Motor Neuron Disease — DCE Clinical Case

DCE Long Case — Bulbar-Onset ALS with Respiratory Failure

Patient summary

Mrs R is a 66-year-old retired librarian referred by her general practitioner with a 14-month history of progressive slurred speech and difficulty swallowing, a 6-month history of progressive right-hand weakness and difficulty writing, and a 2-month history of breathlessness when lying flat, morning headaches, and daytime sleepiness. She has lost 10 kilograms in weight over 6 months. She was commenced on riluzole 50 mg twice daily one month ago by her GP. She lives with her husband, who is her main carer. She has no other past medical history and takes no other regular medications. [1]

Key examination findings

• Bulbar: wasted, fasciculating tongue at rest; brisk jaw jerk; spastic, poorly moving palate; mixed spastic-flaccid dysarthria; weak, bovine cough.
• Upper limbs: wasting and fasciculation of the right first dorsal interosseous and thenar muscles with reduced grip power; reflexes brisk in the right arm including the finger jerks; mild spasticity. Left arm normal. Sensation intact.
• Lower limbs: spastic tone, brisk reflexes, sustained clonus at both ankles, extensor plantar responses; power reduced in ankle dorsiflexion. Sensation intact.
• Respiratory: forced vital capacity 52 per cent predicted erect, 35 per cent supine; sniff nasal inspiratory pressure 36 cmH2O; weak cough; using accessory muscles at rest.
• Other: BMI 19. Arterial blood gas (room air): pH 7.37, pCO2 48 mmHg, pO2 86 mmHH, bicarbonate 28 mmol/L. [1]

Investigations performed

• EMG: active denervation (fibrillations, positive sharp waves) and chronic reinnervation (large polyphasic motor units, reduced recruitment) in bulbar, cervical and lumbar regions; normal sensory studies; no conduction block.
• MRI cervical spine: normal — no cord compression or signal change.
• Bloods: normal full blood count, electrolytes, creatine kinase (mildly elevated at 320), vitamin B12 410 pmol/L, thyroid function normal, glucose normal. Anti-GM1 negative. [1]

Candidate's opening statement (SASPOP)

"This is Mrs R, a 66-year-old retired librarian presenting with a 14-month history of progressive dysarthria and dysphagia, 6 months of right-hand weakness, and 2 months of orthopnoea and morning headache, with significant weight loss. Her principal problems are clinically definite bulbar-onset amyotrophic lateral sclerosis with established respiratory muscle weakness, nutritional decline requiring urgent gastrostomy, distressing pseudobulbar symptoms, and the need to begin advance care planning while she retains capacity." [1]

Structured problem list and integrated management

1. Clinically definite ALS (bulbar onset). Combined UMN and LMN signs in bulbar, cervical and lumbar regions meet the revised El Escorial criteria for clinically definite ALS [5][4]. The EMG confirms widespread active denervation with chronic reinnervation and excludes conduction block; the normal MRI excludes cervical myelopathy; the bloods exclude B12 deficiency. Continue riluzole 50 mg twice daily with monitoring of liver function and full blood count — it provides a modest median survival benefit of about 3 months [2].

2. Symptomatic respiratory muscle weakness — urgent NIV. She has orthopnoea and morning headache, a SNIP of 36 cmH2O (below 40), a supine FVC of 35 per cent predicted (below 50), and established hypercapnia. She meets the criteria to be OFFERED non-invasive ventilation immediately — the single intervention with the largest survival benefit (median 7 to 13 months) [1][3]. Initiate bilevel positive airway pressure, titrated to symptoms and nocturnal capnography, with intensive patient and family education on mask management. The hypercapnia is a late sign; do not allow further decompensation.

3. Nutritional decline — urgent PEG/RIG. BMI 19, 10 kg weight loss, dysphagia, and bulbar disease all indicate gastrostomy. Because her FVC has already fallen below the 50 per cent predicted safety threshold, coordinate periprocedural NIV and prefer a radiologically inserted gastrostomy (RIG), which is safer in respiratory compromise [3]. The principle is that PEG timing is determined by respiratory surveillance — ideally before FVC falls below 50 per cent — and her window is closing.

4. Symptom management.

   • Sialorrhoea: hyoscine hydrobromide 1 mg patch every 72 hours, or glycopyrrolate; botulinum toxin into salivary glands if refractory.
   • Pseudobulbar affect: dextromethorphan-quinidine 20 mg/10 mg twice daily after an ECG (QT interval) [6]; or an SSRI as an alternative.
   • Spasticity: baclofen, titrated from 5 mg three times daily.
   • Communication: speech therapy, voice banking, and augmentative and alternative communication set up before speech is lost.
   • Pain, constipation, mood: address proactively.

5. Multidisciplinary care and advance care planning. Refer to the specialist multidisciplinary MND clinic (independently prolongs survival). Begin advance care planning now while capacity is intact: goals and fears, advance directive, substitute decision-maker (her husband), the future role of tracheostomy ventilation, and the transition to palliative care. Screen cognition with the ECAS — ALS-FTD coexists in 15 per cent and predicts poor NIV adherence and shorter survival. Involve palliative care from diagnosis. Provide psychological support for the patient and her husband, and refer to the MND association for equipment and peer support. [1]

Communication and shared decision-making

The respiratory and nutritional decisions are the shared-decision-making fulcrum. I would frame NIV honestly as the intervention most likely to extend her life and improve her sleep and daytime symptoms, while being clear that it does not halt the disease and will become an increasing part of her day. I would frame PEG as a means of maintaining nutrition, hydration and medication safely, timed now because of her respiratory status. I would return to advance care planning at intervals, respecting that her priorities may shift as the disease progresses, and I would document her decisions in an advance directive with her husband as substitute decision-maker. [1]

DCE Short Case — Focused Combined UMN and LMN Sign Examination

Instruction

"Examine this patient's upper and lower limbs neurologically. He has been having difficulty with his hands and walking." [1]

Systematic examination routine (what to look for at each stage)

1. End of the bed / inspection — wasting of the thenar eminence and first dorsal interosseous, forearm and intrinsic foot muscles; observe the tongue at rest in the floor of the mouth for fasciculations; note any asymmetry, posture or equipment (walking aid, wheelchair).
2. Tone — assess upper and lower limb tone; look for the velocity-dependent catch of spasticity in the legs and arms.
3. Power — test each muscle group, MRC 0 to 5, proximal and distal, comparing sides; note the pattern (often asymmetric at onset).
4. Reflexes — biceps, triceps, supinator, finger jerks, knee and ankle reflexes; plantar responses. Document brisk versus absent, and look specifically for the wasted-muscle-with-brisk-reflex paradox.
5. Coordination — rapid alternating movements, finger-nose, heel-shin; note spasticity slows these, not cerebellar ataxia.
6. Sensation — all modalities, confirming sparing (the key ALS discriminator).
7. Bulbar and cranial nerves — tongue bulk and movement, palate, jaw jerk, gag; assess speech.
8. Gait — spastic gait, possible foot drop. [1]

Key signs the patient demonstrates

A wasted, fasciculating tongue with a brisk jaw jerk; wasted, fasciculating hand muscles (first dorsal interosseous, thenar) with brisk finger jerks in a weak grip; spasticity, hyperreflexia, clonus and extensor plantar responses in the legs; preserved sensation throughout; a spastic gait with possible foot drop. [1]

Presentation template

"I have examined Mr P's neurological system. The key findings are of combined upper and lower motor neuron signs in the same body regions, with sensation spared: there is wasting and fasciculation of the tongue and intrinsic hand muscles with a brisk jaw jerk, and spasticity, hyperreflexia and extensor plantar responses in the legs. There are no cerebellar, extrapyramidal or sensory signs. The most likely diagnosis is motor neuron disease (amyotrophic lateral sclerosis). I would confirm the diagnosis with electromyography to demonstrate widespread active denervation and chronic reinnervation, MRI of the cervical spine to exclude cervical myelopathy, and a screen for treatable mimics including vitamin B12, anti-GM1 antibodies and motor nerve conduction studies to exclude multifocal motor neuropathy." [1]

Discussion questions

"What is your differential from these signs, and how do you exclude cervical myelopathy?" "The combined UMN and LMN pattern in the same region, with bulbar involvement and spared sensation, is highly specific for ALS. The principal mimic is cervical myelopathy, which produces LMN signs at the level of the lesion and UMN signs below, but cannot explain bulbar signs or signs above the lesion; MRI cervical spine excludes it. Multifocal motor neuropathy has no UMN signs and shows conduction block; Kennedy disease is slowly progressive, X-linked, with sensory loss and gynaecomastia; B12 deficiency has sensory signs. The preserved sensation argues against a sensory neuropathy and B12 deficiency [4]."

"What would the EMG show?" "Active denervation (fibrillations, positive sharp waves) together with chronic reinnervation (large polyphasic motor units with reduced recruitment) in at least two of the four body regions, with normal sensory studies and no conduction block. Under the Awaji criteria, fasciculation potentials in affected muscles count as equivalent evidence of active denervation [4][5]."

"What is the single most important management decision for his prognosis?" "Surveillance and timely initiation of non-invasive ventilation for respiratory muscle weakness, because respiratory failure is the usual cause of death and NIV is the single intervention with the largest survival benefit (median 7 to 13 months). I would measure sniff nasal inspiratory pressure and forced vital capacity (erect and supine) at diagnosis and every three months, and offer NIV when symptoms coexist with a SNIP below 40 cmH2O or an FVC below 50 per cent predicted [1][3]."