Chemotherapy-induced neuropathy: This is the most likely diagnosis given the temporal relationship between the induction dose of chemotherapy and the onset of weakness. Many chemotherapy agents used in the treatment of Acute Lymphoblastic Leukemia (ALL) are known to cause neuropathy, with symptoms often appearing after the initiation of treatment.

Vincristine-induced neuropathy: Vincristine is a common chemotherapeutic agent used in ALL treatment protocols and is well-known for causing peripheral neuropathy. The presentation of axonal sensorimotor neuropathy is consistent with vincristine toxicity.
Nutritional deficiencies: Patients undergoing chemotherapy may experience nutritional deficiencies due to poor appetite, nausea, or vomiting, which can lead to neuropathy. Deficiencies in vitamins B12 or B6 can cause neuropathic symptoms.

Paraneoplastic neuropathy: Although less common, paraneoplastic syndromes can occur in patients with cancer, including ALL. These syndromes are caused by the immune response to the tumor and can present with neurological symptoms, including neuropathy. Missing this diagnosis could delay appropriate treatment of the underlying condition.
Infection-related neuropathy: Patients with ALL are immunocompromised and at risk for various infections, some of which can cause neuropathy (e.g., varicella-zoster virus reactivation leading to shingles or CMV infection).

Hereditary neuropathy: While hereditary neuropathies like Charcot-Marie-Tooth disease can present with axonal sensorimotor neuropathy, the acute onset after chemotherapy makes this a less likely explanation in this context. However, it could be considered if there's a family history or if symptoms were present before chemotherapy.
Leukemic infiltration of nerves: Direct infiltration of leukemic cells into the nerves is a rare cause of neuropathy in patients with ALL. This condition would require prompt recognition and treatment to prevent further neurological deterioration.