The given history suggests a small fibre painful peripheral sensory neuropathy, the most common cause of which is diabetes. Joint position sense and vibratory sensation are carried through large fibres, and therefore are not currently affected. Sensory nerves are affected more often than motor, so reflexes usually remain in tact.

Vitamin B12 deficiency causes impairment of joint position and vibratory sensation.

Chronic inflammatory demyelinating polyneuropathy (CIPD) causes a large fibre peripheral neuropathy with areflexia.

In syringomyelia there is impaired pain and temperature noted in the upper limbs.

Finally, with alcoholic polyneuropathy, all fibre types are affected (sensory and motor loss). It is usually gradual with long term alcohol abuse and may be accompanied by a nutritional deficiency. In addition, pain is a more dominant feature.

Peroneal nerve injury is also known as foot drop. The common peroneal nerve supplies the ankle and toe extensor muscle groups as well as sensation over the dorsum of the foot; thus, there is also loss of sensation in these cases.

Ethylene glycol poisoning is the only poison listed that will cause dilation of the pupils whereas all the other listed conditions and poisons will present with small pupils other than in the case of Myotonic dystrophy wherein the patient will present with a cortical cataract.

Uhthoff’s phenomenon is worsening of vision following a rise in body temperature.
Lhermitte’s sign describes paraesthesia in the limbs on neck flexion.
Oppenheim’s sign is seen when scratching of the inner side of leg leads to extension of the toes. It is a sign of cerebral irritation and is not related to multiple sclerosis.
Werdnig-Hoffman’s disease is also known as spinal muscular atrophy.

West Nile virus (WNV) is a single-stranded RNA flavivirus transmitted via the culex mosquito. This previously ‘tropical’ disease has became topical in recent years following a large scale outbreak in the New York area. Incidence of neurological involvement is around 1%, although some suggest that the incidence of meningoencephalitis in America is higher than in other parts of the world. Risk factors for neurological involvement include increasing age, and immunosuppression. The usual picture is of sudden onset fever and myalgia with nausea and vomiting and a non-specific rash. Transient meningitis is occasionally seen. Frank meningoencephalitis is seen in two-thirds of cases with neurological involvement; 15% progress to coma. A flaccid paralysis similar to acute Guillain–Barré is increasingly recognised.
Diagnosis is initially clinical with subsequent serological confirmation. Treatment is supportive; results from trials of antivirals have yielded disappointing results.

In myasthenia gravis, repeated muscle contractions lead to reduced muscle strength. The opposite is however classically seen in the related disorder Lambert-Eaton syndrome. Lambert-Eaton myasthenic syndrome is seen in association with small cell lung cancer, and to a lesser extent breast and ovarian cancer. It may also occur independently as an autoimmune disorder. Lambert-Eaton myasthenic syndrome is caused by an antibody directed against pre-synaptic voltage gated calcium channel in the peripheral nervous system.

Motor neuron disease is a neurological condition of unknown cause which can present with both upper and lower motor neuron signs. It rarely presents before age 40 and various patterns of disease are recognised, including amyotrophic lateral sclerosis, progressive muscular atrophy and bulbar palsy.
Non-invasive ventilation (usually BIPAP) is used at night, with studies having shown a survival benefit of around 7 months. Riluzole prevents stimulation of glutamate receptors, used mainly in amyotrophic lateral sclerosis and has been shown to prolong life by about 3 months.

The most likely diagnosis is idiopathic Parkinson’s disease because of the unilateral presentation. In addition, cogwheel rigidity is a classic presenting symptom. Neuroleptic-induced parkinsonism is usually bilateral and symmetrical. Essential tremors do not cause rest tremors.

Glioblastoma multiforme, also considered as grade IV astrocytoma, is the most malignant form of the tumour and accounts for about 20% of all cerebral tumours. These often remain clinically silent until they have reached a large enough size. In adults, glioblastoma multiforme usually occurs in the cerebral hemispheres, especially the frontal and temporal lobes of the brain. About half occupy more than one hemisphere at presentation, and some are multicentric. Biopsy shows high cellularity with mitoses, pleomorphism, and vascular hyperplasia. Prognosis is extremely poor, with only 20% surviving beyond 1 year and 10% beyond 2 years.

The patient’s history and presentation and familial history, meets the diagnostic criteria for Neurofibromatosis type I, presenting with neurofibromas noted in this patient as hyperpigmented macules and freckles, musculoskeletal disorders like the scoliosis in this case, and a familial history. Neurofibromatosis type I is caused by a mutation on Chromosome 17.