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 an oncological emergency. NICE NG234 advises contacting the MSCC coordinator immediately for suspected MSCC and arranging whole-spine MRI as soon as possible, always within 24 hours when neurological signs or symptoms are present; dexamethasone 16 mg is for people with neurological symptoms or signs of MSCC, not for unexplained UMN foot drop. Early treatment, before severe deficit, gives the best chance of preserving mobility. MND may present with isolated unexplained weakness and cannot be diagnosed from foot drop, fasciculations or a single UMN/LMN pattern alone. Key alert: painless progressive asymmetric limb weakness without sensory symptoms, particularly with fasciculations or mixed UMN and LMN signs = refer to neurology without delay and specify the concern (NICE NG42).

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 is quick to examine and helps separate the two most common causes, but no single muscle test is definitive — interpret it with pain, sensory loss, reflexes and the rest of the examination. 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. Ankle clonus is an important reflex test for UMN pathology — sustained or clearly pathological clonus indicates a corticospinal tract lesion. Foot drop with sustained clonus, extensor plantars, a sensory level or spasticity should prompt urgent assessment for spinal cord or brain disease; urgency of imaging depends on progression, associated cord signs and clinical stability. Never record this as "normal" without actually testing it. A positive Tinel's sign at the fibular head may support local peroneal nerve irritation, but it is neither necessary nor diagnostic — specialist neurophysiology localises the lesion.

The choice between MRI lumbar spine and MRI whole spine is one of the most important imaging decisions in foot drop management. NICE NG59 advises against routine imaging for uncomplicated sciatica in a non-specialist setting; MRI lumbar spine is arranged when L5 radiculopathy is suspected and the result is likely to change management. 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. A ganglion cyst at the fibular head, typically arising from the proximal tibiofibular joint, is a structural cause of CPN palsy that may be surgically treatable. Ultrasound or MRI around the fibular head may be considered by the specialist if a structural lesion is suspected, particularly when there is no convincing compressive history or weakness fails to improve.

The urgency of surgical referral for L4/L5 disc herniation causing foot drop is determined by the power grade and the trajectory, using the local spinal or neurology pathway rather than a generic waiting period — NICE NG59 does not set a universal waiting period for foot drop, and progressive motor deficit may justify earlier spinal surgical assessment. Mild, stable weakness can be managed conservatively initially with close follow-up, but any deterioration mandates prompt referral. The orthosis does not treat the cause but helps prevent secondary harm — falls and fall-related injuries in patients who drag the foot — so assess falls risk early and refer to orthotics when foot clearance is impaired or falls risk is significant. Functional Electrical Stimulation (FES) for UMN foot drop is supported by NICE HTG178 (formerly IPG278, 2009; normal arrangements for clinical governance, consent and audit) and is underused in UK clinical practice — in the evidence reviewed for NICE HTG178, walking speed rose by a mean of 27% in a case series of 111 people after stroke using surface FES, and by 23% (vs 3% with conventional therapy) in a small RCT of implanted FES; a meta-analysis found a mean gain of 0.18 m/s over conventional therapy. 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.

Physiotherapy for radiculopathy should be individualised: exercises (including McKenzie-type extension or nerve glides) are selected after assessment and modified if they worsen radicular pain or neurological deficit — no single programme or fixed schedule is universally effective. Diazepam for acute lumbar muscle spasm is a common habit but NICE NG59 advises not to offer benzodiazepines for low back pain or for sciatica — there is no overall evidence of benefit and there is evidence of harm, and the paraspinal spasm of acute disc herniation settles with time, activity and NSAID analgesia. GPs should explain this to patients who expect a muscle relaxant. Prescribing diazepam, especially as a PRN for recurring back pain episodes, creates iatrogenic benzodiazepine dependence — this is a well-documented prescribing error in back pain management. The same NG59 recommendation covers pregabalin and gabapentin for sciatica: the neuropathic pain guideline (CG173) applies to other neuropathic pain such as a peroneal neuropathy, not to sciatica. NICE NG59 also advises not offering opioids for chronic sciatica.

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, but it is currently the only available neuroprotective treatment in the UK and is started by the specialist team after diagnosis. The decision to start riluzole is made by the neurologist, and GPs continue the prescription — it requires LFT monitoring — ALT monthly for the first 3 months, then every 3 months for the rest of the first year, then periodically (SPC). 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. Respiratory assessment and the timing of non-invasive ventilation (NIV), decided by the MND/respiratory team, is one of the most important interventions, improving survival, 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. Hydrotherapy, where available and selected by a physiotherapist, uses buoyancy to allow active dorsiflexion movements that may be impossible against gravity on land in severe foot drop. 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, in whom foot ulcers substantially increase amputation risk. The instruction to inspect the skin daily, report any redness that does not settle after removing the AFO, or any skin break, to the orthotist or GP immediately (and podiatry in diabetes) 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 via the local spinal/neurology pathway (deteriorating, or MRC ≤3 not improving). 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. A prognosis discussion for persisting CPN palsy is an important component of patient-centred care — recovery depends on whether the lesion is demyelinating or axonal and on the degree and duration of nerve injury, so avoid fixed recovery promises. This conversation should address: realistic functional prognosis, longer-term AFO requirements, driving safety (based on function, not side), and whether specialist review for surgical options is appropriate. The patient continuing to drive when foot drop makes vehicle control unsafe 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.