react to light - pathognomonic)
• UMN signs in legs
• History: past STI, risk behaviour (very relevant to our running patient case!)

GROUP B: BRAIN LESIONS (If Upper Limb Normal on Examination)

6. Parasagittal Cortical/Subcortical Lesion

• Parasagittal meningioma - classic PACES case; middle-aged woman; slowly progressive leg weakness; look for signs of raised ICP; bilateral leg weakness if crosses midline
• Superior sagittal sinus thrombosis (CVST) - young woman on OCP; headache + leg weakness; parasagittal cortical venous infarcts
• Falx meningioma - compresses medial motor cortex
• Parasagittal metastasis
• Cortical vein thrombosis with infarction

7. Anterior Cerebral Artery (ACA) Territory Infarct

• ACA supplies medial frontal and parietal cortex (leg area)
• Contralateral leg monoplegia + sensory loss
• Behavioural changes (frontal lobe involvement) - abulia, incontinence
• Usually bilateral if both ACAs affected (ACA territory infarct is rare but classic)
• Look for: atrial fibrillation, carotid bruit, risk factors for stroke

STEP 5: COMPLETE DDx TABLE FOR PACES

STEP 6: PACES CANDIDATE PRESENTATION

"On examination of this gentleman's lower limbs, I found a left-sided spastic monoparesis. Specifically, the left leg demonstrates increased tone - spasticity, with power reduced to [X]/5, and the left knee jerk is brisk/hyperreflexic with an extensor plantar response, consistent with an upper motor neurone lesion. The right leg is entirely normal.

On sensory testing, there is loss of vibration and joint position sense in the left leg, indicating a left dorsal column deficit. Soft touch and pain sensation are preserved bilaterally, indicating the spinothalamic tracts are intact.

This combination - ipsilateral UMN signs and ipsilateral dorsal column loss, with preserved pain and temperature - is the classic pattern of a Brown-Séquard syndrome or partial hemisection of the spinal cord, most likely at the thoracic or cervical level.

I have not yet examined the upper limbs, cranial nerves, or cerebellum - I would like to do so to further localise the lesion. If the upper limbs are normal, this points to a thoracic cord lesion. If there are upper limb UMN or sensory signs, a cervical cord lesion is more likely. If cranial nerve signs are present, a brainstem lesion is possible.

My leading differential diagnoses are: 1. Multiple sclerosis - most likely in a young adult with this pattern 2. Spinal cord compression - from a disc, meningioma, or metastatic deposit 3. A parasagittal brain lesion - if upper limbs are normal

I would like to complete my examination and then confirm with MRI of the brain and whole spine with gadolinium."

STEP 7: THE EXAMINER'S LIKELY FOLLOW-UP QUESTIONS

"In a classic Brown-Séquard, the spinothalamic fibres crossing contralaterally are also injured, giving contralateral pain and temperature loss below the lesion. Here, pain and touch are preserved bilaterally, suggesting the spinothalamic tract is spared. This is a partial or incomplete Brown-Séquard, which is actually the more common presentation clinically."

"This would indicate a cervical cord lesion above the C5 level, with the leg representation more severely affected than the arms. This pattern is seen in cervical spondylotic myelopathy or a left-sided cervical cord MS plaque."

"The lesion is likely below C5 (thoracic cord) - or alternatively a parasagittal cortical lesion selectively affecting the leg area. A thoracic cord lesion would explain normal upper limbs + left leg UMN + left dorsal column loss."

"MRI of the spine (and brain) with gadolinium - to identify the level and nature of the cord lesion. This will distinguish demyelination (MS plaque - T2 bright, gadolinium enhancing in active disease), structural compression (disc, tumour), inflammatory (transverse myelitis), and syrinx."

• Ms. Yasmeen, 34-year-old woman
• Pain in hands for past few months
• Minimal relief with painkillers + physiotherapy
• Vitals: Temp 38.2°C (low-grade fever), BP 130/60, PR 70, RR 18, SpO2 96% (borderline)