Case Report

Progressive Lower Extremity Weakness and Axonal Sensorimotor Polyneuropathy from a Mutation in KIF5A (c.611G>A;p.Arg204Gln)

Table 1

Differential diagnosis of lower extremity weakness and spasticity.

DiseaseUpper motor neuron signs Peripheral neuropathyCognitive dysfunctionCerebellar ataxiaOther

HSP (Hereditary Spastic Paraparesis)Bilateral symmetric lower extremity spasticity, gait disturbance, urinary urgency, sparing of craniobulbar function, and abnormal SSEP’s

MTHR (methylene tetrahydrofolate reductase) deficiencyBehavior changes, seizures, and leukoencephalopathy

Multiple sclerosisWide range: dysarthria, dysphagia, optic neuritis, nystagmus, chronic pain, fatigue, weakness, and bladder/bowel difficulties

Spinocerebellar ataxiaDysarthria, nystagmus, intentional tremor, and hyporeflexia

Cervical or lumbar spondylosisNeck or back pain, leg or arm weakness, abnormal gait, loss of bowel/bladder control, and MRI imaging of the spine will be abnormal

Arginase deficiencySeizures and tremor, usually evident by age 3

Vitamin B-12 deficiencyMacrocytic anemia

Vitamin E deficiencyRetinitis pigmentosa

Copper deficiencyOptic neuropathy, anemia, and neutropenia

LathyrismFrom excessive consumption of the chickling pea; restricted to India, Bangladesh, and Ethiopia; it results in an irreversible, nonprogressive spastic paraparesis

HTLV-1 (human T lymphocytic virus-1)More frequent in IV drug users, weakness, nocturia, arthralgia, gingival bleeding, dry oral mucosa, and erectile dysfunction

Friedreich’s ataxiaUsually no spasticity (although it can develop later); pes cavus, scoliosis, cardiomyopathy, and arrhythmias

Krabbe’s diseaseLoss of vision is also seen.

ALS (amyotrophic lateral sclerosis)ALS is typically more rapidly progressive and not limited to legs as seen in HSP. Symptoms include upper and lower motor neuron signs, weakness, fasciculations, cramps, dysarthria, dysphagia, dyspnea, muscle spasms, sialorrhea, emotional lability, and cognitive difficulties.

PLS (primary lateral sclerosis)Not limited to legs as seen in HSP; weakness, dysarthria, dysphagia, emotional lability, and bladder urgency can be seen.

Metachromatic leukodystrophySeizures, optic atrophy, and tremors can be seen.

Adrenal leukodystrophyVision loss, seizures, adrenal insufficiency, dysphagia, dysarthria, deafness, weakness, vomiting, or aggression can be seen.