The UMN versus LMN distinction in foot drop determines the entire investigation and management pathway. Upper motor neurone foot drop (brain or spinal cord lesion above L4) is characterised by: spastic increased tone, hyperreflexia, extensor plantar response (Babinski sign upgoing), clonus, minimal wasting early on. Lower motor neurone foot drop (nerve root, plexus, or peripheral nerve) is characterised by: flaccid weakness, absent or reduced reflexes, progressive wasting with time, fasciculations (anterior horn cell or nerve root lesion), sensory loss in the relevant territory. The Babinski sign is the most important single finding — a unilateral upgoing plantar response in a patient with foot drop means the lesion is in the corticospinal tract or cortex, regardless of the pattern of weakness. Malignant spinal cord compression (MSCC) is responsible for approximately 4,000 cases per year in the UK and is the most time-critical oncological emergency a GP will encounter. The NICE guidance on MSCC (NICE CG75, 2008) specifies that any patient with cancer who develops back pain (new or changed) must be assessed for MSCC and if suspected, started on dexamethasone 16 mg/day and referred urgently. Delay in MSCC treatment from symptom onset to treatment of more than 24 hours significantly worsens neurological outcome — patients who are ambulatory at the time of treatment have approximately 80% chance of remaining ambulatory; non-ambulatory patients have only 30% chance of regaining ambulation. The 24-hour MSCC hotline at every UK oncology centre means GPs can phone the specialist and have the patient seen the same day. MND diagnosis delay is one of the most distressing diagnostic experiences for patients — the average 12–18 months from first GP presentation to confirmed MND diagnosis in the UK reflects the subtlety of early signs and the rarity of the condition (2 per 100,000 per year). Key diagnostic alert: painless progressive asymmetric limb weakness in a middle-aged adult without sensory symptoms, particularly if combined with fasciculations or a mixture of UMN and LMN signs = refer neurology immediately without waiting for "further evidence."

The anatomical localisation of foot drop is one of the most intellectually satisfying clinical exercises in general practice because the neurological examination findings directly map to the anatomy. The single most useful examination test is tibialis posterior function (foot inversion): preserved inversion + weak eversion + weak dorsiflexion = CPN at fibular head (tibialis posterior is supplied by the tibial nerve, not the CPN). Weak inversion + weak eversion + weak dorsiflexion = L5 nerve root or more proximal lesion (all three movements involve L5 root-innervated muscles). This takes 20 seconds to examine and immediately divides the two most common causes. Diabetic amyotrophy (Bruns-Garland syndrome) deserves emphasis as a cause of foot drop that is frequently misdiagnosed. It presents as acute severe unilateral thigh and hip pain (often worse at night) followed within days to weeks by rapid-onset proximal and sometimes distal leg weakness including foot drop. The pain precedes and is more prominent than the weakness — the opposite of most disc herniations. It is caused by ischaemic injury to the lumbosacral plexus (vasculitis of the vasa nervorum supplying the plexus) in the setting of diabetes. The clinical picture of a diabetic patient with severe unilateral leg pain + weakness + weight loss mimics malignant plexopathy, and both must be excluded. NCS/EMG is essential to characterise the distribution of nerve damage. Recovery over months to years is the norm with strict glycaemic control, but complete recovery is uncommon. Recognising this as a distinct diabetic complication (rather than attributing it to L5 disc herniation) ensures the patient receives the correct investigation and management.

The MRC power grade documentation is a clinical governance and medicolegal standard — a foot drop case with serial documented power grades (e.g., tibialis anterior MRC 2/5 at first visit → 3/5 at 6 weeks → 4/5 at 3 months) tells a coherent story of recovery that guides management decisions. Without baseline documentation, it is impossible to know if a patient is improving (reassuring conservative management) or static/deteriorating (indicating escalation to surgical intervention). Equally important from a medicolegal perspective: a patient who sustains a permanent foot drop and alleges that the GP failed to act promptly will have a much better outcome for the clinician if serial objective power grades were documented at each visit. The ankle clonus assessment is the most important reflex test for identifying UMN pathology that changes management — sustained clonus (3 or more beats of rhythmic ankle dorsiflexion/plantarflexion when the foot is rapidly dorsiflexed and held) is a UMN sign indicating a lesion in the corticospinal tract. It is absent in normal individuals and in LMN lesions. Any patient with foot drop and clonus needs urgent MRI of the whole spine (at minimum cervical and thoracic) to exclude cord compression. This is an examination finding that should never be recorded as "normal" without actually being tested. The Tinel's sign at the fibular head (tapping the nerve as it curves around the lateral fibular neck, approximately 3 cm below and behind the lateral femoral condyle) is highly specific for CPN entrapment at this site — it is analogous to Tinel's sign at the wrist for carpal tunnel syndrome. Positivity (tingling radiating into the dorsum of the foot) confirms the nerve is sensitised at this anatomical point and is the clinical equivalent of the NCS localisation of conduction slowing across the fibular head.

The choice between MRI lumbar spine and MRI whole spine is one of the most important imaging decisions in foot drop management. MRI lumbar spine alone is appropriate when: the foot drop is clearly LMN (flaccid, areflexic, normal plantars), unilateral, associated with back pain and positive SLR, in a patient without systemic features or known cancer. MRI whole spine is required when: there are any UMN signs (the cord lesion may be cervical or thoracic — ordering lumbar MRI alone will be reported as normal and the myelopathy will continue to progress), when the foot drop is bilateral (single L4/L5 disc herniation very rarely causes bilateral foot drop), when the patient has known malignancy (MSCC can be at any spinal level), or when the clinical picture is atypical. A common medicolegal error pattern is: patient presents with foot drop + spasticity + upgoing plantar → GP orders MRI lumbar spine → reported as "mild degenerative changes" → myelopathy continues for months → delayed diagnosis of cervical myelopathy or thoracic MSCC. The lesson: if in doubt, order whole spine or let neurology arrange imaging. The ganglion cyst at the fibular head is the most important structural cause of CPN palsy to identify because it is completely surgically curable — excision of the cyst restores normal CPN function in the majority of patients within weeks to months. Ganglion cysts at the fibular head typically arise from the proximal tibiofibular joint and are found in approximately 10% of cases of CPN palsy referred for surgical assessment. USS identifies them easily and painlessly and should be considered in all cases of CPN palsy before attributing the cause to positional compression, since the management is fundamentally different (surgery vs conservative).

The urgency of surgical referral for L4/L5 disc herniation causing foot drop is determined by the power grade and the trajectory — the evidence for surgical intervention in discogenic foot drop shows that decompression surgery (discectomy) produces significantly better neurological recovery when performed within 4–6 weeks of onset of severe motor deficit (MRC ≤3) compared to later surgery. The window of opportunity for full recovery narrows substantially after 3 months of severe denervation because irreversible changes occur at the motor end-plate (the neuromuscular junction) when prolonged denervation prevents re-innervation. The clinical rule is: foot drop MRC ≤3 from disc herniation should be referred for neurosurgical assessment within 4–6 weeks, not managed conservatively for 3 months and then referred. Mild foot drop (MRC 4/5 — can lift against resistance but weak) can be managed conservatively initially with close follow-up, but any deterioration mandates immediate referral. The urgent AFO referral principle is that the orthosis does not treat the cause but prevents secondary harm — specifically, falls and fall-related injuries (hip fracture, head injury) that are extremely common in patients with foot drop who drag their foot on the ground. Every day without an AFO in a patient with significant foot drop is a day at heightened falls risk. Providing immediate advice about an interim OTC splint (available at any good pharmacist or online medical supplier for approximately £30–50, while NHS orthotics is arranged) is a practical, harm-reducing intervention that takes 30 seconds to advise and can prevent a serious injury. Functional Electrical Stimulation (FES) for UMN foot drop is a NICE-approved intervention (NICE IPG278) that is underused in UK clinical practice — it produces a 35% improvement in walking speed and a significant improvement in quality of life in patients with chronic hemiplegic foot drop following stroke. NHS FES services are available through rehabilitation medicine and neurology departments — GPs should be aware of this option for stroke patients who have persistent foot drop despite physiotherapy.

The McKenzie extension method for lumbar disc herniation is the most evidence-based physiotherapy technique for L4/L5 radiculopathy — it was developed by New Zealand physiotherapist Robin McKenzie in the 1960s and has been validated in multiple RCTs as superior to general exercise for lumbar radiculopathy. The mechanism is "centralisation" — lumbar extension encourages the nucleus pulposus to migrate anteriorly within the disc, reducing posterior herniation into the neuroforamen. The most important indicator of a good response to McKenzie extension is "centralisation of pain" — the leg pain and foot tingling become less severe and more proximal with each exercise session, eventually becoming limited to the back only. Centralisation is associated with 90% of patients recovering without surgery. Patients should be assessed and taught by a McKenzie-trained physiotherapist and advised to perform extensions 10 times, 6–8 times per day (not once a day — frequency is key). Diazepam for acute lumbar muscle spasm is appropriate for a very short course (maximum 7 days) — it reduces the secondary paraspinal muscle spasm component of acute disc herniation, which can be as debilitating as the radicular pain itself. Critically, GPs must advise that diazepam is for the spasm only, time-limited, and not for ongoing back pain management. Prescribing diazepam as a PRN for recurring back pain episodes creates iatrogenic benzodiazepine dependence — this is a well-documented prescribing error in back pain management. The prescription should state: "Diazepam 2 mg nocte × 7 days only — for acute muscle spasm. Do not repeat."

Riluzole for MND is the only licensed pharmacological treatment for ALS in the UK — it works by reducing glutamate-mediated excitotoxicity (a proposed mechanism of motor neurone death in ALS). The clinical benefit is modest (extends median survival by approximately 2–3 months, and slightly prolongs the time to tracheostomy or death), but it is currently the only available neuroprotective treatment and should be started as early as possible after diagnosis. The decision to start riluzole is made by the neurologist, and GPs continue the prescription — it requires 3-monthly LFT monitoring (hepatotoxic in approximately 2% of patients). The multidisciplinary approach to MND is the most evidence-based aspect of its management — studies show that patients managed in specialist MND multidisciplinary clinics (which include all the above specialists) have significantly better quality of life and longer survival compared to those managed by neurology alone. The timing of non-invasive ventilation (NIV) — initiated when FVC drops below 50% of predicted or when orthopnoea develops — is one of the most important interventions, extending survival by a median of 7 months and substantially improving sleep quality and dyspnoea. GPs should be proactive in connecting MND patients with the MND Association regional care network and specialist MND clinic at the time of diagnosis. The botulinum toxin injection to plantarflexors for stroke-related UMN foot drop is a specialist rehabilitation intervention that can significantly improve AFO tolerance — in stroke patients with spastic equinus (plantarflexion spasticity that holds the foot in a fixed dropped and inverted position), the rigidity of the spastic calf muscles makes AFO fitting and gait retraining difficult. Botulinum toxin injection (guided by ultrasound or EMG) to gastrocnemius and/or soleus reduces this spasticity, allowing the AFO to position the foot correctly and enabling more effective physiotherapy-guided gait training.

The contralateral walking stick recommendation is frequently misunderstood — both patients and some clinicians instinctively use a walking stick on the same side as the weakness. However, the biomechanically correct position for a walking stick is the contralateral hand because: when the weak leg is in the stance phase (bearing weight), the contralateral arm is naturally forward (normal reciprocal arm swing). If the stick is in the contralateral hand, it contacts the ground simultaneously with the weak leg, providing lateral support at the moment of maximum weight-bearing on the affected side. This is how elderly people with hip OA are taught to use sticks, and it applies equally to foot drop where the weak ankle cannot resist lateral sway during stance. Using the stick on the same side as the weakness means it contacts the ground when the strong leg bears weight — providing no benefit at the moment it is most needed. The hydrotherapy recommendation for foot drop rehabilitation is evidence-based — the buoyancy of water effectively reduces the weight of the dropped foot, allowing active dorsiflexion movements that are impossible against gravity on land in severe foot drop (MRC 2/5 — movement with gravity eliminated). This allows earlier active rehabilitation and stimulates neural recovery more effectively than passive splinting alone. The skin inspection under the AFO is a patient safety instruction that is critical in patients with peripheral neuropathy (diabetic or otherwise) — sensory loss means that pressure sores developing under the AFO are not felt, and significant ulceration can occur before the patient notices. This is particularly relevant in diabetic patients where foot ulcers lead to a 15× higher amputation risk. The instruction to inspect the skin daily, remove the AFO if any redness persists beyond 30 minutes after removal, and attend podiatry for any skin break must be given explicitly and documented.

The serial MRC grade documentation at each follow-up visit is the single most important quality indicator for foot drop management — it is the metric that drives every key management decision: continue conservative management (improving), escalate investigation (static), refer urgently for surgery (deteriorating or MRC ≤3 at 4–6 weeks). A GP who documents MRC grades at every visit is able to make these decisions objectively. A GP who documents "foot drop — ongoing" without a power grade is unable to demonstrate appropriate clinical decision-making if the case is ever reviewed. The prognosis discussion at 6 months for CPN palsy is an important component of patient-centred care — patients who have not fully recovered dorsiflexion by 6 months are unlikely to achieve full recovery and need realistic expectations about long-term functional limitations, permanent AFO use, and occupational implications. This conversation should address: realistic functional prognosis, permanent AFO requirements, driving restrictions (if right-sided persistent foot drop), and whether surgical decompression (if not already performed) might still improve function (surgical intervention for CPN palsy can benefit patients up to 12–18 months after onset if NCS shows preserved distal motor responses, suggesting viable nerve trunk despite axonal damage). The patient continuing to drive against medical advice in the context of right-sided foot drop is a public safety issue — if a patient is known to the GP to be driving unsafely and refuses to stop or notify DVLA, the GP has a legal right (and in some circumstances an obligation) to notify the DVLA directly without patient consent, having first informed the patient of this intention. The GMC guidance "Confidentiality: patients' fitness to drive and reporting concerns to the DVLA" details this process. Documentation of the conversation, the patient's refusal, and the subsequent DVLA notification is essential.