Neurological Examination of the Upper Limbs — Clinical Case

DCE Short Case 1 — The Wasted, Fasciculating Hands

Patient brief (provided to trainee)

Patient: Mr David Williams, 64 years old, retired carpenter. ^[1]

Presenting complaint: Progressive weakness and thinning of the hands over 12 months, with difficulty turning keys, opening jars, and buttoning shirts. He has also noticed occasional muscle twitching in the arms. ^[1]

Instruction: "Please examine this patient's upper limbs neurologically. Present your findings and offer a differential diagnosis." ^[1]

Examination findings (trainee elicits):

• Inspection: Wasting of the intrinsic muscles of both hands — dorsal interossei (guttering between the metacarpals), thenar eminence, and hypothenar. Visible fasciculations in the deltoid, biceps, forearm muscles, and first dorsal interossei bilaterally. No tremor. No abnormal posture.
• Tone: Increased in a spastic pattern in both arms, more pronounced in the flexors.
• Power: Shoulder abduction grade 4 (C5, deltoid), elbow flexion grade 4-plus (C5/6, biceps), elbow extension grade 4 (C7, triceps), wrist extension grade 4 (C7), finger flexion grade 4 (C8), finger abduction grade 3 (T1, dorsal interossei), thumb opposition grade 3 (T1, APB).
• Reflexes: Biceps brisk (plus-plus), supinator brisk (plus-plus), triceps brisk (plus-plus), finger jerk present, Hoffman sign positive bilaterally.
• Coordination: Finger-nose test limited by weakness but no intention tremor and no past-pointing in the movements the patient can perform.
• Sensory: Light touch, pinprick, vibration at the distal interphalangeal joints, and joint position sense are all intact bilaterally.
• Cortical sensory: Stereognosis and graphesthesia intact. ^[1]

Candidate's structured presentation (model)

Opening statement: ^[1]

"I examined Mr Williams's upper limbs neurologically. On inspection, there is wasting of the intrinsic muscles of both hands — the dorsal interossei, the thenar eminence, and the hypothenar — with visible fasciculations in the deltoid, biceps, and first dorsal interossei bilaterally. There is no tremor and no abnormal posture. Tone is increased in a spastic pattern. Power is reduced to MRC grade 3 to 4 in a widespread pattern involving the shoulder abductors (C5), the triceps (C7), the finger flexors (C8), the finger abductors (T1), and the thumb opposition (T1). The reflexes are brisk at the biceps, supinator, and triceps, with a positive Hoffman sign bilaterally. Coordination is limited by weakness but shows no intention tremor. Sensation — light touch, pinprick, vibration, and joint position — is entirely intact. ^[1]

My summary is that this patient has a combination of lower motor neuron signs (wasting, fasciculations, weakness) and upper motor neuron signs (increased spastic tone, brisk reflexes, positive Hoffman sign) with intact sensation. This is the clinical signature of motor neuron disease — amyotrophic lateral sclerosis. To complete my examination, I would examine the lower limbs for the mixed UMN and LMN pattern, the cranial nerves for bulbar involvement (tongue wasting and fasciculations, a brisk jaw jerk), and the gait, and I would assess the respiratory function with a forced vital capacity and a sniff nasal inspiratory pressure." ^[1]

Examiner discussion questions

Q1: "How confident are you in the diagnosis of motor neuron disease, and what would you do to confirm it?" ^[1]

"I am highly confident on the clinical picture — the combination of widespread LMN signs (wasting, fasciculations across C5 to T1 myotomes) with UMN signs (spastic tone, brisk reflexes, bilateral Hoffman sign) and entirely intact sensation is the clinical signature of ALS. The El Escorial Revised criteria and the Gold Coast criteria both require this combined pattern with progression and the exclusion of mimics ^[1][2]. To confirm, I would arrange needle electromyography and nerve conduction studies — the EMG shows the denervation (fibrillation potentials, positive sharp waves) and reinnervation (large polyphasic motor units) across at least two spinal regions, and the NCS excludes a demyelinating neuropathy (normal conduction velocities, no conduction block — excluding multifocal motor neuropathy and CIDP). I would arrange an MRI of the brain and cervical spine to exclude a structural mimic. I would send baseline bloods (FBC, U and E, LFT, TSH, B12, CK, protein electrophoresis) and assess the respiratory function. The diagnosis is clinical, supported by the neurophysiology and the exclusion of mimics."

Q2: "What are the key mimics, and how do you exclude each?" ^[1]

"The three key mimics are cervical spondylotic myelopathy, multifocal motor neuropathy with conduction block, and a proximal median or ulnar nerve lesion with a coincidental UMN process. Cervical myelopathy is excluded by the intact sensation (cervical myelopathy produces a sensory level), by the widespread fasciculations across multiple levels (cervical myelopathy confines the LMN signs to the compressed level), and by the MRI of the cervical spine. Multifocal motor neuropathy is excluded by the presence of UMN signs (MMN is a pure LMN disorder — it does not cause increased tone or brisk reflexes), by the nerve conduction studies (MMN shows conduction block, which is absent in ALS), and by the anti-GM1 antibody (positive in up to 50 per cent of MMN but non-specific). A coincidental lesion is excluded by the pattern — the widespread involvement across multiple myotomes and the absence of a sensory deficit point to a single disease process rather than a coincidence." ^[1]

Q3: "How would you discuss the diagnosis and the prognosis with the patient?" ^[1]

"I would discuss the diagnosis with honesty, compassion, and appropriate pace. I would explain that the examination shows a condition called motor neuron disease, in which the nerve cells that control the muscles are progressively affected, causing the weakness and the muscle thinning he has noticed. I would explain that the condition is progressive, that there is currently no cure, but that there are treatments that can slow the progression (riluzole extends survival by approximately 3 months) and manage the symptoms (the secretions, the cramps, the spasticity). I would discuss the multidisciplinary team approach — the neurologist, the respiratory physician, the speech pathologist, the dietitian, the occupational therapist, the physiotherapist, and the palliative care team — and the role of each. I would discuss the respiratory involvement honestly — that respiratory muscle weakness is the commonest cause of death and that non-invasive ventilation extends survival and improves quality of life. I would discuss advance care planning and the goals of care, at the patient's pace and with his family present. I would offer a follow-up appointment and the contact details of the MND association. The single most important principle is that the patient retains autonomy and dignity throughout — the role of the physician is to inform, to support, and to walk alongside the patient, not to dictate." ^[1]

Q4: "What is the role of the Hoffman sign in this patient, and how reliable is it?" ^[1]

"The Hoffman sign in this patient is a supportive UMN sign, consistent with the corticospinal tract involvement of ALS. It is positive bilaterally, which is more significant than a unilateral finding. The evidence from the systematic review by Rhee and colleagues is that the Hoffman sign has variable sensitivity for cervical myelopathy (approximately 20 to 60 per cent across studies) and should not be used in isolation ^[3]. In this patient, I interpret it in the context of the other UMN signs — the increased tone, the brisk reflexes — and the LMN signs, together forming the combined pattern. I do not rely on the Hoffman alone for the diagnosis."

Q5: "What is the single most important lesson from this case?" ^[1]

"The single most important lesson is that the combined UMN and LMN pattern with intact sensation is motor neuron disease until proven otherwise. The registrar who sees the wasted hands and diagnoses a peripheral neuropathy (missing the brisk reflexes and the increased tone), or who sees the brisk reflexes and diagnoses a cervical myelopathy (missing the widespread fasciculations and the intact sensation), has missed the diagnosis. The key teaching point is that the combination of a wasted, fasciculating muscle with a brisk reflex in the same limb — the ALS reflex — is pathognomonic, and it should be actively sought and presented in every short case where the pattern is suspected." ^[1]